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weight/_dep/abseil-cpp/absl/cleanup/BUILD.bazel

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+# Copyright 2021 The Abseil Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+load(
+    "//absl:copts/configure_copts.bzl",
+    "ABSL_DEFAULT_COPTS",
+    "ABSL_DEFAULT_LINKOPTS",
+    "ABSL_TEST_COPTS",
+)
+
+package(
+    default_visibility = ["//visibility:public"],
+    features = [
+        "header_modules",
+        "layering_check",
+        "parse_headers",
+    ],
+)
+
+licenses(["notice"])
+
+cc_library(
+    name = "cleanup_internal",
+    hdrs = ["internal/cleanup.h"],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        "//absl/base:base_internal",
+        "//absl/base:core_headers",
+        "//absl/utility",
+    ],
+)
+
+cc_library(
+    name = "cleanup",
+    hdrs = [
+        "cleanup.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":cleanup_internal",
+        "//absl/base:config",
+        "//absl/base:core_headers",
+    ],
+)
+
+cc_test(
+    name = "cleanup_test",
+    size = "small",
+    srcs = [
+        "cleanup_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    deps = [
+        ":cleanup",
+        "//absl/base:config",
+        "//absl/utility",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

weight/_dep/abseil-cpp/absl/cleanup/cleanup.h

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+// Copyright 2021 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// -----------------------------------------------------------------------------
+// File: cleanup.h
+// -----------------------------------------------------------------------------
+//
+// `absl::Cleanup` implements the scope guard idiom, invoking the contained
+// callback's `operator()() &&` on scope exit.
+//
+// Example:
+//
+// ```
+//   absl::Status CopyGoodData(const char* source_path, const char* sink_path) {
+//     FILE* source_file = fopen(source_path, "r");
+//     if (source_file == nullptr) {
+//       return absl::NotFoundError("No source file");  // No cleanups execute
+//     }
+//
+//     // C++17 style cleanup using class template argument deduction
+//     absl::Cleanup source_closer = [source_file] { fclose(source_file); };
+//
+//     FILE* sink_file = fopen(sink_path, "w");
+//     if (sink_file == nullptr) {
+//       return absl::NotFoundError("No sink file");  // First cleanup executes
+//     }
+//
+//     // C++11 style cleanup using the factory function
+//     auto sink_closer = absl::MakeCleanup([sink_file] { fclose(sink_file); });
+//
+//     Data data;
+//     while (ReadData(source_file, &data)) {
+//       if (!data.IsGood()) {
+//         absl::Status result = absl::FailedPreconditionError("Read bad data");
+//         return result;  // Both cleanups execute
+//       }
+//       SaveData(sink_file, &data);
+//     }
+//
+//     return absl::OkStatus();  // Both cleanups execute
+//   }
+// ```
+//
+// Methods:
+//
+// `std::move(cleanup).Cancel()` will prevent the callback from executing.
+//
+// `std::move(cleanup).Invoke()` will execute the callback early, before
+// destruction, and prevent the callback from executing in the destructor.
+//
+// Usage:
+//
+// `absl::Cleanup` is not an interface type. It is only intended to be used
+// within the body of a function. It is not a value type and instead models a
+// control flow construct. Check out `defer` in Golang for something similar.
+
+#ifndef ABSL_CLEANUP_CLEANUP_H_
+#define ABSL_CLEANUP_CLEANUP_H_
+
+#include <utility>
+
+#include "absl/base/config.h"
+#include "absl/base/macros.h"
+#include "absl/cleanup/internal/cleanup.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+template <typename Arg, typename Callback = void()>
+class ABSL_MUST_USE_RESULT Cleanup final {
+  static_assert(cleanup_internal::WasDeduced<Arg>(),
+                "Explicit template parameters are not supported.");
+
+  static_assert(cleanup_internal::ReturnsVoid<Callback>(),
+                "Callbacks that return values are not supported.");
+
+ public:
+  Cleanup(Callback callback) : storage_(std::move(callback)) {}  // NOLINT
+
+  Cleanup(Cleanup&& other) = default;
+
+  void Cancel() && {
+    ABSL_HARDENING_ASSERT(storage_.IsCallbackEngaged());
+    storage_.DestroyCallback();
+  }
+
+  void Invoke() && {
+    ABSL_HARDENING_ASSERT(storage_.IsCallbackEngaged());
+    storage_.InvokeCallback();
+    storage_.DestroyCallback();
+  }
+
+  ~Cleanup() {
+    if (storage_.IsCallbackEngaged()) {
+      storage_.InvokeCallback();
+      storage_.DestroyCallback();
+    }
+  }
+
+ private:
+  cleanup_internal::Storage<Callback> storage_;
+};
+
+// `absl::Cleanup c = /* callback */;`
+//
+// C++17 type deduction API for creating an instance of `absl::Cleanup`
+#if defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
+template <typename Callback>
+Cleanup(Callback callback) -> Cleanup<cleanup_internal::Tag, Callback>;
+#endif  // defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
+
+// `auto c = absl::MakeCleanup(/* callback */);`
+//
+// C++11 type deduction API for creating an instance of `absl::Cleanup`
+template <typename... Args, typename Callback>
+absl::Cleanup<cleanup_internal::Tag, Callback> MakeCleanup(Callback callback) {
+  static_assert(cleanup_internal::WasDeduced<cleanup_internal::Tag, Args...>(),
+                "Explicit template parameters are not supported.");
+
+  static_assert(cleanup_internal::ReturnsVoid<Callback>(),
+                "Callbacks that return values are not supported.");
+
+  return {std::move(callback)};
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_CLEANUP_CLEANUP_H_

weight/_dep/abseil-cpp/absl/cleanup/cleanup_test.cc

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+// Copyright 2021 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/cleanup/cleanup.h"
+
+#include <functional>
+#include <type_traits>
+#include <utility>
+
+#include "gtest/gtest.h"
+#include "absl/base/config.h"
+#include "absl/utility/utility.h"
+
+namespace {
+
+using Tag = absl::cleanup_internal::Tag;
+
+template <typename Type1, typename Type2>
+constexpr bool IsSame() {
+  return (std::is_same<Type1, Type2>::value);
+}
+
+struct IdentityFactory {
+  template <typename Callback>
+  static Callback AsCallback(Callback callback) {
+    return Callback(std::move(callback));
+  }
+};
+
+// `FunctorClass` is a type used for testing `absl::Cleanup`. It is intended to
+// represent users that make their own move-only callback types outside of
+// `std::function` and lambda literals.
+class FunctorClass {
+  using Callback = std::function<void()>;
+
+ public:
+  explicit FunctorClass(Callback callback) : callback_(std::move(callback)) {}
+
+  FunctorClass(FunctorClass&& other)
+      : callback_(absl::exchange(other.callback_, Callback())) {}
+
+  FunctorClass(const FunctorClass&) = delete;
+
+  FunctorClass& operator=(const FunctorClass&) = delete;
+
+  FunctorClass& operator=(FunctorClass&&) = delete;
+
+  void operator()() const& = delete;
+
+  void operator()() && {
+    ASSERT_TRUE(callback_);
+    callback_();
+    callback_ = nullptr;
+  }
+
+ private:
+  Callback callback_;
+};
+
+struct FunctorClassFactory {
+  template <typename Callback>
+  static FunctorClass AsCallback(Callback callback) {
+    return FunctorClass(std::move(callback));
+  }
+};
+
+struct StdFunctionFactory {
+  template <typename Callback>
+  static std::function<void()> AsCallback(Callback callback) {
+    return std::function<void()>(std::move(callback));
+  }
+};
+
+using CleanupTestParams =
+    ::testing::Types<IdentityFactory, FunctorClassFactory, StdFunctionFactory>;
+template <typename>
+struct CleanupTest : public ::testing::Test {};
+TYPED_TEST_SUITE(CleanupTest, CleanupTestParams);
+
+bool fn_ptr_called = false;
+void FnPtrFunction() { fn_ptr_called = true; }
+
+TYPED_TEST(CleanupTest, FactoryProducesCorrectType) {
+  {
+    auto callback = TypeParam::AsCallback([] {});
+    auto cleanup = absl::MakeCleanup(std::move(callback));
+
+    static_assert(
+        IsSame<absl::Cleanup<Tag, decltype(callback)>, decltype(cleanup)>(),
+        "");
+  }
+
+  {
+    auto cleanup = absl::MakeCleanup(&FnPtrFunction);
+
+    static_assert(IsSame<absl::Cleanup<Tag, void (*)()>, decltype(cleanup)>(),
+                  "");
+  }
+
+  {
+    auto cleanup = absl::MakeCleanup(FnPtrFunction);
+
+    static_assert(IsSame<absl::Cleanup<Tag, void (*)()>, decltype(cleanup)>(),
+                  "");
+  }
+}
+
+#if defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
+TYPED_TEST(CleanupTest, CTADProducesCorrectType) {
+  {
+    auto callback = TypeParam::AsCallback([] {});
+    absl::Cleanup cleanup = std::move(callback);
+
+    static_assert(
+        IsSame<absl::Cleanup<Tag, decltype(callback)>, decltype(cleanup)>(),
+        "");
+  }
+
+  {
+    absl::Cleanup cleanup = &FnPtrFunction;
+
+    static_assert(IsSame<absl::Cleanup<Tag, void (*)()>, decltype(cleanup)>(),
+                  "");
+  }
+
+  {
+    absl::Cleanup cleanup = FnPtrFunction;
+
+    static_assert(IsSame<absl::Cleanup<Tag, void (*)()>, decltype(cleanup)>(),
+                  "");
+  }
+}
+
+TYPED_TEST(CleanupTest, FactoryAndCTADProduceSameType) {
+  {
+    auto callback = IdentityFactory::AsCallback([] {});
+    auto factory_cleanup = absl::MakeCleanup(callback);
+    absl::Cleanup deduction_cleanup = callback;
+
+    static_assert(
+        IsSame<decltype(factory_cleanup), decltype(deduction_cleanup)>(), "");
+  }
+
+  {
+    auto factory_cleanup =
+        absl::MakeCleanup(FunctorClassFactory::AsCallback([] {}));
+    absl::Cleanup deduction_cleanup = FunctorClassFactory::AsCallback([] {});
+
+    static_assert(
+        IsSame<decltype(factory_cleanup), decltype(deduction_cleanup)>(), "");
+  }
+
+  {
+    auto factory_cleanup =
+        absl::MakeCleanup(StdFunctionFactory::AsCallback([] {}));
+    absl::Cleanup deduction_cleanup = StdFunctionFactory::AsCallback([] {});
+
+    static_assert(
+        IsSame<decltype(factory_cleanup), decltype(deduction_cleanup)>(), "");
+  }
+
+  {
+    auto factory_cleanup = absl::MakeCleanup(&FnPtrFunction);
+    absl::Cleanup deduction_cleanup = &FnPtrFunction;
+
+    static_assert(
+        IsSame<decltype(factory_cleanup), decltype(deduction_cleanup)>(), "");
+  }
+
+  {
+    auto factory_cleanup = absl::MakeCleanup(FnPtrFunction);
+    absl::Cleanup deduction_cleanup = FnPtrFunction;
+
+    static_assert(
+        IsSame<decltype(factory_cleanup), decltype(deduction_cleanup)>(), "");
+  }
+}
+#endif  // defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
+
+TYPED_TEST(CleanupTest, BasicUsage) {
+  bool called = false;
+
+  {
+    auto cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback([&called] { called = true; }));
+    EXPECT_FALSE(called);  // Constructor shouldn't invoke the callback
+  }
+
+  EXPECT_TRUE(called);  // Destructor should invoke the callback
+}
+
+TYPED_TEST(CleanupTest, BasicUsageWithFunctionPointer) {
+  fn_ptr_called = false;
+
+  {
+    auto cleanup = absl::MakeCleanup(TypeParam::AsCallback(&FnPtrFunction));
+    EXPECT_FALSE(fn_ptr_called);  // Constructor shouldn't invoke the callback
+  }
+
+  EXPECT_TRUE(fn_ptr_called);  // Destructor should invoke the callback
+}
+
+TYPED_TEST(CleanupTest, Cancel) {
+  bool called = false;
+
+  {
+    auto cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback([&called] { called = true; }));
+    EXPECT_FALSE(called);  // Constructor shouldn't invoke the callback
+
+    std::move(cleanup).Cancel();
+    EXPECT_FALSE(called);  // Cancel shouldn't invoke the callback
+  }
+
+  EXPECT_FALSE(called);  // Destructor shouldn't invoke the callback
+}
+
+TYPED_TEST(CleanupTest, Invoke) {
+  bool called = false;
+
+  {
+    auto cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback([&called] { called = true; }));
+    EXPECT_FALSE(called);  // Constructor shouldn't invoke the callback
+
+    std::move(cleanup).Invoke();
+    EXPECT_TRUE(called);  // Invoke should invoke the callback
+
+    called = false;  // Reset tracker before destructor runs
+  }
+
+  EXPECT_FALSE(called);  // Destructor shouldn't invoke the callback
+}
+
+TYPED_TEST(CleanupTest, Move) {
+  bool called = false;
+
+  {
+    auto moved_from_cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback([&called] { called = true; }));
+    EXPECT_FALSE(called);  // Constructor shouldn't invoke the callback
+
+    {
+      auto moved_to_cleanup = std::move(moved_from_cleanup);
+      EXPECT_FALSE(called);  // Move shouldn't invoke the callback
+    }
+
+    EXPECT_TRUE(called);  // Destructor should invoke the callback
+
+    called = false;  // Reset tracker before destructor runs
+  }
+
+  EXPECT_FALSE(called);  // Destructor shouldn't invoke the callback
+}
+
+int DestructionCount = 0;
+
+struct DestructionCounter {
+  void operator()() {}
+
+  ~DestructionCounter() { ++DestructionCount; }
+};
+
+TYPED_TEST(CleanupTest, DestructorDestroys) {
+  {
+    auto cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback(DestructionCounter()));
+    DestructionCount = 0;
+  }
+
+  EXPECT_EQ(DestructionCount, 1);  // Engaged cleanup destroys
+}
+
+TYPED_TEST(CleanupTest, CancelDestroys) {
+  {
+    auto cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback(DestructionCounter()));
+    DestructionCount = 0;
+
+    std::move(cleanup).Cancel();
+    EXPECT_EQ(DestructionCount, 1);  // Cancel destroys
+  }
+
+  EXPECT_EQ(DestructionCount, 1);  // Canceled cleanup does not double destroy
+}
+
+TYPED_TEST(CleanupTest, InvokeDestroys) {
+  {
+    auto cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback(DestructionCounter()));
+    DestructionCount = 0;
+
+    std::move(cleanup).Invoke();
+    EXPECT_EQ(DestructionCount, 1);  // Invoke destroys
+  }
+
+  EXPECT_EQ(DestructionCount, 1);  // Invoked cleanup does not double destroy
+}
+
+}  // namespace

weight/_dep/abseil-cpp/absl/cleanup/internal/cleanup.h

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+// Copyright 2021 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_CLEANUP_INTERNAL_CLEANUP_H_
+#define ABSL_CLEANUP_INTERNAL_CLEANUP_H_
+
+#include <new>
+#include <type_traits>
+#include <utility>
+
+#include "absl/base/internal/invoke.h"
+#include "absl/base/macros.h"
+#include "absl/base/thread_annotations.h"
+#include "absl/utility/utility.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+namespace cleanup_internal {
+
+struct Tag {};
+
+template <typename Arg, typename... Args>
+constexpr bool WasDeduced() {
+  return (std::is_same<cleanup_internal::Tag, Arg>::value) &&
+         (sizeof...(Args) == 0);
+}
+
+template <typename Callback>
+constexpr bool ReturnsVoid() {
+  return (std::is_same<base_internal::invoke_result_t<Callback>, void>::value);
+}
+
+template <typename Callback>
+class Storage {
+ public:
+  Storage() = delete;
+
+  explicit Storage(Callback callback) {
+    // Placement-new into a character buffer is used for eager destruction when
+    // the cleanup is invoked or cancelled. To ensure this optimizes well, the
+    // behavior is implemented locally instead of using an absl::optional.
+    ::new (GetCallbackBuffer()) Callback(std::move(callback));
+    is_callback_engaged_ = true;
+  }
+
+  Storage(Storage&& other) {
+    ABSL_HARDENING_ASSERT(other.IsCallbackEngaged());
+
+    ::new (GetCallbackBuffer()) Callback(std::move(other.GetCallback()));
+    is_callback_engaged_ = true;
+
+    other.DestroyCallback();
+  }
+
+  Storage(const Storage& other) = delete;
+
+  Storage& operator=(Storage&& other) = delete;
+
+  Storage& operator=(const Storage& other) = delete;
+
+  void* GetCallbackBuffer() { return static_cast<void*>(+callback_buffer_); }
+
+  Callback& GetCallback() {
+    return *reinterpret_cast<Callback*>(GetCallbackBuffer());
+  }
+
+  bool IsCallbackEngaged() const { return is_callback_engaged_; }
+
+  void DestroyCallback() {
+    is_callback_engaged_ = false;
+    GetCallback().~Callback();
+  }
+
+  void InvokeCallback() ABSL_NO_THREAD_SAFETY_ANALYSIS {
+    std::move(GetCallback())();
+  }
+
+ private:
+  bool is_callback_engaged_;
+  alignas(Callback) char callback_buffer_[sizeof(Callback)];
+};
+
+}  // namespace cleanup_internal
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_CLEANUP_INTERNAL_CLEANUP_H_

weight/_dep/abseil-cpp/absl/copts/GENERATED_copts.bzl

@@ -0,0 +1,230 @@
+"""GENERATED! DO NOT MANUALLY EDIT THIS FILE.
+
+(1) Edit absl/copts/copts.py.
+(2) Run `python <path_to_absl>/copts/generate_copts.py`.
+"""
+
+ABSL_CLANG_CL_FLAGS = [
+    "/W3",
+    "/DNOMINMAX",
+    "/DWIN32_LEAN_AND_MEAN",
+    "/D_CRT_SECURE_NO_WARNINGS",
+    "/D_SCL_SECURE_NO_WARNINGS",
+    "/D_ENABLE_EXTENDED_ALIGNED_STORAGE",
+]
+
+ABSL_CLANG_CL_TEST_FLAGS = [
+    "/W3",
+    "/DNOMINMAX",
+    "/DWIN32_LEAN_AND_MEAN",
+    "/D_CRT_SECURE_NO_WARNINGS",
+    "/D_SCL_SECURE_NO_WARNINGS",
+    "/D_ENABLE_EXTENDED_ALIGNED_STORAGE",
+    "-Wno-deprecated-declarations",
+    "-Wno-implicit-int-conversion",
+    "-Wno-missing-prototypes",
+    "-Wno-missing-variable-declarations",
+    "-Wno-shadow",
+    "-Wno-shorten-64-to-32",
+    "-Wno-sign-compare",
+    "-Wno-sign-conversion",
+    "-Wno-unreachable-code-loop-increment",
+    "-Wno-unused-function",
+    "-Wno-unused-member-function",
+    "-Wno-unused-parameter",
+    "-Wno-unused-private-field",
+    "-Wno-unused-template",
+    "-Wno-used-but-marked-unused",
+    "-Wno-gnu-zero-variadic-macro-arguments",
+]
+
+ABSL_GCC_FLAGS = [
+    "-Wall",
+    "-Wextra",
+    "-Wcast-qual",
+    "-Wconversion-null",
+    "-Wformat-security",
+    "-Wmissing-declarations",
+    "-Woverlength-strings",
+    "-Wpointer-arith",
+    "-Wundef",
+    "-Wunused-local-typedefs",
+    "-Wunused-result",
+    "-Wvarargs",
+    "-Wvla",
+    "-Wwrite-strings",
+    "-DNOMINMAX",
+]
+
+ABSL_GCC_TEST_FLAGS = [
+    "-Wall",
+    "-Wextra",
+    "-Wcast-qual",
+    "-Wconversion-null",
+    "-Wformat-security",
+    "-Woverlength-strings",
+    "-Wpointer-arith",
+    "-Wundef",
+    "-Wunused-local-typedefs",
+    "-Wunused-result",
+    "-Wvarargs",
+    "-Wvla",
+    "-Wwrite-strings",
+    "-DNOMINMAX",
+    "-Wno-deprecated-declarations",
+    "-Wno-missing-declarations",
+    "-Wno-self-move",
+    "-Wno-sign-compare",
+    "-Wno-unused-function",
+    "-Wno-unused-parameter",
+    "-Wno-unused-private-field",
+]
+
+ABSL_LLVM_FLAGS = [
+    "-Wall",
+    "-Wextra",
+    "-Wcast-qual",
+    "-Wconversion",
+    "-Wfloat-overflow-conversion",
+    "-Wfloat-zero-conversion",
+    "-Wfor-loop-analysis",
+    "-Wformat-security",
+    "-Wgnu-redeclared-enum",
+    "-Winfinite-recursion",
+    "-Winvalid-constexpr",
+    "-Wliteral-conversion",
+    "-Wmissing-declarations",
+    "-Woverlength-strings",
+    "-Wpointer-arith",
+    "-Wself-assign",
+    "-Wshadow-all",
+    "-Wshorten-64-to-32",
+    "-Wsign-conversion",
+    "-Wstring-conversion",
+    "-Wtautological-overlap-compare",
+    "-Wtautological-unsigned-zero-compare",
+    "-Wundef",
+    "-Wuninitialized",
+    "-Wunreachable-code",
+    "-Wunused-comparison",
+    "-Wunused-local-typedefs",
+    "-Wunused-result",
+    "-Wvla",
+    "-Wwrite-strings",
+    "-Wno-float-conversion",
+    "-Wno-implicit-float-conversion",
+    "-Wno-implicit-int-float-conversion",
+    "-Wno-unknown-warning-option",
+    "-DNOMINMAX",
+]
+
+ABSL_LLVM_TEST_FLAGS = [
+    "-Wall",
+    "-Wextra",
+    "-Wcast-qual",
+    "-Wconversion",
+    "-Wfloat-overflow-conversion",
+    "-Wfloat-zero-conversion",
+    "-Wfor-loop-analysis",
+    "-Wformat-security",
+    "-Wgnu-redeclared-enum",
+    "-Winfinite-recursion",
+    "-Winvalid-constexpr",
+    "-Wliteral-conversion",
+    "-Wmissing-declarations",
+    "-Woverlength-strings",
+    "-Wpointer-arith",
+    "-Wself-assign",
+    "-Wshadow-all",
+    "-Wstring-conversion",
+    "-Wtautological-overlap-compare",
+    "-Wtautological-unsigned-zero-compare",
+    "-Wundef",
+    "-Wuninitialized",
+    "-Wunreachable-code",
+    "-Wunused-comparison",
+    "-Wunused-local-typedefs",
+    "-Wunused-result",
+    "-Wvla",
+    "-Wwrite-strings",
+    "-Wno-float-conversion",
+    "-Wno-implicit-float-conversion",
+    "-Wno-implicit-int-float-conversion",
+    "-Wno-unknown-warning-option",
+    "-DNOMINMAX",
+    "-Wno-deprecated-declarations",
+    "-Wno-implicit-int-conversion",
+    "-Wno-missing-prototypes",
+    "-Wno-missing-variable-declarations",
+    "-Wno-shadow",
+    "-Wno-shorten-64-to-32",
+    "-Wno-sign-compare",
+    "-Wno-sign-conversion",
+    "-Wno-unreachable-code-loop-increment",
+    "-Wno-unused-function",
+    "-Wno-unused-member-function",
+    "-Wno-unused-parameter",
+    "-Wno-unused-private-field",
+    "-Wno-unused-template",
+    "-Wno-used-but-marked-unused",
+    "-Wno-gnu-zero-variadic-macro-arguments",
+]
+
+ABSL_MSVC_FLAGS = [
+    "/W3",
+    "/bigobj",
+    "/wd4005",
+    "/wd4068",
+    "/wd4180",
+    "/wd4244",
+    "/wd4267",
+    "/wd4503",
+    "/wd4800",
+    "/DNOMINMAX",
+    "/DWIN32_LEAN_AND_MEAN",
+    "/D_CRT_SECURE_NO_WARNINGS",
+    "/D_SCL_SECURE_NO_WARNINGS",
+    "/D_ENABLE_EXTENDED_ALIGNED_STORAGE",
+]
+
+ABSL_MSVC_LINKOPTS = [
+    "-ignore:4221",
+]
+
+ABSL_MSVC_TEST_FLAGS = [
+    "/W3",
+    "/bigobj",
+    "/wd4005",
+    "/wd4068",
+    "/wd4180",
+    "/wd4244",
+    "/wd4267",
+    "/wd4503",
+    "/wd4800",
+    "/DNOMINMAX",
+    "/DWIN32_LEAN_AND_MEAN",
+    "/D_CRT_SECURE_NO_WARNINGS",
+    "/D_SCL_SECURE_NO_WARNINGS",
+    "/D_ENABLE_EXTENDED_ALIGNED_STORAGE",
+    "/wd4018",
+    "/wd4101",
+    "/wd4503",
+    "/wd4996",
+    "/DNOMINMAX",
+]
+
+ABSL_RANDOM_HWAES_ARM32_FLAGS = [
+    "-mfpu=neon",
+]
+
+ABSL_RANDOM_HWAES_ARM64_FLAGS = [
+    "-march=armv8-a+crypto",
+]
+
+ABSL_RANDOM_HWAES_MSVC_X64_FLAGS = [
+]
+
+ABSL_RANDOM_HWAES_X64_FLAGS = [
+    "-maes",
+    "-msse4.1",
+]

weight/_dep/abseil-cpp/absl/copts/configure_copts.bzl

@@ -0,0 +1,82 @@
+"""absl specific copts.
+
+This file simply selects the correct options from the generated files.  To
+change Abseil copts, edit absl/copts/copts.py
+"""
+
+load(
+    "//absl:copts/GENERATED_copts.bzl",
+    "ABSL_CLANG_CL_FLAGS",
+    "ABSL_CLANG_CL_TEST_FLAGS",
+    "ABSL_GCC_FLAGS",
+    "ABSL_GCC_TEST_FLAGS",
+    "ABSL_LLVM_FLAGS",
+    "ABSL_LLVM_TEST_FLAGS",
+    "ABSL_MSVC_FLAGS",
+    "ABSL_MSVC_LINKOPTS",
+    "ABSL_MSVC_TEST_FLAGS",
+    "ABSL_RANDOM_HWAES_ARM32_FLAGS",
+    "ABSL_RANDOM_HWAES_ARM64_FLAGS",
+    "ABSL_RANDOM_HWAES_MSVC_X64_FLAGS",
+    "ABSL_RANDOM_HWAES_X64_FLAGS",
+)
+
+ABSL_DEFAULT_COPTS = select({
+    "//absl:msvc_compiler": ABSL_MSVC_FLAGS,
+    "//absl:clang-cl_compiler": ABSL_CLANG_CL_FLAGS,
+    "//absl:clang_compiler": ABSL_LLVM_FLAGS,
+    "//absl:gcc_compiler": ABSL_GCC_FLAGS,
+    "//conditions:default": ABSL_GCC_FLAGS,
+})
+
+ABSL_TEST_COPTS = select({
+    "//absl:msvc_compiler": ABSL_MSVC_TEST_FLAGS,
+    "//absl:clang-cl_compiler": ABSL_CLANG_CL_TEST_FLAGS,
+    "//absl:clang_compiler": ABSL_LLVM_TEST_FLAGS,
+    "//absl:gcc_compiler": ABSL_GCC_TEST_FLAGS,
+    "//conditions:default": ABSL_GCC_TEST_FLAGS,
+})
+
+ABSL_DEFAULT_LINKOPTS = select({
+    "//absl:msvc_compiler": ABSL_MSVC_LINKOPTS,
+    "//conditions:default": [],
+})
+
+# ABSL_RANDOM_RANDEN_COPTS blaze copts flags which are required by each
+# environment to build an accelerated RandenHwAes library.
+ABSL_RANDOM_RANDEN_COPTS = select({
+    # APPLE
+    ":cpu_darwin_x86_64": ABSL_RANDOM_HWAES_X64_FLAGS,
+    ":cpu_darwin": ABSL_RANDOM_HWAES_X64_FLAGS,
+    ":cpu_x64_windows_msvc": ABSL_RANDOM_HWAES_MSVC_X64_FLAGS,
+    ":cpu_x64_windows": ABSL_RANDOM_HWAES_MSVC_X64_FLAGS,
+    ":cpu_k8": ABSL_RANDOM_HWAES_X64_FLAGS,
+    ":cpu_ppc": ["-mcrypto"],
+    ":cpu_aarch64": ABSL_RANDOM_HWAES_ARM64_FLAGS,
+
+    # Supported by default or unsupported.
+    "//conditions:default": [],
+})
+
+# absl_random_randen_copts_init:
+#  Initialize the config targets based on cpu, os, etc. used to select
+#  the required values for ABSL_RANDOM_RANDEN_COPTS
+def absl_random_randen_copts_init():
+    """Initialize the config_settings used by ABSL_RANDOM_RANDEN_COPTS."""
+
+    # CPU configs.
+    # These configs have consistent flags to enable HWAES intsructions.
+    cpu_configs = [
+        "ppc",
+        "k8",
+        "darwin_x86_64",
+        "darwin",
+        "x64_windows_msvc",
+        "x64_windows",
+        "aarch64",
+    ]
+    for cpu in cpu_configs:
+        native.config_setting(
+            name = "cpu_%s" % cpu,
+            values = {"cpu": cpu},
+        )

weight/_dep/abseil-cpp/absl/copts/copts.py

@@ -0,0 +1,191 @@
+"""Abseil compiler options.
+
+This is the source of truth for Abseil compiler options.  To modify Abseil
+compilation options:
+
+  (1) Edit the appropriate list in this file based on the platform the flag is
+      needed on.
+  (2) Run `<path_to_absl>/copts/generate_copts.py`.
+
+The generated copts are consumed by configure_copts.bzl and
+AbseilConfigureCopts.cmake.
+"""
+
+ABSL_GCC_FLAGS = [
+    "-Wall",
+    "-Wextra",
+    "-Wcast-qual",
+    "-Wconversion-null",
+    "-Wformat-security",
+    "-Wmissing-declarations",
+    "-Woverlength-strings",
+    "-Wpointer-arith",
+    "-Wundef",
+    "-Wunused-local-typedefs",
+    "-Wunused-result",
+    "-Wvarargs",
+    "-Wvla",  # variable-length array
+    "-Wwrite-strings",
+    # Don't define min and max macros (Build on Windows using gcc)
+    "-DNOMINMAX",
+]
+
+ABSL_GCC_TEST_ADDITIONAL_FLAGS = [
+    "-Wno-deprecated-declarations",
+    "-Wno-missing-declarations",
+    "-Wno-self-move",
+    "-Wno-sign-compare",
+    "-Wno-unused-function",
+    "-Wno-unused-parameter",
+    "-Wno-unused-private-field",
+]
+
+ABSL_LLVM_FLAGS = [
+    "-Wall",
+    "-Wextra",
+    "-Wcast-qual",
+    "-Wconversion",
+    "-Wfloat-overflow-conversion",
+    "-Wfloat-zero-conversion",
+    "-Wfor-loop-analysis",
+    "-Wformat-security",
+    "-Wgnu-redeclared-enum",
+    "-Winfinite-recursion",
+    "-Winvalid-constexpr",
+    "-Wliteral-conversion",
+    "-Wmissing-declarations",
+    "-Woverlength-strings",
+    "-Wpointer-arith",
+    "-Wself-assign",
+    "-Wshadow-all",
+    "-Wshorten-64-to-32",
+    "-Wsign-conversion",
+    "-Wstring-conversion",
+    "-Wtautological-overlap-compare",
+    "-Wtautological-unsigned-zero-compare",
+    "-Wundef",
+    "-Wuninitialized",
+    "-Wunreachable-code",
+    "-Wunused-comparison",
+    "-Wunused-local-typedefs",
+    "-Wunused-result",
+    "-Wvla",
+    "-Wwrite-strings",
+    # Warnings that are enabled by group warning flags like -Wall that we
+    # explicitly disable.
+    "-Wno-float-conversion",
+    "-Wno-implicit-float-conversion",
+    "-Wno-implicit-int-float-conversion",
+    # Disable warnings on unknown warning flags (when warning flags are
+    # unknown on older compiler versions)
+    "-Wno-unknown-warning-option",
+    # Don't define min and max macros (Build on Windows using clang)
+    "-DNOMINMAX",
+]
+
+ABSL_LLVM_TEST_ADDITIONAL_FLAGS = [
+    "-Wno-deprecated-declarations",
+    "-Wno-implicit-int-conversion",
+    "-Wno-missing-prototypes",
+    "-Wno-missing-variable-declarations",
+    "-Wno-shadow",
+    "-Wno-shorten-64-to-32",
+    "-Wno-sign-compare",
+    "-Wno-sign-conversion",
+    "-Wno-unreachable-code-loop-increment",
+    "-Wno-unused-function",
+    "-Wno-unused-member-function",
+    "-Wno-unused-parameter",
+    "-Wno-unused-private-field",
+    "-Wno-unused-template",
+    "-Wno-used-but-marked-unused",
+    # gtest depends on this GNU extension being offered.
+    "-Wno-gnu-zero-variadic-macro-arguments",
+]
+
+# /Wall with msvc includes unhelpful warnings such as C4711, C4710, ...
+MSVC_BIG_WARNING_FLAGS = [
+    "/W3",
+]
+
+MSVC_WARNING_FLAGS = [
+    # Increase the number of sections available in object files
+    "/bigobj",
+    "/wd4005",  # macro-redefinition
+    "/wd4068",  # unknown pragma
+    # qualifier applied to function type has no meaning; ignored
+    "/wd4180",
+    # conversion from 'type1' to 'type2', possible loss of data
+    "/wd4244",
+    # conversion from 'size_t' to 'type', possible loss of data
+    "/wd4267",
+    # The decorated name was longer than the compiler limit
+    "/wd4503",
+    # forcing value to bool 'true' or 'false' (performance warning)
+    "/wd4800",
+]
+
+MSVC_DEFINES = [
+    "/DNOMINMAX",  # Don't define min and max macros (windows.h)
+    # Don't bloat namespace with incompatible winsock versions.
+    "/DWIN32_LEAN_AND_MEAN",
+    # Don't warn about usage of insecure C functions.
+    "/D_CRT_SECURE_NO_WARNINGS",
+    "/D_SCL_SECURE_NO_WARNINGS",
+    # Introduced in VS 2017 15.8, allow overaligned types in aligned_storage
+    "/D_ENABLE_EXTENDED_ALIGNED_STORAGE",
+]
+
+
+def GccStyleFilterAndCombine(default_flags, test_flags):
+  """Merges default_flags and test_flags for GCC and LLVM.
+
+  Args:
+    default_flags: A list of default compiler flags
+    test_flags: A list of flags that are only used in tests
+
+  Returns:
+    A combined list of default_flags and test_flags, but with all flags of the
+    form '-Wwarning' removed if test_flags contains a flag of the form
+    '-Wno-warning'
+  """
+  remove = set(["-W" + f[5:] for f in test_flags if f[:5] == "-Wno-"])
+  return [f for f in default_flags if f not in remove] + test_flags
+
+COPT_VARS = {
+    "ABSL_GCC_FLAGS": ABSL_GCC_FLAGS,
+    "ABSL_GCC_TEST_FLAGS": GccStyleFilterAndCombine(
+        ABSL_GCC_FLAGS, ABSL_GCC_TEST_ADDITIONAL_FLAGS),
+    "ABSL_LLVM_FLAGS": ABSL_LLVM_FLAGS,
+    "ABSL_LLVM_TEST_FLAGS": GccStyleFilterAndCombine(
+        ABSL_LLVM_FLAGS, ABSL_LLVM_TEST_ADDITIONAL_FLAGS),
+    "ABSL_CLANG_CL_FLAGS":
+        MSVC_BIG_WARNING_FLAGS + MSVC_DEFINES,
+    "ABSL_CLANG_CL_TEST_FLAGS":
+        MSVC_BIG_WARNING_FLAGS + MSVC_DEFINES + ABSL_LLVM_TEST_ADDITIONAL_FLAGS,
+    "ABSL_MSVC_FLAGS":
+        MSVC_BIG_WARNING_FLAGS + MSVC_WARNING_FLAGS + MSVC_DEFINES,
+    "ABSL_MSVC_TEST_FLAGS":
+        MSVC_BIG_WARNING_FLAGS + MSVC_WARNING_FLAGS + MSVC_DEFINES + [
+            "/wd4018",  # signed/unsigned mismatch
+            "/wd4101",  # unreferenced local variable
+            "/wd4503",  # decorated name length exceeded, name was truncated
+            "/wd4996",  # use of deprecated symbol
+            "/DNOMINMAX",  # disable the min() and max() macros from <windows.h>
+        ],
+    "ABSL_MSVC_LINKOPTS": [
+        # Object file doesn't export any previously undefined symbols
+        "-ignore:4221",
+    ],
+    # "HWAES" is an abbreviation for "hardware AES" (AES - Advanced Encryption
+    # Standard). These flags are used for detecting whether or not the target
+    # architecture has hardware support for AES instructions which can be used
+    # to improve performance of some random bit generators.
+    "ABSL_RANDOM_HWAES_ARM64_FLAGS": ["-march=armv8-a+crypto"],
+    "ABSL_RANDOM_HWAES_ARM32_FLAGS": ["-mfpu=neon"],
+    "ABSL_RANDOM_HWAES_X64_FLAGS": [
+        "-maes",
+        "-msse4.1",
+    ],
+    "ABSL_RANDOM_HWAES_MSVC_X64_FLAGS": [],
+}

weight/_dep/abseil-cpp/absl/copts/generate_copts.py

@@ -0,0 +1,109 @@
+#!/usr/bin/env python3
+"""Generate Abseil compile compile option configs.
+
+Usage: <path_to_absl>/copts/generate_copts.py
+
+The configs are generated from copts.py.
+"""
+
+from os import path
+import sys
+from copts import COPT_VARS
+
+
+# Helper functions
+def file_header_lines():
+  return [
+      "GENERATED! DO NOT MANUALLY EDIT THIS FILE.", "",
+      "(1) Edit absl/copts/copts.py.",
+      "(2) Run `python <path_to_absl>/copts/generate_copts.py`."
+  ]
+
+
+def flatten(*lists):
+  return [item for sublist in lists for item in sublist]
+
+
+def relative_filename(filename):
+  return path.join(path.dirname(__file__), filename)
+
+
+# Style classes.  These contain all the syntactic styling needed to generate a
+# copt file for different build tools.
+class CMakeStyle(object):
+  """Style object for CMake copts file."""
+
+  def separator(self):
+    return ""
+
+  def list_introducer(self, name):
+    return "list(APPEND " + name
+
+  def list_closer(self):
+    return ")\n"
+
+  def docstring(self):
+    return "\n".join((("# " + line).strip() for line in file_header_lines()))
+
+  def filename(self):
+    return "GENERATED_AbseilCopts.cmake"
+
+
+class StarlarkStyle(object):
+  """Style object for Starlark copts file."""
+
+  def separator(self):
+    return ","
+
+  def list_introducer(self, name):
+    return name + " = ["
+
+  def list_closer(self):
+    return "]\n"
+
+  def docstring(self):
+    docstring_quotes = "\"\"\""
+    return docstring_quotes + "\n".join(
+        flatten(file_header_lines(), [docstring_quotes]))
+
+  def filename(self):
+    return "GENERATED_copts.bzl"
+
+
+def copt_list(name, arg_list, style):
+  """Copt file generation."""
+
+  make_line = lambda s: "    \"" + s + "\"" + style.separator()
+  external_str_list = [make_line(s) for s in arg_list]
+
+  return "\n".join(
+      flatten(
+          [style.list_introducer(name)],
+          external_str_list,
+          [style.list_closer()]))
+
+
+def generate_copt_file(style):
+  """Creates a generated copt file using the given style object.
+
+  Args:
+    style: either StarlarkStyle() or CMakeStyle()
+  """
+  with open(relative_filename(style.filename()), "w") as f:
+    f.write(style.docstring())
+    f.write("\n")
+    for var_name, arg_list in sorted(COPT_VARS.items()):
+      f.write("\n")
+      f.write(copt_list(var_name, arg_list, style))
+
+
+def main(argv):
+  if len(argv) > 1:
+    raise RuntimeError("generate_copts needs no command line args")
+
+  generate_copt_file(StarlarkStyle())
+  generate_copt_file(CMakeStyle())
+
+
+if __name__ == "__main__":
+  main(sys.argv)

weight/_dep/abseil-cpp/absl/flags/BUILD.bazel

@@ -0,0 +1,601 @@
+#
+# Copyright 2019 The Abseil Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+load(
+    "//absl:copts/configure_copts.bzl",
+    "ABSL_DEFAULT_COPTS",
+    "ABSL_DEFAULT_LINKOPTS",
+    "ABSL_TEST_COPTS",
+)
+
+package(
+    default_visibility = ["//visibility:public"],
+    features = [
+        "header_modules",
+        "layering_check",
+        "parse_headers",
+    ],
+)
+
+licenses(["notice"])
+
+cc_library(
+    name = "path_util",
+    hdrs = [
+        "internal/path_util.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    visibility = [
+        "//absl/flags:__pkg__",
+    ],
+    deps = [
+        "//absl/base:config",
+        "//absl/strings",
+    ],
+)
+
+cc_library(
+    name = "program_name",
+    srcs = [
+        "internal/program_name.cc",
+    ],
+    hdrs = [
+        "internal/program_name.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    visibility = [
+        "//absl/flags:__pkg__",
+        "//absl/log:__pkg__",
+    ],
+    deps = [
+        ":path_util",
+        "//absl/base:config",
+        "//absl/base:core_headers",
+        "//absl/strings",
+        "//absl/synchronization",
+    ],
+)
+
+cc_library(
+    name = "config",
+    srcs = [
+        "usage_config.cc",
+    ],
+    hdrs = [
+        "config.h",
+        "usage_config.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":path_util",
+        ":program_name",
+        "//absl/base:config",
+        "//absl/base:core_headers",
+        "//absl/strings",
+        "//absl/synchronization",
+    ],
+)
+
+cc_library(
+    name = "marshalling",
+    srcs = [
+        "marshalling.cc",
+    ],
+    hdrs = [
+        "marshalling.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        "//absl/base:config",
+        "//absl/base:core_headers",
+        "//absl/base:log_severity",
+        "//absl/numeric:int128",
+        "//absl/strings",
+        "//absl/strings:str_format",
+        "//absl/types:optional",
+    ],
+)
+
+cc_library(
+    name = "commandlineflag_internal",
+    srcs = [
+        "internal/commandlineflag.cc",
+    ],
+    hdrs = [
+        "internal/commandlineflag.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    visibility = [
+        "//visibility:private",
+    ],
+    deps = [
+        "//absl/base:config",
+        "//absl/base:fast_type_id",
+    ],
+)
+
+cc_library(
+    name = "commandlineflag",
+    srcs = [
+        "commandlineflag.cc",
+    ],
+    hdrs = [
+        "commandlineflag.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":commandlineflag_internal",
+        "//absl/base:config",
+        "//absl/base:fast_type_id",
+        "//absl/strings",
+        "//absl/types:optional",
+    ],
+)
+
+cc_library(
+    name = "private_handle_accessor",
+    srcs = [
+        "internal/private_handle_accessor.cc",
+    ],
+    hdrs = [
+        "internal/private_handle_accessor.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    visibility = [
+        "//absl/flags:__pkg__",
+    ],
+    deps = [
+        ":commandlineflag",
+        ":commandlineflag_internal",
+        "//absl/base:config",
+        "//absl/strings",
+    ],
+)
+
+cc_library(
+    name = "reflection",
+    srcs = [
+        "reflection.cc",
+    ],
+    hdrs = [
+        "internal/registry.h",
+        "reflection.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":commandlineflag",
+        ":commandlineflag_internal",
+        ":config",
+        ":private_handle_accessor",
+        "//absl/base:config",
+        "//absl/base:core_headers",
+        "//absl/base:no_destructor",
+        "//absl/container:flat_hash_map",
+        "//absl/strings",
+        "//absl/synchronization",
+    ],
+)
+
+cc_library(
+    name = "flag_internal",
+    srcs = [
+        "internal/flag.cc",
+    ],
+    hdrs = [
+        "internal/flag.h",
+        "internal/sequence_lock.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    visibility = ["//absl/base:__subpackages__"],
+    deps = [
+        ":commandlineflag",
+        ":commandlineflag_internal",
+        ":config",
+        ":marshalling",
+        ":reflection",
+        "//absl/base",
+        "//absl/base:config",
+        "//absl/base:core_headers",
+        "//absl/base:dynamic_annotations",
+        "//absl/memory",
+        "//absl/meta:type_traits",
+        "//absl/strings",
+        "//absl/synchronization",
+        "//absl/utility",
+    ],
+)
+
+cc_library(
+    name = "flag",
+    hdrs = [
+        "declare.h",
+        "flag.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":config",
+        ":flag_internal",
+        ":reflection",
+        "//absl/base",
+        "//absl/base:config",
+        "//absl/base:core_headers",
+        "//absl/strings",
+    ],
+)
+
+cc_library(
+    name = "usage_internal",
+    srcs = [
+        "internal/usage.cc",
+    ],
+    hdrs = [
+        "internal/usage.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    visibility = [
+        "//absl/flags:__pkg__",
+    ],
+    deps = [
+        ":commandlineflag",
+        ":config",
+        ":flag",
+        ":flag_internal",
+        ":path_util",
+        ":private_handle_accessor",
+        ":program_name",
+        ":reflection",
+        "//absl/base:config",
+        "//absl/base:core_headers",
+        "//absl/strings",
+        "//absl/synchronization",
+    ],
+)
+
+cc_library(
+    name = "usage",
+    srcs = [
+        "usage.cc",
+    ],
+    hdrs = [
+        "usage.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":usage_internal",
+        "//absl/base:config",
+        "//absl/base:core_headers",
+        "//absl/base:raw_logging_internal",
+        "//absl/strings",
+        "//absl/synchronization",
+    ],
+)
+
+cc_library(
+    name = "parse",
+    srcs = ["parse.cc"],
+    hdrs = [
+        "internal/parse.h",
+        "parse.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":commandlineflag",
+        ":commandlineflag_internal",
+        ":config",
+        ":flag",
+        ":flag_internal",
+        ":private_handle_accessor",
+        ":program_name",
+        ":reflection",
+        ":usage",
+        ":usage_internal",
+        "//absl/algorithm:container",
+        "//absl/base:config",
+        "//absl/base:core_headers",
+        "//absl/strings",
+        "//absl/synchronization",
+    ],
+)
+
+############################################################################
+# Unit tests in alphabetical order.
+
+cc_test(
+    name = "commandlineflag_test",
+    size = "small",
+    srcs = [
+        "commandlineflag_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    tags = [
+        "no_test:os:android",
+        "no_test:os:ios",
+        "no_test_android",
+        "no_test_ios",
+        "no_test_wasm",
+    ],
+    deps = [
+        ":commandlineflag",
+        ":commandlineflag_internal",
+        ":config",
+        ":flag",
+        ":private_handle_accessor",
+        ":reflection",
+        "//absl/memory",
+        "//absl/strings",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "config_test",
+    size = "small",
+    srcs = [
+        "config_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":config",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "flag_test",
+    size = "small",
+    srcs = [
+        "flag_test.cc",
+        "flag_test_defs.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    tags = [
+        "no_test:os:android",
+        "no_test:os:ios",
+        "no_test_android",
+        "no_test_ios",
+        "no_test_wasm",
+    ],
+    deps = [
+        ":config",
+        ":flag",
+        ":flag_internal",
+        ":marshalling",
+        ":reflection",
+        "//absl/base:core_headers",
+        "//absl/base:malloc_internal",
+        "//absl/numeric:int128",
+        "//absl/strings",
+        "//absl/time",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_binary(
+    name = "flag_benchmark",
+    testonly = 1,
+    srcs = [
+        "flag_benchmark.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = select({
+        "//conditions:default": [],
+    }) + ABSL_DEFAULT_LINKOPTS,
+    tags = ["benchmark"],
+    visibility = ["//visibility:private"],
+    deps = [
+        "flag_benchmark.lds",
+        ":flag",
+        ":marshalling",
+        ":parse",
+        ":reflection",
+        "//absl/strings",
+        "//absl/time",
+        "//absl/types:optional",
+        "@com_github_google_benchmark//:benchmark_main",
+    ],
+)
+
+cc_test(
+    name = "marshalling_test",
+    size = "small",
+    srcs = [
+        "marshalling_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":marshalling",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "parse_test",
+    size = "small",
+    timeout = "moderate",
+    srcs = [
+        "parse_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    tags = [
+        "no_test:os:android",
+        "no_test:os:ios",
+        "no_test_android",
+        "no_test_ios",
+        "no_test_wasm",
+    ],
+    deps = [
+        ":flag",
+        ":parse",
+        ":reflection",
+        ":usage_internal",
+        "//absl/base:scoped_set_env",
+        "//absl/log",
+        "//absl/strings",
+        "//absl/types:span",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "path_util_test",
+    size = "small",
+    srcs = [
+        "internal/path_util_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":path_util",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "program_name_test",
+    size = "small",
+    srcs = [
+        "internal/program_name_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    tags = ["no_test_wasm"],
+    deps = [
+        ":program_name",
+        "//absl/strings",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "reflection_test",
+    size = "small",
+    srcs = [
+        "reflection_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    tags = [
+        "no_test:os:android",
+        "no_test:os:ios",
+        "no_test_android",
+        "no_test_ios",
+        "no_test_wasm",
+    ],
+    deps = [
+        ":commandlineflag_internal",
+        ":flag",
+        ":marshalling",
+        ":reflection",
+        ":usage_internal",
+        "//absl/memory",
+        "//absl/strings",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "sequence_lock_test",
+    size = "small",
+    timeout = "moderate",
+    srcs = [
+        "internal/sequence_lock_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    shard_count = 31,
+    tags = ["no_test_wasm"],
+    deps = [
+        ":flag_internal",
+        "//absl/base",
+        "//absl/container:fixed_array",
+        "//absl/time",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "usage_config_test",
+    size = "small",
+    srcs = [
+        "usage_config_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":config",
+        ":path_util",
+        ":program_name",
+        "//absl/strings",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "usage_test",
+    size = "small",
+    srcs = [
+        "internal/usage_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    tags = [
+        "no_test:os:android",
+        "no_test:os:ios",
+        "no_test_android",
+        "no_test_ios",
+        "no_test_wasm",
+    ],
+    deps = [
+        ":config",
+        ":flag",
+        ":parse",
+        ":path_util",
+        ":program_name",
+        ":reflection",
+        ":usage",
+        ":usage_internal",
+        "//absl/strings",
+        "@com_google_googletest//:gtest",
+    ],
+)

weight/_dep/abseil-cpp/absl/flags/CMakeLists.txt

@@ -0,0 +1,471 @@
+#
+# Copyright 2019 The Abseil Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# Internal-only target, do not depend on directly.
+absl_cc_library(
+  NAME
+    flags_path_util
+  HDRS
+    "internal/path_util.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::strings
+  PUBLIC
+)
+
+# Internal-only target, do not depend on directly.
+absl_cc_library(
+  NAME
+    flags_program_name
+  SRCS
+    "internal/program_name.cc"
+  HDRS
+    "internal/program_name.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::core_headers
+    absl::flags_path_util
+    absl::strings
+    absl::synchronization
+  PUBLIC
+)
+
+absl_cc_library(
+  NAME
+    flags_config
+  SRCS
+    "usage_config.cc"
+  HDRS
+    "config.h"
+    "usage_config.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::flags_path_util
+    absl::flags_program_name
+    absl::core_headers
+    absl::strings
+    absl::synchronization
+)
+
+absl_cc_library(
+  NAME
+    flags_marshalling
+  SRCS
+    "marshalling.cc"
+  HDRS
+    "marshalling.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::core_headers
+    absl::log_severity
+    absl::int128
+    absl::optional
+    absl::strings
+    absl::str_format
+)
+
+# Internal-only target, do not depend on directly.
+absl_cc_library(
+  NAME
+    flags_commandlineflag_internal
+  SRCS
+    "internal/commandlineflag.cc"
+  HDRS
+    "internal/commandlineflag.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::dynamic_annotations
+    absl::fast_type_id
+)
+
+absl_cc_library(
+  NAME
+    flags_commandlineflag
+  SRCS
+    "commandlineflag.cc"
+  HDRS
+    "commandlineflag.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::fast_type_id
+    absl::flags_commandlineflag_internal
+    absl::optional
+    absl::strings
+)
+
+# Internal-only target, do not depend on directly.
+absl_cc_library(
+  NAME
+    flags_private_handle_accessor
+  SRCS
+    "internal/private_handle_accessor.cc"
+  HDRS
+    "internal/private_handle_accessor.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::flags_commandlineflag
+    absl::flags_commandlineflag_internal
+    absl::strings
+)
+
+absl_cc_library(
+  NAME
+    flags_reflection
+  SRCS
+    "reflection.cc"
+  HDRS
+    "reflection.h"
+    "internal/registry.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::flags_commandlineflag
+    absl::flags_private_handle_accessor
+    absl::flags_config
+    absl::strings
+    absl::synchronization
+    absl::flat_hash_map
+    absl::no_destructor
+)
+
+# Internal-only target, do not depend on directly.
+absl_cc_library(
+  NAME
+    flags_internal
+  SRCS
+    "internal/flag.cc"
+  HDRS
+    "internal/flag.h"
+    "internal/sequence_lock.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::base
+    absl::config
+    absl::flags_commandlineflag
+    absl::flags_commandlineflag_internal
+    absl::flags_config
+    absl::flags_marshalling
+    absl::synchronization
+    absl::meta
+    absl::utility
+  PUBLIC
+)
+
+absl_cc_library(
+  NAME
+    flags
+  HDRS
+    "declare.h"
+    "flag.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::flags_commandlineflag
+    absl::flags_config
+    absl::flags_internal
+    absl::flags_reflection
+    absl::base
+    absl::core_headers
+    absl::strings
+)
+
+# Internal-only target, do not depend on directly.
+absl_cc_library(
+  NAME
+    flags_usage_internal
+  SRCS
+    "internal/usage.cc"
+  HDRS
+    "internal/usage.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::flags_config
+    absl::flags
+    absl::flags_commandlineflag
+    absl::flags_internal
+    absl::flags_path_util
+    absl::flags_private_handle_accessor
+    absl::flags_program_name
+    absl::flags_reflection
+    absl::strings
+    absl::synchronization
+)
+
+absl_cc_library(
+  NAME
+    flags_usage
+  SRCS
+    "usage.cc"
+  HDRS
+    "usage.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::core_headers
+    absl::flags_usage_internal
+    absl::raw_logging_internal
+    absl::strings
+    absl::synchronization
+)
+
+absl_cc_library(
+  NAME
+    flags_parse
+  SRCS
+    "parse.cc"
+  HDRS
+    "internal/parse.h"
+    "parse.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::algorithm_container
+    absl::config
+    absl::core_headers
+    absl::flags_config
+    absl::flags
+    absl::flags_commandlineflag
+    absl::flags_commandlineflag_internal
+    absl::flags_internal
+    absl::flags_private_handle_accessor
+    absl::flags_program_name
+    absl::flags_reflection
+    absl::flags_usage
+    absl::strings
+    absl::synchronization
+)
+
+############################################################################
+# Unit tests in alphabetical order.
+
+absl_cc_test(
+  NAME
+    flags_commandlineflag_test
+  SRCS
+    "commandlineflag_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::flags
+    absl::flags_commandlineflag
+    absl::flags_commandlineflag_internal
+    absl::flags_config
+    absl::flags_private_handle_accessor
+    absl::flags_reflection
+    absl::memory
+    absl::strings
+    GTest::gtest_main
+)
+
+absl_cc_test(
+  NAME
+    flags_config_test
+  SRCS
+    "config_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::flags_config
+    GTest::gtest_main
+)
+
+absl_cc_test(
+  NAME
+    flags_flag_test
+  SRCS
+    "flag_test.cc"
+    "flag_test_defs.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::core_headers
+    absl::flags
+    absl::flags_config
+    absl::flags_internal
+    absl::flags_marshalling
+    absl::flags_reflection
+    absl::int128
+    absl::strings
+    absl::time
+    GTest::gtest_main
+)
+
+absl_cc_test(
+  NAME
+    flags_marshalling_test
+  SRCS
+    "marshalling_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::flags_marshalling
+    GTest::gtest_main
+)
+
+absl_cc_test(
+  NAME
+    flags_parse_test
+  SRCS
+    "parse_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::flags
+    absl::flags_parse
+    absl::flags_reflection
+    absl::flags_usage_internal
+    absl::log
+    absl::scoped_set_env
+    absl::span
+    absl::strings
+    GTest::gmock_main
+)
+
+absl_cc_test(
+  NAME
+    flags_path_util_test
+  SRCS
+    "internal/path_util_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::flags_path_util
+    GTest::gtest_main
+)
+
+absl_cc_test(
+  NAME
+    flags_program_name_test
+  SRCS
+    "internal/program_name_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::flags_program_name
+    absl::strings
+    GTest::gtest_main
+)
+
+absl_cc_test(
+  NAME
+    flags_reflection_test
+  SRCS
+    "reflection_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::flags_commandlineflag_internal
+    absl::flags
+    absl::flags_reflection
+    absl::flags_usage
+    absl::memory
+    absl::strings
+    GTest::gmock_main
+)
+
+absl_cc_test(
+  NAME
+    flags_sequence_lock_test
+  SRCS
+    "internal/sequence_lock_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::base
+    absl::flags_internal
+    absl::time
+    GTest::gmock_main
+)
+
+absl_cc_test(
+  NAME
+    flags_usage_config_test
+  SRCS
+    "usage_config_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::flags_config
+    absl::flags_path_util
+    absl::flags_program_name
+    absl::strings
+    GTest::gtest_main
+)
+
+absl_cc_test(
+  NAME
+    flags_usage_test
+  SRCS
+    "internal/usage_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::flags_config
+    absl::flags
+    absl::flags_path_util
+    absl::flags_program_name
+    absl::flags_parse
+    absl::flags_reflection
+    absl::flags_usage
+    absl::strings
+    GTest::gmock
+)

weight/_dep/abseil-cpp/absl/flags/commandlineflag.cc

@@ -0,0 +1,34 @@
+//
+// Copyright 2020 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/flags/commandlineflag.h"
+
+#include <string>
+
+#include "absl/base/config.h"
+#include "absl/flags/internal/commandlineflag.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+bool CommandLineFlag::IsRetired() const { return false; }
+bool CommandLineFlag::ParseFrom(absl::string_view value, std::string* error) {
+  return ParseFrom(value, flags_internal::SET_FLAGS_VALUE,
+                   flags_internal::kProgrammaticChange, *error);
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/flags/commandlineflag.h

@@ -0,0 +1,200 @@
+//
+// Copyright 2020 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// -----------------------------------------------------------------------------
+// File: commandlineflag.h
+// -----------------------------------------------------------------------------
+//
+// This header file defines the `CommandLineFlag`, which acts as a type-erased
+// handle for accessing metadata about the Abseil Flag in question.
+//
+// Because an actual Abseil flag is of an unspecified type, you should not
+// manipulate or interact directly with objects of that type. Instead, use the
+// CommandLineFlag type as an intermediary.
+#ifndef ABSL_FLAGS_COMMANDLINEFLAG_H_
+#define ABSL_FLAGS_COMMANDLINEFLAG_H_
+
+#include <memory>
+#include <string>
+
+#include "absl/base/config.h"
+#include "absl/base/internal/fast_type_id.h"
+#include "absl/flags/internal/commandlineflag.h"
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace flags_internal {
+class PrivateHandleAccessor;
+}  // namespace flags_internal
+
+// CommandLineFlag
+//
+// This type acts as a type-erased handle for an instance of an Abseil Flag and
+// holds reflection information pertaining to that flag. Use CommandLineFlag to
+// access a flag's name, location, help string etc.
+//
+// To obtain an absl::CommandLineFlag, invoke `absl::FindCommandLineFlag()`
+// passing it the flag name string.
+//
+// Example:
+//
+//   // Obtain reflection handle for a flag named "flagname".
+//   const absl::CommandLineFlag* my_flag_data =
+//        absl::FindCommandLineFlag("flagname");
+//
+//   // Now you can get flag info from that reflection handle.
+//   std::string flag_location = my_flag_data->Filename();
+//   ...
+class CommandLineFlag {
+ public:
+  constexpr CommandLineFlag() = default;
+
+  // Not copyable/assignable.
+  CommandLineFlag(const CommandLineFlag&) = delete;
+  CommandLineFlag& operator=(const CommandLineFlag&) = delete;
+
+  // absl::CommandLineFlag::IsOfType()
+  //
+  // Return true iff flag has type T.
+  template <typename T>
+  inline bool IsOfType() const {
+    return TypeId() == base_internal::FastTypeId<T>();
+  }
+
+  // absl::CommandLineFlag::TryGet()
+  //
+  // Attempts to retrieve the flag value. Returns value on success,
+  // absl::nullopt otherwise.
+  template <typename T>
+  absl::optional<T> TryGet() const {
+    if (IsRetired() || !IsOfType<T>()) {
+      return absl::nullopt;
+    }
+
+    // Implementation notes:
+    //
+    // We are wrapping a union around the value of `T` to serve three purposes:
+    //
+    //  1. `U.value` has correct size and alignment for a value of type `T`
+    //  2. The `U.value` constructor is not invoked since U's constructor does
+    //     not do it explicitly.
+    //  3. The `U.value` destructor is invoked since U's destructor does it
+    //     explicitly. This makes `U` a kind of RAII wrapper around non default
+    //     constructible value of T, which is destructed when we leave the
+    //     scope. We do need to destroy U.value, which is constructed by
+    //     CommandLineFlag::Read even though we left it in a moved-from state
+    //     after std::move.
+    //
+    // All of this serves to avoid requiring `T` being default constructible.
+    union U {
+      T value;
+      U() {}
+      ~U() { value.~T(); }
+    };
+    U u;
+
+    Read(&u.value);
+    // allow retired flags to be "read", so we can report invalid access.
+    if (IsRetired()) {
+      return absl::nullopt;
+    }
+    return std::move(u.value);
+  }
+
+  // absl::CommandLineFlag::Name()
+  //
+  // Returns name of this flag.
+  virtual absl::string_view Name() const = 0;
+
+  // absl::CommandLineFlag::Filename()
+  //
+  // Returns name of the file where this flag is defined.
+  virtual std::string Filename() const = 0;
+
+  // absl::CommandLineFlag::Help()
+  //
+  // Returns help message associated with this flag.
+  virtual std::string Help() const = 0;
+
+  // absl::CommandLineFlag::IsRetired()
+  //
+  // Returns true iff this object corresponds to retired flag.
+  virtual bool IsRetired() const;
+
+  // absl::CommandLineFlag::DefaultValue()
+  //
+  // Returns the default value for this flag.
+  virtual std::string DefaultValue() const = 0;
+
+  // absl::CommandLineFlag::CurrentValue()
+  //
+  // Returns the current value for this flag.
+  virtual std::string CurrentValue() const = 0;
+
+  // absl::CommandLineFlag::ParseFrom()
+  //
+  // Sets the value of the flag based on specified string `value`. If the flag
+  // was successfully set to new value, it returns true. Otherwise, sets `error`
+  // to indicate the error, leaves the flag unchanged, and returns false.
+  bool ParseFrom(absl::string_view value, std::string* error);
+
+ protected:
+  ~CommandLineFlag() = default;
+
+ private:
+  friend class flags_internal::PrivateHandleAccessor;
+
+  // Sets the value of the flag based on specified string `value`. If the flag
+  // was successfully set to new value, it returns true. Otherwise, sets `error`
+  // to indicate the error, leaves the flag unchanged, and returns false. There
+  // are three ways to set the flag's value:
+  //  * Update the current flag value
+  //  * Update the flag's default value
+  //  * Update the current flag value if it was never set before
+  // The mode is selected based on `set_mode` parameter.
+  virtual bool ParseFrom(absl::string_view value,
+                         flags_internal::FlagSettingMode set_mode,
+                         flags_internal::ValueSource source,
+                         std::string& error) = 0;
+
+  // Returns id of the flag's value type.
+  virtual flags_internal::FlagFastTypeId TypeId() const = 0;
+
+  // Interface to save flag to some persistent state. Returns current flag state
+  // or nullptr if flag does not support saving and restoring a state.
+  virtual std::unique_ptr<flags_internal::FlagStateInterface> SaveState() = 0;
+
+  // Copy-construct a new value of the flag's type in a memory referenced by
+  // the dst based on the current flag's value.
+  virtual void Read(void* dst) const = 0;
+
+  // To be deleted. Used to return true if flag's current value originated from
+  // command line.
+  virtual bool IsSpecifiedOnCommandLine() const = 0;
+
+  // Validates supplied value using validator or parseflag routine
+  virtual bool ValidateInputValue(absl::string_view value) const = 0;
+
+  // Checks that flags default value can be converted to string and back to the
+  // flag's value type.
+  virtual void CheckDefaultValueParsingRoundtrip() const = 0;
+};
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_FLAGS_COMMANDLINEFLAG_H_

weight/_dep/abseil-cpp/absl/flags/commandlineflag_test.cc

@@ -0,0 +1,231 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/flags/commandlineflag.h"
+
+#include <memory>
+#include <string>
+
+#include "gtest/gtest.h"
+#include "absl/flags/flag.h"
+#include "absl/flags/internal/commandlineflag.h"
+#include "absl/flags/internal/private_handle_accessor.h"
+#include "absl/flags/reflection.h"
+#include "absl/flags/usage_config.h"
+#include "absl/memory/memory.h"
+#include "absl/strings/match.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/string_view.h"
+
+ABSL_FLAG(int, int_flag, 201, "int_flag help");
+ABSL_FLAG(std::string, string_flag, "dflt",
+          absl::StrCat("string_flag", " help"));
+ABSL_RETIRED_FLAG(bool, bool_retired_flag, false, "bool_retired_flag help");
+
+// These are only used to test default values.
+ABSL_FLAG(int, int_flag2, 201, "");
+ABSL_FLAG(std::string, string_flag2, "dflt", "");
+
+namespace {
+
+namespace flags = absl::flags_internal;
+
+class CommandLineFlagTest : public testing::Test {
+ protected:
+  static void SetUpTestSuite() {
+    // Install a function to normalize filenames before this test is run.
+    absl::FlagsUsageConfig default_config;
+    default_config.normalize_filename = &CommandLineFlagTest::NormalizeFileName;
+    absl::SetFlagsUsageConfig(default_config);
+  }
+
+  void SetUp() override { flag_saver_ = absl::make_unique<absl::FlagSaver>(); }
+  void TearDown() override { flag_saver_.reset(); }
+
+ private:
+  static std::string NormalizeFileName(absl::string_view fname) {
+#ifdef _WIN32
+    std::string normalized(fname);
+    std::replace(normalized.begin(), normalized.end(), '\\', '/');
+    fname = normalized;
+#endif
+    return std::string(fname);
+  }
+
+  std::unique_ptr<absl::FlagSaver> flag_saver_;
+};
+
+TEST_F(CommandLineFlagTest, TestAttributesAccessMethods) {
+  auto* flag_01 = absl::FindCommandLineFlag("int_flag");
+
+  ASSERT_TRUE(flag_01);
+  EXPECT_EQ(flag_01->Name(), "int_flag");
+  EXPECT_EQ(flag_01->Help(), "int_flag help");
+  EXPECT_TRUE(!flag_01->IsRetired());
+  EXPECT_TRUE(flag_01->IsOfType<int>());
+  EXPECT_TRUE(!flag_01->IsOfType<bool>());
+  EXPECT_TRUE(!flag_01->IsOfType<std::string>());
+  EXPECT_TRUE(absl::EndsWith(flag_01->Filename(),
+                             "absl/flags/commandlineflag_test.cc"))
+      << flag_01->Filename();
+
+  auto* flag_02 = absl::FindCommandLineFlag("string_flag");
+
+  ASSERT_TRUE(flag_02);
+  EXPECT_EQ(flag_02->Name(), "string_flag");
+  EXPECT_EQ(flag_02->Help(), "string_flag help");
+  EXPECT_TRUE(!flag_02->IsRetired());
+  EXPECT_TRUE(flag_02->IsOfType<std::string>());
+  EXPECT_TRUE(!flag_02->IsOfType<bool>());
+  EXPECT_TRUE(!flag_02->IsOfType<int>());
+  EXPECT_TRUE(absl::EndsWith(flag_02->Filename(),
+                             "absl/flags/commandlineflag_test.cc"))
+      << flag_02->Filename();
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(CommandLineFlagTest, TestValueAccessMethods) {
+  absl::SetFlag(&FLAGS_int_flag2, 301);
+  auto* flag_01 = absl::FindCommandLineFlag("int_flag2");
+
+  ASSERT_TRUE(flag_01);
+  EXPECT_EQ(flag_01->CurrentValue(), "301");
+  EXPECT_EQ(flag_01->DefaultValue(), "201");
+
+  absl::SetFlag(&FLAGS_string_flag2, "new_str_value");
+  auto* flag_02 = absl::FindCommandLineFlag("string_flag2");
+
+  ASSERT_TRUE(flag_02);
+  EXPECT_EQ(flag_02->CurrentValue(), "new_str_value");
+  EXPECT_EQ(flag_02->DefaultValue(), "dflt");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(CommandLineFlagTest, TestParseFromCurrentValue) {
+  std::string err;
+
+  auto* flag_01 = absl::FindCommandLineFlag("int_flag");
+  EXPECT_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
+
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "11", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange, err));
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 11);
+  EXPECT_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
+
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "-123", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange,
+      err));
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), -123);
+  EXPECT_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
+
+  EXPECT_TRUE(!flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "xyz", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange,
+      err));
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), -123);
+  EXPECT_EQ(err, "Illegal value 'xyz' specified for flag 'int_flag'");
+  EXPECT_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
+
+  EXPECT_TRUE(!flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "A1", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange, err));
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), -123);
+  EXPECT_EQ(err, "Illegal value 'A1' specified for flag 'int_flag'");
+  EXPECT_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
+
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "0x10", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange,
+      err));
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 16);
+  EXPECT_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
+
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "011", flags::SET_FLAGS_VALUE, flags::kCommandLine, err));
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 11);
+  EXPECT_TRUE(flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
+
+  EXPECT_TRUE(!flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange, err));
+  EXPECT_EQ(err, "Illegal value '' specified for flag 'int_flag'");
+
+  auto* flag_02 = absl::FindCommandLineFlag("string_flag");
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_02, "xyz", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange,
+      err));
+  EXPECT_EQ(absl::GetFlag(FLAGS_string_flag), "xyz");
+
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_02, "", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange, err));
+  EXPECT_EQ(absl::GetFlag(FLAGS_string_flag), "");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(CommandLineFlagTest, TestParseFromDefaultValue) {
+  std::string err;
+
+  auto* flag_01 = absl::FindCommandLineFlag("int_flag");
+
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "111", flags::SET_FLAGS_DEFAULT, flags::kProgrammaticChange,
+      err));
+  EXPECT_EQ(flag_01->DefaultValue(), "111");
+
+  auto* flag_02 = absl::FindCommandLineFlag("string_flag");
+
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_02, "abc", flags::SET_FLAGS_DEFAULT, flags::kProgrammaticChange,
+      err));
+  EXPECT_EQ(flag_02->DefaultValue(), "abc");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(CommandLineFlagTest, TestParseFromIfDefault) {
+  std::string err;
+
+  auto* flag_01 = absl::FindCommandLineFlag("int_flag");
+
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "22", flags::SET_FLAG_IF_DEFAULT, flags::kProgrammaticChange,
+      err))
+      << err;
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 22);
+
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "33", flags::SET_FLAG_IF_DEFAULT, flags::kProgrammaticChange,
+      err));
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 22);
+  // EXPECT_EQ(err, "ERROR: int_flag is already set to 22");
+
+  // Reset back to default value
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "201", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange,
+      err));
+
+  EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
+      *flag_01, "33", flags::SET_FLAG_IF_DEFAULT, flags::kProgrammaticChange,
+      err));
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 201);
+  // EXPECT_EQ(err, "ERROR: int_flag is already set to 201");
+}
+
+}  // namespace

weight/_dep/abseil-cpp/absl/flags/config.h

@@ -0,0 +1,68 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_FLAGS_CONFIG_H_
+#define ABSL_FLAGS_CONFIG_H_
+
+// Determine if we should strip string literals from the Flag objects.
+// By default we strip string literals on mobile platforms.
+#if !defined(ABSL_FLAGS_STRIP_NAMES)
+
+#if defined(__ANDROID__)
+#define ABSL_FLAGS_STRIP_NAMES 1
+
+#elif defined(__APPLE__)
+#include <TargetConditionals.h>
+#if defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE
+#define ABSL_FLAGS_STRIP_NAMES 1
+#elif defined(TARGET_OS_EMBEDDED) && TARGET_OS_EMBEDDED
+#define ABSL_FLAGS_STRIP_NAMES 1
+#endif  // TARGET_OS_*
+#endif
+
+#endif  // !defined(ABSL_FLAGS_STRIP_NAMES)
+
+#if !defined(ABSL_FLAGS_STRIP_NAMES)
+// If ABSL_FLAGS_STRIP_NAMES wasn't set on the command line or above,
+// the default is not to strip.
+#define ABSL_FLAGS_STRIP_NAMES 0
+#endif
+
+#if !defined(ABSL_FLAGS_STRIP_HELP)
+// By default, if we strip names, we also strip help.
+#define ABSL_FLAGS_STRIP_HELP ABSL_FLAGS_STRIP_NAMES
+#endif
+
+// These macros represent the "source of truth" for the list of supported
+// built-in types.
+#define ABSL_FLAGS_INTERNAL_BUILTIN_TYPES(A) \
+  A(bool, bool)                              \
+  A(short, short)                            \
+  A(unsigned short, unsigned_short)          \
+  A(int, int)                                \
+  A(unsigned int, unsigned_int)              \
+  A(long, long)                              \
+  A(unsigned long, unsigned_long)            \
+  A(long long, long_long)                    \
+  A(unsigned long long, unsigned_long_long)  \
+  A(double, double)                          \
+  A(float, float)
+
+#define ABSL_FLAGS_INTERNAL_SUPPORTED_TYPES(A) \
+  ABSL_FLAGS_INTERNAL_BUILTIN_TYPES(A)         \
+  A(std::string, std_string)                   \
+  A(std::vector<std::string>, std_vector_of_string)
+
+#endif  // ABSL_FLAGS_CONFIG_H_

weight/_dep/abseil-cpp/absl/flags/config_test.cc

@@ -0,0 +1,61 @@
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/flags/config.h"
+
+#ifdef __APPLE__
+#include <TargetConditionals.h>
+#endif
+
+#include "gtest/gtest.h"
+
+#ifndef ABSL_FLAGS_STRIP_NAMES
+#error ABSL_FLAGS_STRIP_NAMES is not defined
+#endif
+
+#ifndef ABSL_FLAGS_STRIP_HELP
+#error ABSL_FLAGS_STRIP_HELP is not defined
+#endif
+
+namespace {
+
+// Test that ABSL_FLAGS_STRIP_NAMES and ABSL_FLAGS_STRIP_HELP are configured how
+// we expect them to be configured by default. If you override this
+// configuration, this test will fail, but the code should still be safe to use.
+TEST(FlagsConfigTest, Test) {
+#if defined(__ANDROID__)
+  EXPECT_EQ(ABSL_FLAGS_STRIP_NAMES, 1);
+  EXPECT_EQ(ABSL_FLAGS_STRIP_HELP, 1);
+#elif defined(__myriad2__)
+  EXPECT_EQ(ABSL_FLAGS_STRIP_NAMES, 0);
+  EXPECT_EQ(ABSL_FLAGS_STRIP_HELP, 0);
+#elif defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE
+  EXPECT_EQ(ABSL_FLAGS_STRIP_NAMES, 1);
+  EXPECT_EQ(ABSL_FLAGS_STRIP_HELP, 1);
+#elif defined(TARGET_OS_EMBEDDED) && TARGET_OS_EMBEDDED
+  EXPECT_EQ(ABSL_FLAGS_STRIP_NAMES, 1);
+  EXPECT_EQ(ABSL_FLAGS_STRIP_HELP, 1);
+#elif defined(__APPLE__)
+  EXPECT_EQ(ABSL_FLAGS_STRIP_NAMES, 0);
+  EXPECT_EQ(ABSL_FLAGS_STRIP_HELP, 0);
+#elif defined(_WIN32)
+  EXPECT_EQ(ABSL_FLAGS_STRIP_NAMES, 0);
+  EXPECT_EQ(ABSL_FLAGS_STRIP_HELP, 0);
+#elif defined(__linux__)
+  EXPECT_EQ(ABSL_FLAGS_STRIP_NAMES, 0);
+  EXPECT_EQ(ABSL_FLAGS_STRIP_HELP, 0);
+#endif
+}
+
+}  // namespace

weight/_dep/abseil-cpp/absl/flags/declare.h

@@ -0,0 +1,68 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// -----------------------------------------------------------------------------
+// File: declare.h
+// -----------------------------------------------------------------------------
+//
+// This file defines the ABSL_DECLARE_FLAG macro, allowing you to declare an
+// `absl::Flag` for use within a translation unit. You should place this
+// declaration within the header file associated with the .cc file that defines
+// and owns the `Flag`.
+
+#ifndef ABSL_FLAGS_DECLARE_H_
+#define ABSL_FLAGS_DECLARE_H_
+
+#include "absl/base/config.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace flags_internal {
+
+// absl::Flag<T> represents a flag of type 'T' created by ABSL_FLAG.
+template <typename T>
+class Flag;
+
+}  // namespace flags_internal
+
+// Flag
+//
+// Forward declaration of the `absl::Flag` type for use in defining the macro.
+template <typename T>
+using Flag = flags_internal::Flag<T>;
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+// ABSL_DECLARE_FLAG()
+//
+// This macro is a convenience for declaring use of an `absl::Flag` within a
+// translation unit. This macro should be used within a header file to
+// declare usage of the flag within any .cc file including that header file.
+//
+// The ABSL_DECLARE_FLAG(type, name) macro expands to:
+//
+//   extern absl::Flag<type> FLAGS_name;
+#define ABSL_DECLARE_FLAG(type, name) ABSL_DECLARE_FLAG_INTERNAL(type, name)
+
+// Internal implementation of ABSL_DECLARE_FLAG to allow macro expansion of its
+// arguments. Clients must use ABSL_DECLARE_FLAG instead.
+#define ABSL_DECLARE_FLAG_INTERNAL(type, name)               \
+  extern absl::Flag<type> FLAGS_##name;                      \
+  namespace absl /* block flags in namespaces */ {}          \
+  /* second redeclaration is to allow applying attributes */ \
+  extern absl::Flag<type> FLAGS_##name
+
+#endif  // ABSL_FLAGS_DECLARE_H_

weight/_dep/abseil-cpp/absl/flags/flag.h

@@ -0,0 +1,301 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// -----------------------------------------------------------------------------
+// File: flag.h
+// -----------------------------------------------------------------------------
+//
+// This header file defines the `absl::Flag<T>` type for holding command-line
+// flag data, and abstractions to create, get and set such flag data.
+//
+// It is important to note that this type is **unspecified** (an implementation
+// detail) and you do not construct or manipulate actual `absl::Flag<T>`
+// instances. Instead, you define and declare flags using the
+// `ABSL_FLAG()` and `ABSL_DECLARE_FLAG()` macros, and get and set flag values
+// using the `absl::GetFlag()` and `absl::SetFlag()` functions.
+
+#ifndef ABSL_FLAGS_FLAG_H_
+#define ABSL_FLAGS_FLAG_H_
+
+#include <string>
+#include <type_traits>
+
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
+#include "absl/base/optimization.h"
+#include "absl/flags/config.h"
+#include "absl/flags/internal/flag.h"
+#include "absl/flags/internal/registry.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+// Flag
+//
+// An `absl::Flag` holds a command-line flag value, providing a runtime
+// parameter to a binary. Such flags should be defined in the global namespace
+// and (preferably) in the module containing the binary's `main()` function.
+//
+// You should not construct and cannot use the `absl::Flag` type directly;
+// instead, you should declare flags using the `ABSL_DECLARE_FLAG()` macro
+// within a header file, and define your flag using `ABSL_FLAG()` within your
+// header's associated `.cc` file. Such flags will be named `FLAGS_name`.
+//
+// Example:
+//
+//    .h file
+//
+//      // Declares usage of a flag named "FLAGS_count"
+//      ABSL_DECLARE_FLAG(int, count);
+//
+//    .cc file
+//
+//      // Defines a flag named "FLAGS_count" with a default `int` value of 0.
+//      ABSL_FLAG(int, count, 0, "Count of items to process");
+//
+// No public methods of `absl::Flag<T>` are part of the Abseil Flags API.
+//
+// For type support of Abseil Flags, see the marshalling.h header file, which
+// discusses supported standard types, optional flags, and additional Abseil
+// type support.
+
+template <typename T>
+using Flag = flags_internal::Flag<T>;
+
+// GetFlag()
+//
+// Returns the value (of type `T`) of an `absl::Flag<T>` instance, by value. Do
+// not construct an `absl::Flag<T>` directly and call `absl::GetFlag()`;
+// instead, refer to flag's constructed variable name (e.g. `FLAGS_name`).
+// Because this function returns by value and not by reference, it is
+// thread-safe, but note that the operation may be expensive; as a result, avoid
+// `absl::GetFlag()` within any tight loops.
+//
+// Example:
+//
+//   // FLAGS_count is a Flag of type `int`
+//   int my_count = absl::GetFlag(FLAGS_count);
+//
+//   // FLAGS_firstname is a Flag of type `std::string`
+//   std::string first_name = absl::GetFlag(FLAGS_firstname);
+template <typename T>
+ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) {
+  return flags_internal::FlagImplPeer::InvokeGet<T>(flag);
+}
+
+// SetFlag()
+//
+// Sets the value of an `absl::Flag` to the value `v`. Do not construct an
+// `absl::Flag<T>` directly and call `absl::SetFlag()`; instead, use the
+// flag's variable name (e.g. `FLAGS_name`). This function is
+// thread-safe, but is potentially expensive. Avoid setting flags in general,
+// but especially within performance-critical code.
+template <typename T>
+void SetFlag(absl::Flag<T>* flag, const T& v) {
+  flags_internal::FlagImplPeer::InvokeSet(*flag, v);
+}
+
+// Overload of `SetFlag()` to allow callers to pass in a value that is
+// convertible to `T`. E.g., use this overload to pass a "const char*" when `T`
+// is `std::string`.
+template <typename T, typename V>
+void SetFlag(absl::Flag<T>* flag, const V& v) {
+  T value(v);
+  flags_internal::FlagImplPeer::InvokeSet(*flag, value);
+}
+
+// GetFlagReflectionHandle()
+//
+// Returns the reflection handle corresponding to specified Abseil Flag
+// instance. Use this handle to access flag's reflection information, like name,
+// location, default value etc.
+//
+// Example:
+//
+//   std::string = absl::GetFlagReflectionHandle(FLAGS_count).DefaultValue();
+
+template <typename T>
+const CommandLineFlag& GetFlagReflectionHandle(const absl::Flag<T>& f) {
+  return flags_internal::FlagImplPeer::InvokeReflect(f);
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+
+// ABSL_FLAG()
+//
+// This macro defines an `absl::Flag<T>` instance of a specified type `T`:
+//
+//   ABSL_FLAG(T, name, default_value, help);
+//
+// where:
+//
+//   * `T` is a supported flag type (see the list of types in `marshalling.h`),
+//   * `name` designates the name of the flag (as a global variable
+//     `FLAGS_name`),
+//   * `default_value` is an expression holding the default value for this flag
+//     (which must be implicitly convertible to `T`),
+//   * `help` is the help text, which can also be an expression.
+//
+// This macro expands to a flag named 'FLAGS_name' of type 'T':
+//
+//   absl::Flag<T> FLAGS_name = ...;
+//
+// Note that all such instances are created as global variables.
+//
+// For `ABSL_FLAG()` values that you wish to expose to other translation units,
+// it is recommended to define those flags within the `.cc` file associated with
+// the header where the flag is declared.
+//
+// Note: do not construct objects of type `absl::Flag<T>` directly. Only use the
+// `ABSL_FLAG()` macro for such construction.
+#define ABSL_FLAG(Type, name, default_value, help) \
+  ABSL_FLAG_IMPL(Type, name, default_value, help)
+
+// ABSL_FLAG().OnUpdate()
+//
+// Defines a flag of type `T` with a callback attached:
+//
+//   ABSL_FLAG(T, name, default_value, help).OnUpdate(callback);
+//
+// `callback` should be convertible to `void (*)()`.
+//
+// After any setting of the flag value, the callback will be called at least
+// once. A rapid sequence of changes may be merged together into the same
+// callback. No concurrent calls to the callback will be made for the same
+// flag. Callbacks are allowed to read the current value of the flag but must
+// not mutate that flag.
+//
+// The update mechanism guarantees "eventual consistency"; if the callback
+// derives an auxiliary data structure from the flag value, it is guaranteed
+// that eventually the flag value and the derived data structure will be
+// consistent.
+//
+// Note: ABSL_FLAG.OnUpdate() does not have a public definition. Hence, this
+// comment serves as its API documentation.
+
+// -----------------------------------------------------------------------------
+// Implementation details below this section
+// -----------------------------------------------------------------------------
+
+// ABSL_FLAG_IMPL macro definition conditional on ABSL_FLAGS_STRIP_NAMES
+#define ABSL_FLAG_IMPL_FLAG_PTR(flag) flag
+#define ABSL_FLAG_IMPL_HELP_ARG(name)                      \
+  absl::flags_internal::HelpArg<AbslFlagHelpGenFor##name>( \
+      FLAGS_help_storage_##name)
+#define ABSL_FLAG_IMPL_DEFAULT_ARG(Type, name) \
+  absl::flags_internal::DefaultArg<Type, AbslFlagDefaultGenFor##name>(0)
+
+#if ABSL_FLAGS_STRIP_NAMES
+#define ABSL_FLAG_IMPL_FLAGNAME(txt) ""
+#define ABSL_FLAG_IMPL_FILENAME() ""
+#define ABSL_FLAG_IMPL_REGISTRAR(T, flag)                                      \
+  absl::flags_internal::FlagRegistrar<T, false>(ABSL_FLAG_IMPL_FLAG_PTR(flag), \
+                                                nullptr)
+#else
+#define ABSL_FLAG_IMPL_FLAGNAME(txt) txt
+#define ABSL_FLAG_IMPL_FILENAME() __FILE__
+#define ABSL_FLAG_IMPL_REGISTRAR(T, flag)                                     \
+  absl::flags_internal::FlagRegistrar<T, true>(ABSL_FLAG_IMPL_FLAG_PTR(flag), \
+                                               __FILE__)
+#endif
+
+// ABSL_FLAG_IMPL macro definition conditional on ABSL_FLAGS_STRIP_HELP
+
+#if ABSL_FLAGS_STRIP_HELP
+#define ABSL_FLAG_IMPL_FLAGHELP(txt) absl::flags_internal::kStrippedFlagHelp
+#else
+#define ABSL_FLAG_IMPL_FLAGHELP(txt) txt
+#endif
+
+// AbslFlagHelpGenFor##name is used to encapsulate both immediate (method Const)
+// and lazy (method NonConst) evaluation of help message expression. We choose
+// between the two via the call to HelpArg in absl::Flag instantiation below.
+// If help message expression is constexpr evaluable compiler will optimize
+// away this whole struct.
+// TODO(rogeeff): place these generated structs into local namespace and apply
+// ABSL_INTERNAL_UNIQUE_SHORT_NAME.
+// TODO(rogeeff): Apply __attribute__((nodebug)) to FLAGS_help_storage_##name
+#define ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, txt)                       \
+  struct AbslFlagHelpGenFor##name {                                          \
+    /* The expression is run in the caller as part of the   */               \
+    /* default value argument. That keeps temporaries alive */               \
+    /* long enough for NonConst to work correctly.          */               \
+    static constexpr absl::string_view Value(                                \
+        absl::string_view absl_flag_help = ABSL_FLAG_IMPL_FLAGHELP(txt)) {   \
+      return absl_flag_help;                                                 \
+    }                                                                        \
+    static std::string NonConst() { return std::string(Value()); }           \
+  };                                                                         \
+  constexpr auto FLAGS_help_storage_##name ABSL_INTERNAL_UNIQUE_SMALL_NAME() \
+      ABSL_ATTRIBUTE_SECTION_VARIABLE(flags_help_cold) =                     \
+          absl::flags_internal::HelpStringAsArray<AbslFlagHelpGenFor##name>( \
+              0);
+
+#define ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value)     \
+  struct AbslFlagDefaultGenFor##name {                                        \
+    Type value = absl::flags_internal::InitDefaultValue<Type>(default_value); \
+    static void Gen(void* absl_flag_default_loc) {                            \
+      new (absl_flag_default_loc) Type(AbslFlagDefaultGenFor##name{}.value);  \
+    }                                                                         \
+  };
+
+// ABSL_FLAG_IMPL
+//
+// Note: Name of registrar object is not arbitrary. It is used to "grab"
+// global name for FLAGS_no<flag_name> symbol, thus preventing the possibility
+// of defining two flags with names foo and nofoo.
+#define ABSL_FLAG_IMPL(Type, name, default_value, help)                       \
+  extern ::absl::Flag<Type> FLAGS_##name;                                     \
+  namespace absl /* block flags in namespaces */ {}                           \
+  ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value)           \
+  ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help)                             \
+  ABSL_CONST_INIT absl::Flag<Type> FLAGS_##name{                              \
+      ABSL_FLAG_IMPL_FLAGNAME(#name), ABSL_FLAG_IMPL_FILENAME(),              \
+      ABSL_FLAG_IMPL_HELP_ARG(name), ABSL_FLAG_IMPL_DEFAULT_ARG(Type, name)}; \
+  extern absl::flags_internal::FlagRegistrarEmpty FLAGS_no##name;             \
+  absl::flags_internal::FlagRegistrarEmpty FLAGS_no##name =                   \
+      ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name)
+
+// ABSL_RETIRED_FLAG
+//
+// Designates the flag (which is usually pre-existing) as "retired." A retired
+// flag is a flag that is now unused by the program, but may still be passed on
+// the command line, usually by production scripts. A retired flag is ignored
+// and code can't access it at runtime.
+//
+// This macro registers a retired flag with given name and type, with a name
+// identical to the name of the original flag you are retiring. The retired
+// flag's type can change over time, so that you can retire code to support a
+// custom flag type.
+//
+// This macro has the same signature as `ABSL_FLAG`. To retire a flag, simply
+// replace an `ABSL_FLAG` definition with `ABSL_RETIRED_FLAG`, leaving the
+// arguments unchanged (unless of course you actually want to retire the flag
+// type at this time as well).
+//
+// `default_value` is only used as a double check on the type. `explanation` is
+// unused.
+// TODO(rogeeff): replace RETIRED_FLAGS with FLAGS once forward declarations of
+// retired flags are cleaned up.
+#define ABSL_RETIRED_FLAG(type, name, default_value, explanation)      \
+  static absl::flags_internal::RetiredFlag<type> RETIRED_FLAGS_##name; \
+  ABSL_ATTRIBUTE_UNUSED static const auto RETIRED_FLAGS_REG_##name =   \
+      (RETIRED_FLAGS_##name.Retire(#name),                             \
+       ::absl::flags_internal::FlagRegistrarEmpty{})
+
+#endif  // ABSL_FLAGS_FLAG_H_

weight/_dep/abseil-cpp/absl/flags/flag_benchmark.cc

@@ -0,0 +1,251 @@
+//
+// Copyright 2020 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <stdint.h>
+
+#include <string>
+#include <vector>
+
+#include "absl/flags/flag.h"
+#include "absl/flags/marshalling.h"
+#include "absl/flags/parse.h"
+#include "absl/flags/reflection.h"
+#include "absl/strings/string_view.h"
+#include "absl/time/time.h"
+#include "absl/types/optional.h"
+#include "benchmark/benchmark.h"
+
+namespace {
+using String = std::string;
+using VectorOfStrings = std::vector<std::string>;
+using AbslDuration = absl::Duration;
+
+// We do not want to take over marshalling for the types absl::optional<int>,
+// absl::optional<std::string> which we do not own. Instead we introduce unique
+// "aliases" to these types, which we do.
+using AbslOptionalInt = absl::optional<int>;
+struct OptionalInt : AbslOptionalInt {
+  using AbslOptionalInt::AbslOptionalInt;
+};
+// Next two functions represent Abseil Flags marshalling for OptionalInt.
+bool AbslParseFlag(absl::string_view src, OptionalInt* flag,
+                   std::string* error) {
+  int val;
+  if (src.empty())
+    flag->reset();
+  else if (!absl::ParseFlag(src, &val, error))
+    return false;
+  *flag = val;
+  return true;
+}
+std::string AbslUnparseFlag(const OptionalInt& flag) {
+  return !flag ? "" : absl::UnparseFlag(*flag);
+}
+
+using AbslOptionalString = absl::optional<std::string>;
+struct OptionalString : AbslOptionalString {
+  using AbslOptionalString::AbslOptionalString;
+};
+// Next two functions represent Abseil Flags marshalling for OptionalString.
+bool AbslParseFlag(absl::string_view src, OptionalString* flag,
+                   std::string* error) {
+  std::string val;
+  if (src.empty())
+    flag->reset();
+  else if (!absl::ParseFlag(src, &val, error))
+    return false;
+  *flag = val;
+  return true;
+}
+std::string AbslUnparseFlag(const OptionalString& flag) {
+  return !flag ? "" : absl::UnparseFlag(*flag);
+}
+
+struct UDT {
+  UDT() = default;
+  UDT(const UDT&) {}
+  UDT& operator=(const UDT&) { return *this; }
+};
+// Next two functions represent Abseil Flags marshalling for UDT.
+bool AbslParseFlag(absl::string_view, UDT*, std::string*) { return true; }
+std::string AbslUnparseFlag(const UDT&) { return ""; }
+
+}  // namespace
+
+#define BENCHMARKED_TYPES(A) \
+  A(bool)                    \
+  A(int16_t)                 \
+  A(uint16_t)                \
+  A(int32_t)                 \
+  A(uint32_t)                \
+  A(int64_t)                 \
+  A(uint64_t)                \
+  A(double)                  \
+  A(float)                   \
+  A(String)                  \
+  A(VectorOfStrings)         \
+  A(OptionalInt)             \
+  A(OptionalString)          \
+  A(AbslDuration)            \
+  A(UDT)
+
+#define REPLICATE_0(A, T, name, index) A(T, name, index)
+#define REPLICATE_1(A, T, name, index) \
+  REPLICATE_0(A, T, name, index##0) REPLICATE_0(A, T, name, index##1)
+#define REPLICATE_2(A, T, name, index) \
+  REPLICATE_1(A, T, name, index##0) REPLICATE_1(A, T, name, index##1)
+#define REPLICATE_3(A, T, name, index) \
+  REPLICATE_2(A, T, name, index##0) REPLICATE_2(A, T, name, index##1)
+#define REPLICATE_4(A, T, name, index) \
+  REPLICATE_3(A, T, name, index##0) REPLICATE_3(A, T, name, index##1)
+#define REPLICATE_5(A, T, name, index) \
+  REPLICATE_4(A, T, name, index##0) REPLICATE_4(A, T, name, index##1)
+#define REPLICATE_6(A, T, name, index) \
+  REPLICATE_5(A, T, name, index##0) REPLICATE_5(A, T, name, index##1)
+#define REPLICATE_7(A, T, name, index) \
+  REPLICATE_6(A, T, name, index##0) REPLICATE_6(A, T, name, index##1)
+#define REPLICATE_8(A, T, name, index) \
+  REPLICATE_7(A, T, name, index##0) REPLICATE_7(A, T, name, index##1)
+#define REPLICATE_9(A, T, name, index) \
+  REPLICATE_8(A, T, name, index##0) REPLICATE_8(A, T, name, index##1)
+#if defined(_MSC_VER)
+#define REPLICATE(A, T, name) \
+  REPLICATE_7(A, T, name, 0) REPLICATE_7(A, T, name, 1)
+#define SINGLE_FLAG(T) FLAGS_##T##_flag_00000000
+#else
+#define REPLICATE(A, T, name) \
+  REPLICATE_9(A, T, name, 0) REPLICATE_9(A, T, name, 1)
+#define SINGLE_FLAG(T) FLAGS_##T##_flag_0000000000
+#endif
+#define REPLICATE_ALL(A, T, name) \
+  REPLICATE_9(A, T, name, 0) REPLICATE_9(A, T, name, 1)
+
+#define COUNT(T, name, index) +1
+constexpr size_t kNumFlags = 0 REPLICATE(COUNT, _, _);
+
+#if defined(__clang__) && defined(__linux__)
+// Force the flags used for benchmarks into a separate ELF section.
+// This ensures that, even when other parts of the code might change size,
+// the layout of the flags across cachelines is kept constant. This makes
+// benchmark results more reproducible across unrelated code changes.
+#pragma clang section data = ".benchmark_flags"
+#endif
+#define DEFINE_FLAG(T, name, index) ABSL_FLAG(T, name##_##index, {}, "");
+#define FLAG_DEF(T) REPLICATE(DEFINE_FLAG, T, T##_flag);
+BENCHMARKED_TYPES(FLAG_DEF)
+#if defined(__clang__) && defined(__linux__)
+#pragma clang section data = ""
+#endif
+// Register thousands of flags to bloat up the size of the registry.
+// This mimics real life production binaries.
+#define BLOAT_FLAG(_unused1, _unused2, index) \
+  ABSL_FLAG(int, bloat_flag_##index, 0, "");
+REPLICATE_ALL(BLOAT_FLAG, _, _)
+
+namespace {
+
+#define FLAG_PTR(T, name, index) &FLAGS_##name##_##index,
+#define FLAG_PTR_ARR(T)                              \
+  static constexpr absl::Flag<T>* FlagPtrs_##T[] = { \
+      REPLICATE(FLAG_PTR, T, T##_flag)};
+BENCHMARKED_TYPES(FLAG_PTR_ARR)
+
+#define BM_SingleGetFlag(T)                                    \
+  void BM_SingleGetFlag_##T(benchmark::State& state) {         \
+    for (auto _ : state) {                                     \
+      benchmark::DoNotOptimize(absl::GetFlag(SINGLE_FLAG(T))); \
+    }                                                          \
+  }                                                            \
+  BENCHMARK(BM_SingleGetFlag_##T)->ThreadRange(1, 16);
+
+BENCHMARKED_TYPES(BM_SingleGetFlag)
+
+template <typename T>
+struct Accumulator {
+  using type = T;
+};
+template <>
+struct Accumulator<String> {
+  using type = size_t;
+};
+template <>
+struct Accumulator<VectorOfStrings> {
+  using type = size_t;
+};
+template <>
+struct Accumulator<OptionalInt> {
+  using type = bool;
+};
+template <>
+struct Accumulator<OptionalString> {
+  using type = bool;
+};
+template <>
+struct Accumulator<UDT> {
+  using type = bool;
+};
+
+template <typename T>
+void Accumulate(typename Accumulator<T>::type& a, const T& f) {
+  a += f;
+}
+void Accumulate(bool& a, bool f) { a = a || f; }
+void Accumulate(size_t& a, const std::string& f) { a += f.size(); }
+void Accumulate(size_t& a, const std::vector<std::string>& f) { a += f.size(); }
+void Accumulate(bool& a, const OptionalInt& f) { a |= f.has_value(); }
+void Accumulate(bool& a, const OptionalString& f) { a |= f.has_value(); }
+void Accumulate(bool& a, const UDT& f) {
+  a |= reinterpret_cast<int64_t>(&f) & 0x1;
+}
+
+#define BM_ManyGetFlag(T)                            \
+  void BM_ManyGetFlag_##T(benchmark::State& state) { \
+    Accumulator<T>::type res = {};                   \
+    while (state.KeepRunningBatch(kNumFlags)) {      \
+      for (auto* flag_ptr : FlagPtrs_##T) {          \
+        Accumulate(res, absl::GetFlag(*flag_ptr));   \
+      }                                              \
+    }                                                \
+    benchmark::DoNotOptimize(res);                   \
+  }                                                  \
+  BENCHMARK(BM_ManyGetFlag_##T)->ThreadRange(1, 8);
+
+BENCHMARKED_TYPES(BM_ManyGetFlag)
+
+void BM_ThreadedFindCommandLineFlag(benchmark::State& state) {
+  char dummy[] = "dummy";
+  char* argv[] = {dummy};
+  // We need to ensure that flags have been parsed. That is where the registry
+  // is finalized.
+  absl::ParseCommandLine(1, argv);
+
+  while (state.KeepRunningBatch(kNumFlags)) {
+    for (auto* flag_ptr : FlagPtrs_bool) {
+      benchmark::DoNotOptimize(absl::FindCommandLineFlag(flag_ptr->Name()));
+    }
+  }
+}
+BENCHMARK(BM_ThreadedFindCommandLineFlag)->ThreadRange(1, 16);
+
+}  // namespace
+
+#ifdef __llvm__
+// To view disassembly use: gdb ${BINARY}  -batch -ex "disassemble /s $FUNC"
+#define InvokeGetFlag(T)                                             \
+  T AbslInvokeGetFlag##T() { return absl::GetFlag(SINGLE_FLAG(T)); } \
+  int odr##T = (benchmark::DoNotOptimize(AbslInvokeGetFlag##T), 1);
+
+BENCHMARKED_TYPES(InvokeGetFlag)
+#endif  // __llvm__

weight/_dep/abseil-cpp/absl/flags/flag_benchmark.lds

@@ -0,0 +1,13 @@
+/* This linker script forces the flags used by flags_benchmark
+ * into a separate page-aligned section. This isn't necessary for
+ * correctness but ensures that the benchmark results are more
+ * reproducible across unrelated code changes.
+ */
+SECTIONS {
+  .benchmark_flags : {
+    . = ALIGN(0x1000);
+    * (.benchmark_flags);
+  }
+}
+
+INSERT AFTER .data

weight/_dep/abseil-cpp/absl/flags/flag_test.cc

@@ -0,0 +1,1217 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/flags/flag.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <atomic>
+#include <cmath>
+#include <new>
+#include <string>
+#include <thread>  // NOLINT
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "absl/base/attributes.h"
+#include "absl/base/macros.h"
+#include "absl/flags/config.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/internal/flag.h"
+#include "absl/flags/marshalling.h"
+#include "absl/flags/reflection.h"
+#include "absl/flags/usage_config.h"
+#include "absl/numeric/int128.h"
+#include "absl/strings/match.h"
+#include "absl/strings/numbers.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_split.h"
+#include "absl/strings/string_view.h"
+#include "absl/time/time.h"
+
+ABSL_DECLARE_FLAG(int64_t, mistyped_int_flag);
+ABSL_DECLARE_FLAG(std::vector<std::string>, mistyped_string_flag);
+
+namespace {
+
+namespace flags = absl::flags_internal;
+
+std::string TestHelpMsg() { return "dynamic help"; }
+#if defined(_MSC_VER) && !defined(__clang__)
+std::string TestLiteralHelpMsg() { return "literal help"; }
+#endif
+template <typename T>
+void TestMakeDflt(void* dst) {
+  new (dst) T{};
+}
+void TestCallback() {}
+
+struct UDT {
+  UDT() = default;
+  UDT(const UDT&) = default;
+  UDT& operator=(const UDT&) = default;
+};
+bool AbslParseFlag(absl::string_view, UDT*, std::string*) { return true; }
+std::string AbslUnparseFlag(const UDT&) { return ""; }
+
+class FlagTest : public testing::Test {
+ protected:
+  static void SetUpTestSuite() {
+    // Install a function to normalize filenames before this test is run.
+    absl::FlagsUsageConfig default_config;
+    default_config.normalize_filename = &FlagTest::NormalizeFileName;
+    absl::SetFlagsUsageConfig(default_config);
+  }
+
+ private:
+  static std::string NormalizeFileName(absl::string_view fname) {
+#ifdef _WIN32
+    std::string normalized(fname);
+    std::replace(normalized.begin(), normalized.end(), '\\', '/');
+    fname = normalized;
+#endif
+    return std::string(fname);
+  }
+  absl::FlagSaver flag_saver_;
+};
+
+struct S1 {
+  S1() = default;
+  S1(const S1&) = default;
+  int32_t f1;
+  int64_t f2;
+};
+
+struct S2 {
+  S2() = default;
+  S2(const S2&) = default;
+  int64_t f1;
+  double f2;
+};
+
+TEST_F(FlagTest, Traits) {
+  EXPECT_EQ(flags::StorageKind<int>(),
+            flags::FlagValueStorageKind::kValueAndInitBit);
+  EXPECT_EQ(flags::StorageKind<bool>(),
+            flags::FlagValueStorageKind::kValueAndInitBit);
+  EXPECT_EQ(flags::StorageKind<double>(),
+            flags::FlagValueStorageKind::kOneWordAtomic);
+  EXPECT_EQ(flags::StorageKind<int64_t>(),
+            flags::FlagValueStorageKind::kOneWordAtomic);
+
+  EXPECT_EQ(flags::StorageKind<S1>(),
+            flags::FlagValueStorageKind::kSequenceLocked);
+  EXPECT_EQ(flags::StorageKind<S2>(),
+            flags::FlagValueStorageKind::kSequenceLocked);
+// Make sure absl::Duration uses the sequence-locked code path. MSVC 2015
+// doesn't consider absl::Duration to be trivially-copyable so we just
+// restrict this to clang as it seems to be a well-behaved compiler.
+#ifdef __clang__
+  EXPECT_EQ(flags::StorageKind<absl::Duration>(),
+            flags::FlagValueStorageKind::kSequenceLocked);
+#endif
+
+  EXPECT_EQ(flags::StorageKind<std::string>(),
+            flags::FlagValueStorageKind::kAlignedBuffer);
+  EXPECT_EQ(flags::StorageKind<std::vector<std::string>>(),
+            flags::FlagValueStorageKind::kAlignedBuffer);
+
+  EXPECT_EQ(flags::StorageKind<absl::int128>(),
+            flags::FlagValueStorageKind::kSequenceLocked);
+  EXPECT_EQ(flags::StorageKind<absl::uint128>(),
+            flags::FlagValueStorageKind::kSequenceLocked);
+}
+
+// --------------------------------------------------------------------
+
+constexpr flags::FlagHelpArg help_arg{flags::FlagHelpMsg("literal help"),
+                                      flags::FlagHelpKind::kLiteral};
+
+using String = std::string;
+using int128 = absl::int128;
+using uint128 = absl::uint128;
+
+#define DEFINE_CONSTRUCTED_FLAG(T, dflt, dflt_kind)                        \
+  constexpr flags::FlagDefaultArg f1default##T{                            \
+      flags::FlagDefaultSrc{dflt}, flags::FlagDefaultKind::dflt_kind};     \
+  constexpr absl::Flag<T> f1##T{"f1", "file", help_arg, f1default##T};     \
+  ABSL_CONST_INIT absl::Flag<T> f2##T {                                    \
+    "f2", "file",                                                          \
+        {flags::FlagHelpMsg(&TestHelpMsg), flags::FlagHelpKind::kGenFunc}, \
+        flags::FlagDefaultArg {                                            \
+      flags::FlagDefaultSrc(&TestMakeDflt<T>),                             \
+          flags::FlagDefaultKind::kGenFunc                                 \
+    }                                                                      \
+  }
+
+DEFINE_CONSTRUCTED_FLAG(bool, true, kOneWord);
+DEFINE_CONSTRUCTED_FLAG(int16_t, 1, kOneWord);
+DEFINE_CONSTRUCTED_FLAG(uint16_t, 2, kOneWord);
+DEFINE_CONSTRUCTED_FLAG(int32_t, 3, kOneWord);
+DEFINE_CONSTRUCTED_FLAG(uint32_t, 4, kOneWord);
+DEFINE_CONSTRUCTED_FLAG(int64_t, 5, kOneWord);
+DEFINE_CONSTRUCTED_FLAG(uint64_t, 6, kOneWord);
+DEFINE_CONSTRUCTED_FLAG(float, 7.8, kOneWord);
+DEFINE_CONSTRUCTED_FLAG(double, 9.10, kOneWord);
+DEFINE_CONSTRUCTED_FLAG(String, &TestMakeDflt<String>, kGenFunc);
+DEFINE_CONSTRUCTED_FLAG(UDT, &TestMakeDflt<UDT>, kGenFunc);
+DEFINE_CONSTRUCTED_FLAG(int128, 13, kGenFunc);
+DEFINE_CONSTRUCTED_FLAG(uint128, 14, kGenFunc);
+
+template <typename T>
+bool TestConstructionFor(const absl::Flag<T>& f1, absl::Flag<T>& f2) {
+  EXPECT_EQ(absl::GetFlagReflectionHandle(f1).Name(), "f1");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(f1).Help(), "literal help");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(f1).Filename(), "file");
+
+  flags::FlagRegistrar<T, false>(ABSL_FLAG_IMPL_FLAG_PTR(f2), nullptr)
+      .OnUpdate(TestCallback);
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(f2).Name(), "f2");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(f2).Help(), "dynamic help");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(f2).Filename(), "file");
+
+  return true;
+}
+
+#define TEST_CONSTRUCTED_FLAG(T) TestConstructionFor(f1##T, f2##T);
+
+TEST_F(FlagTest, TestConstruction) {
+  TEST_CONSTRUCTED_FLAG(bool);
+  TEST_CONSTRUCTED_FLAG(int16_t);
+  TEST_CONSTRUCTED_FLAG(uint16_t);
+  TEST_CONSTRUCTED_FLAG(int32_t);
+  TEST_CONSTRUCTED_FLAG(uint32_t);
+  TEST_CONSTRUCTED_FLAG(int64_t);
+  TEST_CONSTRUCTED_FLAG(uint64_t);
+  TEST_CONSTRUCTED_FLAG(float);
+  TEST_CONSTRUCTED_FLAG(double);
+  TEST_CONSTRUCTED_FLAG(String);
+  TEST_CONSTRUCTED_FLAG(UDT);
+  TEST_CONSTRUCTED_FLAG(int128);
+  TEST_CONSTRUCTED_FLAG(uint128);
+}
+
+// --------------------------------------------------------------------
+
+}  // namespace
+
+ABSL_DECLARE_FLAG(bool, test_flag_01);
+ABSL_DECLARE_FLAG(int, test_flag_02);
+ABSL_DECLARE_FLAG(int16_t, test_flag_03);
+ABSL_DECLARE_FLAG(uint16_t, test_flag_04);
+ABSL_DECLARE_FLAG(int32_t, test_flag_05);
+ABSL_DECLARE_FLAG(uint32_t, test_flag_06);
+ABSL_DECLARE_FLAG(int64_t, test_flag_07);
+ABSL_DECLARE_FLAG(uint64_t, test_flag_08);
+ABSL_DECLARE_FLAG(double, test_flag_09);
+ABSL_DECLARE_FLAG(float, test_flag_10);
+ABSL_DECLARE_FLAG(std::string, test_flag_11);
+ABSL_DECLARE_FLAG(absl::Duration, test_flag_12);
+ABSL_DECLARE_FLAG(absl::int128, test_flag_13);
+ABSL_DECLARE_FLAG(absl::uint128, test_flag_14);
+
+namespace {
+
+#if !ABSL_FLAGS_STRIP_NAMES
+
+TEST_F(FlagTest, TestFlagDeclaration) {
+  // test that we can access flag objects.
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_01).Name(),
+            "test_flag_01");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_02).Name(),
+            "test_flag_02");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_03).Name(),
+            "test_flag_03");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_04).Name(),
+            "test_flag_04");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_05).Name(),
+            "test_flag_05");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_06).Name(),
+            "test_flag_06");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_07).Name(),
+            "test_flag_07");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_08).Name(),
+            "test_flag_08");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_09).Name(),
+            "test_flag_09");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_10).Name(),
+            "test_flag_10");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_11).Name(),
+            "test_flag_11");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_12).Name(),
+            "test_flag_12");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_13).Name(),
+            "test_flag_13");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_14).Name(),
+            "test_flag_14");
+}
+#endif  // !ABSL_FLAGS_STRIP_NAMES
+
+// --------------------------------------------------------------------
+
+}  // namespace
+
+ABSL_FLAG(bool, test_flag_01, true, "test flag 01");
+ABSL_FLAG(int, test_flag_02, 1234, "test flag 02");
+ABSL_FLAG(int16_t, test_flag_03, -34, "test flag 03");
+ABSL_FLAG(uint16_t, test_flag_04, 189, "test flag 04");
+ABSL_FLAG(int32_t, test_flag_05, 10765, "test flag 05");
+ABSL_FLAG(uint32_t, test_flag_06, 40000, "test flag 06");
+ABSL_FLAG(int64_t, test_flag_07, -1234567, "test flag 07");
+ABSL_FLAG(uint64_t, test_flag_08, 9876543, "test flag 08");
+ABSL_FLAG(double, test_flag_09, -9.876e-50, "test flag 09");
+ABSL_FLAG(float, test_flag_10, 1.234e12f, "test flag 10");
+ABSL_FLAG(std::string, test_flag_11, "", "test flag 11");
+ABSL_FLAG(absl::Duration, test_flag_12, absl::Minutes(10), "test flag 12");
+ABSL_FLAG(absl::int128, test_flag_13, absl::MakeInt128(-1, 0), "test flag 13");
+ABSL_FLAG(absl::uint128, test_flag_14, absl::MakeUint128(0, 0xFFFAAABBBCCCDDD),
+          "test flag 14");
+
+namespace {
+
+#if !ABSL_FLAGS_STRIP_NAMES
+TEST_F(FlagTest, TestFlagDefinition) {
+  absl::string_view expected_file_name = "absl/flags/flag_test.cc";
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_01).Name(),
+            "test_flag_01");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_01).Help(),
+            "test flag 01");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_01).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_01).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_02).Name(),
+            "test_flag_02");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_02).Help(),
+            "test flag 02");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_02).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_02).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_03).Name(),
+            "test_flag_03");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_03).Help(),
+            "test flag 03");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_03).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_03).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_04).Name(),
+            "test_flag_04");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_04).Help(),
+            "test flag 04");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_04).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_04).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_05).Name(),
+            "test_flag_05");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_05).Help(),
+            "test flag 05");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_05).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_05).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_06).Name(),
+            "test_flag_06");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_06).Help(),
+            "test flag 06");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_06).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_06).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_07).Name(),
+            "test_flag_07");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_07).Help(),
+            "test flag 07");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_07).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_07).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_08).Name(),
+            "test_flag_08");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_08).Help(),
+            "test flag 08");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_08).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_08).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_09).Name(),
+            "test_flag_09");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_09).Help(),
+            "test flag 09");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_09).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_09).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_10).Name(),
+            "test_flag_10");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_10).Help(),
+            "test flag 10");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_10).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_10).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_11).Name(),
+            "test_flag_11");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_11).Help(),
+            "test flag 11");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_11).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_11).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_12).Name(),
+            "test_flag_12");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_12).Help(),
+            "test flag 12");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_12).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_12).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_13).Name(),
+            "test_flag_13");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_13).Help(),
+            "test flag 13");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_13).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_13).Filename();
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_14).Name(),
+            "test_flag_14");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_14).Help(),
+            "test flag 14");
+  EXPECT_TRUE(absl::EndsWith(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_14).Filename(),
+      expected_file_name))
+      << absl::GetFlagReflectionHandle(FLAGS_test_flag_14).Filename();
+}
+#endif  // !ABSL_FLAGS_STRIP_NAMES
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagTest, TestDefault) {
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_01).DefaultValue(),
+            "true");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_02).DefaultValue(),
+            "1234");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_03).DefaultValue(),
+            "-34");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_04).DefaultValue(),
+            "189");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_05).DefaultValue(),
+            "10765");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_06).DefaultValue(),
+            "40000");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_07).DefaultValue(),
+            "-1234567");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_08).DefaultValue(),
+            "9876543");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_09).DefaultValue(),
+            "-9.876e-50");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_10).DefaultValue(),
+            "1.234e+12");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_11).DefaultValue(),
+            "");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_12).DefaultValue(),
+            "10m");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_13).DefaultValue(),
+            "-18446744073709551616");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_14).DefaultValue(),
+            "1152827684197027293");
+
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_01).CurrentValue(),
+            "true");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_02).CurrentValue(),
+            "1234");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_03).CurrentValue(),
+            "-34");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_04).CurrentValue(),
+            "189");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_05).CurrentValue(),
+            "10765");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_06).CurrentValue(),
+            "40000");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_07).CurrentValue(),
+            "-1234567");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_08).CurrentValue(),
+            "9876543");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_09).CurrentValue(),
+            "-9.876e-50");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_10).CurrentValue(),
+            "1.234e+12");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_11).CurrentValue(),
+            "");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_12).CurrentValue(),
+            "10m");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_13).CurrentValue(),
+            "-18446744073709551616");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_14).CurrentValue(),
+            "1152827684197027293");
+
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_01), true);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_02), 1234);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_03), -34);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_04), 189);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_05), 10765);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_06), 40000);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_07), -1234567);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_08), 9876543);
+  EXPECT_NEAR(absl::GetFlag(FLAGS_test_flag_09), -9.876e-50, 1e-55);
+  EXPECT_NEAR(absl::GetFlag(FLAGS_test_flag_10), 1.234e12f, 1e5f);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_11), "");
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_12), absl::Minutes(10));
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_13), absl::MakeInt128(-1, 0));
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_14),
+            absl::MakeUint128(0, 0xFFFAAABBBCCCDDD));
+}
+
+// --------------------------------------------------------------------
+
+struct NonTriviallyCopyableAggregate {
+  NonTriviallyCopyableAggregate() = default;
+  NonTriviallyCopyableAggregate(const NonTriviallyCopyableAggregate& rhs)
+      : value(rhs.value) {}
+  NonTriviallyCopyableAggregate& operator=(
+      const NonTriviallyCopyableAggregate& rhs) {
+    value = rhs.value;
+    return *this;
+  }
+
+  int value;
+};
+bool AbslParseFlag(absl::string_view src, NonTriviallyCopyableAggregate* f,
+                   std::string* e) {
+  return absl::ParseFlag(src, &f->value, e);
+}
+std::string AbslUnparseFlag(const NonTriviallyCopyableAggregate& ntc) {
+  return absl::StrCat(ntc.value);
+}
+
+bool operator==(const NonTriviallyCopyableAggregate& ntc1,
+                const NonTriviallyCopyableAggregate& ntc2) {
+  return ntc1.value == ntc2.value;
+}
+
+}  // namespace
+
+ABSL_FLAG(bool, test_flag_eb_01, {}, "");
+ABSL_FLAG(int32_t, test_flag_eb_02, {}, "");
+ABSL_FLAG(int64_t, test_flag_eb_03, {}, "");
+ABSL_FLAG(double, test_flag_eb_04, {}, "");
+ABSL_FLAG(std::string, test_flag_eb_05, {}, "");
+ABSL_FLAG(NonTriviallyCopyableAggregate, test_flag_eb_06, {}, "");
+
+namespace {
+
+TEST_F(FlagTest, TestEmptyBracesDefault) {
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_eb_01).DefaultValue(),
+            "false");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_eb_02).DefaultValue(),
+            "0");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_eb_03).DefaultValue(),
+            "0");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_eb_04).DefaultValue(),
+            "0");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_eb_05).DefaultValue(),
+            "");
+  EXPECT_EQ(absl::GetFlagReflectionHandle(FLAGS_test_flag_eb_06).DefaultValue(),
+            "0");
+
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_01), false);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_02), 0);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_03), 0);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_04), 0.0);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_05), "");
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_06),
+            NonTriviallyCopyableAggregate{});
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagTest, TestGetSet) {
+  absl::SetFlag(&FLAGS_test_flag_01, false);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_01), false);
+
+  absl::SetFlag(&FLAGS_test_flag_02, 321);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_02), 321);
+
+  absl::SetFlag(&FLAGS_test_flag_03, 67);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_03), 67);
+
+  absl::SetFlag(&FLAGS_test_flag_04, 1);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_04), 1);
+
+  absl::SetFlag(&FLAGS_test_flag_05, -908);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_05), -908);
+
+  absl::SetFlag(&FLAGS_test_flag_06, 4001);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_06), 4001);
+
+  absl::SetFlag(&FLAGS_test_flag_07, -23456);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_07), -23456);
+
+  absl::SetFlag(&FLAGS_test_flag_08, 975310);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_08), 975310);
+
+  absl::SetFlag(&FLAGS_test_flag_09, 1.00001);
+  EXPECT_NEAR(absl::GetFlag(FLAGS_test_flag_09), 1.00001, 1e-10);
+
+  absl::SetFlag(&FLAGS_test_flag_10, -3.54f);
+  EXPECT_NEAR(absl::GetFlag(FLAGS_test_flag_10), -3.54f, 1e-6f);
+
+  absl::SetFlag(&FLAGS_test_flag_11, "asdf");
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_11), "asdf");
+
+  absl::SetFlag(&FLAGS_test_flag_12, absl::Seconds(110));
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_12), absl::Seconds(110));
+
+  absl::SetFlag(&FLAGS_test_flag_13, absl::MakeInt128(-1, 0));
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_13), absl::MakeInt128(-1, 0));
+
+  absl::SetFlag(&FLAGS_test_flag_14, absl::MakeUint128(0, 0xFFFAAABBBCCCDDD));
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_14),
+            absl::MakeUint128(0, 0xFFFAAABBBCCCDDD));
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagTest, TestGetViaReflection) {
+  auto* handle = absl::FindCommandLineFlag("test_flag_01");
+  EXPECT_EQ(*handle->TryGet<bool>(), true);
+  handle = absl::FindCommandLineFlag("test_flag_02");
+  EXPECT_EQ(*handle->TryGet<int>(), 1234);
+  handle = absl::FindCommandLineFlag("test_flag_03");
+  EXPECT_EQ(*handle->TryGet<int16_t>(), -34);
+  handle = absl::FindCommandLineFlag("test_flag_04");
+  EXPECT_EQ(*handle->TryGet<uint16_t>(), 189);
+  handle = absl::FindCommandLineFlag("test_flag_05");
+  EXPECT_EQ(*handle->TryGet<int32_t>(), 10765);
+  handle = absl::FindCommandLineFlag("test_flag_06");
+  EXPECT_EQ(*handle->TryGet<uint32_t>(), 40000);
+  handle = absl::FindCommandLineFlag("test_flag_07");
+  EXPECT_EQ(*handle->TryGet<int64_t>(), -1234567);
+  handle = absl::FindCommandLineFlag("test_flag_08");
+  EXPECT_EQ(*handle->TryGet<uint64_t>(), 9876543);
+  handle = absl::FindCommandLineFlag("test_flag_09");
+  EXPECT_NEAR(*handle->TryGet<double>(), -9.876e-50, 1e-55);
+  handle = absl::FindCommandLineFlag("test_flag_10");
+  EXPECT_NEAR(*handle->TryGet<float>(), 1.234e12f, 1e5f);
+  handle = absl::FindCommandLineFlag("test_flag_11");
+  EXPECT_EQ(*handle->TryGet<std::string>(), "");
+  handle = absl::FindCommandLineFlag("test_flag_12");
+  EXPECT_EQ(*handle->TryGet<absl::Duration>(), absl::Minutes(10));
+  handle = absl::FindCommandLineFlag("test_flag_13");
+  EXPECT_EQ(*handle->TryGet<absl::int128>(), absl::MakeInt128(-1, 0));
+  handle = absl::FindCommandLineFlag("test_flag_14");
+  EXPECT_EQ(*handle->TryGet<absl::uint128>(),
+            absl::MakeUint128(0, 0xFFFAAABBBCCCDDD));
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagTest, ConcurrentSetAndGet) {
+  static constexpr int kNumThreads = 8;
+  // Two arbitrary durations. One thread will concurrently flip the flag
+  // between these two values, while the other threads read it and verify
+  // that no other value is seen.
+  static const absl::Duration kValidDurations[] = {
+      absl::Seconds(int64_t{0x6cebf47a9b68c802}) + absl::Nanoseconds(229702057),
+      absl::Seconds(int64_t{0x23fec0307e4e9d3}) + absl::Nanoseconds(44555374)};
+  absl::SetFlag(&FLAGS_test_flag_12, kValidDurations[0]);
+
+  std::atomic<bool> stop{false};
+  std::vector<std::thread> threads;
+  auto* handle = absl::FindCommandLineFlag("test_flag_12");
+  for (int i = 0; i < kNumThreads; i++) {
+    threads.emplace_back([&]() {
+      while (!stop.load(std::memory_order_relaxed)) {
+        // Try loading the flag both directly and via a reflection
+        // handle.
+        absl::Duration v = absl::GetFlag(FLAGS_test_flag_12);
+        EXPECT_TRUE(v == kValidDurations[0] || v == kValidDurations[1]);
+        v = *handle->TryGet<absl::Duration>();
+        EXPECT_TRUE(v == kValidDurations[0] || v == kValidDurations[1]);
+      }
+    });
+  }
+  absl::Time end_time = absl::Now() + absl::Seconds(1);
+  int i = 0;
+  while (absl::Now() < end_time) {
+    absl::SetFlag(&FLAGS_test_flag_12,
+                  kValidDurations[i++ % ABSL_ARRAYSIZE(kValidDurations)]);
+  }
+  stop.store(true, std::memory_order_relaxed);
+  for (auto& t : threads) t.join();
+}
+
+// --------------------------------------------------------------------
+
+int GetDflt1() { return 1; }
+
+}  // namespace
+
+ABSL_FLAG(int, test_int_flag_with_non_const_default, GetDflt1(),
+          "test int flag non const default");
+ABSL_FLAG(std::string, test_string_flag_with_non_const_default,
+          absl::StrCat("AAA", "BBB"), "test string flag non const default");
+
+namespace {
+
+TEST_F(FlagTest, TestNonConstexprDefault) {
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_int_flag_with_non_const_default), 1);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_string_flag_with_non_const_default),
+            "AAABBB");
+}
+
+// --------------------------------------------------------------------
+
+}  // namespace
+
+ABSL_FLAG(bool, test_flag_with_non_const_help, true,
+          absl::StrCat("test ", "flag ", "non const help"));
+
+namespace {
+
+#if !ABSL_FLAGS_STRIP_HELP
+TEST_F(FlagTest, TestNonConstexprHelp) {
+  EXPECT_EQ(
+      absl::GetFlagReflectionHandle(FLAGS_test_flag_with_non_const_help).Help(),
+      "test flag non const help");
+}
+#endif  //! ABSL_FLAGS_STRIP_HELP
+
+// --------------------------------------------------------------------
+
+int cb_test_value = -1;
+void TestFlagCB();
+
+}  // namespace
+
+ABSL_FLAG(int, test_flag_with_cb, 100, "").OnUpdate(TestFlagCB);
+
+ABSL_FLAG(int, test_flag_with_lambda_cb, 200, "").OnUpdate([]() {
+  cb_test_value = absl::GetFlag(FLAGS_test_flag_with_lambda_cb) +
+                  absl::GetFlag(FLAGS_test_flag_with_cb);
+});
+
+namespace {
+
+void TestFlagCB() { cb_test_value = absl::GetFlag(FLAGS_test_flag_with_cb); }
+
+// Tests side-effects of callback invocation.
+TEST_F(FlagTest, CallbackInvocation) {
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_with_cb), 100);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_with_lambda_cb), 200);
+  EXPECT_EQ(cb_test_value, 300);
+
+  absl::SetFlag(&FLAGS_test_flag_with_cb, 1);
+  EXPECT_EQ(cb_test_value, 1);
+
+  absl::SetFlag(&FLAGS_test_flag_with_lambda_cb, 3);
+  EXPECT_EQ(cb_test_value, 4);
+}
+
+// --------------------------------------------------------------------
+
+struct CustomUDT {
+  CustomUDT() : a(1), b(1) {}
+  CustomUDT(int a_, int b_) : a(a_), b(b_) {}
+
+  friend bool operator==(const CustomUDT& f1, const CustomUDT& f2) {
+    return f1.a == f2.a && f1.b == f2.b;
+  }
+
+  int a;
+  int b;
+};
+bool AbslParseFlag(absl::string_view in, CustomUDT* f, std::string*) {
+  std::vector<absl::string_view> parts =
+      absl::StrSplit(in, ':', absl::SkipWhitespace());
+
+  if (parts.size() != 2) return false;
+
+  if (!absl::SimpleAtoi(parts[0], &f->a)) return false;
+
+  if (!absl::SimpleAtoi(parts[1], &f->b)) return false;
+
+  return true;
+}
+std::string AbslUnparseFlag(const CustomUDT& f) {
+  return absl::StrCat(f.a, ":", f.b);
+}
+
+}  // namespace
+
+ABSL_FLAG(CustomUDT, test_flag_custom_udt, CustomUDT(), "test flag custom UDT");
+
+namespace {
+
+TEST_F(FlagTest, TestCustomUDT) {
+  EXPECT_EQ(flags::StorageKind<CustomUDT>(),
+            flags::FlagValueStorageKind::kOneWordAtomic);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_custom_udt), CustomUDT(1, 1));
+  absl::SetFlag(&FLAGS_test_flag_custom_udt, CustomUDT(2, 3));
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_custom_udt), CustomUDT(2, 3));
+}
+
+// MSVC produces link error on the type mismatch.
+// Linux does not have build errors and validations work as expected.
+#if !defined(_WIN32) && GTEST_HAS_DEATH_TEST
+
+using FlagDeathTest = FlagTest;
+
+TEST_F(FlagDeathTest, TestTypeMismatchValidations) {
+#if !defined(NDEBUG)
+  EXPECT_DEATH_IF_SUPPORTED(
+      static_cast<void>(absl::GetFlag(FLAGS_mistyped_int_flag)),
+      "Flag 'mistyped_int_flag' is defined as one type and declared "
+      "as another");
+  EXPECT_DEATH_IF_SUPPORTED(
+      static_cast<void>(absl::GetFlag(FLAGS_mistyped_string_flag)),
+      "Flag 'mistyped_string_flag' is defined as one type and "
+      "declared as another");
+#endif
+
+  EXPECT_DEATH_IF_SUPPORTED(
+      absl::SetFlag(&FLAGS_mistyped_int_flag, 1),
+      "Flag 'mistyped_int_flag' is defined as one type and declared "
+      "as another");
+  EXPECT_DEATH_IF_SUPPORTED(
+      absl::SetFlag(&FLAGS_mistyped_string_flag, std::vector<std::string>{}),
+      "Flag 'mistyped_string_flag' is defined as one type and declared as "
+      "another");
+}
+
+#endif
+
+// --------------------------------------------------------------------
+
+// A contrived type that offers implicit and explicit conversion from specific
+// source types.
+struct ConversionTestVal {
+  ConversionTestVal() = default;
+  explicit ConversionTestVal(int a_in) : a(a_in) {}
+
+  enum class ViaImplicitConv { kTen = 10, kEleven };
+  // NOLINTNEXTLINE
+  ConversionTestVal(ViaImplicitConv from) : a(static_cast<int>(from)) {}
+
+  int a;
+};
+
+bool AbslParseFlag(absl::string_view in, ConversionTestVal* val_out,
+                   std::string*) {
+  if (!absl::SimpleAtoi(in, &val_out->a)) {
+    return false;
+  }
+  return true;
+}
+std::string AbslUnparseFlag(const ConversionTestVal& val) {
+  return absl::StrCat(val.a);
+}
+
+}  // namespace
+
+// Flag default values can be specified with a value that converts to the flag
+// value type implicitly.
+ABSL_FLAG(ConversionTestVal, test_flag_implicit_conv,
+          ConversionTestVal::ViaImplicitConv::kTen,
+          "test flag init via implicit conversion");
+
+namespace {
+
+TEST_F(FlagTest, CanSetViaImplicitConversion) {
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_implicit_conv).a, 10);
+  absl::SetFlag(&FLAGS_test_flag_implicit_conv,
+                ConversionTestVal::ViaImplicitConv::kEleven);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_implicit_conv).a, 11);
+}
+
+// --------------------------------------------------------------------
+
+struct NonDfltConstructible {
+ public:
+  // This constructor tests that we can initialize the flag with int value
+  NonDfltConstructible(int i) : value(i) {}  // NOLINT
+
+  // This constructor tests that we can't initialize the flag with char value
+  // but can with explicitly constructed NonDfltConstructible.
+  explicit NonDfltConstructible(char c) : value(100 + static_cast<int>(c)) {}
+
+  int value;
+};
+
+bool AbslParseFlag(absl::string_view in, NonDfltConstructible* ndc_out,
+                   std::string*) {
+  return absl::SimpleAtoi(in, &ndc_out->value);
+}
+std::string AbslUnparseFlag(const NonDfltConstructible& ndc) {
+  return absl::StrCat(ndc.value);
+}
+
+}  // namespace
+
+ABSL_FLAG(NonDfltConstructible, ndc_flag1, NonDfltConstructible('1'),
+          "Flag with non default constructible type");
+ABSL_FLAG(NonDfltConstructible, ndc_flag2, 0,
+          "Flag with non default constructible type");
+
+namespace {
+
+TEST_F(FlagTest, TestNonDefaultConstructibleType) {
+  EXPECT_EQ(absl::GetFlag(FLAGS_ndc_flag1).value, '1' + 100);
+  EXPECT_EQ(absl::GetFlag(FLAGS_ndc_flag2).value, 0);
+
+  absl::SetFlag(&FLAGS_ndc_flag1, NonDfltConstructible('A'));
+  absl::SetFlag(&FLAGS_ndc_flag2, 25);
+
+  EXPECT_EQ(absl::GetFlag(FLAGS_ndc_flag1).value, 'A' + 100);
+  EXPECT_EQ(absl::GetFlag(FLAGS_ndc_flag2).value, 25);
+}
+
+}  // namespace
+
+// --------------------------------------------------------------------
+
+ABSL_RETIRED_FLAG(bool, old_bool_flag, true, "old descr");
+ABSL_RETIRED_FLAG(int, old_int_flag, (int)std::sqrt(10), "old descr");
+ABSL_RETIRED_FLAG(std::string, old_str_flag, "", absl::StrCat("old ", "descr"));
+
+namespace {
+
+bool initialization_order_fiasco_test ABSL_ATTRIBUTE_UNUSED = [] {
+  // Iterate over all the flags during static initialization.
+  // This should not trigger ASan's initialization-order-fiasco.
+  auto* handle1 = absl::FindCommandLineFlag("flag_on_separate_file");
+  auto* handle2 = absl::FindCommandLineFlag("retired_flag_on_separate_file");
+  if (handle1 != nullptr && handle2 != nullptr) {
+    return handle1->Name() == handle2->Name();
+  }
+  return true;
+}();
+
+TEST_F(FlagTest, TestRetiredFlagRegistration) {
+  auto* handle = absl::FindCommandLineFlag("old_bool_flag");
+  EXPECT_TRUE(handle->IsOfType<bool>());
+  EXPECT_TRUE(handle->IsRetired());
+  handle = absl::FindCommandLineFlag("old_int_flag");
+  EXPECT_TRUE(handle->IsOfType<int>());
+  EXPECT_TRUE(handle->IsRetired());
+  handle = absl::FindCommandLineFlag("old_str_flag");
+  EXPECT_TRUE(handle->IsOfType<std::string>());
+  EXPECT_TRUE(handle->IsRetired());
+}
+
+}  // namespace
+
+// --------------------------------------------------------------------
+
+namespace {
+
+// User-defined type with small alignment, but size exceeding 16.
+struct SmallAlignUDT {
+  SmallAlignUDT() : c('A'), s(12) {}
+  char c;
+  int16_t s;
+  char bytes[14];
+};
+
+bool AbslParseFlag(absl::string_view, SmallAlignUDT*, std::string*) {
+  return true;
+}
+std::string AbslUnparseFlag(const SmallAlignUDT&) { return ""; }
+
+// User-defined type with small size, but not trivially copyable.
+struct NonTriviallyCopyableUDT {
+  NonTriviallyCopyableUDT() : c('A') {}
+  NonTriviallyCopyableUDT(const NonTriviallyCopyableUDT& rhs) : c(rhs.c) {}
+  NonTriviallyCopyableUDT& operator=(const NonTriviallyCopyableUDT& rhs) {
+    c = rhs.c;
+    return *this;
+  }
+
+  char c;
+};
+
+bool AbslParseFlag(absl::string_view, NonTriviallyCopyableUDT*, std::string*) {
+  return true;
+}
+std::string AbslUnparseFlag(const NonTriviallyCopyableUDT&) { return ""; }
+
+}  // namespace
+
+ABSL_FLAG(SmallAlignUDT, test_flag_sa_udt, {}, "help");
+ABSL_FLAG(NonTriviallyCopyableUDT, test_flag_ntc_udt, {}, "help");
+
+namespace {
+
+TEST_F(FlagTest, TestSmallAlignUDT) {
+  SmallAlignUDT value = absl::GetFlag(FLAGS_test_flag_sa_udt);
+  EXPECT_EQ(value.c, 'A');
+  EXPECT_EQ(value.s, 12);
+
+  value.c = 'B';
+  value.s = 45;
+  absl::SetFlag(&FLAGS_test_flag_sa_udt, value);
+  value = absl::GetFlag(FLAGS_test_flag_sa_udt);
+  EXPECT_EQ(value.c, 'B');
+  EXPECT_EQ(value.s, 45);
+}
+
+TEST_F(FlagTest, TestNonTriviallyCopyableUDT) {
+  NonTriviallyCopyableUDT value = absl::GetFlag(FLAGS_test_flag_ntc_udt);
+  EXPECT_EQ(value.c, 'A');
+
+  value.c = 'B';
+  absl::SetFlag(&FLAGS_test_flag_ntc_udt, value);
+  value = absl::GetFlag(FLAGS_test_flag_ntc_udt);
+  EXPECT_EQ(value.c, 'B');
+}
+
+}  // namespace
+
+// --------------------------------------------------------------------
+
+namespace {
+
+enum TestE { A = 1, B = 2, C = 3 };
+
+struct EnumWrapper {
+  EnumWrapper() : e(A) {}
+
+  TestE e;
+};
+
+bool AbslParseFlag(absl::string_view, EnumWrapper*, std::string*) {
+  return true;
+}
+std::string AbslUnparseFlag(const EnumWrapper&) { return ""; }
+
+}  // namespace
+
+ABSL_FLAG(EnumWrapper, test_enum_wrapper_flag, {}, "help");
+
+TEST_F(FlagTest, TesTypeWrappingEnum) {
+  EnumWrapper value = absl::GetFlag(FLAGS_test_enum_wrapper_flag);
+  EXPECT_EQ(value.e, A);
+
+  value.e = B;
+  absl::SetFlag(&FLAGS_test_enum_wrapper_flag, value);
+  value = absl::GetFlag(FLAGS_test_enum_wrapper_flag);
+  EXPECT_EQ(value.e, B);
+}
+
+// This is a compile test to ensure macros are expanded within ABSL_FLAG and
+// ABSL_DECLARE_FLAG.
+#define FLAG_NAME_MACRO(name) prefix_##name
+ABSL_DECLARE_FLAG(int, FLAG_NAME_MACRO(test_macro_named_flag));
+ABSL_FLAG(int, FLAG_NAME_MACRO(test_macro_named_flag), 0,
+          "Testing macro expansion within ABSL_FLAG");
+
+TEST_F(FlagTest, MacroWithinAbslFlag) {
+  EXPECT_EQ(absl::GetFlag(FLAGS_prefix_test_macro_named_flag), 0);
+  absl::SetFlag(&FLAGS_prefix_test_macro_named_flag, 1);
+  EXPECT_EQ(absl::GetFlag(FLAGS_prefix_test_macro_named_flag), 1);
+}
+
+// --------------------------------------------------------------------
+
+#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ <= 5
+#define ABSL_SKIP_OPTIONAL_BOOL_TEST_DUE_TO_GCC_BUG
+#endif
+
+#ifndef ABSL_SKIP_OPTIONAL_BOOL_TEST_DUE_TO_GCC_BUG
+ABSL_FLAG(absl::optional<bool>, optional_bool, absl::nullopt, "help");
+#endif
+ABSL_FLAG(absl::optional<int>, optional_int, {}, "help");
+ABSL_FLAG(absl::optional<double>, optional_double, 9.3, "help");
+ABSL_FLAG(absl::optional<std::string>, optional_string, absl::nullopt, "help");
+ABSL_FLAG(absl::optional<absl::Duration>, optional_duration, absl::nullopt,
+          "help");
+ABSL_FLAG(absl::optional<absl::optional<int>>, optional_optional_int,
+          absl::nullopt, "help");
+#if defined(ABSL_HAVE_STD_OPTIONAL) && !defined(ABSL_USES_STD_OPTIONAL)
+ABSL_FLAG(std::optional<int64_t>, std_optional_int64, std::nullopt, "help");
+#endif
+
+namespace {
+
+#ifndef ABSL_SKIP_OPTIONAL_BOOL_TEST_DUE_TO_GCC_BUG
+TEST_F(FlagTest, TestOptionalBool) {
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_bool).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_bool), absl::nullopt);
+
+  absl::SetFlag(&FLAGS_optional_bool, false);
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_bool).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_bool), false);
+
+  absl::SetFlag(&FLAGS_optional_bool, true);
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_bool).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_bool), true);
+
+  absl::SetFlag(&FLAGS_optional_bool, absl::nullopt);
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_bool).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_bool), absl::nullopt);
+}
+
+// --------------------------------------------------------------------
+#endif
+
+TEST_F(FlagTest, TestOptionalInt) {
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_int).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_int), absl::nullopt);
+
+  absl::SetFlag(&FLAGS_optional_int, 0);
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_int).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_int), 0);
+
+  absl::SetFlag(&FLAGS_optional_int, 10);
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_int).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_int), 10);
+
+  absl::SetFlag(&FLAGS_optional_int, absl::nullopt);
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_int).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_int), absl::nullopt);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagTest, TestOptionalDouble) {
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_double).has_value());
+  EXPECT_DOUBLE_EQ(*absl::GetFlag(FLAGS_optional_double), 9.3);
+
+  absl::SetFlag(&FLAGS_optional_double, 0.0);
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_double).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_double), 0.0);
+
+  absl::SetFlag(&FLAGS_optional_double, 1.234);
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_double).has_value());
+  EXPECT_DOUBLE_EQ(*absl::GetFlag(FLAGS_optional_double), 1.234);
+
+  absl::SetFlag(&FLAGS_optional_double, absl::nullopt);
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_double).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_double), absl::nullopt);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagTest, TestOptionalString) {
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_string).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_string), absl::nullopt);
+
+  // Setting optional string to "" leads to undefined behavior.
+
+  absl::SetFlag(&FLAGS_optional_string, " ");
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_string).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_string), " ");
+
+  absl::SetFlag(&FLAGS_optional_string, "QWERTY");
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_string).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_string), "QWERTY");
+
+  absl::SetFlag(&FLAGS_optional_string, absl::nullopt);
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_string).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_string), absl::nullopt);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagTest, TestOptionalDuration) {
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_duration).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_duration), absl::nullopt);
+
+  absl::SetFlag(&FLAGS_optional_duration, absl::ZeroDuration());
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_duration).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_duration), absl::Seconds(0));
+
+  absl::SetFlag(&FLAGS_optional_duration, absl::Hours(3));
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_duration).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_duration), absl::Hours(3));
+
+  absl::SetFlag(&FLAGS_optional_duration, absl::nullopt);
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_duration).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_duration), absl::nullopt);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagTest, TestOptionalOptional) {
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_optional_int).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_optional_int), absl::nullopt);
+
+  absl::optional<int> nullint{absl::nullopt};
+
+  absl::SetFlag(&FLAGS_optional_optional_int, nullint);
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_optional_int).has_value());
+  EXPECT_NE(absl::GetFlag(FLAGS_optional_optional_int), nullint);
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_optional_int),
+            absl::optional<absl::optional<int>>{nullint});
+
+  absl::SetFlag(&FLAGS_optional_optional_int, 0);
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_optional_int).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_optional_int), 0);
+
+  absl::SetFlag(&FLAGS_optional_optional_int, absl::optional<int>{0});
+  EXPECT_TRUE(absl::GetFlag(FLAGS_optional_optional_int).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_optional_int), 0);
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_optional_int), absl::optional<int>{0});
+
+  absl::SetFlag(&FLAGS_optional_optional_int, absl::nullopt);
+  EXPECT_FALSE(absl::GetFlag(FLAGS_optional_optional_int).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_optional_optional_int), absl::nullopt);
+}
+
+// --------------------------------------------------------------------
+
+#if defined(ABSL_HAVE_STD_OPTIONAL) && !defined(ABSL_USES_STD_OPTIONAL)
+
+TEST_F(FlagTest, TestStdOptional) {
+  EXPECT_FALSE(absl::GetFlag(FLAGS_std_optional_int64).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_std_optional_int64), std::nullopt);
+
+  absl::SetFlag(&FLAGS_std_optional_int64, 0);
+  EXPECT_TRUE(absl::GetFlag(FLAGS_std_optional_int64).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_std_optional_int64), 0);
+
+  absl::SetFlag(&FLAGS_std_optional_int64, 0xFFFFFFFFFF16);
+  EXPECT_TRUE(absl::GetFlag(FLAGS_std_optional_int64).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_std_optional_int64), 0xFFFFFFFFFF16);
+
+  absl::SetFlag(&FLAGS_std_optional_int64, std::nullopt);
+  EXPECT_FALSE(absl::GetFlag(FLAGS_std_optional_int64).has_value());
+  EXPECT_EQ(absl::GetFlag(FLAGS_std_optional_int64), std::nullopt);
+}
+
+// --------------------------------------------------------------------
+
+#endif
+
+}  // namespace

weight/_dep/abseil-cpp/absl/flags/flag_test_defs.cc

@@ -0,0 +1,24 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// This file is used to test the mismatch of the flag type between definition
+// and declaration. These are definitions. flag_test.cc contains declarations.
+#include <string>
+#include "absl/flags/flag.h"
+
+ABSL_FLAG(int, mistyped_int_flag, 0, "");
+ABSL_FLAG(std::string, mistyped_string_flag, "", "");
+ABSL_FLAG(bool, flag_on_separate_file, false, "");
+ABSL_RETIRED_FLAG(bool, retired_flag_on_separate_file, false, "");

weight/_dep/abseil-cpp/absl/flags/internal/commandlineflag.h

@@ -0,0 +1,68 @@
+//
+// Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
+#define ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
+
+#include "absl/base/config.h"
+#include "absl/base/internal/fast_type_id.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace flags_internal {
+
+// An alias for flag fast type id. This value identifies the flag value type
+// similarly to typeid(T), without relying on RTTI being available. In most
+// cases this id is enough to uniquely identify the flag's value type. In a few
+// cases we'll have to resort to using actual RTTI implementation if it is
+// available.
+using FlagFastTypeId = absl::base_internal::FastTypeIdType;
+
+// Options that control SetCommandLineOptionWithMode.
+enum FlagSettingMode {
+  // update the flag's value unconditionally (can call this multiple times).
+  SET_FLAGS_VALUE,
+  // update the flag's value, but *only if* it has not yet been updated
+  // with SET_FLAGS_VALUE, SET_FLAG_IF_DEFAULT, or "FLAGS_xxx = nondef".
+  SET_FLAG_IF_DEFAULT,
+  // set the flag's default value to this.  If the flag has not been updated
+  // yet (via SET_FLAGS_VALUE, SET_FLAG_IF_DEFAULT, or "FLAGS_xxx = nondef")
+  // change the flag's current value to the new default value as well.
+  SET_FLAGS_DEFAULT
+};
+
+// Options that control ParseFrom: Source of a value.
+enum ValueSource {
+  // Flag is being set by value specified on a command line.
+  kCommandLine,
+  // Flag is being set by value specified in the code.
+  kProgrammaticChange,
+};
+
+// Handle to FlagState objects. Specific flag state objects will restore state
+// of a flag produced this flag state from method CommandLineFlag::SaveState().
+class FlagStateInterface {
+ public:
+  virtual ~FlagStateInterface();
+
+  // Restores the flag originated this object to the saved state.
+  virtual void Restore() const = 0;
+};
+
+}  // namespace flags_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_

weight/_dep/abseil-cpp/absl/flags/internal/flag.h

@@ -0,0 +1,796 @@
+//
+// Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_FLAGS_INTERNAL_FLAG_H_
+#define ABSL_FLAGS_INTERNAL_FLAG_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <atomic>
+#include <cstring>
+#include <memory>
+#include <new>
+#include <string>
+#include <type_traits>
+#include <typeinfo>
+
+#include "absl/base/attributes.h"
+#include "absl/base/call_once.h"
+#include "absl/base/casts.h"
+#include "absl/base/config.h"
+#include "absl/base/optimization.h"
+#include "absl/base/thread_annotations.h"
+#include "absl/flags/commandlineflag.h"
+#include "absl/flags/config.h"
+#include "absl/flags/internal/commandlineflag.h"
+#include "absl/flags/internal/registry.h"
+#include "absl/flags/internal/sequence_lock.h"
+#include "absl/flags/marshalling.h"
+#include "absl/meta/type_traits.h"
+#include "absl/strings/string_view.h"
+#include "absl/synchronization/mutex.h"
+#include "absl/utility/utility.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+///////////////////////////////////////////////////////////////////////////////
+// Forward declaration of absl::Flag<T> public API.
+namespace flags_internal {
+template <typename T>
+class Flag;
+}  // namespace flags_internal
+
+template <typename T>
+using Flag = flags_internal::Flag<T>;
+
+template <typename T>
+ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag);
+
+template <typename T>
+void SetFlag(absl::Flag<T>* flag, const T& v);
+
+template <typename T, typename V>
+void SetFlag(absl::Flag<T>* flag, const V& v);
+
+template <typename U>
+const CommandLineFlag& GetFlagReflectionHandle(const absl::Flag<U>& f);
+
+///////////////////////////////////////////////////////////////////////////////
+// Flag value type operations, eg., parsing, copying, etc. are provided
+// by function specific to that type with a signature matching FlagOpFn.
+
+namespace flags_internal {
+
+enum class FlagOp {
+  kAlloc,
+  kDelete,
+  kCopy,
+  kCopyConstruct,
+  kSizeof,
+  kFastTypeId,
+  kRuntimeTypeId,
+  kParse,
+  kUnparse,
+  kValueOffset,
+};
+using FlagOpFn = void* (*)(FlagOp, const void*, void*, void*);
+
+// Forward declaration for Flag value specific operations.
+template <typename T>
+void* FlagOps(FlagOp op, const void* v1, void* v2, void* v3);
+
+// Allocate aligned memory for a flag value.
+inline void* Alloc(FlagOpFn op) {
+  return op(FlagOp::kAlloc, nullptr, nullptr, nullptr);
+}
+// Deletes memory interpreting obj as flag value type pointer.
+inline void Delete(FlagOpFn op, void* obj) {
+  op(FlagOp::kDelete, nullptr, obj, nullptr);
+}
+// Copies src to dst interpreting as flag value type pointers.
+inline void Copy(FlagOpFn op, const void* src, void* dst) {
+  op(FlagOp::kCopy, src, dst, nullptr);
+}
+// Construct a copy of flag value in a location pointed by dst
+// based on src - pointer to the flag's value.
+inline void CopyConstruct(FlagOpFn op, const void* src, void* dst) {
+  op(FlagOp::kCopyConstruct, src, dst, nullptr);
+}
+// Makes a copy of flag value pointed by obj.
+inline void* Clone(FlagOpFn op, const void* obj) {
+  void* res = flags_internal::Alloc(op);
+  flags_internal::CopyConstruct(op, obj, res);
+  return res;
+}
+// Returns true if parsing of input text is successful.
+inline bool Parse(FlagOpFn op, absl::string_view text, void* dst,
+                  std::string* error) {
+  return op(FlagOp::kParse, &text, dst, error) != nullptr;
+}
+// Returns string representing supplied value.
+inline std::string Unparse(FlagOpFn op, const void* val) {
+  std::string result;
+  op(FlagOp::kUnparse, val, &result, nullptr);
+  return result;
+}
+// Returns size of flag value type.
+inline size_t Sizeof(FlagOpFn op) {
+  // This sequence of casts reverses the sequence from
+  // `flags_internal::FlagOps()`
+  return static_cast<size_t>(reinterpret_cast<intptr_t>(
+      op(FlagOp::kSizeof, nullptr, nullptr, nullptr)));
+}
+// Returns fast type id corresponding to the value type.
+inline FlagFastTypeId FastTypeId(FlagOpFn op) {
+  return reinterpret_cast<FlagFastTypeId>(
+      op(FlagOp::kFastTypeId, nullptr, nullptr, nullptr));
+}
+// Returns fast type id corresponding to the value type.
+inline const std::type_info* RuntimeTypeId(FlagOpFn op) {
+  return reinterpret_cast<const std::type_info*>(
+      op(FlagOp::kRuntimeTypeId, nullptr, nullptr, nullptr));
+}
+// Returns offset of the field value_ from the field impl_ inside of
+// absl::Flag<T> data. Given FlagImpl pointer p you can get the
+// location of the corresponding value as:
+//      reinterpret_cast<char*>(p) + ValueOffset().
+inline ptrdiff_t ValueOffset(FlagOpFn op) {
+  // This sequence of casts reverses the sequence from
+  // `flags_internal::FlagOps()`
+  return static_cast<ptrdiff_t>(reinterpret_cast<intptr_t>(
+      op(FlagOp::kValueOffset, nullptr, nullptr, nullptr)));
+}
+
+// Returns an address of RTTI's typeid(T).
+template <typename T>
+inline const std::type_info* GenRuntimeTypeId() {
+#ifdef ABSL_INTERNAL_HAS_RTTI
+  return &typeid(T);
+#else
+  return nullptr;
+#endif
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Flag help auxiliary structs.
+
+// This is help argument for absl::Flag encapsulating the string literal pointer
+// or pointer to function generating it as well as enum descriminating two
+// cases.
+using HelpGenFunc = std::string (*)();
+
+template <size_t N>
+struct FixedCharArray {
+  char value[N];
+
+  template <size_t... I>
+  static constexpr FixedCharArray<N> FromLiteralString(
+      absl::string_view str, absl::index_sequence<I...>) {
+    return (void)str, FixedCharArray<N>({{str[I]..., '\0'}});
+  }
+};
+
+template <typename Gen, size_t N = Gen::Value().size()>
+constexpr FixedCharArray<N + 1> HelpStringAsArray(int) {
+  return FixedCharArray<N + 1>::FromLiteralString(
+      Gen::Value(), absl::make_index_sequence<N>{});
+}
+
+template <typename Gen>
+constexpr std::false_type HelpStringAsArray(char) {
+  return std::false_type{};
+}
+
+union FlagHelpMsg {
+  constexpr explicit FlagHelpMsg(const char* help_msg) : literal(help_msg) {}
+  constexpr explicit FlagHelpMsg(HelpGenFunc help_gen) : gen_func(help_gen) {}
+
+  const char* literal;
+  HelpGenFunc gen_func;
+};
+
+enum class FlagHelpKind : uint8_t { kLiteral = 0, kGenFunc = 1 };
+
+struct FlagHelpArg {
+  FlagHelpMsg source;
+  FlagHelpKind kind;
+};
+
+extern const char kStrippedFlagHelp[];
+
+// These two HelpArg overloads allows us to select at compile time one of two
+// way to pass Help argument to absl::Flag. We'll be passing
+// AbslFlagHelpGenFor##name as Gen and integer 0 as a single argument to prefer
+// first overload if possible. If help message is evaluatable on constexpr
+// context We'll be able to make FixedCharArray out of it and we'll choose first
+// overload. In this case the help message expression is immediately evaluated
+// and is used to construct the absl::Flag. No additional code is generated by
+// ABSL_FLAG Otherwise SFINAE kicks in and first overload is dropped from the
+// consideration, in which case the second overload will be used. The second
+// overload does not attempt to evaluate the help message expression
+// immediately and instead delays the evaluation by returning the function
+// pointer (&T::NonConst) generating the help message when necessary. This is
+// evaluatable in constexpr context, but the cost is an extra function being
+// generated in the ABSL_FLAG code.
+template <typename Gen, size_t N>
+constexpr FlagHelpArg HelpArg(const FixedCharArray<N>& value) {
+  return {FlagHelpMsg(value.value), FlagHelpKind::kLiteral};
+}
+
+template <typename Gen>
+constexpr FlagHelpArg HelpArg(std::false_type) {
+  return {FlagHelpMsg(&Gen::NonConst), FlagHelpKind::kGenFunc};
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Flag default value auxiliary structs.
+
+// Signature for the function generating the initial flag value (usually
+// based on default value supplied in flag's definition)
+using FlagDfltGenFunc = void (*)(void*);
+
+union FlagDefaultSrc {
+  constexpr explicit FlagDefaultSrc(FlagDfltGenFunc gen_func_arg)
+      : gen_func(gen_func_arg) {}
+
+#define ABSL_FLAGS_INTERNAL_DFLT_FOR_TYPE(T, name) \
+  T name##_value;                                  \
+  constexpr explicit FlagDefaultSrc(T value) : name##_value(value) {}  // NOLINT
+  ABSL_FLAGS_INTERNAL_BUILTIN_TYPES(ABSL_FLAGS_INTERNAL_DFLT_FOR_TYPE)
+#undef ABSL_FLAGS_INTERNAL_DFLT_FOR_TYPE
+
+  void* dynamic_value;
+  FlagDfltGenFunc gen_func;
+};
+
+enum class FlagDefaultKind : uint8_t {
+  kDynamicValue = 0,
+  kGenFunc = 1,
+  kOneWord = 2  // for default values UP to one word in size
+};
+
+struct FlagDefaultArg {
+  FlagDefaultSrc source;
+  FlagDefaultKind kind;
+};
+
+// This struct and corresponding overload to InitDefaultValue are used to
+// facilitate usage of {} as default value in ABSL_FLAG macro.
+// TODO(rogeeff): Fix handling types with explicit constructors.
+struct EmptyBraces {};
+
+template <typename T>
+constexpr T InitDefaultValue(T t) {
+  return t;
+}
+
+template <typename T>
+constexpr T InitDefaultValue(EmptyBraces) {
+  return T{};
+}
+
+template <typename ValueT, typename GenT,
+          typename std::enable_if<std::is_integral<ValueT>::value, int>::type =
+              ((void)GenT{}, 0)>
+constexpr FlagDefaultArg DefaultArg(int) {
+  return {FlagDefaultSrc(GenT{}.value), FlagDefaultKind::kOneWord};
+}
+
+template <typename ValueT, typename GenT>
+constexpr FlagDefaultArg DefaultArg(char) {
+  return {FlagDefaultSrc(&GenT::Gen), FlagDefaultKind::kGenFunc};
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Flag current value auxiliary structs.
+
+constexpr int64_t UninitializedFlagValue() {
+  return static_cast<int64_t>(0xababababababababll);
+}
+
+template <typename T>
+using FlagUseValueAndInitBitStorage =
+    std::integral_constant<bool, std::is_trivially_copyable<T>::value &&
+                                     std::is_default_constructible<T>::value &&
+                                     (sizeof(T) < 8)>;
+
+template <typename T>
+using FlagUseOneWordStorage =
+    std::integral_constant<bool, std::is_trivially_copyable<T>::value &&
+                                     (sizeof(T) <= 8)>;
+
+template <class T>
+using FlagUseSequenceLockStorage =
+    std::integral_constant<bool, std::is_trivially_copyable<T>::value &&
+                                     (sizeof(T) > 8)>;
+
+enum class FlagValueStorageKind : uint8_t {
+  kValueAndInitBit = 0,
+  kOneWordAtomic = 1,
+  kSequenceLocked = 2,
+  kAlignedBuffer = 3,
+};
+
+template <typename T>
+static constexpr FlagValueStorageKind StorageKind() {
+  return FlagUseValueAndInitBitStorage<T>::value
+             ? FlagValueStorageKind::kValueAndInitBit
+         : FlagUseOneWordStorage<T>::value
+             ? FlagValueStorageKind::kOneWordAtomic
+         : FlagUseSequenceLockStorage<T>::value
+             ? FlagValueStorageKind::kSequenceLocked
+             : FlagValueStorageKind::kAlignedBuffer;
+}
+
+struct FlagOneWordValue {
+  constexpr explicit FlagOneWordValue(int64_t v) : value(v) {}
+  std::atomic<int64_t> value;
+};
+
+template <typename T>
+struct alignas(8) FlagValueAndInitBit {
+  T value;
+  // Use an int instead of a bool to guarantee that a non-zero value has
+  // a bit set.
+  uint8_t init;
+};
+
+template <typename T,
+          FlagValueStorageKind Kind = flags_internal::StorageKind<T>()>
+struct FlagValue;
+
+template <typename T>
+struct FlagValue<T, FlagValueStorageKind::kValueAndInitBit> : FlagOneWordValue {
+  constexpr FlagValue() : FlagOneWordValue(0) {}
+  bool Get(const SequenceLock&, T& dst) const {
+    int64_t storage = value.load(std::memory_order_acquire);
+    if (ABSL_PREDICT_FALSE(storage == 0)) {
+      return false;
+    }
+    dst = absl::bit_cast<FlagValueAndInitBit<T>>(storage).value;
+    return true;
+  }
+};
+
+template <typename T>
+struct FlagValue<T, FlagValueStorageKind::kOneWordAtomic> : FlagOneWordValue {
+  constexpr FlagValue() : FlagOneWordValue(UninitializedFlagValue()) {}
+  bool Get(const SequenceLock&, T& dst) const {
+    int64_t one_word_val = value.load(std::memory_order_acquire);
+    if (ABSL_PREDICT_FALSE(one_word_val == UninitializedFlagValue())) {
+      return false;
+    }
+    std::memcpy(&dst, static_cast<const void*>(&one_word_val), sizeof(T));
+    return true;
+  }
+};
+
+template <typename T>
+struct FlagValue<T, FlagValueStorageKind::kSequenceLocked> {
+  bool Get(const SequenceLock& lock, T& dst) const {
+    return lock.TryRead(&dst, value_words, sizeof(T));
+  }
+
+  static constexpr int kNumWords =
+      flags_internal::AlignUp(sizeof(T), sizeof(uint64_t)) / sizeof(uint64_t);
+
+  alignas(T) alignas(
+      std::atomic<uint64_t>) std::atomic<uint64_t> value_words[kNumWords];
+};
+
+template <typename T>
+struct FlagValue<T, FlagValueStorageKind::kAlignedBuffer> {
+  bool Get(const SequenceLock&, T&) const { return false; }
+
+  alignas(T) char value[sizeof(T)];
+};
+
+///////////////////////////////////////////////////////////////////////////////
+// Flag callback auxiliary structs.
+
+// Signature for the mutation callback used by watched Flags
+// The callback is noexcept.
+// TODO(rogeeff): add noexcept after C++17 support is added.
+using FlagCallbackFunc = void (*)();
+
+struct FlagCallback {
+  FlagCallbackFunc func;
+  absl::Mutex guard;  // Guard for concurrent callback invocations.
+};
+
+///////////////////////////////////////////////////////////////////////////////
+// Flag implementation, which does not depend on flag value type.
+// The class encapsulates the Flag's data and access to it.
+
+struct DynValueDeleter {
+  explicit DynValueDeleter(FlagOpFn op_arg = nullptr);
+  void operator()(void* ptr) const;
+
+  FlagOpFn op;
+};
+
+class FlagState;
+
+class FlagImpl final : public CommandLineFlag {
+ public:
+  constexpr FlagImpl(const char* name, const char* filename, FlagOpFn op,
+                     FlagHelpArg help, FlagValueStorageKind value_kind,
+                     FlagDefaultArg default_arg)
+      : name_(name),
+        filename_(filename),
+        op_(op),
+        help_(help.source),
+        help_source_kind_(static_cast<uint8_t>(help.kind)),
+        value_storage_kind_(static_cast<uint8_t>(value_kind)),
+        def_kind_(static_cast<uint8_t>(default_arg.kind)),
+        modified_(false),
+        on_command_line_(false),
+        callback_(nullptr),
+        default_value_(default_arg.source),
+        data_guard_{} {}
+
+  // Constant access methods
+  int64_t ReadOneWord() const ABSL_LOCKS_EXCLUDED(*DataGuard());
+  bool ReadOneBool() const ABSL_LOCKS_EXCLUDED(*DataGuard());
+  void Read(void* dst) const override ABSL_LOCKS_EXCLUDED(*DataGuard());
+  void Read(bool* value) const ABSL_LOCKS_EXCLUDED(*DataGuard()) {
+    *value = ReadOneBool();
+  }
+  template <typename T,
+            absl::enable_if_t<flags_internal::StorageKind<T>() ==
+                                  FlagValueStorageKind::kOneWordAtomic,
+                              int> = 0>
+  void Read(T* value) const ABSL_LOCKS_EXCLUDED(*DataGuard()) {
+    int64_t v = ReadOneWord();
+    std::memcpy(value, static_cast<const void*>(&v), sizeof(T));
+  }
+  template <typename T,
+            typename std::enable_if<flags_internal::StorageKind<T>() ==
+                                        FlagValueStorageKind::kValueAndInitBit,
+                                    int>::type = 0>
+  void Read(T* value) const ABSL_LOCKS_EXCLUDED(*DataGuard()) {
+    *value = absl::bit_cast<FlagValueAndInitBit<T>>(ReadOneWord()).value;
+  }
+
+  // Mutating access methods
+  void Write(const void* src) ABSL_LOCKS_EXCLUDED(*DataGuard());
+
+  // Interfaces to operate on callbacks.
+  void SetCallback(const FlagCallbackFunc mutation_callback)
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
+  void InvokeCallback() const ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
+
+  // Used in read/write operations to validate source/target has correct type.
+  // For example if flag is declared as absl::Flag<int> FLAGS_foo, a call to
+  // absl::GetFlag(FLAGS_foo) validates that the type of FLAGS_foo is indeed
+  // int. To do that we pass the "assumed" type id (which is deduced from type
+  // int) as an argument `type_id`, which is in turn is validated against the
+  // type id stored in flag object by flag definition statement.
+  void AssertValidType(FlagFastTypeId type_id,
+                       const std::type_info* (*gen_rtti)()) const;
+
+ private:
+  template <typename T>
+  friend class Flag;
+  friend class FlagState;
+
+  // Ensures that `data_guard_` is initialized and returns it.
+  absl::Mutex* DataGuard() const
+      ABSL_LOCK_RETURNED(reinterpret_cast<absl::Mutex*>(data_guard_));
+  // Returns heap allocated value of type T initialized with default value.
+  std::unique_ptr<void, DynValueDeleter> MakeInitValue() const
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
+  // Flag initialization called via absl::call_once.
+  void Init();
+
+  // Offset value access methods. One per storage kind. These methods to not
+  // respect const correctness, so be very carefull using them.
+
+  // This is a shared helper routine which encapsulates most of the magic. Since
+  // it is only used inside the three routines below, which are defined in
+  // flag.cc, we can define it in that file as well.
+  template <typename StorageT>
+  StorageT* OffsetValue() const;
+  // This is an accessor for a value stored in an aligned buffer storage
+  // used for non-trivially-copyable data types.
+  // Returns a mutable pointer to the start of a buffer.
+  void* AlignedBufferValue() const;
+
+  // The same as above, but used for sequencelock-protected storage.
+  std::atomic<uint64_t>* AtomicBufferValue() const;
+
+  // This is an accessor for a value stored as one word atomic. Returns a
+  // mutable reference to an atomic value.
+  std::atomic<int64_t>& OneWordValue() const;
+
+  // Attempts to parse supplied `value` string. If parsing is successful,
+  // returns new value. Otherwise returns nullptr.
+  std::unique_ptr<void, DynValueDeleter> TryParse(absl::string_view value,
+                                                  std::string& err) const
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
+  // Stores the flag value based on the pointer to the source.
+  void StoreValue(const void* src) ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
+
+  // Copy the flag data, protected by `seq_lock_` into `dst`.
+  //
+  // REQUIRES: ValueStorageKind() == kSequenceLocked.
+  void ReadSequenceLockedData(void* dst) const
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
+
+  FlagHelpKind HelpSourceKind() const {
+    return static_cast<FlagHelpKind>(help_source_kind_);
+  }
+  FlagValueStorageKind ValueStorageKind() const {
+    return static_cast<FlagValueStorageKind>(value_storage_kind_);
+  }
+  FlagDefaultKind DefaultKind() const
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard()) {
+    return static_cast<FlagDefaultKind>(def_kind_);
+  }
+
+  // CommandLineFlag interface implementation
+  absl::string_view Name() const override;
+  std::string Filename() const override;
+  std::string Help() const override;
+  FlagFastTypeId TypeId() const override;
+  bool IsSpecifiedOnCommandLine() const override
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
+  std::string DefaultValue() const override ABSL_LOCKS_EXCLUDED(*DataGuard());
+  std::string CurrentValue() const override ABSL_LOCKS_EXCLUDED(*DataGuard());
+  bool ValidateInputValue(absl::string_view value) const override
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
+  void CheckDefaultValueParsingRoundtrip() const override
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
+
+  int64_t ModificationCount() const ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
+
+  // Interfaces to save and restore flags to/from persistent state.
+  // Returns current flag state or nullptr if flag does not support
+  // saving and restoring a state.
+  std::unique_ptr<FlagStateInterface> SaveState() override
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
+
+  // Restores the flag state to the supplied state object. If there is
+  // nothing to restore returns false. Otherwise returns true.
+  bool RestoreState(const FlagState& flag_state)
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
+
+  bool ParseFrom(absl::string_view value, FlagSettingMode set_mode,
+                 ValueSource source, std::string& error) override
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
+
+  // Immutable flag's state.
+
+  // Flags name passed to ABSL_FLAG as second arg.
+  const char* const name_;
+  // The file name where ABSL_FLAG resides.
+  const char* const filename_;
+  // Type-specific operations "vtable".
+  const FlagOpFn op_;
+  // Help message literal or function to generate it.
+  const FlagHelpMsg help_;
+  // Indicates if help message was supplied as literal or generator func.
+  const uint8_t help_source_kind_ : 1;
+  // Kind of storage this flag is using for the flag's value.
+  const uint8_t value_storage_kind_ : 2;
+
+  uint8_t : 0;  // The bytes containing the const bitfields must not be
+                // shared with bytes containing the mutable bitfields.
+
+  // Mutable flag's state (guarded by `data_guard_`).
+
+  // def_kind_ is not guard by DataGuard() since it is accessed in Init without
+  // locks.
+  uint8_t def_kind_ : 2;
+  // Has this flag's value been modified?
+  bool modified_ : 1 ABSL_GUARDED_BY(*DataGuard());
+  // Has this flag been specified on command line.
+  bool on_command_line_ : 1 ABSL_GUARDED_BY(*DataGuard());
+
+  // Unique tag for absl::call_once call to initialize this flag.
+  absl::once_flag init_control_;
+
+  // Sequence lock / mutation counter.
+  flags_internal::SequenceLock seq_lock_;
+
+  // Optional flag's callback and absl::Mutex to guard the invocations.
+  FlagCallback* callback_ ABSL_GUARDED_BY(*DataGuard());
+  // Either a pointer to the function generating the default value based on the
+  // value specified in ABSL_FLAG or pointer to the dynamically set default
+  // value via SetCommandLineOptionWithMode. def_kind_ is used to distinguish
+  // these two cases.
+  FlagDefaultSrc default_value_;
+
+  // This is reserved space for an absl::Mutex to guard flag data. It will be
+  // initialized in FlagImpl::Init via placement new.
+  // We can't use "absl::Mutex data_guard_", since this class is not literal.
+  // We do not want to use "absl::Mutex* data_guard_", since this would require
+  // heap allocation during initialization, which is both slows program startup
+  // and can fail. Using reserved space + placement new allows us to avoid both
+  // problems.
+  alignas(absl::Mutex) mutable char data_guard_[sizeof(absl::Mutex)];
+};
+
+///////////////////////////////////////////////////////////////////////////////
+// The Flag object parameterized by the flag's value type. This class implements
+// flag reflection handle interface.
+
+template <typename T>
+class Flag {
+ public:
+  constexpr Flag(const char* name, const char* filename, FlagHelpArg help,
+                 const FlagDefaultArg default_arg)
+      : impl_(name, filename, &FlagOps<T>, help,
+              flags_internal::StorageKind<T>(), default_arg),
+        value_() {}
+
+  // CommandLineFlag interface
+  absl::string_view Name() const { return impl_.Name(); }
+  std::string Filename() const { return impl_.Filename(); }
+  std::string Help() const { return impl_.Help(); }
+  // Do not use. To be removed.
+  bool IsSpecifiedOnCommandLine() const {
+    return impl_.IsSpecifiedOnCommandLine();
+  }
+  std::string DefaultValue() const { return impl_.DefaultValue(); }
+  std::string CurrentValue() const { return impl_.CurrentValue(); }
+
+ private:
+  template <typename, bool>
+  friend class FlagRegistrar;
+  friend class FlagImplPeer;
+
+  T Get() const {
+    // See implementation notes in CommandLineFlag::Get().
+    union U {
+      T value;
+      U() {}
+      ~U() { value.~T(); }
+    };
+    U u;
+
+#if !defined(NDEBUG)
+    impl_.AssertValidType(base_internal::FastTypeId<T>(), &GenRuntimeTypeId<T>);
+#endif
+
+    if (ABSL_PREDICT_FALSE(!value_.Get(impl_.seq_lock_, u.value))) {
+      impl_.Read(&u.value);
+    }
+    return std::move(u.value);
+  }
+  void Set(const T& v) {
+    impl_.AssertValidType(base_internal::FastTypeId<T>(), &GenRuntimeTypeId<T>);
+    impl_.Write(&v);
+  }
+
+  // Access to the reflection.
+  const CommandLineFlag& Reflect() const { return impl_; }
+
+  // Flag's data
+  // The implementation depends on value_ field to be placed exactly after the
+  // impl_ field, so that impl_ can figure out the offset to the value and
+  // access it.
+  FlagImpl impl_;
+  FlagValue<T> value_;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+// Trampoline for friend access
+
+class FlagImplPeer {
+ public:
+  template <typename T, typename FlagType>
+  static T InvokeGet(const FlagType& flag) {
+    return flag.Get();
+  }
+  template <typename FlagType, typename T>
+  static void InvokeSet(FlagType& flag, const T& v) {
+    flag.Set(v);
+  }
+  template <typename FlagType>
+  static const CommandLineFlag& InvokeReflect(const FlagType& f) {
+    return f.Reflect();
+  }
+};
+
+///////////////////////////////////////////////////////////////////////////////
+// Implementation of Flag value specific operations routine.
+template <typename T>
+void* FlagOps(FlagOp op, const void* v1, void* v2, void* v3) {
+  switch (op) {
+    case FlagOp::kAlloc: {
+      std::allocator<T> alloc;
+      return std::allocator_traits<std::allocator<T>>::allocate(alloc, 1);
+    }
+    case FlagOp::kDelete: {
+      T* p = static_cast<T*>(v2);
+      p->~T();
+      std::allocator<T> alloc;
+      std::allocator_traits<std::allocator<T>>::deallocate(alloc, p, 1);
+      return nullptr;
+    }
+    case FlagOp::kCopy:
+      *static_cast<T*>(v2) = *static_cast<const T*>(v1);
+      return nullptr;
+    case FlagOp::kCopyConstruct:
+      new (v2) T(*static_cast<const T*>(v1));
+      return nullptr;
+    case FlagOp::kSizeof:
+      return reinterpret_cast<void*>(static_cast<uintptr_t>(sizeof(T)));
+    case FlagOp::kFastTypeId:
+      return const_cast<void*>(base_internal::FastTypeId<T>());
+    case FlagOp::kRuntimeTypeId:
+      return const_cast<std::type_info*>(GenRuntimeTypeId<T>());
+    case FlagOp::kParse: {
+      // Initialize the temporary instance of type T based on current value in
+      // destination (which is going to be flag's default value).
+      T temp(*static_cast<T*>(v2));
+      if (!absl::ParseFlag<T>(*static_cast<const absl::string_view*>(v1), &temp,
+                              static_cast<std::string*>(v3))) {
+        return nullptr;
+      }
+      *static_cast<T*>(v2) = std::move(temp);
+      return v2;
+    }
+    case FlagOp::kUnparse:
+      *static_cast<std::string*>(v2) =
+          absl::UnparseFlag<T>(*static_cast<const T*>(v1));
+      return nullptr;
+    case FlagOp::kValueOffset: {
+      // Round sizeof(FlagImp) to a multiple of alignof(FlagValue<T>) to get the
+      // offset of the data.
+      size_t round_to = alignof(FlagValue<T>);
+      size_t offset =
+          (sizeof(FlagImpl) + round_to - 1) / round_to * round_to;
+      return reinterpret_cast<void*>(offset);
+    }
+  }
+  return nullptr;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// This class facilitates Flag object registration and tail expression-based
+// flag definition, for example:
+// ABSL_FLAG(int, foo, 42, "Foo help").OnUpdate(NotifyFooWatcher);
+struct FlagRegistrarEmpty {};
+template <typename T, bool do_register>
+class FlagRegistrar {
+ public:
+  explicit FlagRegistrar(Flag<T>& flag, const char* filename) : flag_(flag) {
+    if (do_register)
+      flags_internal::RegisterCommandLineFlag(flag_.impl_, filename);
+  }
+
+  FlagRegistrar OnUpdate(FlagCallbackFunc cb) && {
+    flag_.impl_.SetCallback(cb);
+    return *this;
+  }
+
+  // Make the registrar "die" gracefully as an empty struct on a line where
+  // registration happens. Registrar objects are intended to live only as
+  // temporary.
+  operator FlagRegistrarEmpty() const { return {}; }  // NOLINT
+
+ private:
+  Flag<T>& flag_;  // Flag being registered (not owned).
+};
+
+}  // namespace flags_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_FLAGS_INTERNAL_FLAG_H_

weight/_dep/abseil-cpp/absl/flags/marshalling.cc

@@ -0,0 +1,291 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/flags/marshalling.h"
+
+#include <stddef.h>
+
+#include <cmath>
+#include <limits>
+#include <sstream>
+#include <string>
+#include <type_traits>
+#include <vector>
+
+#include "absl/base/config.h"
+#include "absl/base/log_severity.h"
+#include "absl/base/macros.h"
+#include "absl/numeric/int128.h"
+#include "absl/strings/ascii.h"
+#include "absl/strings/match.h"
+#include "absl/strings/numbers.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+#include "absl/strings/str_join.h"
+#include "absl/strings/str_split.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace flags_internal {
+
+// --------------------------------------------------------------------
+// AbslParseFlag specializations for boolean type.
+
+bool AbslParseFlag(absl::string_view text, bool* dst, std::string*) {
+  const char* kTrue[] = {"1", "t", "true", "y", "yes"};
+  const char* kFalse[] = {"0", "f", "false", "n", "no"};
+  static_assert(sizeof(kTrue) == sizeof(kFalse), "true_false_equal");
+
+  text = absl::StripAsciiWhitespace(text);
+
+  for (size_t i = 0; i < ABSL_ARRAYSIZE(kTrue); ++i) {
+    if (absl::EqualsIgnoreCase(text, kTrue[i])) {
+      *dst = true;
+      return true;
+    } else if (absl::EqualsIgnoreCase(text, kFalse[i])) {
+      *dst = false;
+      return true;
+    }
+  }
+  return false;  // didn't match a legal input
+}
+
+// --------------------------------------------------------------------
+// AbslParseFlag for integral types.
+
+// Return the base to use for parsing text as an integer.  Leading 0x
+// puts us in base 16.  But leading 0 does not put us in base 8. It
+// caused too many bugs when we had that behavior.
+static int NumericBase(absl::string_view text) {
+  if (text.empty()) return 0;
+  size_t num_start = (text[0] == '-' || text[0] == '+') ? 1 : 0;
+  const bool hex = (text.size() >= num_start + 2 && text[num_start] == '0' &&
+                    (text[num_start + 1] == 'x' || text[num_start + 1] == 'X'));
+  return hex ? 16 : 10;
+}
+
+template <typename IntType>
+inline bool ParseFlagImpl(absl::string_view text, IntType& dst) {
+  text = absl::StripAsciiWhitespace(text);
+
+  return absl::numbers_internal::safe_strtoi_base(text, &dst,
+                                                  NumericBase(text));
+}
+
+bool AbslParseFlag(absl::string_view text, short* dst, std::string*) {
+  int val;
+  if (!ParseFlagImpl(text, val)) return false;
+  if (static_cast<short>(val) != val)  // worked, but number out of range
+    return false;
+  *dst = static_cast<short>(val);
+  return true;
+}
+
+bool AbslParseFlag(absl::string_view text, unsigned short* dst, std::string*) {
+  unsigned int val;
+  if (!ParseFlagImpl(text, val)) return false;
+  if (static_cast<unsigned short>(val) !=
+      val)  // worked, but number out of range
+    return false;
+  *dst = static_cast<unsigned short>(val);
+  return true;
+}
+
+bool AbslParseFlag(absl::string_view text, int* dst, std::string*) {
+  return ParseFlagImpl(text, *dst);
+}
+
+bool AbslParseFlag(absl::string_view text, unsigned int* dst, std::string*) {
+  return ParseFlagImpl(text, *dst);
+}
+
+bool AbslParseFlag(absl::string_view text, long* dst, std::string*) {
+  return ParseFlagImpl(text, *dst);
+}
+
+bool AbslParseFlag(absl::string_view text, unsigned long* dst, std::string*) {
+  return ParseFlagImpl(text, *dst);
+}
+
+bool AbslParseFlag(absl::string_view text, long long* dst, std::string*) {
+  return ParseFlagImpl(text, *dst);
+}
+
+bool AbslParseFlag(absl::string_view text, unsigned long long* dst,
+                   std::string*) {
+  return ParseFlagImpl(text, *dst);
+}
+
+bool AbslParseFlag(absl::string_view text, absl::int128* dst, std::string*) {
+  text = absl::StripAsciiWhitespace(text);
+
+  // check hex
+  int base = NumericBase(text);
+  if (!absl::numbers_internal::safe_strto128_base(text, dst, base)) {
+    return false;
+  }
+
+  return base == 16 ? absl::SimpleHexAtoi(text, dst)
+                    : absl::SimpleAtoi(text, dst);
+}
+
+bool AbslParseFlag(absl::string_view text, absl::uint128* dst, std::string*) {
+  text = absl::StripAsciiWhitespace(text);
+
+  // check hex
+  int base = NumericBase(text);
+  if (!absl::numbers_internal::safe_strtou128_base(text, dst, base)) {
+    return false;
+  }
+
+  return base == 16 ? absl::SimpleHexAtoi(text, dst)
+                    : absl::SimpleAtoi(text, dst);
+}
+
+// --------------------------------------------------------------------
+// AbslParseFlag for floating point types.
+
+bool AbslParseFlag(absl::string_view text, float* dst, std::string*) {
+  return absl::SimpleAtof(text, dst);
+}
+
+bool AbslParseFlag(absl::string_view text, double* dst, std::string*) {
+  return absl::SimpleAtod(text, dst);
+}
+
+// --------------------------------------------------------------------
+// AbslParseFlag for strings.
+
+bool AbslParseFlag(absl::string_view text, std::string* dst, std::string*) {
+  dst->assign(text.data(), text.size());
+  return true;
+}
+
+// --------------------------------------------------------------------
+// AbslParseFlag for vector of strings.
+
+bool AbslParseFlag(absl::string_view text, std::vector<std::string>* dst,
+                   std::string*) {
+  // An empty flag value corresponds to an empty vector, not a vector
+  // with a single, empty std::string.
+  if (text.empty()) {
+    dst->clear();
+    return true;
+  }
+  *dst = absl::StrSplit(text, ',', absl::AllowEmpty());
+  return true;
+}
+
+// --------------------------------------------------------------------
+// AbslUnparseFlag specializations for various builtin flag types.
+
+std::string Unparse(bool v) { return v ? "true" : "false"; }
+std::string Unparse(short v) { return absl::StrCat(v); }
+std::string Unparse(unsigned short v) { return absl::StrCat(v); }
+std::string Unparse(int v) { return absl::StrCat(v); }
+std::string Unparse(unsigned int v) { return absl::StrCat(v); }
+std::string Unparse(long v) { return absl::StrCat(v); }
+std::string Unparse(unsigned long v) { return absl::StrCat(v); }
+std::string Unparse(long long v) { return absl::StrCat(v); }
+std::string Unparse(unsigned long long v) { return absl::StrCat(v); }
+std::string Unparse(absl::int128 v) {
+  std::stringstream ss;
+  ss << v;
+  return ss.str();
+}
+std::string Unparse(absl::uint128 v) {
+  std::stringstream ss;
+  ss << v;
+  return ss.str();
+}
+
+template <typename T>
+std::string UnparseFloatingPointVal(T v) {
+  // digits10 is guaranteed to roundtrip correctly in string -> value -> string
+  // conversions, but may not be enough to represent all the values correctly.
+  std::string digit10_str =
+      absl::StrFormat("%.*g", std::numeric_limits<T>::digits10, v);
+  if (std::isnan(v) || std::isinf(v)) return digit10_str;
+
+  T roundtrip_val = 0;
+  std::string err;
+  if (absl::ParseFlag(digit10_str, &roundtrip_val, &err) &&
+      roundtrip_val == v) {
+    return digit10_str;
+  }
+
+  // max_digits10 is the number of base-10 digits that are necessary to uniquely
+  // represent all distinct values.
+  return absl::StrFormat("%.*g", std::numeric_limits<T>::max_digits10, v);
+}
+std::string Unparse(float v) { return UnparseFloatingPointVal(v); }
+std::string Unparse(double v) { return UnparseFloatingPointVal(v); }
+std::string AbslUnparseFlag(absl::string_view v) { return std::string(v); }
+std::string AbslUnparseFlag(const std::vector<std::string>& v) {
+  return absl::StrJoin(v, ",");
+}
+
+}  // namespace flags_internal
+
+bool AbslParseFlag(absl::string_view text, absl::LogSeverity* dst,
+                   std::string* err) {
+  text = absl::StripAsciiWhitespace(text);
+  if (text.empty()) {
+    *err = "no value provided";
+    return false;
+  }
+  if (absl::EqualsIgnoreCase(text, "dfatal")) {
+    *dst = absl::kLogDebugFatal;
+    return true;
+  }
+  if (absl::EqualsIgnoreCase(text, "klogdebugfatal")) {
+    *dst = absl::kLogDebugFatal;
+    return true;
+  }
+  if (text.front() == 'k' || text.front() == 'K') text.remove_prefix(1);
+  if (absl::EqualsIgnoreCase(text, "info")) {
+    *dst = absl::LogSeverity::kInfo;
+    return true;
+  }
+  if (absl::EqualsIgnoreCase(text, "warning")) {
+    *dst = absl::LogSeverity::kWarning;
+    return true;
+  }
+  if (absl::EqualsIgnoreCase(text, "error")) {
+    *dst = absl::LogSeverity::kError;
+    return true;
+  }
+  if (absl::EqualsIgnoreCase(text, "fatal")) {
+    *dst = absl::LogSeverity::kFatal;
+    return true;
+  }
+  std::underlying_type<absl::LogSeverity>::type numeric_value;
+  if (absl::ParseFlag(text, &numeric_value, err)) {
+    *dst = static_cast<absl::LogSeverity>(numeric_value);
+    return true;
+  }
+  *err =
+      "only integers, absl::LogSeverity enumerators, and DFATAL are accepted";
+  return false;
+}
+
+std::string AbslUnparseFlag(absl::LogSeverity v) {
+  if (v == absl::NormalizeLogSeverity(v)) return absl::LogSeverityName(v);
+  return absl::UnparseFlag(static_cast<int>(v));
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/flags/parse.cc

@@ -0,0 +1,943 @@
+//
+// Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/flags/parse.h"
+
+#include <stdlib.h>
+
+#include <algorithm>
+#include <cstdint>
+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+#include <ostream>
+#include <string>
+#include <tuple>
+#include <utility>
+#include <vector>
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+#include "absl/algorithm/container.h"
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
+#include "absl/base/const_init.h"
+#include "absl/base/thread_annotations.h"
+#include "absl/flags/commandlineflag.h"
+#include "absl/flags/config.h"
+#include "absl/flags/flag.h"
+#include "absl/flags/internal/commandlineflag.h"
+#include "absl/flags/internal/flag.h"
+#include "absl/flags/internal/parse.h"
+#include "absl/flags/internal/private_handle_accessor.h"
+#include "absl/flags/internal/program_name.h"
+#include "absl/flags/internal/usage.h"
+#include "absl/flags/reflection.h"
+#include "absl/flags/usage.h"
+#include "absl/flags/usage_config.h"
+#include "absl/strings/ascii.h"
+#include "absl/strings/internal/damerau_levenshtein_distance.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_join.h"
+#include "absl/strings/string_view.h"
+#include "absl/strings/strip.h"
+#include "absl/synchronization/mutex.h"
+
+// --------------------------------------------------------------------
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace flags_internal {
+namespace {
+
+ABSL_CONST_INIT absl::Mutex processing_checks_guard(absl::kConstInit);
+
+ABSL_CONST_INIT bool flagfile_needs_processing
+    ABSL_GUARDED_BY(processing_checks_guard) = false;
+ABSL_CONST_INIT bool fromenv_needs_processing
+    ABSL_GUARDED_BY(processing_checks_guard) = false;
+ABSL_CONST_INIT bool tryfromenv_needs_processing
+    ABSL_GUARDED_BY(processing_checks_guard) = false;
+
+ABSL_CONST_INIT absl::Mutex specified_flags_guard(absl::kConstInit);
+ABSL_CONST_INIT std::vector<const CommandLineFlag*>* specified_flags
+    ABSL_GUARDED_BY(specified_flags_guard) = nullptr;
+
+// Suggesting at most kMaxHints flags in case of misspellings.
+ABSL_CONST_INIT const size_t kMaxHints = 100;
+// Suggesting only flags which have a smaller distance than kMaxDistance.
+ABSL_CONST_INIT const size_t kMaxDistance = 3;
+
+struct SpecifiedFlagsCompare {
+  bool operator()(const CommandLineFlag* a, const CommandLineFlag* b) const {
+    return a->Name() < b->Name();
+  }
+  bool operator()(const CommandLineFlag* a, absl::string_view b) const {
+    return a->Name() < b;
+  }
+  bool operator()(absl::string_view a, const CommandLineFlag* b) const {
+    return a < b->Name();
+  }
+};
+
+}  // namespace
+}  // namespace flags_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+// These flags influence how command line flags are parsed and are only intended
+// to be set on the command line.  Avoid reading or setting them from C++ code.
+ABSL_FLAG(std::vector<std::string>, flagfile, {},
+          "comma-separated list of files to load flags from")
+    .OnUpdate([]() {
+      if (absl::GetFlag(FLAGS_flagfile).empty()) return;
+
+      absl::MutexLock l(&absl::flags_internal::processing_checks_guard);
+
+      // Setting this flag twice before it is handled most likely an internal
+      // error and should be reviewed by developers.
+      if (absl::flags_internal::flagfile_needs_processing) {
+        ABSL_INTERNAL_LOG(WARNING, "flagfile set twice before it is handled");
+      }
+
+      absl::flags_internal::flagfile_needs_processing = true;
+    });
+ABSL_FLAG(std::vector<std::string>, fromenv, {},
+          "comma-separated list of flags to set from the environment"
+          " [use 'export FLAGS_flag1=value']")
+    .OnUpdate([]() {
+      if (absl::GetFlag(FLAGS_fromenv).empty()) return;
+
+      absl::MutexLock l(&absl::flags_internal::processing_checks_guard);
+
+      // Setting this flag twice before it is handled most likely an internal
+      // error and should be reviewed by developers.
+      if (absl::flags_internal::fromenv_needs_processing) {
+        ABSL_INTERNAL_LOG(WARNING, "fromenv set twice before it is handled.");
+      }
+
+      absl::flags_internal::fromenv_needs_processing = true;
+    });
+ABSL_FLAG(std::vector<std::string>, tryfromenv, {},
+          "comma-separated list of flags to try to set from the environment if "
+          "present")
+    .OnUpdate([]() {
+      if (absl::GetFlag(FLAGS_tryfromenv).empty()) return;
+
+      absl::MutexLock l(&absl::flags_internal::processing_checks_guard);
+
+      // Setting this flag twice before it is handled most likely an internal
+      // error and should be reviewed by developers.
+      if (absl::flags_internal::tryfromenv_needs_processing) {
+        ABSL_INTERNAL_LOG(WARNING,
+                          "tryfromenv set twice before it is handled.");
+      }
+
+      absl::flags_internal::tryfromenv_needs_processing = true;
+    });
+
+// Rather than reading or setting --undefok from C++ code, please consider using
+// ABSL_RETIRED_FLAG instead.
+ABSL_FLAG(std::vector<std::string>, undefok, {},
+          "comma-separated list of flag names that it is okay to specify "
+          "on the command line even if the program does not define a flag "
+          "with that name");
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace flags_internal {
+
+namespace {
+
+class ArgsList {
+ public:
+  ArgsList() : next_arg_(0) {}
+  ArgsList(int argc, char* argv[]) : args_(argv, argv + argc), next_arg_(0) {}
+  explicit ArgsList(const std::vector<std::string>& args)
+      : args_(args), next_arg_(0) {}
+
+  // Returns success status: true if parsing successful, false otherwise.
+  bool ReadFromFlagfile(const std::string& flag_file_name);
+
+  size_t Size() const { return args_.size() - next_arg_; }
+  size_t FrontIndex() const { return next_arg_; }
+  absl::string_view Front() const { return args_[next_arg_]; }
+  void PopFront() { next_arg_++; }
+
+ private:
+  std::vector<std::string> args_;
+  size_t next_arg_;
+};
+
+bool ArgsList::ReadFromFlagfile(const std::string& flag_file_name) {
+  std::ifstream flag_file(flag_file_name);
+
+  if (!flag_file) {
+    flags_internal::ReportUsageError(
+        absl::StrCat("Can't open flagfile ", flag_file_name), true);
+
+    return false;
+  }
+
+  // This argument represents fake argv[0], which should be present in all arg
+  // lists.
+  args_.emplace_back("");
+
+  std::string line;
+  bool success = true;
+
+  while (std::getline(flag_file, line)) {
+    absl::string_view stripped = absl::StripLeadingAsciiWhitespace(line);
+
+    if (stripped.empty() || stripped[0] == '#') {
+      // Comment or empty line; just ignore.
+      continue;
+    }
+
+    if (stripped[0] == '-') {
+      if (stripped == "--") {
+        flags_internal::ReportUsageError(
+            "Flagfile can't contain position arguments or --", true);
+
+        success = false;
+        break;
+      }
+
+      args_.emplace_back(stripped);
+      continue;
+    }
+
+    flags_internal::ReportUsageError(
+        absl::StrCat("Unexpected line in the flagfile ", flag_file_name, ": ",
+                     line),
+        true);
+
+    success = false;
+  }
+
+  return success;
+}
+
+// --------------------------------------------------------------------
+
+// Reads the environment variable with name `name` and stores results in
+// `value`. If variable is not present in environment returns false, otherwise
+// returns true.
+bool GetEnvVar(const char* var_name, std::string& var_value) {
+#ifdef _WIN32
+  char buf[1024];
+  auto get_res = GetEnvironmentVariableA(var_name, buf, sizeof(buf));
+  if (get_res >= sizeof(buf)) {
+    return false;
+  }
+
+  if (get_res == 0) {
+    return false;
+  }
+
+  var_value = std::string(buf, get_res);
+#else
+  const char* val = ::getenv(var_name);
+  if (val == nullptr) {
+    return false;
+  }
+
+  var_value = val;
+#endif
+
+  return true;
+}
+
+// --------------------------------------------------------------------
+
+// Returns:
+//  Flag name or empty if arg= --
+//  Flag value after = in --flag=value (empty if --foo)
+//  "Is empty value" status. True if arg= --foo=, false otherwise. This is
+//  required to separate --foo from --foo=.
+// For example:
+//      arg           return values
+//   "--foo=bar" -> {"foo", "bar", false}.
+//   "--foo"     -> {"foo", "", false}.
+//   "--foo="    -> {"foo", "", true}.
+std::tuple<absl::string_view, absl::string_view, bool> SplitNameAndValue(
+    absl::string_view arg) {
+  // Allow -foo and --foo
+  absl::ConsumePrefix(&arg, "-");
+
+  if (arg.empty()) {
+    return std::make_tuple("", "", false);
+  }
+
+  auto equal_sign_pos = arg.find('=');
+
+  absl::string_view flag_name = arg.substr(0, equal_sign_pos);
+
+  absl::string_view value;
+  bool is_empty_value = false;
+
+  if (equal_sign_pos != absl::string_view::npos) {
+    value = arg.substr(equal_sign_pos + 1);
+    is_empty_value = value.empty();
+  }
+
+  return std::make_tuple(flag_name, value, is_empty_value);
+}
+
+// --------------------------------------------------------------------
+
+// Returns:
+//  found flag or nullptr
+//  is negative in case of --nofoo
+std::tuple<CommandLineFlag*, bool> LocateFlag(absl::string_view flag_name) {
+  CommandLineFlag* flag = absl::FindCommandLineFlag(flag_name);
+  bool is_negative = false;
+
+  if (!flag && absl::ConsumePrefix(&flag_name, "no")) {
+    flag = absl::FindCommandLineFlag(flag_name);
+    is_negative = true;
+  }
+
+  return std::make_tuple(flag, is_negative);
+}
+
+// --------------------------------------------------------------------
+
+// Verify that default values of typed flags must be convertible to string and
+// back.
+void CheckDefaultValuesParsingRoundtrip() {
+#ifndef NDEBUG
+  flags_internal::ForEachFlag([&](CommandLineFlag& flag) {
+    if (flag.IsRetired()) return;
+
+#define ABSL_FLAGS_INTERNAL_IGNORE_TYPE(T, _) \
+  if (flag.IsOfType<T>()) return;
+
+    ABSL_FLAGS_INTERNAL_SUPPORTED_TYPES(ABSL_FLAGS_INTERNAL_IGNORE_TYPE)
+#undef ABSL_FLAGS_INTERNAL_IGNORE_TYPE
+
+    flags_internal::PrivateHandleAccessor::CheckDefaultValueParsingRoundtrip(
+        flag);
+  });
+#endif
+}
+
+// --------------------------------------------------------------------
+
+// Returns success status, which is true if we successfully read all flag files,
+// in which case new ArgLists are appended to the input_args in a reverse order
+// of file names in the input flagfiles list. This order ensures that flags from
+// the first flagfile in the input list are processed before the second flagfile
+// etc.
+bool ReadFlagfiles(const std::vector<std::string>& flagfiles,
+                   std::vector<ArgsList>& input_args) {
+  bool success = true;
+  for (auto it = flagfiles.rbegin(); it != flagfiles.rend(); ++it) {
+    ArgsList al;
+
+    if (al.ReadFromFlagfile(*it)) {
+      input_args.push_back(al);
+    } else {
+      success = false;
+    }
+  }
+
+  return success;
+}
+
+// Returns success status, which is true if were able to locate all environment
+// variables correctly or if fail_on_absent_in_env is false. The environment
+// variable names are expected to be of the form `FLAGS_<flag_name>`, where
+// `flag_name` is a string from the input flag_names list. If successful we
+// append a single ArgList at the end of the input_args.
+bool ReadFlagsFromEnv(const std::vector<std::string>& flag_names,
+                      std::vector<ArgsList>& input_args,
+                      bool fail_on_absent_in_env) {
+  bool success = true;
+  std::vector<std::string> args;
+
+  // This argument represents fake argv[0], which should be present in all arg
+  // lists.
+  args.emplace_back("");
+
+  for (const auto& flag_name : flag_names) {
+    // Avoid infinite recursion.
+    if (flag_name == "fromenv" || flag_name == "tryfromenv") {
+      flags_internal::ReportUsageError(
+          absl::StrCat("Infinite recursion on flag ", flag_name), true);
+
+      success = false;
+      continue;
+    }
+
+    const std::string envname = absl::StrCat("FLAGS_", flag_name);
+    std::string envval;
+    if (!GetEnvVar(envname.c_str(), envval)) {
+      if (fail_on_absent_in_env) {
+        flags_internal::ReportUsageError(
+            absl::StrCat(envname, " not found in environment"), true);
+
+        success = false;
+      }
+
+      continue;
+    }
+
+    args.push_back(absl::StrCat("--", flag_name, "=", envval));
+  }
+
+  if (success) {
+    input_args.emplace_back(args);
+  }
+
+  return success;
+}
+
+// --------------------------------------------------------------------
+
+// Returns success status, which is true if were able to handle all generator
+// flags (flagfile, fromenv, tryfromemv) successfully.
+bool HandleGeneratorFlags(std::vector<ArgsList>& input_args,
+                          std::vector<std::string>& flagfile_value) {
+  bool success = true;
+
+  absl::MutexLock l(&flags_internal::processing_checks_guard);
+
+  // flagfile could have been set either on a command line or
+  // programmatically before invoking ParseCommandLine. Note that we do not
+  // actually process arguments specified in the flagfile, but instead
+  // create a secondary arguments list to be processed along with the rest
+  // of the command line arguments. Since we always the process most recently
+  // created list of arguments first, this will result in flagfile argument
+  // being processed before any other argument in the command line. If
+  // FLAGS_flagfile contains more than one file name we create multiple new
+  // levels of arguments in a reverse order of file names. Thus we always
+  // process arguments from first file before arguments containing in a
+  // second file, etc. If flagfile contains another
+  // --flagfile inside of it, it will produce new level of arguments and
+  // processed before the rest of the flagfile. We are also collecting all
+  // flagfiles set on original command line. Unlike the rest of the flags,
+  // this flag can be set multiple times and is expected to be handled
+  // multiple times. We are collecting them all into a single list and set
+  // the value of FLAGS_flagfile to that value at the end of the parsing.
+  if (flags_internal::flagfile_needs_processing) {
+    auto flagfiles = absl::GetFlag(FLAGS_flagfile);
+
+    if (input_args.size() == 1) {
+      flagfile_value.insert(flagfile_value.end(), flagfiles.begin(),
+                            flagfiles.end());
+    }
+
+    success &= ReadFlagfiles(flagfiles, input_args);
+
+    flags_internal::flagfile_needs_processing = false;
+  }
+
+  // Similar to flagfile fromenv/tryfromemv can be set both
+  // programmatically and at runtime on a command line. Unlike flagfile these
+  // can't be recursive.
+  if (flags_internal::fromenv_needs_processing) {
+    auto flags_list = absl::GetFlag(FLAGS_fromenv);
+
+    success &= ReadFlagsFromEnv(flags_list, input_args, true);
+
+    flags_internal::fromenv_needs_processing = false;
+  }
+
+  if (flags_internal::tryfromenv_needs_processing) {
+    auto flags_list = absl::GetFlag(FLAGS_tryfromenv);
+
+    success &= ReadFlagsFromEnv(flags_list, input_args, false);
+
+    flags_internal::tryfromenv_needs_processing = false;
+  }
+
+  return success;
+}
+
+// --------------------------------------------------------------------
+
+void ResetGeneratorFlags(const std::vector<std::string>& flagfile_value) {
+  // Setting flagfile to the value which collates all the values set on a
+  // command line and programmatically. So if command line looked like
+  // --flagfile=f1 --flagfile=f2 the final value of the FLAGS_flagfile flag is
+  // going to be {"f1", "f2"}
+  if (!flagfile_value.empty()) {
+    absl::SetFlag(&FLAGS_flagfile, flagfile_value);
+    absl::MutexLock l(&flags_internal::processing_checks_guard);
+    flags_internal::flagfile_needs_processing = false;
+  }
+
+  // fromenv/tryfromenv are set to <undefined> value.
+  if (!absl::GetFlag(FLAGS_fromenv).empty()) {
+    absl::SetFlag(&FLAGS_fromenv, {});
+  }
+  if (!absl::GetFlag(FLAGS_tryfromenv).empty()) {
+    absl::SetFlag(&FLAGS_tryfromenv, {});
+  }
+
+  absl::MutexLock l(&flags_internal::processing_checks_guard);
+  flags_internal::fromenv_needs_processing = false;
+  flags_internal::tryfromenv_needs_processing = false;
+}
+
+// --------------------------------------------------------------------
+
+// Returns:
+//  success status
+//  deduced value
+// We are also mutating curr_list in case if we need to get a hold of next
+// argument in the input.
+std::tuple<bool, absl::string_view> DeduceFlagValue(const CommandLineFlag& flag,
+                                                    absl::string_view value,
+                                                    bool is_negative,
+                                                    bool is_empty_value,
+                                                    ArgsList* curr_list) {
+  // Value is either an argument suffix after `=` in "--foo=<value>"
+  // or separate argument in case of "--foo" "<value>".
+
+  // boolean flags have these forms:
+  //   --foo
+  //   --nofoo
+  //   --foo=true
+  //   --foo=false
+  //   --nofoo=<value> is not supported
+  //   --foo <value> is not supported
+
+  // non boolean flags have these forms:
+  // --foo=<value>
+  // --foo <value>
+  // --nofoo is not supported
+
+  if (flag.IsOfType<bool>()) {
+    if (value.empty()) {
+      if (is_empty_value) {
+        // "--bool_flag=" case
+        flags_internal::ReportUsageError(
+            absl::StrCat(
+                "Missing the value after assignment for the boolean flag '",
+                flag.Name(), "'"),
+            true);
+        return std::make_tuple(false, "");
+      }
+
+      // "--bool_flag" case
+      value = is_negative ? "0" : "1";
+    } else if (is_negative) {
+      // "--nobool_flag=Y" case
+      flags_internal::ReportUsageError(
+          absl::StrCat("Negative form with assignment is not valid for the "
+                       "boolean flag '",
+                       flag.Name(), "'"),
+          true);
+      return std::make_tuple(false, "");
+    }
+  } else if (is_negative) {
+    // "--noint_flag=1" case
+    flags_internal::ReportUsageError(
+        absl::StrCat("Negative form is not valid for the flag '", flag.Name(),
+                     "'"),
+        true);
+    return std::make_tuple(false, "");
+  } else if (value.empty() && (!is_empty_value)) {
+    if (curr_list->Size() == 1) {
+      // "--int_flag" case
+      flags_internal::ReportUsageError(
+          absl::StrCat("Missing the value for the flag '", flag.Name(), "'"),
+          true);
+      return std::make_tuple(false, "");
+    }
+
+    // "--int_flag" "10" case
+    curr_list->PopFront();
+    value = curr_list->Front();
+
+    // Heuristic to detect the case where someone treats a string arg
+    // like a bool or just forgets to pass a value:
+    // --my_string_var --foo=bar
+    // We look for a flag of string type, whose value begins with a
+    // dash and corresponds to known flag or standalone --.
+    if (!value.empty() && value[0] == '-' && flag.IsOfType<std::string>()) {
+      auto maybe_flag_name = std::get<0>(SplitNameAndValue(value.substr(1)));
+
+      if (maybe_flag_name.empty() ||
+          std::get<0>(LocateFlag(maybe_flag_name)) != nullptr) {
+        // "--string_flag" "--known_flag" case
+        ABSL_INTERNAL_LOG(
+            WARNING,
+            absl::StrCat("Did you really mean to set flag '", flag.Name(),
+                         "' to the value '", value, "'?"));
+      }
+    }
+  }
+
+  return std::make_tuple(true, value);
+}
+
+// --------------------------------------------------------------------
+
+bool CanIgnoreUndefinedFlag(absl::string_view flag_name) {
+  auto undefok = absl::GetFlag(FLAGS_undefok);
+  if (std::find(undefok.begin(), undefok.end(), flag_name) != undefok.end()) {
+    return true;
+  }
+
+  if (absl::ConsumePrefix(&flag_name, "no") &&
+      std::find(undefok.begin(), undefok.end(), flag_name) != undefok.end()) {
+    return true;
+  }
+
+  return false;
+}
+
+// --------------------------------------------------------------------
+
+void ReportUnrecognizedFlags(
+    const std::vector<UnrecognizedFlag>& unrecognized_flags,
+    bool report_as_fatal_error) {
+  for (const auto& unrecognized : unrecognized_flags) {
+    // Verify if flag_name has the "no" already removed
+    std::vector<std::string> misspelling_hints;
+    if (unrecognized.source == UnrecognizedFlag::kFromArgv) {
+      misspelling_hints =
+          flags_internal::GetMisspellingHints(unrecognized.flag_name);
+    }
+
+    if (misspelling_hints.empty()) {
+      flags_internal::ReportUsageError(
+          absl::StrCat("Unknown command line flag '", unrecognized.flag_name,
+                       "'"),
+          report_as_fatal_error);
+    } else {
+      flags_internal::ReportUsageError(
+          absl::StrCat("Unknown command line flag '", unrecognized.flag_name,
+                       "'. Did you mean: ",
+                       absl::StrJoin(misspelling_hints, ", "), " ?"),
+          report_as_fatal_error);
+    }
+  }
+}
+
+}  // namespace
+
+// --------------------------------------------------------------------
+
+bool WasPresentOnCommandLine(absl::string_view flag_name) {
+  absl::ReaderMutexLock l(&specified_flags_guard);
+  ABSL_INTERNAL_CHECK(specified_flags != nullptr,
+                      "ParseCommandLine is not invoked yet");
+
+  return std::binary_search(specified_flags->begin(), specified_flags->end(),
+                            flag_name, SpecifiedFlagsCompare{});
+}
+
+// --------------------------------------------------------------------
+
+struct BestHints {
+  explicit BestHints(uint8_t _max) : best_distance(_max + 1) {}
+  bool AddHint(absl::string_view hint, uint8_t distance) {
+    if (hints.size() >= kMaxHints) return false;
+    if (distance == best_distance) {
+      hints.emplace_back(hint);
+    }
+    if (distance < best_distance) {
+      best_distance = distance;
+      hints = std::vector<std::string>{std::string(hint)};
+    }
+    return true;
+  }
+
+  uint8_t best_distance;
+  std::vector<std::string> hints;
+};
+
+// Return the list of flags with the smallest Damerau-Levenshtein distance to
+// the given flag.
+std::vector<std::string> GetMisspellingHints(const absl::string_view flag) {
+  const size_t maxCutoff = std::min(flag.size() / 2 + 1, kMaxDistance);
+  auto undefok = absl::GetFlag(FLAGS_undefok);
+  BestHints best_hints(static_cast<uint8_t>(maxCutoff));
+  flags_internal::ForEachFlag([&](const CommandLineFlag& f) {
+    if (best_hints.hints.size() >= kMaxHints) return;
+    uint8_t distance = strings_internal::CappedDamerauLevenshteinDistance(
+        flag, f.Name(), best_hints.best_distance);
+    best_hints.AddHint(f.Name(), distance);
+    // For boolean flags, also calculate distance to the negated form.
+    if (f.IsOfType<bool>()) {
+      const std::string negated_flag = absl::StrCat("no", f.Name());
+      distance = strings_internal::CappedDamerauLevenshteinDistance(
+          flag, negated_flag, best_hints.best_distance);
+      best_hints.AddHint(negated_flag, distance);
+    }
+  });
+  // Finally calculate distance to flags in "undefok".
+  absl::c_for_each(undefok, [&](const absl::string_view f) {
+    if (best_hints.hints.size() >= kMaxHints) return;
+    uint8_t distance = strings_internal::CappedDamerauLevenshteinDistance(
+        flag, f, best_hints.best_distance);
+    best_hints.AddHint(absl::StrCat(f, " (undefok)"), distance);
+  });
+  return best_hints.hints;
+}
+
+// --------------------------------------------------------------------
+
+std::vector<char*> ParseCommandLineImpl(int argc, char* argv[],
+                                        UsageFlagsAction usage_flag_action,
+                                        OnUndefinedFlag undef_flag_action,
+                                        std::ostream& error_help_output) {
+  std::vector<char*> positional_args;
+  std::vector<UnrecognizedFlag> unrecognized_flags;
+
+  auto help_mode = flags_internal::ParseAbseilFlagsOnlyImpl(
+      argc, argv, positional_args, unrecognized_flags, usage_flag_action);
+
+  if (undef_flag_action != OnUndefinedFlag::kIgnoreUndefined) {
+    flags_internal::ReportUnrecognizedFlags(
+        unrecognized_flags,
+        (undef_flag_action == OnUndefinedFlag::kAbortIfUndefined));
+
+    if (undef_flag_action == OnUndefinedFlag::kAbortIfUndefined) {
+      if (!unrecognized_flags.empty()) {
+        flags_internal::HandleUsageFlags(error_help_output,
+        ProgramUsageMessage()); std::exit(1);
+      }
+    }
+  }
+
+  flags_internal::MaybeExit(help_mode);
+
+  return positional_args;
+}
+
+// --------------------------------------------------------------------
+
+// This function handles all Abseil Flags and built-in usage flags and, if any
+// help mode was handled, it returns that help mode. The caller of this function
+// can decide to exit based on the returned help mode.
+// The caller may decide to handle unrecognized positional arguments and
+// unrecognized flags first before exiting.
+//
+// Returns:
+// * HelpMode::kFull if parsing errors were detected in recognized arguments
+// * The HelpMode that was handled in case when `usage_flag_action` is
+//   UsageFlagsAction::kHandleUsage and a usage flag was specified on the
+//   commandline
+// * Otherwise it returns HelpMode::kNone
+HelpMode ParseAbseilFlagsOnlyImpl(
+    int argc, char* argv[], std::vector<char*>& positional_args,
+    std::vector<UnrecognizedFlag>& unrecognized_flags,
+    UsageFlagsAction usage_flag_action) {
+  ABSL_INTERNAL_CHECK(argc > 0, "Missing argv[0]");
+
+  using flags_internal::ArgsList;
+  using flags_internal::specified_flags;
+
+  std::vector<std::string> flagfile_value;
+  std::vector<ArgsList> input_args;
+
+  // Once parsing has started we will not allow more flag registrations.
+  flags_internal::FinalizeRegistry();
+
+  // This routine does not return anything since we abort on failure.
+  flags_internal::CheckDefaultValuesParsingRoundtrip();
+
+  input_args.push_back(ArgsList(argc, argv));
+
+  // Set program invocation name if it is not set before.
+  if (flags_internal::ProgramInvocationName() == "UNKNOWN") {
+    flags_internal::SetProgramInvocationName(argv[0]);
+  }
+  positional_args.push_back(argv[0]);
+
+  absl::MutexLock l(&flags_internal::specified_flags_guard);
+  if (specified_flags == nullptr) {
+    specified_flags = new std::vector<const CommandLineFlag*>;
+  } else {
+    specified_flags->clear();
+  }
+
+  // Iterate through the list of the input arguments. First level are
+  // arguments originated from argc/argv. Following levels are arguments
+  // originated from recursive parsing of flagfile(s).
+  bool success = true;
+  while (!input_args.empty()) {
+    // First we process the built-in generator flags.
+    success &= flags_internal::HandleGeneratorFlags(input_args, flagfile_value);
+
+    // Select top-most (most recent) arguments list. If it is empty drop it
+    // and re-try.
+    ArgsList& curr_list = input_args.back();
+
+    // Every ArgsList starts with real or fake program name, so we can always
+    // start by skipping it.
+    curr_list.PopFront();
+
+    if (curr_list.Size() == 0) {
+      input_args.pop_back();
+      continue;
+    }
+
+    // Handle the next argument in the current list. If the stack of argument
+    // lists contains only one element - we are processing an argument from
+    // the original argv.
+    absl::string_view arg(curr_list.Front());
+    bool arg_from_argv = input_args.size() == 1;
+
+    // If argument does not start with '-' or is just "-" - this is
+    // positional argument.
+    if (!absl::ConsumePrefix(&arg, "-") || arg.empty()) {
+      ABSL_INTERNAL_CHECK(arg_from_argv,
+                          "Flagfile cannot contain positional argument");
+
+      positional_args.push_back(argv[curr_list.FrontIndex()]);
+      continue;
+    }
+
+    // Split the current argument on '=' to deduce the argument flag name and
+    // value. If flag name is empty it means we've got an "--" argument. Value
+    // can be empty either if there were no '=' in argument string at all or
+    // an argument looked like "--foo=". In a latter case is_empty_value is
+    // true.
+    absl::string_view flag_name;
+    absl::string_view value;
+    bool is_empty_value = false;
+
+    std::tie(flag_name, value, is_empty_value) =
+        flags_internal::SplitNameAndValue(arg);
+
+    // Standalone "--" argument indicates that the rest of the arguments are
+    // positional. We do not support positional arguments in flagfiles.
+    if (flag_name.empty()) {
+      ABSL_INTERNAL_CHECK(arg_from_argv,
+                          "Flagfile cannot contain positional argument");
+
+      curr_list.PopFront();
+      break;
+    }
+
+    // Locate the flag based on flag name. Handle both --foo and --nofoo.
+    CommandLineFlag* flag = nullptr;
+    bool is_negative = false;
+    std::tie(flag, is_negative) = flags_internal::LocateFlag(flag_name);
+
+    if (flag == nullptr) {
+      // Usage flags are not modeled as Abseil flags. Locate them separately.
+      if (flags_internal::DeduceUsageFlags(flag_name, value)) {
+        continue;
+      }
+      unrecognized_flags.emplace_back(arg_from_argv
+                                          ? UnrecognizedFlag::kFromArgv
+                                          : UnrecognizedFlag::kFromFlagfile,
+                                      flag_name);
+      continue;
+    }
+
+    // Deduce flag's value (from this or next argument).
+    bool value_success = true;
+    std::tie(value_success, value) = flags_internal::DeduceFlagValue(
+        *flag, value, is_negative, is_empty_value, &curr_list);
+    success &= value_success;
+
+    // Set the located flag to a new value, unless it is retired. Setting
+    // retired flag fails, but we ignoring it here while also reporting access
+    // to retired flag.
+    std::string error;
+    if (!flags_internal::PrivateHandleAccessor::ParseFrom(
+            *flag, value, flags_internal::SET_FLAGS_VALUE,
+            flags_internal::kCommandLine, error)) {
+      if (flag->IsRetired()) continue;
+
+      flags_internal::ReportUsageError(error, true);
+      success = false;
+    } else {
+      specified_flags->push_back(flag);
+    }
+  }
+
+  flags_internal::ResetGeneratorFlags(flagfile_value);
+
+  // All the remaining arguments are positional.
+  if (!input_args.empty()) {
+    for (size_t arg_index = input_args.back().FrontIndex();
+         arg_index < static_cast<size_t>(argc); ++arg_index) {
+      positional_args.push_back(argv[arg_index]);
+    }
+  }
+
+  // Trim and sort the vector.
+  specified_flags->shrink_to_fit();
+  std::sort(specified_flags->begin(), specified_flags->end(),
+            flags_internal::SpecifiedFlagsCompare{});
+
+  // Filter out unrecognized flags, which are ok to ignore.
+  std::vector<UnrecognizedFlag> filtered;
+  filtered.reserve(unrecognized_flags.size());
+  for (const auto& unrecognized : unrecognized_flags) {
+    if (flags_internal::CanIgnoreUndefinedFlag(unrecognized.flag_name))
+      continue;
+    filtered.push_back(unrecognized);
+  }
+
+  std::swap(unrecognized_flags, filtered);
+
+  if (!success) {
+#if ABSL_FLAGS_STRIP_NAMES
+    flags_internal::ReportUsageError(
+        "NOTE: command line flags are disabled in this build", true);
+#else
+    flags_internal::HandleUsageFlags(std::cerr, ProgramUsageMessage());
+#endif
+    return HelpMode::kFull;  // We just need to make sure the exit with
+                             // code 1.
+  }
+
+  return usage_flag_action == UsageFlagsAction::kHandleUsage
+             ? flags_internal::HandleUsageFlags(std::cout,
+                                                ProgramUsageMessage())
+             : HelpMode::kNone;
+}
+
+}  // namespace flags_internal
+
+void ParseAbseilFlagsOnly(int argc, char* argv[],
+                          std::vector<char*>& positional_args,
+                          std::vector<UnrecognizedFlag>& unrecognized_flags) {
+  auto help_mode = flags_internal::ParseAbseilFlagsOnlyImpl(
+      argc, argv, positional_args, unrecognized_flags,
+      flags_internal::UsageFlagsAction::kHandleUsage);
+
+  flags_internal::MaybeExit(help_mode);
+}
+
+// --------------------------------------------------------------------
+
+void ReportUnrecognizedFlags(
+    const std::vector<UnrecognizedFlag>& unrecognized_flags) {
+  flags_internal::ReportUnrecognizedFlags(unrecognized_flags, true);
+}
+
+// --------------------------------------------------------------------
+
+std::vector<char*> ParseCommandLine(int argc, char* argv[]) {
+  return flags_internal::ParseCommandLineImpl(
+      argc, argv, flags_internal::UsageFlagsAction::kHandleUsage,
+      flags_internal::OnUndefinedFlag::kAbortIfUndefined);
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/flags/parse.h

@@ -0,0 +1,130 @@
+//
+// Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// -----------------------------------------------------------------------------
+// File: parse.h
+// -----------------------------------------------------------------------------
+//
+// This file defines the main parsing function for Abseil flags:
+// `absl::ParseCommandLine()`.
+
+#ifndef ABSL_FLAGS_PARSE_H_
+#define ABSL_FLAGS_PARSE_H_
+
+#include <string>
+#include <vector>
+
+#include "absl/base/config.h"
+#include "absl/flags/internal/parse.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+// This type represent information about an unrecognized flag in the command
+// line.
+struct UnrecognizedFlag {
+  enum Source { kFromArgv, kFromFlagfile };
+
+  explicit UnrecognizedFlag(Source s, absl::string_view f)
+      : source(s), flag_name(f) {}
+  // This field indicates where we found this flag: on the original command line
+  // or read in some flag file.
+  Source source;
+  // Name of the flag we did not recognize in --flag_name=value or --flag_name.
+  std::string flag_name;
+};
+
+inline bool operator==(const UnrecognizedFlag& lhs,
+                       const UnrecognizedFlag& rhs) {
+  return lhs.source == rhs.source && lhs.flag_name == rhs.flag_name;
+}
+
+namespace flags_internal {
+
+HelpMode ParseAbseilFlagsOnlyImpl(
+    int argc, char* argv[], std::vector<char*>& positional_args,
+    std::vector<UnrecognizedFlag>& unrecognized_flags,
+    UsageFlagsAction usage_flag_action);
+
+}  // namespace flags_internal
+
+// ParseAbseilFlagsOnly()
+//
+// Parses a list of command-line arguments, passed in the `argc` and `argv[]`
+// parameters, into a set of Abseil Flag values, returning any unparsed
+// arguments in `positional_args` and `unrecognized_flags` output parameters.
+//
+// This function classifies all the arguments (including content of the
+// flagfiles, if any) into one of the following groups:
+//
+//   * arguments specified as "--flag=value" or "--flag value" that match
+//     registered or built-in Abseil Flags. These are "Abseil Flag arguments."
+//   * arguments specified as "--flag" that are unrecognized as Abseil Flags
+//   * arguments that are not specified as "--flag" are positional arguments
+//   * arguments that follow the flag-terminating delimiter (`--`) are also
+//     treated as positional arguments regardless of their syntax.
+//
+// All of the deduced Abseil Flag arguments are then parsed into their
+// corresponding flag values. If any syntax errors are found in these arguments,
+// the binary exits with code 1.
+//
+// This function also handles Abseil Flags built-in usage flags (e.g. --help)
+// if any were present on the command line.
+//
+// All the remaining positional arguments including original program name
+// (argv[0]) are are returned in the `positional_args` output parameter.
+//
+// All unrecognized flags that are not otherwise ignored are returned in the
+// `unrecognized_flags` output parameter. Note that the special `undefok`
+// flag allows you to specify flags which can be safely ignored; `undefok`
+// specifies these flags as a comma-separated list. Any unrecognized flags
+// that appear within `undefok` will therefore be ignored and not included in
+// the `unrecognized_flag` output parameter.
+//
+void ParseAbseilFlagsOnly(int argc, char* argv[],
+                          std::vector<char*>& positional_args,
+                          std::vector<UnrecognizedFlag>& unrecognized_flags);
+
+// ReportUnrecognizedFlags()
+//
+// Reports an error to `stderr` for all non-ignored unrecognized flags in
+// the provided `unrecognized_flags` list.
+void ReportUnrecognizedFlags(
+    const std::vector<UnrecognizedFlag>& unrecognized_flags);
+
+// ParseCommandLine()
+//
+// First parses Abseil Flags only from the command line according to the
+// description in `ParseAbseilFlagsOnly`. In addition this function handles
+// unrecognized and usage flags.
+//
+// If any unrecognized flags are located they are reported using
+// `ReportUnrecognizedFlags`.
+//
+// If any errors detected during command line parsing, this routine reports a
+// usage message and aborts the program.
+//
+// If any built-in usage flags were specified on the command line (e.g.
+// `--help`), this function reports help messages and then gracefully exits the
+// program.
+//
+// This function returns all the remaining positional arguments collected by
+// `ParseAbseilFlagsOnly`.
+std::vector<char*> ParseCommandLine(int argc, char* argv[]);
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_FLAGS_PARSE_H_

weight/_dep/abseil-cpp/absl/flags/parse_test.cc

@@ -0,0 +1,1087 @@
+//
+// Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/flags/parse.h"
+
+#include <stdlib.h>
+
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/base/internal/scoped_set_env.h"
+#include "absl/flags/flag.h"
+#include "absl/flags/internal/parse.h"
+#include "absl/flags/internal/usage.h"
+#include "absl/flags/reflection.h"
+#include "absl/log/log.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/string_view.h"
+#include "absl/strings/substitute.h"
+#include "absl/types/span.h"
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+// Define 125 similar flags to test kMaxHints for flag suggestions.
+#define FLAG_MULT(x) F3(x)
+#define TEST_FLAG_HEADER FLAG_HEADER_
+
+#define F(name) ABSL_FLAG(int, name, 0, "");
+
+#define F1(name) \
+  F(name##1);    \
+  F(name##2);    \
+  F(name##3);    \
+  F(name##4);    \
+  F(name##5);
+/**/
+#define F2(name) \
+  F1(name##1);   \
+  F1(name##2);   \
+  F1(name##3);   \
+  F1(name##4);   \
+  F1(name##5);
+/**/
+#define F3(name) \
+  F2(name##1);   \
+  F2(name##2);   \
+  F2(name##3);   \
+  F2(name##4);   \
+  F2(name##5);
+/**/
+
+FLAG_MULT(TEST_FLAG_HEADER)
+
+namespace {
+
+using absl::base_internal::ScopedSetEnv;
+
+struct UDT {
+  UDT() = default;
+  UDT(const UDT&) = default;
+  UDT& operator=(const UDT&) = default;
+  UDT(int v) : value(v) {}  // NOLINT
+
+  int value;
+};
+
+bool AbslParseFlag(absl::string_view in, UDT* udt, std::string* err) {
+  if (in == "A") {
+    udt->value = 1;
+    return true;
+  }
+  if (in == "AAA") {
+    udt->value = 10;
+    return true;
+  }
+
+  *err = "Use values A, AAA instead";
+  return false;
+}
+std::string AbslUnparseFlag(const UDT& udt) {
+  return udt.value == 1 ? "A" : "AAA";
+}
+
+std::string GetTestTmpDirEnvVar(const char* const env_var_name) {
+#ifdef _WIN32
+  char buf[MAX_PATH];
+  auto get_res = GetEnvironmentVariableA(env_var_name, buf, sizeof(buf));
+  if (get_res >= sizeof(buf) || get_res == 0) {
+    return "";
+  }
+
+  return std::string(buf, get_res);
+#else
+  const char* val = ::getenv(env_var_name);
+  if (val == nullptr) {
+    return "";
+  }
+
+  return val;
+#endif
+}
+
+const std::string& GetTestTempDir() {
+  static std::string* temp_dir_name = []() -> std::string* {
+    std::string* res = new std::string(GetTestTmpDirEnvVar("TEST_TMPDIR"));
+
+    if (res->empty()) {
+      *res = GetTestTmpDirEnvVar("TMPDIR");
+    }
+
+    if (res->empty()) {
+#ifdef _WIN32
+      char temp_path_buffer[MAX_PATH];
+
+      auto len = GetTempPathA(MAX_PATH, temp_path_buffer);
+      if (len < MAX_PATH && len != 0) {
+        std::string temp_dir_name = temp_path_buffer;
+        if (!absl::EndsWith(temp_dir_name, "\\")) {
+          temp_dir_name.push_back('\\');
+        }
+        absl::StrAppend(&temp_dir_name, "parse_test.", GetCurrentProcessId());
+        if (CreateDirectoryA(temp_dir_name.c_str(), nullptr)) {
+          *res = temp_dir_name;
+        }
+      }
+#else
+      char temp_dir_template[] = "/tmp/parse_test.XXXXXX";
+      if (auto* unique_name = ::mkdtemp(temp_dir_template)) {
+        *res = unique_name;
+      }
+#endif
+    }
+
+    if (res->empty()) {
+      LOG(FATAL) << "Failed to make temporary directory for data files";
+    }
+
+#ifdef _WIN32
+    *res += "\\";
+#else
+    *res += "/";
+#endif
+
+    return res;
+  }();
+
+  return *temp_dir_name;
+}
+
+struct FlagfileData {
+  const absl::string_view file_name;
+  const absl::Span<const char* const> file_lines;
+};
+
+// clang-format off
+constexpr const char* const ff1_data[] = {
+    "# comment    ",
+    "  # comment  ",
+    "",
+    "     ",
+    "--int_flag=-1",
+    "  --string_flag=q2w2  ",
+    "  ##   ",
+    "  --double_flag=0.1",
+    "--bool_flag=Y  "
+};
+
+constexpr const char* const ff2_data[] = {
+    "# Setting legacy flag",
+    "--legacy_int=1111",
+    "--legacy_bool",
+    "--nobool_flag",
+    "--legacy_str=aqsw",
+    "--int_flag=100",
+    "   ## ============="
+};
+// clang-format on
+
+// Builds flagfile flag in the flagfile_flag buffer and returns it. This
+// function also creates a temporary flagfile based on FlagfileData input.
+// We create a flagfile in a temporary directory with the name specified in
+// FlagfileData and populate it with lines specified in FlagfileData. If $0 is
+// referenced in any of the lines in FlagfileData they are replaced with
+// temporary directory location. This way we can test inclusion of one flagfile
+// from another flagfile.
+const char* GetFlagfileFlag(const std::vector<FlagfileData>& ffd,
+                            std::string& flagfile_flag) {
+  flagfile_flag = "--flagfile=";
+  absl::string_view separator;
+  for (const auto& flagfile_data : ffd) {
+    std::string flagfile_name =
+        absl::StrCat(GetTestTempDir(), flagfile_data.file_name);
+
+    std::ofstream flagfile_out(flagfile_name);
+    for (auto line : flagfile_data.file_lines) {
+      flagfile_out << absl::Substitute(line, GetTestTempDir()) << "\n";
+    }
+
+    absl::StrAppend(&flagfile_flag, separator, flagfile_name);
+    separator = ",";
+  }
+
+  return flagfile_flag.c_str();
+}
+
+}  // namespace
+
+ABSL_FLAG(int, int_flag, 1, "");
+ABSL_FLAG(double, double_flag, 1.1, "");
+ABSL_FLAG(std::string, string_flag, "a", "");
+ABSL_FLAG(bool, bool_flag, false, "");
+ABSL_FLAG(UDT, udt_flag, -1, "");
+ABSL_RETIRED_FLAG(int, legacy_int, 1, "");
+ABSL_RETIRED_FLAG(bool, legacy_bool, false, "");
+ABSL_RETIRED_FLAG(std::string, legacy_str, "l", "");
+
+namespace {
+
+namespace flags = absl::flags_internal;
+using testing::AllOf;
+using testing::ElementsAreArray;
+using testing::HasSubstr;
+
+class ParseTest : public testing::Test {
+ public:
+  ~ParseTest() override { flags::SetFlagsHelpMode(flags::HelpMode::kNone); }
+
+ private:
+  absl::FlagSaver flag_saver_;
+};
+
+// --------------------------------------------------------------------
+
+template <int N>
+flags::HelpMode InvokeParseAbslOnlyImpl(const char* (&in_argv)[N]) {
+  std::vector<char*> positional_args;
+  std::vector<absl::UnrecognizedFlag> unrecognized_flags;
+
+  return flags::ParseAbseilFlagsOnlyImpl(N, const_cast<char**>(in_argv),
+                                         positional_args, unrecognized_flags,
+                                         flags::UsageFlagsAction::kHandleUsage);
+}
+
+// --------------------------------------------------------------------
+
+template <int N>
+void InvokeParseAbslOnly(const char* (&in_argv)[N]) {
+  std::vector<char*> positional_args;
+  std::vector<absl::UnrecognizedFlag> unrecognized_flags;
+
+  absl::ParseAbseilFlagsOnly(2, const_cast<char**>(in_argv), positional_args,
+                             unrecognized_flags);
+}
+
+// --------------------------------------------------------------------
+
+template <int N>
+std::vector<char*> InvokeParseCommandLineImpl(const char* (&in_argv)[N]) {
+  return flags::ParseCommandLineImpl(
+      N, const_cast<char**>(in_argv), flags::UsageFlagsAction::kHandleUsage,
+      flags::OnUndefinedFlag::kAbortIfUndefined, std::cerr);
+}
+
+// --------------------------------------------------------------------
+
+template <int N>
+std::vector<char*> InvokeParse(const char* (&in_argv)[N]) {
+  return absl::ParseCommandLine(N, const_cast<char**>(in_argv));
+}
+
+// --------------------------------------------------------------------
+
+template <int N>
+void TestParse(const char* (&in_argv)[N], int int_flag_value,
+               double double_flag_val, absl::string_view string_flag_val,
+               bool bool_flag_val, int exp_position_args = 0) {
+  auto out_args = InvokeParse(in_argv);
+
+  EXPECT_EQ(out_args.size(), 1 + exp_position_args);
+  EXPECT_STREQ(out_args[0], "testbin");
+
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), int_flag_value);
+  EXPECT_NEAR(absl::GetFlag(FLAGS_double_flag), double_flag_val, 0.0001);
+  EXPECT_EQ(absl::GetFlag(FLAGS_string_flag), string_flag_val);
+  EXPECT_EQ(absl::GetFlag(FLAGS_bool_flag), bool_flag_val);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestEmptyArgv) {
+  const char* in_argv[] = {"testbin"};
+
+  auto out_args = InvokeParse(in_argv);
+
+  EXPECT_EQ(out_args.size(), 1);
+  EXPECT_STREQ(out_args[0], "testbin");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestValidIntArg) {
+  const char* in_args1[] = {
+      "testbin",
+      "--int_flag=10",
+  };
+  TestParse(in_args1, 10, 1.1, "a", false);
+
+  const char* in_args2[] = {
+      "testbin",
+      "-int_flag=020",
+  };
+  TestParse(in_args2, 20, 1.1, "a", false);
+
+  const char* in_args3[] = {
+      "testbin",
+      "--int_flag",
+      "-30",
+  };
+  TestParse(in_args3, -30, 1.1, "a", false);
+
+  const char* in_args4[] = {
+      "testbin",
+      "-int_flag",
+      "0x21",
+  };
+  TestParse(in_args4, 33, 1.1, "a", false);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestValidDoubleArg) {
+  const char* in_args1[] = {
+      "testbin",
+      "--double_flag=2.3",
+  };
+  TestParse(in_args1, 1, 2.3, "a", false);
+
+  const char* in_args2[] = {
+      "testbin",
+      "--double_flag=0x1.2",
+  };
+  TestParse(in_args2, 1, 1.125, "a", false);
+
+  const char* in_args3[] = {
+      "testbin",
+      "--double_flag",
+      "99.7",
+  };
+  TestParse(in_args3, 1, 99.7, "a", false);
+
+  const char* in_args4[] = {
+      "testbin",
+      "--double_flag",
+      "0x20.1",
+  };
+  TestParse(in_args4, 1, 32.0625, "a", false);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestValidStringArg) {
+  const char* in_args1[] = {
+      "testbin",
+      "--string_flag=aqswde",
+  };
+  TestParse(in_args1, 1, 1.1, "aqswde", false);
+
+  const char* in_args2[] = {
+      "testbin",
+      "-string_flag=a=b=c",
+  };
+  TestParse(in_args2, 1, 1.1, "a=b=c", false);
+
+  const char* in_args3[] = {
+      "testbin",
+      "--string_flag",
+      "zaxscd",
+  };
+  TestParse(in_args3, 1, 1.1, "zaxscd", false);
+
+  const char* in_args4[] = {
+      "testbin",
+      "-string_flag",
+      "--int_flag",
+  };
+  TestParse(in_args4, 1, 1.1, "--int_flag", false);
+
+  const char* in_args5[] = {
+      "testbin",
+      "--string_flag",
+      "--no_a_flag=11",
+  };
+  TestParse(in_args5, 1, 1.1, "--no_a_flag=11", false);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestValidBoolArg) {
+  const char* in_args1[] = {
+      "testbin",
+      "--bool_flag",
+  };
+  TestParse(in_args1, 1, 1.1, "a", true);
+
+  const char* in_args2[] = {
+      "testbin",
+      "--nobool_flag",
+  };
+  TestParse(in_args2, 1, 1.1, "a", false);
+
+  const char* in_args3[] = {
+      "testbin",
+      "--bool_flag=true",
+  };
+  TestParse(in_args3, 1, 1.1, "a", true);
+
+  const char* in_args4[] = {
+      "testbin",
+      "-bool_flag=false",
+  };
+  TestParse(in_args4, 1, 1.1, "a", false);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestValidUDTArg) {
+  const char* in_args1[] = {
+      "testbin",
+      "--udt_flag=A",
+  };
+  InvokeParse(in_args1);
+
+  EXPECT_EQ(absl::GetFlag(FLAGS_udt_flag).value, 1);
+
+  const char* in_args2[] = {"testbin", "--udt_flag", "AAA"};
+  InvokeParse(in_args2);
+
+  EXPECT_EQ(absl::GetFlag(FLAGS_udt_flag).value, 10);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestValidMultipleArg) {
+  const char* in_args1[] = {
+      "testbin",           "--bool_flag",       "--int_flag=2",
+      "--double_flag=0.1", "--string_flag=asd",
+  };
+  TestParse(in_args1, 2, 0.1, "asd", true);
+
+  const char* in_args2[] = {
+      "testbin", "--string_flag=", "--nobool_flag", "--int_flag",
+      "-011",    "--double_flag",  "-1e-2",
+  };
+  TestParse(in_args2, -11, -0.01, "", false);
+
+  const char* in_args3[] = {
+      "testbin",          "--int_flag",         "-0", "--string_flag", "\"\"",
+      "--bool_flag=true", "--double_flag=1e18",
+  };
+  TestParse(in_args3, 0, 1e18, "\"\"", true);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestPositionalArgs) {
+  const char* in_args1[] = {
+      "testbin",
+      "p1",
+      "p2",
+  };
+  TestParse(in_args1, 1, 1.1, "a", false, 2);
+
+  auto out_args1 = InvokeParse(in_args1);
+
+  EXPECT_STREQ(out_args1[1], "p1");
+  EXPECT_STREQ(out_args1[2], "p2");
+
+  const char* in_args2[] = {
+      "testbin",
+      "--int_flag=2",
+      "p1",
+  };
+  TestParse(in_args2, 2, 1.1, "a", false, 1);
+
+  auto out_args2 = InvokeParse(in_args2);
+
+  EXPECT_STREQ(out_args2[1], "p1");
+
+  const char* in_args3[] = {"testbin", "p1",          "--int_flag=3",
+                            "p2",      "--bool_flag", "true"};
+  TestParse(in_args3, 3, 1.1, "a", true, 3);
+
+  auto out_args3 = InvokeParse(in_args3);
+
+  EXPECT_STREQ(out_args3[1], "p1");
+  EXPECT_STREQ(out_args3[2], "p2");
+  EXPECT_STREQ(out_args3[3], "true");
+
+  const char* in_args4[] = {
+      "testbin",
+      "--",
+      "p1",
+      "p2",
+  };
+  TestParse(in_args4, 3, 1.1, "a", true, 2);
+
+  auto out_args4 = InvokeParse(in_args4);
+
+  EXPECT_STREQ(out_args4[1], "p1");
+  EXPECT_STREQ(out_args4[2], "p2");
+
+  const char* in_args5[] = {
+      "testbin", "p1", "--int_flag=4", "--", "--bool_flag", "false", "p2",
+  };
+  TestParse(in_args5, 4, 1.1, "a", true, 4);
+
+  auto out_args5 = InvokeParse(in_args5);
+
+  EXPECT_STREQ(out_args5[1], "p1");
+  EXPECT_STREQ(out_args5[2], "--bool_flag");
+  EXPECT_STREQ(out_args5[3], "false");
+  EXPECT_STREQ(out_args5[4], "p2");
+}
+
+// --------------------------------------------------------------------
+
+using ParseDeathTest = ParseTest;
+
+TEST_F(ParseDeathTest, TestUndefinedArg) {
+  const char* in_args1[] = {
+      "testbin",
+      "--undefined_flag",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args1),
+                            "Unknown command line flag 'undefined_flag'");
+
+  const char* in_args2[] = {
+      "testbin",
+      "--noprefixed_flag",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args2),
+                            "Unknown command line flag 'noprefixed_flag'");
+
+  const char* in_args3[] = {
+      "testbin",
+      "--Int_flag=1",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args3),
+                            "Unknown command line flag 'Int_flag'");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, TestInvalidBoolFlagFormat) {
+  const char* in_args1[] = {
+      "testbin",
+      "--bool_flag=",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(
+      InvokeParse(in_args1),
+      "Missing the value after assignment for the boolean flag 'bool_flag'");
+
+  const char* in_args2[] = {
+      "testbin",
+      "--nobool_flag=true",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args2),
+               "Negative form with assignment is not valid for the boolean "
+               "flag 'bool_flag'");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, TestInvalidNonBoolFlagFormat) {
+  const char* in_args1[] = {
+      "testbin",
+      "--nostring_flag",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args1),
+               "Negative form is not valid for the flag 'string_flag'");
+
+  const char* in_args2[] = {
+      "testbin",
+      "--int_flag",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args2),
+               "Missing the value for the flag 'int_flag'");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, TestInvalidUDTFlagFormat) {
+  const char* in_args1[] = {
+      "testbin",
+      "--udt_flag=1",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args1),
+               "Illegal value '1' specified for flag 'udt_flag'; Use values A, "
+               "AAA instead");
+
+  const char* in_args2[] = {
+      "testbin",
+      "--udt_flag",
+      "AA",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args2),
+               "Illegal value 'AA' specified for flag 'udt_flag'; Use values "
+               "A, AAA instead");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, TestFlagSuggestions) {
+  const char* in_args1[] = {
+      "testbin",
+      "--legacy_boo",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(
+      InvokeParse(in_args1),
+      "Unknown command line flag 'legacy_boo'. Did you mean: legacy_bool ?");
+
+  const char* in_args2[] = {"testbin", "--foo", "--undefok=foo1"};
+  EXPECT_DEATH_IF_SUPPORTED(
+      InvokeParse(in_args2),
+      "Unknown command line flag 'foo'. Did you mean: foo1 \\(undefok\\)?");
+
+  const char* in_args3[] = {
+      "testbin",
+      "--nolegacy_ino",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args3),
+                            "Unknown command line flag 'nolegacy_ino'. Did "
+                            "you mean: nolegacy_bool, legacy_int ?");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, GetHints) {
+  EXPECT_THAT(absl::flags_internal::GetMisspellingHints("legacy_boo"),
+              testing::ContainerEq(std::vector<std::string>{"legacy_bool"}));
+  EXPECT_THAT(absl::flags_internal::GetMisspellingHints("nolegacy_itn"),
+              testing::ContainerEq(std::vector<std::string>{"legacy_int"}));
+  EXPECT_THAT(absl::flags_internal::GetMisspellingHints("nolegacy_int1"),
+              testing::ContainerEq(std::vector<std::string>{"legacy_int"}));
+  EXPECT_THAT(absl::flags_internal::GetMisspellingHints("nolegacy_int"),
+              testing::ContainerEq(std::vector<std::string>{"legacy_int"}));
+  EXPECT_THAT(absl::flags_internal::GetMisspellingHints("nolegacy_ino"),
+              testing::ContainerEq(
+                  std::vector<std::string>{"nolegacy_bool", "legacy_int"}));
+  EXPECT_THAT(
+      absl::flags_internal::GetMisspellingHints("FLAG_HEADER_000").size(), 100);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestLegacyFlags) {
+  const char* in_args1[] = {
+      "testbin",
+      "--legacy_int=11",
+  };
+  TestParse(in_args1, 1, 1.1, "a", false);
+
+  const char* in_args2[] = {
+      "testbin",
+      "--legacy_bool",
+  };
+  TestParse(in_args2, 1, 1.1, "a", false);
+
+  const char* in_args3[] = {
+      "testbin",       "--legacy_int", "22",           "--int_flag=2",
+      "--legacy_bool", "true",         "--legacy_str", "--string_flag=qwe",
+  };
+  TestParse(in_args3, 2, 1.1, "a", false, 1);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestSimpleValidFlagfile) {
+  std::string flagfile_flag;
+
+  const char* in_args1[] = {
+      "testbin",
+      GetFlagfileFlag({{"parse_test.ff1", absl::MakeConstSpan(ff1_data)}},
+                      flagfile_flag),
+  };
+  TestParse(in_args1, -1, 0.1, "q2w2  ", true);
+
+  const char* in_args2[] = {
+      "testbin",
+      GetFlagfileFlag({{"parse_test.ff2", absl::MakeConstSpan(ff2_data)}},
+                      flagfile_flag),
+  };
+  TestParse(in_args2, 100, 0.1, "q2w2  ", false);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestValidMultiFlagfile) {
+  std::string flagfile_flag;
+
+  const char* in_args1[] = {
+      "testbin",
+      GetFlagfileFlag({{"parse_test.ff2", absl::MakeConstSpan(ff2_data)},
+                       {"parse_test.ff1", absl::MakeConstSpan(ff1_data)}},
+                      flagfile_flag),
+  };
+  TestParse(in_args1, -1, 0.1, "q2w2  ", true);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestFlagfileMixedWithRegularFlags) {
+  std::string flagfile_flag;
+
+  const char* in_args1[] = {
+      "testbin", "--int_flag=3",
+      GetFlagfileFlag({{"parse_test.ff1", absl::MakeConstSpan(ff1_data)}},
+                      flagfile_flag),
+      "-double_flag=0.2"};
+  TestParse(in_args1, -1, 0.2, "q2w2  ", true);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestFlagfileInFlagfile) {
+  std::string flagfile_flag;
+
+  constexpr const char* const ff3_data[] = {
+      "--flagfile=$0/parse_test.ff1",
+      "--flagfile=$0/parse_test.ff2",
+  };
+
+  GetFlagfileFlag({{"parse_test.ff2", absl::MakeConstSpan(ff2_data)},
+                   {"parse_test.ff1", absl::MakeConstSpan(ff1_data)}},
+                      flagfile_flag);
+
+  const char* in_args1[] = {
+      "testbin",
+      GetFlagfileFlag({{"parse_test.ff3", absl::MakeConstSpan(ff3_data)}},
+                      flagfile_flag),
+  };
+  TestParse(in_args1, 100, 0.1, "q2w2  ", false);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, TestInvalidFlagfiles) {
+  std::string flagfile_flag;
+
+  constexpr const char* const ff4_data[] = {
+    "--unknown_flag=10"
+  };
+
+  const char* in_args1[] = {
+      "testbin",
+      GetFlagfileFlag({{"parse_test.ff4",
+                        absl::MakeConstSpan(ff4_data)}}, flagfile_flag),
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args1),
+               "Unknown command line flag 'unknown_flag'");
+
+  constexpr const char* const ff5_data[] = {
+    "--int_flag 10",
+  };
+
+  const char* in_args2[] = {
+      "testbin",
+      GetFlagfileFlag({{"parse_test.ff5",
+                        absl::MakeConstSpan(ff5_data)}}, flagfile_flag),
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args2),
+               "Unknown command line flag 'int_flag 10'");
+
+  constexpr const char* const ff6_data[] = {
+      "--int_flag=10", "--", "arg1", "arg2", "arg3",
+  };
+
+  const char* in_args3[] = {
+      "testbin",
+      GetFlagfileFlag({{"parse_test.ff6", absl::MakeConstSpan(ff6_data)}},
+                      flagfile_flag),
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args3),
+               "Flagfile can't contain position arguments or --");
+
+  const char* in_args4[] = {
+      "testbin",
+      "--flagfile=invalid_flag_file",
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args4),
+                            "Can't open flagfile invalid_flag_file");
+
+  constexpr const char* const ff7_data[] = {
+      "--int_flag=10",
+      "*bin*",
+      "--str_flag=aqsw",
+  };
+
+  const char* in_args5[] = {
+      "testbin",
+      GetFlagfileFlag({{"parse_test.ff7", absl::MakeConstSpan(ff7_data)}},
+                      flagfile_flag),
+  };
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args5),
+               "Unexpected line in the flagfile .*: \\*bin\\*");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestReadingRequiredFlagsFromEnv) {
+  const char* in_args1[] = {"testbin",
+                            "--fromenv=int_flag,bool_flag,string_flag"};
+
+  ScopedSetEnv set_int_flag("FLAGS_int_flag", "33");
+  ScopedSetEnv set_bool_flag("FLAGS_bool_flag", "True");
+  ScopedSetEnv set_string_flag("FLAGS_string_flag", "AQ12");
+
+  TestParse(in_args1, 33, 1.1, "AQ12", true);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, TestReadingUnsetRequiredFlagsFromEnv) {
+  const char* in_args1[] = {"testbin", "--fromenv=int_flag"};
+
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args1),
+               "FLAGS_int_flag not found in environment");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, TestRecursiveFlagsFromEnv) {
+  const char* in_args1[] = {"testbin", "--fromenv=tryfromenv"};
+
+  ScopedSetEnv set_tryfromenv("FLAGS_tryfromenv", "int_flag");
+
+  EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args1),
+                            "Infinite recursion on flag tryfromenv");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestReadingOptionalFlagsFromEnv) {
+  const char* in_args1[] = {
+      "testbin", "--tryfromenv=int_flag,bool_flag,string_flag,other_flag"};
+
+  ScopedSetEnv set_int_flag("FLAGS_int_flag", "17");
+  ScopedSetEnv set_bool_flag("FLAGS_bool_flag", "Y");
+
+  TestParse(in_args1, 17, 1.1, "a", true);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestReadingFlagsFromEnvMoxedWithRegularFlags) {
+  const char* in_args1[] = {
+      "testbin",
+      "--bool_flag=T",
+      "--tryfromenv=int_flag,bool_flag",
+      "--int_flag=-21",
+  };
+
+  ScopedSetEnv set_int_flag("FLAGS_int_flag", "-15");
+  ScopedSetEnv set_bool_flag("FLAGS_bool_flag", "F");
+
+  TestParse(in_args1, -21, 1.1, "a", false);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, TestSimpleHelpFlagHandling) {
+  const char* in_args1[] = {
+      "testbin",
+      "--help",
+  };
+
+  EXPECT_EQ(InvokeParseAbslOnlyImpl(in_args1), flags::HelpMode::kImportant);
+  EXPECT_EXIT(InvokeParse(in_args1), testing::ExitedWithCode(1), "");
+
+  const char* in_args2[] = {
+      "testbin",
+      "--help",
+      "--int_flag=3",
+  };
+
+  EXPECT_EQ(InvokeParseAbslOnlyImpl(in_args2), flags::HelpMode::kImportant);
+  EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 3);
+
+  const char* in_args3[] = {"testbin", "--help", "some_positional_arg"};
+
+  EXPECT_EQ(InvokeParseAbslOnlyImpl(in_args3), flags::HelpMode::kImportant);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestSubstringHelpFlagHandling) {
+  const char* in_args1[] = {
+      "testbin",
+      "--help=abcd",
+  };
+
+  EXPECT_EQ(InvokeParseAbslOnlyImpl(in_args1), flags::HelpMode::kMatch);
+  EXPECT_EQ(flags::GetFlagsHelpMatchSubstr(), "abcd");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, TestVersionHandling) {
+  const char* in_args1[] = {
+      "testbin",
+      "--version",
+  };
+
+  EXPECT_EQ(InvokeParseAbslOnlyImpl(in_args1), flags::HelpMode::kVersion);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, TestCheckArgsHandling) {
+  const char* in_args1[] = {"testbin", "--only_check_args", "--int_flag=211"};
+
+  EXPECT_EQ(InvokeParseAbslOnlyImpl(in_args1), flags::HelpMode::kOnlyCheckArgs);
+  EXPECT_EXIT(InvokeParseAbslOnly(in_args1), testing::ExitedWithCode(0), "");
+  EXPECT_EXIT(InvokeParse(in_args1), testing::ExitedWithCode(0), "");
+
+  const char* in_args2[] = {"testbin", "--only_check_args", "--unknown_flag=a"};
+
+  EXPECT_EQ(InvokeParseAbslOnlyImpl(in_args2), flags::HelpMode::kOnlyCheckArgs);
+  EXPECT_EXIT(InvokeParseAbslOnly(in_args2), testing::ExitedWithCode(0), "");
+  EXPECT_EXIT(InvokeParse(in_args2), testing::ExitedWithCode(1), "");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, WasPresentOnCommandLine) {
+  const char* in_args1[] = {
+      "testbin",        "arg1", "--bool_flag",
+      "--int_flag=211", "arg2", "--double_flag=1.1",
+      "--string_flag",  "asd",  "--",
+      "--some_flag",    "arg4",
+  };
+
+  InvokeParse(in_args1);
+
+  EXPECT_TRUE(flags::WasPresentOnCommandLine("bool_flag"));
+  EXPECT_TRUE(flags::WasPresentOnCommandLine("int_flag"));
+  EXPECT_TRUE(flags::WasPresentOnCommandLine("double_flag"));
+  EXPECT_TRUE(flags::WasPresentOnCommandLine("string_flag"));
+  EXPECT_FALSE(flags::WasPresentOnCommandLine("some_flag"));
+  EXPECT_FALSE(flags::WasPresentOnCommandLine("another_flag"));
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, ParseAbseilFlagsOnlySuccess) {
+  const char* in_args[] = {
+      "testbin",
+      "arg1",
+      "--bool_flag",
+      "--int_flag=211",
+      "arg2",
+      "--double_flag=1.1",
+      "--undef_flag1",
+      "--undef_flag2=123",
+      "--string_flag",
+      "asd",
+      "--",
+      "--some_flag",
+      "arg4",
+  };
+
+  std::vector<char*> positional_args;
+  std::vector<absl::UnrecognizedFlag> unrecognized_flags;
+
+  absl::ParseAbseilFlagsOnly(13, const_cast<char**>(in_args), positional_args,
+                             unrecognized_flags);
+  EXPECT_THAT(positional_args,
+              ElementsAreArray(
+                  {absl::string_view("testbin"), absl::string_view("arg1"),
+                   absl::string_view("arg2"), absl::string_view("--some_flag"),
+                   absl::string_view("arg4")}));
+  EXPECT_THAT(unrecognized_flags,
+              ElementsAreArray(
+                  {absl::UnrecognizedFlag(absl::UnrecognizedFlag::kFromArgv,
+                                          "undef_flag1"),
+                   absl::UnrecognizedFlag(absl::UnrecognizedFlag::kFromArgv,
+                                          "undef_flag2")}));
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, ParseAbseilFlagsOnlyFailure) {
+  const char* in_args[] = {
+      "testbin",
+      "--int_flag=21.1",
+  };
+
+  EXPECT_DEATH_IF_SUPPORTED(
+      InvokeParseAbslOnly(in_args),
+      "Illegal value '21.1' specified for flag 'int_flag'");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, UndefOkFlagsAreIgnored) {
+  const char* in_args[] = {
+      "testbin",           "--undef_flag1",
+      "--undef_flag2=123", "--undefok=undef_flag2",
+      "--undef_flag3",     "value",
+  };
+
+  std::vector<char*> positional_args;
+  std::vector<absl::UnrecognizedFlag> unrecognized_flags;
+
+  absl::ParseAbseilFlagsOnly(6, const_cast<char**>(in_args), positional_args,
+                             unrecognized_flags);
+  EXPECT_THAT(positional_args, ElementsAreArray({absl::string_view("testbin"),
+                                                 absl::string_view("value")}));
+  EXPECT_THAT(unrecognized_flags,
+              ElementsAreArray(
+                  {absl::UnrecognizedFlag(absl::UnrecognizedFlag::kFromArgv,
+                                          "undef_flag1"),
+                   absl::UnrecognizedFlag(absl::UnrecognizedFlag::kFromArgv,
+                                          "undef_flag3")}));
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, AllUndefOkFlagsAreIgnored) {
+  const char* in_args[] = {
+      "testbin",
+      "--undef_flag1",
+      "--undef_flag2=123",
+      "--undefok=undef_flag2,undef_flag1,undef_flag3",
+      "--undef_flag3",
+      "value",
+      "--",
+      "--undef_flag4",
+  };
+
+  std::vector<char*> positional_args;
+  std::vector<absl::UnrecognizedFlag> unrecognized_flags;
+
+  absl::ParseAbseilFlagsOnly(8, const_cast<char**>(in_args), positional_args,
+                             unrecognized_flags);
+  EXPECT_THAT(positional_args,
+              ElementsAreArray({absl::string_view("testbin"),
+                                absl::string_view("value"),
+                                absl::string_view("--undef_flag4")}));
+  EXPECT_THAT(unrecognized_flags, testing::IsEmpty());
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseDeathTest, ExitOnUnrecognizedFlagPrintsHelp) {
+  const char* in_args[] = {
+      "testbin",
+      "--undef_flag1",
+      "--help=int_flag",
+  };
+
+  EXPECT_EXIT(InvokeParseCommandLineImpl(in_args), testing::ExitedWithCode(1),
+              AllOf(HasSubstr("Unknown command line flag 'undef_flag1'"),
+                    HasSubstr("Try --helpfull to get a list of all flags")));
+}
+
+// --------------------------------------------------------------------
+
+}  // namespace

weight/_dep/abseil-cpp/absl/flags/reflection.h

@@ -0,0 +1,90 @@
+//
+// Copyright 2020 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// -----------------------------------------------------------------------------
+// File: reflection.h
+// -----------------------------------------------------------------------------
+//
+// This file defines the routines to access and operate on an Abseil Flag's
+// reflection handle.
+
+#ifndef ABSL_FLAGS_REFLECTION_H_
+#define ABSL_FLAGS_REFLECTION_H_
+
+#include <string>
+
+#include "absl/base/config.h"
+#include "absl/container/flat_hash_map.h"
+#include "absl/flags/commandlineflag.h"
+#include "absl/flags/internal/commandlineflag.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace flags_internal {
+class FlagSaverImpl;
+}  // namespace flags_internal
+
+// FindCommandLineFlag()
+//
+// Returns the reflection handle of an Abseil flag of the specified name, or
+// `nullptr` if not found. This function will emit a warning if the name of a
+// 'retired' flag is specified.
+absl::CommandLineFlag* FindCommandLineFlag(absl::string_view name);
+
+// Returns current state of the Flags registry in a form of mapping from flag
+// name to a flag reflection handle.
+absl::flat_hash_map<absl::string_view, absl::CommandLineFlag*> GetAllFlags();
+
+//------------------------------------------------------------------------------
+// FlagSaver
+//------------------------------------------------------------------------------
+//
+// A FlagSaver object stores the state of flags in the scope where the FlagSaver
+// is defined, allowing modification of those flags within that scope and
+// automatic restoration of the flags to their previous state upon leaving the
+// scope.
+//
+// A FlagSaver can be used within tests to temporarily change the test
+// environment and restore the test case to its previous state.
+//
+// Example:
+//
+//   void MyFunc() {
+//    absl::FlagSaver fs;
+//    ...
+//    absl::SetFlag(&FLAGS_myFlag, otherValue);
+//    ...
+//  } // scope of FlagSaver left, flags return to previous state
+//
+// This class is thread-safe.
+
+class FlagSaver {
+ public:
+  FlagSaver();
+  ~FlagSaver();
+
+  FlagSaver(const FlagSaver&) = delete;
+  void operator=(const FlagSaver&) = delete;
+
+ private:
+  flags_internal::FlagSaverImpl* impl_;
+};
+
+//-----------------------------------------------------------------------------
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_FLAGS_REFLECTION_H_

weight/_dep/abseil-cpp/absl/flags/reflection_test.cc

@@ -0,0 +1,265 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/flags/reflection.h"
+
+#include <memory>
+#include <string>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/flags/declare.h"
+#include "absl/flags/flag.h"
+#include "absl/flags/internal/commandlineflag.h"
+#include "absl/flags/marshalling.h"
+#include "absl/memory/memory.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_split.h"
+
+ABSL_FLAG(int, int_flag, 1, "int_flag help");
+ABSL_FLAG(std::string, string_flag, "dflt", "string_flag help");
+ABSL_RETIRED_FLAG(bool, bool_retired_flag, false, "bool_retired_flag help");
+
+namespace {
+
+class ReflectionTest : public testing::Test {
+ protected:
+  void SetUp() override { flag_saver_ = absl::make_unique<absl::FlagSaver>(); }
+  void TearDown() override { flag_saver_.reset(); }
+
+ private:
+  std::unique_ptr<absl::FlagSaver> flag_saver_;
+};
+
+// --------------------------------------------------------------------
+
+TEST_F(ReflectionTest, TestFindCommandLineFlag) {
+  auto* handle = absl::FindCommandLineFlag("some_flag");
+  EXPECT_EQ(handle, nullptr);
+
+  handle = absl::FindCommandLineFlag("int_flag");
+  EXPECT_NE(handle, nullptr);
+
+  handle = absl::FindCommandLineFlag("string_flag");
+  EXPECT_NE(handle, nullptr);
+
+  handle = absl::FindCommandLineFlag("bool_retired_flag");
+  EXPECT_NE(handle, nullptr);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ReflectionTest, TestGetAllFlags) {
+  auto all_flags = absl::GetAllFlags();
+  EXPECT_NE(all_flags.find("int_flag"), all_flags.end());
+  EXPECT_EQ(all_flags.find("bool_retired_flag"), all_flags.end());
+  EXPECT_EQ(all_flags.find("some_undefined_flag"), all_flags.end());
+
+  std::vector<absl::string_view> flag_names_first_attempt;
+  auto all_flags_1 = absl::GetAllFlags();
+  for (auto f : all_flags_1) {
+    flag_names_first_attempt.push_back(f.first);
+  }
+
+  std::vector<absl::string_view> flag_names_second_attempt;
+  auto all_flags_2 = absl::GetAllFlags();
+  for (auto f : all_flags_2) {
+    flag_names_second_attempt.push_back(f.first);
+  }
+
+  EXPECT_THAT(flag_names_first_attempt,
+              ::testing::UnorderedElementsAreArray(flag_names_second_attempt));
+}
+
+// --------------------------------------------------------------------
+
+struct CustomUDT {
+  CustomUDT() : a(1), b(1) {}
+  CustomUDT(int a_, int b_) : a(a_), b(b_) {}
+
+  friend bool operator==(const CustomUDT& f1, const CustomUDT& f2) {
+    return f1.a == f2.a && f1.b == f2.b;
+  }
+
+  int a;
+  int b;
+};
+bool AbslParseFlag(absl::string_view in, CustomUDT* f, std::string*) {
+  std::vector<absl::string_view> parts =
+      absl::StrSplit(in, ':', absl::SkipWhitespace());
+
+  if (parts.size() != 2) return false;
+
+  if (!absl::SimpleAtoi(parts[0], &f->a)) return false;
+
+  if (!absl::SimpleAtoi(parts[1], &f->b)) return false;
+
+  return true;
+}
+std::string AbslUnparseFlag(const CustomUDT& f) {
+  return absl::StrCat(f.a, ":", f.b);
+}
+
+}  // namespace
+
+// --------------------------------------------------------------------
+
+ABSL_FLAG(bool, test_flag_01, true, "");
+ABSL_FLAG(int, test_flag_02, 1234, "");
+ABSL_FLAG(int16_t, test_flag_03, -34, "");
+ABSL_FLAG(uint16_t, test_flag_04, 189, "");
+ABSL_FLAG(int32_t, test_flag_05, 10765, "");
+ABSL_FLAG(uint32_t, test_flag_06, 40000, "");
+ABSL_FLAG(int64_t, test_flag_07, -1234567, "");
+ABSL_FLAG(uint64_t, test_flag_08, 9876543, "");
+ABSL_FLAG(double, test_flag_09, -9.876e-50, "");
+ABSL_FLAG(float, test_flag_10, 1.234e12f, "");
+ABSL_FLAG(std::string, test_flag_11, "", "");
+ABSL_FLAG(absl::Duration, test_flag_12, absl::Minutes(10), "");
+static int counter = 0;
+ABSL_FLAG(int, test_flag_13, 200, "").OnUpdate([]() { counter++; });
+ABSL_FLAG(CustomUDT, test_flag_14, {}, "");
+
+namespace {
+
+TEST_F(ReflectionTest, TestFlagSaverInScope) {
+  {
+    absl::FlagSaver s;
+    counter = 0;
+    absl::SetFlag(&FLAGS_test_flag_01, false);
+    absl::SetFlag(&FLAGS_test_flag_02, -1021);
+    absl::SetFlag(&FLAGS_test_flag_03, 6009);
+    absl::SetFlag(&FLAGS_test_flag_04, 44);
+    absl::SetFlag(&FLAGS_test_flag_05, +800);
+    absl::SetFlag(&FLAGS_test_flag_06, -40978756);
+    absl::SetFlag(&FLAGS_test_flag_07, 23405);
+    absl::SetFlag(&FLAGS_test_flag_08, 975310);
+    absl::SetFlag(&FLAGS_test_flag_09, 1.00001);
+    absl::SetFlag(&FLAGS_test_flag_10, -3.54f);
+    absl::SetFlag(&FLAGS_test_flag_11, "asdf");
+    absl::SetFlag(&FLAGS_test_flag_12, absl::Hours(20));
+    absl::SetFlag(&FLAGS_test_flag_13, 4);
+    absl::SetFlag(&FLAGS_test_flag_14, CustomUDT{-1, -2});
+  }
+
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_01), true);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_02), 1234);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_03), -34);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_04), 189);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_05), 10765);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_06), 40000);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_07), -1234567);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_08), 9876543);
+  EXPECT_NEAR(absl::GetFlag(FLAGS_test_flag_09), -9.876e-50, 1e-55);
+  EXPECT_NEAR(absl::GetFlag(FLAGS_test_flag_10), 1.234e12f, 1e5f);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_11), "");
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_12), absl::Minutes(10));
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_13), 200);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_14), CustomUDT{});
+  EXPECT_EQ(counter, 2);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ReflectionTest, TestFlagSaverVsUpdateViaReflection) {
+  {
+    absl::FlagSaver s;
+    counter = 0;
+    std::string error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_01")->ParseFrom("false", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_02")->ParseFrom("-4536", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_03")->ParseFrom("111", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_04")->ParseFrom("909", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_05")->ParseFrom("-2004", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_06")->ParseFrom("1000023", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_07")->ParseFrom("69305", &error))
+        << error;
+    EXPECT_TRUE(absl::FindCommandLineFlag("test_flag_08")
+                    ->ParseFrom("1000000001", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_09")->ParseFrom("2.09021", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_10")->ParseFrom("-33.1", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_11")->ParseFrom("ADD_FOO", &error))
+        << error;
+    EXPECT_TRUE(absl::FindCommandLineFlag("test_flag_12")
+                    ->ParseFrom("3h11m16s", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_13")->ParseFrom("0", &error))
+        << error;
+    EXPECT_TRUE(
+        absl::FindCommandLineFlag("test_flag_14")->ParseFrom("10:1", &error))
+        << error;
+  }
+
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_01), true);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_02), 1234);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_03), -34);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_04), 189);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_05), 10765);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_06), 40000);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_07), -1234567);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_08), 9876543);
+  EXPECT_NEAR(absl::GetFlag(FLAGS_test_flag_09), -9.876e-50, 1e-55);
+  EXPECT_NEAR(absl::GetFlag(FLAGS_test_flag_10), 1.234e12f, 1e5f);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_11), "");
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_12), absl::Minutes(10));
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_13), 200);
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_14), CustomUDT{});
+  EXPECT_EQ(counter, 2);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ReflectionTest, TestMultipleFlagSaversInEnclosedScopes) {
+  {
+    absl::FlagSaver s;
+    absl::SetFlag(&FLAGS_test_flag_08, 10);
+    EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_08), 10);
+    {
+      absl::FlagSaver s;
+      absl::SetFlag(&FLAGS_test_flag_08, 20);
+      EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_08), 20);
+      {
+        absl::FlagSaver s;
+        absl::SetFlag(&FLAGS_test_flag_08, -200);
+        EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_08), -200);
+      }
+      EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_08), 20);
+    }
+    EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_08), 10);
+  }
+  EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_08), 9876543);
+}
+
+}  // namespace

weight/_dep/abseil-cpp/absl/flags/usage.cc

@@ -0,0 +1,66 @@
+//
+// Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#include "absl/flags/usage.h"
+
+#include <stdlib.h>
+
+#include <string>
+
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
+#include "absl/base/const_init.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/base/thread_annotations.h"
+#include "absl/flags/internal/usage.h"
+#include "absl/strings/string_view.h"
+#include "absl/synchronization/mutex.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace flags_internal {
+namespace {
+ABSL_CONST_INIT absl::Mutex usage_message_guard(absl::kConstInit);
+ABSL_CONST_INIT std::string* program_usage_message
+    ABSL_GUARDED_BY(usage_message_guard) = nullptr;
+}  // namespace
+}  // namespace flags_internal
+
+// --------------------------------------------------------------------
+// Sets the "usage" message to be used by help reporting routines.
+void SetProgramUsageMessage(absl::string_view new_usage_message) {
+  absl::MutexLock l(&flags_internal::usage_message_guard);
+
+  if (flags_internal::program_usage_message != nullptr) {
+    ABSL_INTERNAL_LOG(FATAL, "SetProgramUsageMessage() called twice.");
+    std::exit(1);
+  }
+
+  flags_internal::program_usage_message = new std::string(new_usage_message);
+}
+
+// --------------------------------------------------------------------
+// Returns the usage message set by SetProgramUsageMessage().
+// Note: We able to return string_view here only because calling
+// SetProgramUsageMessage twice is prohibited.
+absl::string_view ProgramUsageMessage() {
+  absl::MutexLock l(&flags_internal::usage_message_guard);
+
+  return flags_internal::program_usage_message != nullptr
+             ? absl::string_view(*flags_internal::program_usage_message)
+             : "Warning: SetProgramUsageMessage() never called";
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/flags/usage_config.cc

@@ -0,0 +1,165 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/flags/usage_config.h"
+
+#include <functional>
+#include <iostream>
+#include <string>
+
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
+#include "absl/base/const_init.h"
+#include "absl/base/thread_annotations.h"
+#include "absl/flags/internal/path_util.h"
+#include "absl/flags/internal/program_name.h"
+#include "absl/strings/match.h"
+#include "absl/strings/string_view.h"
+#include "absl/strings/strip.h"
+#include "absl/synchronization/mutex.h"
+
+extern "C" {
+
+// Additional report of fatal usage error message before we std::exit. Error is
+// fatal if is_fatal argument to ReportUsageError is true.
+ABSL_ATTRIBUTE_WEAK void ABSL_INTERNAL_C_SYMBOL(
+    AbslInternalReportFatalUsageError)(absl::string_view) {}
+
+}  // extern "C"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace flags_internal {
+
+namespace {
+
+// --------------------------------------------------------------------
+// Returns true if flags defined in the filename should be reported with
+// -helpshort flag.
+
+bool ContainsHelpshortFlags(absl::string_view filename) {
+  // By default we only want flags in binary's main. We expect the main
+  // routine to reside in <program>.cc or <program>-main.cc or
+  // <program>_main.cc, where the <program> is the name of the binary
+  // (without .exe on Windows).
+  auto suffix = flags_internal::Basename(filename);
+  auto program_name = flags_internal::ShortProgramInvocationName();
+  absl::string_view program_name_ref = program_name;
+#if defined(_WIN32)
+  absl::ConsumeSuffix(&program_name_ref, ".exe");
+#endif
+  if (!absl::ConsumePrefix(&suffix, program_name_ref))
+    return false;
+  return absl::StartsWith(suffix, ".") || absl::StartsWith(suffix, "-main.") ||
+         absl::StartsWith(suffix, "_main.");
+}
+
+// --------------------------------------------------------------------
+// Returns true if flags defined in the filename should be reported with
+// -helppackage flag.
+
+bool ContainsHelppackageFlags(absl::string_view filename) {
+  // TODO(rogeeff): implement properly when registry is available.
+  return ContainsHelpshortFlags(filename);
+}
+
+// --------------------------------------------------------------------
+// Generates program version information into supplied output.
+
+std::string VersionString() {
+  std::string version_str(flags_internal::ShortProgramInvocationName());
+
+  version_str += "\n";
+
+#if !defined(NDEBUG)
+  version_str += "Debug build (NDEBUG not #defined)\n";
+#endif
+
+  return version_str;
+}
+
+// --------------------------------------------------------------------
+// Normalizes the filename specific to the build system/filesystem used.
+
+std::string NormalizeFilename(absl::string_view filename) {
+  // Skip any leading slashes
+  auto pos = filename.find_first_not_of("\\/");
+  if (pos == absl::string_view::npos) return "";
+
+  filename.remove_prefix(pos);
+  return std::string(filename);
+}
+
+// --------------------------------------------------------------------
+
+ABSL_CONST_INIT absl::Mutex custom_usage_config_guard(absl::kConstInit);
+ABSL_CONST_INIT FlagsUsageConfig* custom_usage_config
+    ABSL_GUARDED_BY(custom_usage_config_guard) = nullptr;
+
+}  // namespace
+
+FlagsUsageConfig GetUsageConfig() {
+  absl::MutexLock l(&custom_usage_config_guard);
+
+  if (custom_usage_config) return *custom_usage_config;
+
+  FlagsUsageConfig default_config;
+  default_config.contains_helpshort_flags = &ContainsHelpshortFlags;
+  default_config.contains_help_flags = &ContainsHelppackageFlags;
+  default_config.contains_helppackage_flags = &ContainsHelppackageFlags;
+  default_config.version_string = &VersionString;
+  default_config.normalize_filename = &NormalizeFilename;
+
+  return default_config;
+}
+
+void ReportUsageError(absl::string_view msg, bool is_fatal) {
+  std::cerr << "ERROR: " << msg << std::endl;
+
+  if (is_fatal) {
+    ABSL_INTERNAL_C_SYMBOL(AbslInternalReportFatalUsageError)(msg);
+  }
+}
+
+}  // namespace flags_internal
+
+void SetFlagsUsageConfig(FlagsUsageConfig usage_config) {
+  absl::MutexLock l(&flags_internal::custom_usage_config_guard);
+
+  if (!usage_config.contains_helpshort_flags)
+    usage_config.contains_helpshort_flags =
+        flags_internal::ContainsHelpshortFlags;
+
+  if (!usage_config.contains_help_flags)
+    usage_config.contains_help_flags = flags_internal::ContainsHelppackageFlags;
+
+  if (!usage_config.contains_helppackage_flags)
+    usage_config.contains_helppackage_flags =
+        flags_internal::ContainsHelppackageFlags;
+
+  if (!usage_config.version_string)
+    usage_config.version_string = flags_internal::VersionString;
+
+  if (!usage_config.normalize_filename)
+    usage_config.normalize_filename = flags_internal::NormalizeFilename;
+
+  if (flags_internal::custom_usage_config)
+    *flags_internal::custom_usage_config = usage_config;
+  else
+    flags_internal::custom_usage_config = new FlagsUsageConfig(usage_config);
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/flags/usage_config.h

@@ -0,0 +1,135 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// -----------------------------------------------------------------------------
+// File: usage_config.h
+// -----------------------------------------------------------------------------
+//
+// This file defines the main usage reporting configuration interfaces and
+// documents Abseil's supported built-in usage flags. If these flags are found
+// when parsing a command-line, Abseil will exit the program and display
+// appropriate help messages.
+#ifndef ABSL_FLAGS_USAGE_CONFIG_H_
+#define ABSL_FLAGS_USAGE_CONFIG_H_
+
+#include <functional>
+#include <string>
+
+#include "absl/base/config.h"
+#include "absl/strings/string_view.h"
+
+// -----------------------------------------------------------------------------
+// Built-in Usage Flags
+// -----------------------------------------------------------------------------
+//
+// Abseil supports the following built-in usage flags. When passed, these flags
+// exit the program and :
+//
+// * --help
+//     Shows help on important flags for this binary
+// * --helpfull
+//     Shows help on all flags
+// * --helpshort
+//     Shows help on only the main module for this program
+// * --helppackage
+//     Shows help on all modules in the main package
+// * --version
+//     Shows the version and build info for this binary and exits
+// * --only_check_args
+//     Exits after checking all flags
+// * --helpon
+//     Shows help on the modules named by this flag value
+// * --helpmatch
+//     Shows help on modules whose name contains the specified substring
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+namespace flags_internal {
+using FlagKindFilter = std::function<bool (absl::string_view)>;
+}  // namespace flags_internal
+
+// FlagsUsageConfig
+//
+// This structure contains the collection of callbacks for changing the behavior
+// of the usage reporting routines in Abseil Flags.
+struct FlagsUsageConfig {
+  // Returns true if flags defined in the given source code file should be
+  // reported with --helpshort flag. For example, if the file
+  // "path/to/my/code.cc" defines the flag "--my_flag", and
+  // contains_helpshort_flags("path/to/my/code.cc") returns true, invoking the
+  // program with --helpshort will include information about --my_flag in the
+  // program output.
+  flags_internal::FlagKindFilter contains_helpshort_flags;
+
+  // Returns true if flags defined in the filename should be reported with
+  // --help flag. For example, if the file
+  // "path/to/my/code.cc" defines the flag "--my_flag", and
+  // contains_help_flags("path/to/my/code.cc") returns true, invoking the
+  // program with --help will include information about --my_flag in the
+  // program output.
+  flags_internal::FlagKindFilter contains_help_flags;
+
+  // Returns true if flags defined in the filename should be reported with
+  // --helppackage flag. For example, if the file
+  // "path/to/my/code.cc" defines the flag "--my_flag", and
+  // contains_helppackage_flags("path/to/my/code.cc") returns true, invoking the
+  // program with --helppackage will include information about --my_flag in the
+  // program output.
+  flags_internal::FlagKindFilter contains_helppackage_flags;
+
+  // Generates string containing program version. This is the string reported
+  // when user specifies --version in a command line.
+  std::function<std::string()> version_string;
+
+  // Normalizes the filename specific to the build system/filesystem used. This
+  // routine is used when we report the information about the flag definition
+  // location. For instance, if your build resides at some location you do not
+  // want to expose in the usage output, you can trim it to show only relevant
+  // part.
+  // For example:
+  //   normalize_filename("/my_company/some_long_path/src/project/file.cc")
+  // might produce
+  //   "project/file.cc".
+  std::function<std::string(absl::string_view)> normalize_filename;
+};
+
+// SetFlagsUsageConfig()
+//
+// Sets the usage reporting configuration callbacks. If any of the callbacks are
+// not set in usage_config instance, then the default value of the callback is
+// used.
+void SetFlagsUsageConfig(FlagsUsageConfig usage_config);
+
+namespace flags_internal {
+
+FlagsUsageConfig GetUsageConfig();
+
+void ReportUsageError(absl::string_view msg, bool is_fatal);
+
+}  // namespace flags_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+extern "C" {
+
+// Additional report of fatal usage error message before we std::exit. Error is
+// fatal if is_fatal argument to ReportUsageError is true.
+void ABSL_INTERNAL_C_SYMBOL(AbslInternalReportFatalUsageError)(
+    absl::string_view);
+
+}  // extern "C"
+
+#endif  // ABSL_FLAGS_USAGE_CONFIG_H_

weight/_dep/abseil-cpp/absl/flags/usage_config_test.cc

@@ -0,0 +1,205 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/flags/usage_config.h"
+
+#include <string>
+
+#include "gtest/gtest.h"
+#include "absl/flags/internal/path_util.h"
+#include "absl/flags/internal/program_name.h"
+#include "absl/strings/match.h"
+#include "absl/strings/string_view.h"
+
+namespace {
+
+class FlagsUsageConfigTest : public testing::Test {
+ protected:
+  void SetUp() override {
+    // Install Default config for the use on this unit test.
+    // Binary may install a custom config before tests are run.
+    absl::FlagsUsageConfig default_config;
+    absl::SetFlagsUsageConfig(default_config);
+  }
+};
+
+namespace flags = absl::flags_internal;
+
+bool TstContainsHelpshortFlags(absl::string_view f) {
+  return absl::StartsWith(flags::Basename(f), "progname.");
+}
+
+bool TstContainsHelppackageFlags(absl::string_view f) {
+  return absl::EndsWith(flags::Package(f), "aaa/");
+}
+
+bool TstContainsHelpFlags(absl::string_view f) {
+  return absl::EndsWith(flags::Package(f), "zzz/");
+}
+
+std::string TstVersionString() { return "program 1.0.0"; }
+
+std::string TstNormalizeFilename(absl::string_view filename) {
+  return std::string(filename.substr(2));
+}
+
+void TstReportUsageMessage(absl::string_view msg) {}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagsUsageConfigTest, TestGetSetFlagsUsageConfig) {
+  EXPECT_TRUE(flags::GetUsageConfig().contains_helpshort_flags);
+  EXPECT_TRUE(flags::GetUsageConfig().contains_help_flags);
+  EXPECT_TRUE(flags::GetUsageConfig().contains_helppackage_flags);
+  EXPECT_TRUE(flags::GetUsageConfig().version_string);
+  EXPECT_TRUE(flags::GetUsageConfig().normalize_filename);
+
+  absl::FlagsUsageConfig empty_config;
+  empty_config.contains_helpshort_flags = &TstContainsHelpshortFlags;
+  empty_config.contains_help_flags = &TstContainsHelpFlags;
+  empty_config.contains_helppackage_flags = &TstContainsHelppackageFlags;
+  empty_config.version_string = &TstVersionString;
+  empty_config.normalize_filename = &TstNormalizeFilename;
+  absl::SetFlagsUsageConfig(empty_config);
+
+  EXPECT_TRUE(flags::GetUsageConfig().contains_helpshort_flags);
+  EXPECT_TRUE(flags::GetUsageConfig().contains_help_flags);
+  EXPECT_TRUE(flags::GetUsageConfig().contains_helppackage_flags);
+  EXPECT_TRUE(flags::GetUsageConfig().version_string);
+  EXPECT_TRUE(flags::GetUsageConfig().normalize_filename);
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagsUsageConfigTest, TestContainsHelpshortFlags) {
+#if defined(_WIN32)
+  flags::SetProgramInvocationName("usage_config_test.exe");
+#else
+  flags::SetProgramInvocationName("usage_config_test");
+#endif
+
+  auto config = flags::GetUsageConfig();
+  EXPECT_TRUE(config.contains_helpshort_flags("adir/cd/usage_config_test.cc"));
+  EXPECT_TRUE(
+      config.contains_helpshort_flags("aaaa/usage_config_test-main.cc"));
+  EXPECT_TRUE(config.contains_helpshort_flags("abc/usage_config_test_main.cc"));
+  EXPECT_FALSE(config.contains_helpshort_flags("usage_config_main.cc"));
+
+  absl::FlagsUsageConfig empty_config;
+  empty_config.contains_helpshort_flags = &TstContainsHelpshortFlags;
+  absl::SetFlagsUsageConfig(empty_config);
+
+  EXPECT_TRUE(
+      flags::GetUsageConfig().contains_helpshort_flags("aaa/progname.cpp"));
+  EXPECT_FALSE(
+      flags::GetUsageConfig().contains_helpshort_flags("aaa/progmane.cpp"));
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagsUsageConfigTest, TestContainsHelpFlags) {
+  flags::SetProgramInvocationName("usage_config_test");
+
+  auto config = flags::GetUsageConfig();
+  EXPECT_TRUE(config.contains_help_flags("zzz/usage_config_test.cc"));
+  EXPECT_TRUE(
+      config.contains_help_flags("bdir/a/zzz/usage_config_test-main.cc"));
+  EXPECT_TRUE(
+      config.contains_help_flags("//aqse/zzz/usage_config_test_main.cc"));
+  EXPECT_FALSE(config.contains_help_flags("zzz/aa/usage_config_main.cc"));
+
+  absl::FlagsUsageConfig empty_config;
+  empty_config.contains_help_flags = &TstContainsHelpFlags;
+  absl::SetFlagsUsageConfig(empty_config);
+
+  EXPECT_TRUE(flags::GetUsageConfig().contains_help_flags("zzz/main-body.c"));
+  EXPECT_FALSE(
+      flags::GetUsageConfig().contains_help_flags("zzz/dir/main-body.c"));
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagsUsageConfigTest, TestContainsHelppackageFlags) {
+  flags::SetProgramInvocationName("usage_config_test");
+
+  auto config = flags::GetUsageConfig();
+  EXPECT_TRUE(config.contains_helppackage_flags("aaa/usage_config_test.cc"));
+  EXPECT_TRUE(
+      config.contains_helppackage_flags("bbdir/aaa/usage_config_test-main.cc"));
+  EXPECT_TRUE(config.contains_helppackage_flags(
+      "//aqswde/aaa/usage_config_test_main.cc"));
+  EXPECT_FALSE(config.contains_helppackage_flags("aadir/usage_config_main.cc"));
+
+  absl::FlagsUsageConfig empty_config;
+  empty_config.contains_helppackage_flags = &TstContainsHelppackageFlags;
+  absl::SetFlagsUsageConfig(empty_config);
+
+  EXPECT_TRUE(
+      flags::GetUsageConfig().contains_helppackage_flags("aaa/main-body.c"));
+  EXPECT_FALSE(
+      flags::GetUsageConfig().contains_helppackage_flags("aadir/main-body.c"));
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagsUsageConfigTest, TestVersionString) {
+  flags::SetProgramInvocationName("usage_config_test");
+
+#ifdef NDEBUG
+  std::string expected_output = "usage_config_test\n";
+#else
+  std::string expected_output =
+      "usage_config_test\nDebug build (NDEBUG not #defined)\n";
+#endif
+
+  EXPECT_EQ(flags::GetUsageConfig().version_string(), expected_output);
+
+  absl::FlagsUsageConfig empty_config;
+  empty_config.version_string = &TstVersionString;
+  absl::SetFlagsUsageConfig(empty_config);
+
+  EXPECT_EQ(flags::GetUsageConfig().version_string(), "program 1.0.0");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(FlagsUsageConfigTest, TestNormalizeFilename) {
+  // This tests the default implementation.
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("a/a.cc"), "a/a.cc");
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("/a/a.cc"), "a/a.cc");
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("///a/a.cc"), "a/a.cc");
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("/"), "");
+
+  // This tests that the custom implementation is called.
+  absl::FlagsUsageConfig empty_config;
+  empty_config.normalize_filename = &TstNormalizeFilename;
+  absl::SetFlagsUsageConfig(empty_config);
+
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("a/a.cc"), "a.cc");
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("aaa/a.cc"), "a/a.cc");
+
+  // This tests that the default implementation is called.
+  empty_config.normalize_filename = nullptr;
+  absl::SetFlagsUsageConfig(empty_config);
+
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("a/a.cc"), "a/a.cc");
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("/a/a.cc"), "a/a.cc");
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("///a/a.cc"), "a/a.cc");
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("\\a\\a.cc"), "a\\a.cc");
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("//"), "");
+  EXPECT_EQ(flags::GetUsageConfig().normalize_filename("\\\\"), "");
+}
+
+}  // namespace

weight/_dep/abseil-cpp/absl/strings/escaping.cc

@@ -0,0 +1,957 @@
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/escaping.h"
+
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+#include <limits>
+#include <string>
+
+#include "absl/base/config.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/base/internal/unaligned_access.h"
+#include "absl/strings/ascii.h"
+#include "absl/strings/charset.h"
+#include "absl/strings/internal/escaping.h"
+#include "absl/strings/internal/resize_uninitialized.h"
+#include "absl/strings/internal/utf8.h"
+#include "absl/strings/numbers.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace {
+
+// These are used for the leave_nulls_escaped argument to CUnescapeInternal().
+constexpr bool kUnescapeNulls = false;
+
+inline bool is_octal_digit(char c) { return ('0' <= c) && (c <= '7'); }
+
+inline unsigned int hex_digit_to_int(char c) {
+  static_assert('0' == 0x30 && 'A' == 0x41 && 'a' == 0x61,
+                "Character set must be ASCII.");
+  assert(absl::ascii_isxdigit(static_cast<unsigned char>(c)));
+  unsigned int x = static_cast<unsigned char>(c);
+  if (x > '9') {
+    x += 9;
+  }
+  return x & 0xf;
+}
+
+inline bool IsSurrogate(char32_t c, absl::string_view src, std::string* error) {
+  if (c >= 0xD800 && c <= 0xDFFF) {
+    if (error) {
+      *error = absl::StrCat("invalid surrogate character (0xD800-DFFF): \\",
+                            src);
+    }
+    return true;
+  }
+  return false;
+}
+
+// ----------------------------------------------------------------------
+// CUnescapeInternal()
+//    Implements both CUnescape() and CUnescapeForNullTerminatedString().
+//
+//    Unescapes C escape sequences and is the reverse of CEscape().
+//
+//    If 'source' is valid, stores the unescaped string and its size in
+//    'dest' and 'dest_len' respectively, and returns true. Otherwise
+//    returns false and optionally stores the error description in
+//    'error'. Set 'error' to nullptr to disable error reporting.
+//
+//    'dest' should point to a buffer that is at least as big as 'source'.
+//    'source' and 'dest' may be the same.
+//
+//     NOTE: any changes to this function must also be reflected in the older
+//     UnescapeCEscapeSequences().
+// ----------------------------------------------------------------------
+bool CUnescapeInternal(absl::string_view source, bool leave_nulls_escaped,
+                       char* dest, ptrdiff_t* dest_len, std::string* error) {
+  char* d = dest;
+  const char* p = source.data();
+  const char* end = p + source.size();
+  const char* last_byte = end - 1;
+
+  // Small optimization for case where source = dest and there's no escaping
+  while (p == d && p < end && *p != '\\') p++, d++;
+
+  while (p < end) {
+    if (*p != '\\') {
+      *d++ = *p++;
+    } else {
+      if (++p > last_byte) {  // skip past the '\\'
+        if (error) *error = "String cannot end with \\";
+        return false;
+      }
+      switch (*p) {
+        case 'a':  *d++ = '\a';  break;
+        case 'b':  *d++ = '\b';  break;
+        case 'f':  *d++ = '\f';  break;
+        case 'n':  *d++ = '\n';  break;
+        case 'r':  *d++ = '\r';  break;
+        case 't':  *d++ = '\t';  break;
+        case 'v':  *d++ = '\v';  break;
+        case '\\': *d++ = '\\';  break;
+        case '?':  *d++ = '\?';  break;    // \?  Who knew?
+        case '\'': *d++ = '\'';  break;
+        case '"':  *d++ = '\"';  break;
+        case '0':
+        case '1':
+        case '2':
+        case '3':
+        case '4':
+        case '5':
+        case '6':
+        case '7': {
+          // octal digit: 1 to 3 digits
+          const char* octal_start = p;
+          unsigned int ch = static_cast<unsigned int>(*p - '0');  // digit 1
+          if (p < last_byte && is_octal_digit(p[1]))
+            ch = ch * 8 + static_cast<unsigned int>(*++p - '0');  // digit 2
+          if (p < last_byte && is_octal_digit(p[1]))
+            ch = ch * 8 + static_cast<unsigned int>(*++p - '0');  // digit 3
+          if (ch > 0xff) {
+            if (error) {
+              *error = "Value of \\" +
+                       std::string(octal_start,
+                                   static_cast<size_t>(p + 1 - octal_start)) +
+                       " exceeds 0xff";
+            }
+            return false;
+          }
+          if ((ch == 0) && leave_nulls_escaped) {
+            // Copy the escape sequence for the null character
+            const size_t octal_size = static_cast<size_t>(p + 1 - octal_start);
+            *d++ = '\\';
+            memmove(d, octal_start, octal_size);
+            d += octal_size;
+            break;
+          }
+          *d++ = static_cast<char>(ch);
+          break;
+        }
+        case 'x':
+        case 'X': {
+          if (p >= last_byte) {
+            if (error) *error = "String cannot end with \\x";
+            return false;
+          } else if (!absl::ascii_isxdigit(static_cast<unsigned char>(p[1]))) {
+            if (error) *error = "\\x cannot be followed by a non-hex digit";
+            return false;
+          }
+          unsigned int ch = 0;
+          const char* hex_start = p;
+          while (p < last_byte &&
+                 absl::ascii_isxdigit(static_cast<unsigned char>(p[1])))
+            // Arbitrarily many hex digits
+            ch = (ch << 4) + hex_digit_to_int(*++p);
+          if (ch > 0xFF) {
+            if (error) {
+              *error = "Value of \\" +
+                       std::string(hex_start,
+                                   static_cast<size_t>(p + 1 - hex_start)) +
+                       " exceeds 0xff";
+            }
+            return false;
+          }
+          if ((ch == 0) && leave_nulls_escaped) {
+            // Copy the escape sequence for the null character
+            const size_t hex_size = static_cast<size_t>(p + 1 - hex_start);
+            *d++ = '\\';
+            memmove(d, hex_start, hex_size);
+            d += hex_size;
+            break;
+          }
+          *d++ = static_cast<char>(ch);
+          break;
+        }
+        case 'u': {
+          // \uhhhh => convert 4 hex digits to UTF-8
+          char32_t rune = 0;
+          const char* hex_start = p;
+          if (p + 4 >= end) {
+            if (error) {
+              *error = "\\u must be followed by 4 hex digits: \\" +
+                       std::string(hex_start,
+                                   static_cast<size_t>(p + 1 - hex_start));
+            }
+            return false;
+          }
+          for (int i = 0; i < 4; ++i) {
+            // Look one char ahead.
+            if (absl::ascii_isxdigit(static_cast<unsigned char>(p[1]))) {
+              rune = (rune << 4) + hex_digit_to_int(*++p);  // Advance p.
+            } else {
+              if (error) {
+                *error = "\\u must be followed by 4 hex digits: \\" +
+                         std::string(hex_start,
+                                     static_cast<size_t>(p + 1 - hex_start));
+              }
+              return false;
+            }
+          }
+          if ((rune == 0) && leave_nulls_escaped) {
+            // Copy the escape sequence for the null character
+            *d++ = '\\';
+            memmove(d, hex_start, 5);  // u0000
+            d += 5;
+            break;
+          }
+          if (IsSurrogate(rune, absl::string_view(hex_start, 5), error)) {
+            return false;
+          }
+          d += strings_internal::EncodeUTF8Char(d, rune);
+          break;
+        }
+        case 'U': {
+          // \Uhhhhhhhh => convert 8 hex digits to UTF-8
+          char32_t rune = 0;
+          const char* hex_start = p;
+          if (p + 8 >= end) {
+            if (error) {
+              *error = "\\U must be followed by 8 hex digits: \\" +
+                       std::string(hex_start,
+                                   static_cast<size_t>(p + 1 - hex_start));
+            }
+            return false;
+          }
+          for (int i = 0; i < 8; ++i) {
+            // Look one char ahead.
+            if (absl::ascii_isxdigit(static_cast<unsigned char>(p[1]))) {
+              // Don't change rune until we're sure this
+              // is within the Unicode limit, but do advance p.
+              uint32_t newrune = (rune << 4) + hex_digit_to_int(*++p);
+              if (newrune > 0x10FFFF) {
+                if (error) {
+                  *error = "Value of \\" +
+                           std::string(hex_start,
+                                       static_cast<size_t>(p + 1 - hex_start)) +
+                           " exceeds Unicode limit (0x10FFFF)";
+                }
+                return false;
+              } else {
+                rune = newrune;
+              }
+            } else {
+              if (error) {
+                *error = "\\U must be followed by 8 hex digits: \\" +
+                         std::string(hex_start,
+                                     static_cast<size_t>(p + 1 - hex_start));
+              }
+              return false;
+            }
+          }
+          if ((rune == 0) && leave_nulls_escaped) {
+            // Copy the escape sequence for the null character
+            *d++ = '\\';
+            memmove(d, hex_start, 9);  // U00000000
+            d += 9;
+            break;
+          }
+          if (IsSurrogate(rune, absl::string_view(hex_start, 9), error)) {
+            return false;
+          }
+          d += strings_internal::EncodeUTF8Char(d, rune);
+          break;
+        }
+        default: {
+          if (error) *error = std::string("Unknown escape sequence: \\") + *p;
+          return false;
+        }
+      }
+      p++;                                 // read past letter we escaped
+    }
+  }
+  *dest_len = d - dest;
+  return true;
+}
+
+// ----------------------------------------------------------------------
+// CUnescapeInternal()
+//
+//    Same as above but uses a std::string for output. 'source' and 'dest'
+//    may be the same.
+// ----------------------------------------------------------------------
+bool CUnescapeInternal(absl::string_view source, bool leave_nulls_escaped,
+                       std::string* dest, std::string* error) {
+  strings_internal::STLStringResizeUninitialized(dest, source.size());
+
+  ptrdiff_t dest_size;
+  if (!CUnescapeInternal(source,
+                         leave_nulls_escaped,
+                         &(*dest)[0],
+                         &dest_size,
+                         error)) {
+    return false;
+  }
+  dest->erase(static_cast<size_t>(dest_size));
+  return true;
+}
+
+// ----------------------------------------------------------------------
+// CEscape()
+// CHexEscape()
+// Utf8SafeCEscape()
+// Utf8SafeCHexEscape()
+//    Escapes 'src' using C-style escape sequences.  This is useful for
+//    preparing query flags.  The 'Hex' version uses hexadecimal rather than
+//    octal sequences.  The 'Utf8Safe' version does not touch UTF-8 bytes.
+//
+//    Escaped chars: \n, \r, \t, ", ', \, and !absl::ascii_isprint().
+// ----------------------------------------------------------------------
+std::string CEscapeInternal(absl::string_view src, bool use_hex,
+                            bool utf8_safe) {
+  std::string dest;
+  bool last_hex_escape = false;  // true if last output char was \xNN.
+
+  for (char c : src) {
+    bool is_hex_escape = false;
+    switch (c) {
+      case '\n': dest.append("\\" "n"); break;
+      case '\r': dest.append("\\" "r"); break;
+      case '\t': dest.append("\\" "t"); break;
+      case '\"': dest.append("\\" "\""); break;
+      case '\'': dest.append("\\" "'"); break;
+      case '\\': dest.append("\\" "\\"); break;
+      default: {
+        // Note that if we emit \xNN and the src character after that is a hex
+        // digit then that digit must be escaped too to prevent it being
+        // interpreted as part of the character code by C.
+        const unsigned char uc = static_cast<unsigned char>(c);
+        if ((!utf8_safe || uc < 0x80) &&
+            (!absl::ascii_isprint(uc) ||
+             (last_hex_escape && absl::ascii_isxdigit(uc)))) {
+          if (use_hex) {
+            dest.append("\\" "x");
+            dest.push_back(numbers_internal::kHexChar[uc / 16]);
+            dest.push_back(numbers_internal::kHexChar[uc % 16]);
+            is_hex_escape = true;
+          } else {
+            dest.append("\\");
+            dest.push_back(numbers_internal::kHexChar[uc / 64]);
+            dest.push_back(numbers_internal::kHexChar[(uc % 64) / 8]);
+            dest.push_back(numbers_internal::kHexChar[uc % 8]);
+          }
+        } else {
+          dest.push_back(c);
+          break;
+        }
+      }
+    }
+    last_hex_escape = is_hex_escape;
+  }
+
+  return dest;
+}
+
+/* clang-format off */
+constexpr unsigned char kCEscapedLen[256] = {
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 4, 4, 2, 4, 4,  // \t, \n, \r
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1,  // ", '
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // '0'..'9'
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 'A'..'O'
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1,  // 'P'..'Z', '\'
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 'a'..'o'
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4,  // 'p'..'z', DEL
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+};
+/* clang-format on */
+
+// Calculates the length of the C-style escaped version of 'src'.
+// Assumes that non-printable characters are escaped using octal sequences, and
+// that UTF-8 bytes are not handled specially.
+inline size_t CEscapedLength(absl::string_view src) {
+  size_t escaped_len = 0;
+  // The maximum value of kCEscapedLen[x] is 4, so we can escape any string of
+  // length size_t_max/4 without checking for overflow.
+  size_t unchecked_limit =
+      std::min<size_t>(src.size(), std::numeric_limits<size_t>::max() / 4);
+  size_t i = 0;
+  while (i < unchecked_limit) {
+    // Common case: No need to check for overflow.
+    escaped_len += kCEscapedLen[static_cast<unsigned char>(src[i++])];
+  }
+  while (i < src.size()) {
+    // Beyond unchecked_limit we need to check for overflow before adding.
+    size_t char_len = kCEscapedLen[static_cast<unsigned char>(src[i++])];
+    ABSL_INTERNAL_CHECK(
+        escaped_len <= std::numeric_limits<size_t>::max() - char_len,
+        "escaped_len overflow");
+    escaped_len += char_len;
+  }
+  return escaped_len;
+}
+
+void CEscapeAndAppendInternal(absl::string_view src, std::string* dest) {
+  size_t escaped_len = CEscapedLength(src);
+  if (escaped_len == src.size()) {
+    dest->append(src.data(), src.size());
+    return;
+  }
+
+  size_t cur_dest_len = dest->size();
+  ABSL_INTERNAL_CHECK(
+      cur_dest_len <= std::numeric_limits<size_t>::max() - escaped_len,
+      "std::string size overflow");
+  strings_internal::STLStringResizeUninitialized(dest,
+                                                 cur_dest_len + escaped_len);
+  char* append_ptr = &(*dest)[cur_dest_len];
+
+  for (char c : src) {
+    size_t char_len = kCEscapedLen[static_cast<unsigned char>(c)];
+    if (char_len == 1) {
+      *append_ptr++ = c;
+    } else if (char_len == 2) {
+      switch (c) {
+        case '\n':
+          *append_ptr++ = '\\';
+          *append_ptr++ = 'n';
+          break;
+        case '\r':
+          *append_ptr++ = '\\';
+          *append_ptr++ = 'r';
+          break;
+        case '\t':
+          *append_ptr++ = '\\';
+          *append_ptr++ = 't';
+          break;
+        case '\"':
+          *append_ptr++ = '\\';
+          *append_ptr++ = '\"';
+          break;
+        case '\'':
+          *append_ptr++ = '\\';
+          *append_ptr++ = '\'';
+          break;
+        case '\\':
+          *append_ptr++ = '\\';
+          *append_ptr++ = '\\';
+          break;
+      }
+    } else {
+      *append_ptr++ = '\\';
+      *append_ptr++ = '0' + static_cast<unsigned char>(c) / 64;
+      *append_ptr++ = '0' + (static_cast<unsigned char>(c) % 64) / 8;
+      *append_ptr++ = '0' + static_cast<unsigned char>(c) % 8;
+    }
+  }
+}
+
+// Reverses the mapping in Base64EscapeInternal; see that method's
+// documentation for details of the mapping.
+bool Base64UnescapeInternal(const char* src_param, size_t szsrc, char* dest,
+                            size_t szdest, const signed char* unbase64,
+                            size_t* len) {
+  static const char kPad64Equals = '=';
+  static const char kPad64Dot = '.';
+
+  size_t destidx = 0;
+  int decode = 0;
+  int state = 0;
+  unsigned char ch = 0;
+  unsigned int temp = 0;
+
+  // If "char" is signed by default, using *src as an array index results in
+  // accessing negative array elements. Treat the input as a pointer to
+  // unsigned char to avoid this.
+  const unsigned char* src = reinterpret_cast<const unsigned char*>(src_param);
+
+  // The GET_INPUT macro gets the next input character, skipping
+  // over any whitespace, and stopping when we reach the end of the
+  // string or when we read any non-data character.  The arguments are
+  // an arbitrary identifier (used as a label for goto) and the number
+  // of data bytes that must remain in the input to avoid aborting the
+  // loop.
+#define GET_INPUT(label, remain)                                \
+  label:                                                        \
+  --szsrc;                                                      \
+  ch = *src++;                                                  \
+  decode = unbase64[ch];                                        \
+  if (decode < 0) {                                             \
+    if (absl::ascii_isspace(ch) && szsrc >= remain) goto label; \
+    state = 4 - remain;                                         \
+    break;                                                      \
+  }
+
+  // if dest is null, we're just checking to see if it's legal input
+  // rather than producing output.  (I suspect this could just be done
+  // with a regexp...).  We duplicate the loop so this test can be
+  // outside it instead of in every iteration.
+
+  if (dest) {
+    // This loop consumes 4 input bytes and produces 3 output bytes
+    // per iteration.  We can't know at the start that there is enough
+    // data left in the string for a full iteration, so the loop may
+    // break out in the middle; if so 'state' will be set to the
+    // number of input bytes read.
+
+    while (szsrc >= 4) {
+      // We'll start by optimistically assuming that the next four
+      // bytes of the string (src[0..3]) are four good data bytes
+      // (that is, no nulls, whitespace, padding chars, or illegal
+      // chars).  We need to test src[0..2] for nulls individually
+      // before constructing temp to preserve the property that we
+      // never read past a null in the string (no matter how long
+      // szsrc claims the string is).
+
+      if (!src[0] || !src[1] || !src[2] ||
+          ((temp = ((unsigned(unbase64[src[0]]) << 18) |
+                    (unsigned(unbase64[src[1]]) << 12) |
+                    (unsigned(unbase64[src[2]]) << 6) |
+                    (unsigned(unbase64[src[3]])))) &
+           0x80000000)) {
+        // Iff any of those four characters was bad (null, illegal,
+        // whitespace, padding), then temp's high bit will be set
+        // (because unbase64[] is -1 for all bad characters).
+        //
+        // We'll back up and resort to the slower decoder, which knows
+        // how to handle those cases.
+
+        GET_INPUT(first, 4);
+        temp = static_cast<unsigned char>(decode);
+        GET_INPUT(second, 3);
+        temp = (temp << 6) | static_cast<unsigned char>(decode);
+        GET_INPUT(third, 2);
+        temp = (temp << 6) | static_cast<unsigned char>(decode);
+        GET_INPUT(fourth, 1);
+        temp = (temp << 6) | static_cast<unsigned char>(decode);
+      } else {
+        // We really did have four good data bytes, so advance four
+        // characters in the string.
+
+        szsrc -= 4;
+        src += 4;
+      }
+
+      // temp has 24 bits of input, so write that out as three bytes.
+
+      if (destidx + 3 > szdest) return false;
+      dest[destidx + 2] = static_cast<char>(temp);
+      temp >>= 8;
+      dest[destidx + 1] = static_cast<char>(temp);
+      temp >>= 8;
+      dest[destidx] = static_cast<char>(temp);
+      destidx += 3;
+    }
+  } else {
+    while (szsrc >= 4) {
+      if (!src[0] || !src[1] || !src[2] ||
+          ((temp = ((unsigned(unbase64[src[0]]) << 18) |
+                    (unsigned(unbase64[src[1]]) << 12) |
+                    (unsigned(unbase64[src[2]]) << 6) |
+                    (unsigned(unbase64[src[3]])))) &
+           0x80000000)) {
+        GET_INPUT(first_no_dest, 4);
+        GET_INPUT(second_no_dest, 3);
+        GET_INPUT(third_no_dest, 2);
+        GET_INPUT(fourth_no_dest, 1);
+      } else {
+        szsrc -= 4;
+        src += 4;
+      }
+      destidx += 3;
+    }
+  }
+
+#undef GET_INPUT
+
+  // if the loop terminated because we read a bad character, return
+  // now.
+  if (decode < 0 && ch != kPad64Equals && ch != kPad64Dot &&
+      !absl::ascii_isspace(ch))
+    return false;
+
+  if (ch == kPad64Equals || ch == kPad64Dot) {
+    // if we stopped by hitting an '=' or '.', un-read that character -- we'll
+    // look at it again when we count to check for the proper number of
+    // equals signs at the end.
+    ++szsrc;
+    --src;
+  } else {
+    // This loop consumes 1 input byte per iteration.  It's used to
+    // clean up the 0-3 input bytes remaining when the first, faster
+    // loop finishes.  'temp' contains the data from 'state' input
+    // characters read by the first loop.
+    while (szsrc > 0) {
+      --szsrc;
+      ch = *src++;
+      decode = unbase64[ch];
+      if (decode < 0) {
+        if (absl::ascii_isspace(ch)) {
+          continue;
+        } else if (ch == kPad64Equals || ch == kPad64Dot) {
+          // back up one character; we'll read it again when we check
+          // for the correct number of pad characters at the end.
+          ++szsrc;
+          --src;
+          break;
+        } else {
+          return false;
+        }
+      }
+
+      // Each input character gives us six bits of output.
+      temp = (temp << 6) | static_cast<unsigned char>(decode);
+      ++state;
+      if (state == 4) {
+        // If we've accumulated 24 bits of output, write that out as
+        // three bytes.
+        if (dest) {
+          if (destidx + 3 > szdest) return false;
+          dest[destidx + 2] = static_cast<char>(temp);
+          temp >>= 8;
+          dest[destidx + 1] = static_cast<char>(temp);
+          temp >>= 8;
+          dest[destidx] = static_cast<char>(temp);
+        }
+        destidx += 3;
+        state = 0;
+        temp = 0;
+      }
+    }
+  }
+
+  // Process the leftover data contained in 'temp' at the end of the input.
+  int expected_equals = 0;
+  switch (state) {
+    case 0:
+      // Nothing left over; output is a multiple of 3 bytes.
+      break;
+
+    case 1:
+      // Bad input; we have 6 bits left over.
+      return false;
+
+    case 2:
+      // Produce one more output byte from the 12 input bits we have left.
+      if (dest) {
+        if (destidx + 1 > szdest) return false;
+        temp >>= 4;
+        dest[destidx] = static_cast<char>(temp);
+      }
+      ++destidx;
+      expected_equals = 2;
+      break;
+
+    case 3:
+      // Produce two more output bytes from the 18 input bits we have left.
+      if (dest) {
+        if (destidx + 2 > szdest) return false;
+        temp >>= 2;
+        dest[destidx + 1] = static_cast<char>(temp);
+        temp >>= 8;
+        dest[destidx] = static_cast<char>(temp);
+      }
+      destidx += 2;
+      expected_equals = 1;
+      break;
+
+    default:
+      // state should have no other values at this point.
+      ABSL_RAW_LOG(FATAL, "This can't happen; base64 decoder state = %d",
+                   state);
+  }
+
+  // The remainder of the string should be all whitespace, mixed with
+  // exactly 0 equals signs, or exactly 'expected_equals' equals
+  // signs.  (Always accepting 0 equals signs is an Abseil extension
+  // not covered in the RFC, as is accepting dot as the pad character.)
+
+  int equals = 0;
+  while (szsrc > 0) {
+    if (*src == kPad64Equals || *src == kPad64Dot)
+      ++equals;
+    else if (!absl::ascii_isspace(*src))
+      return false;
+    --szsrc;
+    ++src;
+  }
+
+  const bool ok = (equals == 0 || equals == expected_equals);
+  if (ok) *len = destidx;
+  return ok;
+}
+
+// The arrays below map base64-escaped characters back to their original values.
+// For the inverse case, see k(WebSafe)Base64Chars in the internal
+// escaping.cc.
+// These arrays were generated by the following inversion code:
+// #include <sys/time.h>
+// #include <stdlib.h>
+// #include <string.h>
+// main()
+// {
+//   static const char Base64[] =
+//     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+//   char* pos;
+//   int idx, i, j;
+//   printf("    ");
+//   for (i = 0; i < 255; i += 8) {
+//     for (j = i; j < i + 8; j++) {
+//       pos = strchr(Base64, j);
+//       if ((pos == nullptr) || (j == 0))
+//         idx = -1;
+//       else
+//         idx = pos - Base64;
+//       if (idx == -1)
+//         printf(" %2d,     ", idx);
+//       else
+//         printf(" %2d/*%c*/,", idx, j);
+//     }
+//     printf("\n    ");
+//   }
+// }
+//
+// where the value of "Base64[]" was replaced by one of k(WebSafe)Base64Chars
+// in the internal escaping.cc.
+/* clang-format off */
+constexpr signed char kUnBase64[] = {
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      62/*+*/, -1,      -1,      -1,      63/*/ */,
+    52/*0*/, 53/*1*/, 54/*2*/, 55/*3*/, 56/*4*/, 57/*5*/, 58/*6*/, 59/*7*/,
+    60/*8*/, 61/*9*/, -1,      -1,      -1,      -1,      -1,      -1,
+    -1,       0/*A*/,  1/*B*/,  2/*C*/,  3/*D*/,  4/*E*/,  5/*F*/,  6/*G*/,
+    07/*H*/,  8/*I*/,  9/*J*/, 10/*K*/, 11/*L*/, 12/*M*/, 13/*N*/, 14/*O*/,
+    15/*P*/, 16/*Q*/, 17/*R*/, 18/*S*/, 19/*T*/, 20/*U*/, 21/*V*/, 22/*W*/,
+    23/*X*/, 24/*Y*/, 25/*Z*/, -1,      -1,      -1,      -1,      -1,
+    -1,      26/*a*/, 27/*b*/, 28/*c*/, 29/*d*/, 30/*e*/, 31/*f*/, 32/*g*/,
+    33/*h*/, 34/*i*/, 35/*j*/, 36/*k*/, 37/*l*/, 38/*m*/, 39/*n*/, 40/*o*/,
+    41/*p*/, 42/*q*/, 43/*r*/, 44/*s*/, 45/*t*/, 46/*u*/, 47/*v*/, 48/*w*/,
+    49/*x*/, 50/*y*/, 51/*z*/, -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1
+};
+
+constexpr signed char kUnWebSafeBase64[] = {
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      62/*-*/, -1,      -1,
+    52/*0*/, 53/*1*/, 54/*2*/, 55/*3*/, 56/*4*/, 57/*5*/, 58/*6*/, 59/*7*/,
+    60/*8*/, 61/*9*/, -1,      -1,      -1,      -1,      -1,      -1,
+    -1,       0/*A*/,  1/*B*/,  2/*C*/,  3/*D*/,  4/*E*/,  5/*F*/,  6/*G*/,
+    07/*H*/,  8/*I*/,  9/*J*/, 10/*K*/, 11/*L*/, 12/*M*/, 13/*N*/, 14/*O*/,
+    15/*P*/, 16/*Q*/, 17/*R*/, 18/*S*/, 19/*T*/, 20/*U*/, 21/*V*/, 22/*W*/,
+    23/*X*/, 24/*Y*/, 25/*Z*/, -1,      -1,      -1,      -1,      63/*_*/,
+    -1,      26/*a*/, 27/*b*/, 28/*c*/, 29/*d*/, 30/*e*/, 31/*f*/, 32/*g*/,
+    33/*h*/, 34/*i*/, 35/*j*/, 36/*k*/, 37/*l*/, 38/*m*/, 39/*n*/, 40/*o*/,
+    41/*p*/, 42/*q*/, 43/*r*/, 44/*s*/, 45/*t*/, 46/*u*/, 47/*v*/, 48/*w*/,
+    49/*x*/, 50/*y*/, 51/*z*/, -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
+    -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1
+};
+/* clang-format on */
+
+template <typename String>
+bool Base64UnescapeInternal(const char* src, size_t slen, String* dest,
+                            const signed char* unbase64) {
+  // Determine the size of the output string.  Base64 encodes every 3 bytes into
+  // 4 characters.  Any leftover chars are added directly for good measure.
+  const size_t dest_len = 3 * (slen / 4) + (slen % 4);
+
+  strings_internal::STLStringResizeUninitialized(dest, dest_len);
+
+  // We are getting the destination buffer by getting the beginning of the
+  // string and converting it into a char *.
+  size_t len;
+  const bool ok =
+      Base64UnescapeInternal(src, slen, &(*dest)[0], dest_len, unbase64, &len);
+  if (!ok) {
+    dest->clear();
+    return false;
+  }
+
+  // could be shorter if there was padding
+  assert(len <= dest_len);
+  dest->erase(len);
+
+  return true;
+}
+
+/* clang-format off */
+constexpr char kHexValueLenient[256] = {
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  1,  2,  3,  4,  5,  6, 7, 8, 9, 0, 0, 0, 0, 0, 0,  // '0'..'9'
+    0, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0,  // 'A'..'F'
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0,  // 'a'..'f'
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+};
+
+/* clang-format on */
+
+// This is a templated function so that T can be either a char*
+// or a string.  This works because we use the [] operator to access
+// individual characters at a time.
+template <typename T>
+void HexStringToBytesInternal(const char* from, T to, size_t num) {
+  for (size_t i = 0; i < num; i++) {
+    to[i] = static_cast<char>(kHexValueLenient[from[i * 2] & 0xFF] << 4) +
+            (kHexValueLenient[from[i * 2 + 1] & 0xFF]);
+  }
+}
+
+// This is a templated function so that T can be either a char* or a
+// std::string.
+template <typename T>
+void BytesToHexStringInternal(const unsigned char* src, T dest, size_t num) {
+  auto dest_ptr = &dest[0];
+  for (auto src_ptr = src; src_ptr != (src + num); ++src_ptr, dest_ptr += 2) {
+    const char* hex_p = &numbers_internal::kHexTable[*src_ptr * 2];
+    std::copy(hex_p, hex_p + 2, dest_ptr);
+  }
+}
+
+}  // namespace
+
+// ----------------------------------------------------------------------
+// CUnescape()
+//
+// See CUnescapeInternal() for implementation details.
+// ----------------------------------------------------------------------
+bool CUnescape(absl::string_view source, std::string* dest,
+               std::string* error) {
+  return CUnescapeInternal(source, kUnescapeNulls, dest, error);
+}
+
+std::string CEscape(absl::string_view src) {
+  std::string dest;
+  CEscapeAndAppendInternal(src, &dest);
+  return dest;
+}
+
+std::string CHexEscape(absl::string_view src) {
+  return CEscapeInternal(src, true, false);
+}
+
+std::string Utf8SafeCEscape(absl::string_view src) {
+  return CEscapeInternal(src, false, true);
+}
+
+std::string Utf8SafeCHexEscape(absl::string_view src) {
+  return CEscapeInternal(src, true, true);
+}
+
+bool Base64Unescape(absl::string_view src, std::string* dest) {
+  return Base64UnescapeInternal(src.data(), src.size(), dest, kUnBase64);
+}
+
+bool WebSafeBase64Unescape(absl::string_view src, std::string* dest) {
+  return Base64UnescapeInternal(src.data(), src.size(), dest, kUnWebSafeBase64);
+}
+
+void Base64Escape(absl::string_view src, std::string* dest) {
+  strings_internal::Base64EscapeInternal(
+      reinterpret_cast<const unsigned char*>(src.data()), src.size(), dest,
+      true, strings_internal::kBase64Chars);
+}
+
+void WebSafeBase64Escape(absl::string_view src, std::string* dest) {
+  strings_internal::Base64EscapeInternal(
+      reinterpret_cast<const unsigned char*>(src.data()), src.size(), dest,
+      false, strings_internal::kWebSafeBase64Chars);
+}
+
+std::string Base64Escape(absl::string_view src) {
+  std::string dest;
+  strings_internal::Base64EscapeInternal(
+      reinterpret_cast<const unsigned char*>(src.data()), src.size(), &dest,
+      true, strings_internal::kBase64Chars);
+  return dest;
+}
+
+std::string WebSafeBase64Escape(absl::string_view src) {
+  std::string dest;
+  strings_internal::Base64EscapeInternal(
+      reinterpret_cast<const unsigned char*>(src.data()), src.size(), &dest,
+      false, strings_internal::kWebSafeBase64Chars);
+  return dest;
+}
+
+std::string HexStringToBytes(absl::string_view from) {
+  std::string result;
+  const auto num = from.size() / 2;
+  strings_internal::STLStringResizeUninitialized(&result, num);
+  absl::HexStringToBytesInternal<std::string&>(from.data(), result, num);
+  return result;
+}
+
+std::string BytesToHexString(absl::string_view from) {
+  std::string result;
+  strings_internal::STLStringResizeUninitialized(&result, 2 * from.size());
+  absl::BytesToHexStringInternal<std::string&>(
+      reinterpret_cast<const unsigned char*>(from.data()), result, from.size());
+  return result;
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/strings/escaping_test.cc

@@ -0,0 +1,714 @@
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/escaping.h"
+
+#include <array>
+#include <cstddef>
+#include <cstdio>
+#include <cstring>
+#include <initializer_list>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "absl/log/check.h"
+#include "absl/strings/str_cat.h"
+
+#include "absl/strings/internal/escaping_test_common.h"
+#include "absl/strings/string_view.h"
+
+namespace {
+
+struct epair {
+  std::string escaped;
+  std::string unescaped;
+};
+
+TEST(CEscape, EscapeAndUnescape) {
+  const std::string inputs[] = {
+      std::string("foo\nxx\r\b\0023"),
+      std::string(""),
+      std::string("abc"),
+      std::string("\1chad_rules"),
+      std::string("\1arnar_drools"),
+      std::string("xxxx\r\t'\"\\"),
+      std::string("\0xx\0", 4),
+      std::string("\x01\x31"),
+      std::string("abc\xb\x42\141bc"),
+      std::string("123\1\x31\x32\x33"),
+      std::string("\xc1\xca\x1b\x62\x19o\xcc\x04"),
+      std::string(
+          "\\\"\xe8\xb0\xb7\xe6\xad\x8c\\\" is Google\\\'s Chinese name"),
+  };
+  // Do this twice, once for octal escapes and once for hex escapes.
+  for (int kind = 0; kind < 4; kind++) {
+    for (const std::string& original : inputs) {
+      std::string escaped;
+      switch (kind) {
+        case 0:
+          escaped = absl::CEscape(original);
+          break;
+        case 1:
+          escaped = absl::CHexEscape(original);
+          break;
+        case 2:
+          escaped = absl::Utf8SafeCEscape(original);
+          break;
+        case 3:
+          escaped = absl::Utf8SafeCHexEscape(original);
+          break;
+      }
+      std::string unescaped_str;
+      EXPECT_TRUE(absl::CUnescape(escaped, &unescaped_str));
+      EXPECT_EQ(unescaped_str, original);
+
+      unescaped_str.erase();
+      std::string error;
+      EXPECT_TRUE(absl::CUnescape(escaped, &unescaped_str, &error));
+      EXPECT_EQ(error, "");
+
+      // Check in-place unescaping
+      std::string s = escaped;
+      EXPECT_TRUE(absl::CUnescape(s, &s));
+      ASSERT_EQ(s, original);
+    }
+  }
+  // Check that all possible two character strings can be escaped then
+  // unescaped successfully.
+  for (int char0 = 0; char0 < 256; char0++) {
+    for (int char1 = 0; char1 < 256; char1++) {
+      char chars[2];
+      chars[0] = char0;
+      chars[1] = char1;
+      std::string s(chars, 2);
+      std::string escaped = absl::CHexEscape(s);
+      std::string unescaped;
+      EXPECT_TRUE(absl::CUnescape(escaped, &unescaped));
+      EXPECT_EQ(s, unescaped);
+    }
+  }
+}
+
+TEST(CEscape, BasicEscaping) {
+  epair oct_values[] = {
+      {"foo\\rbar\\nbaz\\t", "foo\rbar\nbaz\t"},
+      {"\\'full of \\\"sound\\\" and \\\"fury\\\"\\'",
+       "'full of \"sound\" and \"fury\"'"},
+      {"signi\\\\fying\\\\ nothing\\\\", "signi\\fying\\ nothing\\"},
+      {"\\010\\t\\n\\013\\014\\r", "\010\011\012\013\014\015"}
+  };
+  epair hex_values[] = {
+      {"ubik\\rubik\\nubik\\t", "ubik\rubik\nubik\t"},
+      {"I\\\'ve just seen a \\\"face\\\"",
+       "I've just seen a \"face\""},
+      {"hel\\\\ter\\\\skel\\\\ter\\\\", "hel\\ter\\skel\\ter\\"},
+      {"\\x08\\t\\n\\x0b\\x0c\\r", "\010\011\012\013\014\015"}
+  };
+  epair utf8_oct_values[] = {
+      {"\xe8\xb0\xb7\xe6\xad\x8c\\r\xe8\xb0\xb7\xe6\xad\x8c\\nbaz\\t",
+       "\xe8\xb0\xb7\xe6\xad\x8c\r\xe8\xb0\xb7\xe6\xad\x8c\nbaz\t"},
+      {"\\\"\xe8\xb0\xb7\xe6\xad\x8c\\\" is Google\\\'s Chinese name",
+       "\"\xe8\xb0\xb7\xe6\xad\x8c\" is Google\'s Chinese name"},
+      {"\xe3\x83\xa1\xe3\x83\xbc\xe3\x83\xab\\\\are\\\\Japanese\\\\chars\\\\",
+       "\xe3\x83\xa1\xe3\x83\xbc\xe3\x83\xab\\are\\Japanese\\chars\\"},
+      {"\xed\x81\xac\xeb\xa1\xac\\010\\t\\n\\013\\014\\r",
+       "\xed\x81\xac\xeb\xa1\xac\010\011\012\013\014\015"}
+  };
+  epair utf8_hex_values[] = {
+      {"\x20\xe4\xbd\xa0\\t\xe5\xa5\xbd,\\r!\\n",
+       "\x20\xe4\xbd\xa0\t\xe5\xa5\xbd,\r!\n"},
+      {"\xe8\xa9\xa6\xe9\xa8\x93\\\' means \\\"test\\\"",
+       "\xe8\xa9\xa6\xe9\xa8\x93\' means \"test\""},
+      {"\\\\\xe6\x88\x91\\\\:\\\\\xe6\x9d\xa8\xe6\xac\xa2\\\\",
+       "\\\xe6\x88\x91\\:\\\xe6\x9d\xa8\xe6\xac\xa2\\"},
+      {"\xed\x81\xac\xeb\xa1\xac\\x08\\t\\n\\x0b\\x0c\\r",
+       "\xed\x81\xac\xeb\xa1\xac\010\011\012\013\014\015"}
+  };
+
+  for (const epair& val : oct_values) {
+    std::string escaped = absl::CEscape(val.unescaped);
+    EXPECT_EQ(escaped, val.escaped);
+  }
+  for (const epair& val : hex_values) {
+    std::string escaped = absl::CHexEscape(val.unescaped);
+    EXPECT_EQ(escaped, val.escaped);
+  }
+  for (const epair& val : utf8_oct_values) {
+    std::string escaped = absl::Utf8SafeCEscape(val.unescaped);
+    EXPECT_EQ(escaped, val.escaped);
+  }
+  for (const epair& val : utf8_hex_values) {
+    std::string escaped = absl::Utf8SafeCHexEscape(val.unescaped);
+    EXPECT_EQ(escaped, val.escaped);
+  }
+}
+
+TEST(Unescape, BasicFunction) {
+  epair tests[] =
+    {{"", ""},
+     {"\\u0030", "0"},
+     {"\\u00A3", "\xC2\xA3"},
+     {"\\u22FD", "\xE2\x8B\xBD"},
+     {"\\U00010000", "\xF0\x90\x80\x80"},
+     {"\\U0010FFFD", "\xF4\x8F\xBF\xBD"}};
+  for (const epair& val : tests) {
+    std::string out;
+    EXPECT_TRUE(absl::CUnescape(val.escaped, &out));
+    EXPECT_EQ(out, val.unescaped);
+  }
+  std::string bad[] = {"\\u1",         // too short
+                       "\\U1",         // too short
+                       "\\Uffffff",    // exceeds 0x10ffff (largest Unicode)
+                       "\\U00110000",  // exceeds 0x10ffff (largest Unicode)
+                       "\\uD835",      // surrogate character (D800-DFFF)
+                       "\\U0000DD04",  // surrogate character (D800-DFFF)
+                       "\\777",        // exceeds 0xff
+                       "\\xABCD"};     // exceeds 0xff
+  for (const std::string& e : bad) {
+    std::string error;
+    std::string out;
+    EXPECT_FALSE(absl::CUnescape(e, &out, &error));
+    EXPECT_FALSE(error.empty());
+
+    out.erase();
+    EXPECT_FALSE(absl::CUnescape(e, &out));
+  }
+}
+
+class CUnescapeTest : public testing::Test {
+ protected:
+  static const char kStringWithMultipleOctalNulls[];
+  static const char kStringWithMultipleHexNulls[];
+  static const char kStringWithMultipleUnicodeNulls[];
+
+  std::string result_string_;
+};
+
+const char CUnescapeTest::kStringWithMultipleOctalNulls[] =
+    "\\0\\n"    // null escape \0 plus newline
+    "0\\n"      // just a number 0 (not a null escape) plus newline
+    "\\00\\12"  // null escape \00 plus octal newline code
+    "\\000";    // null escape \000
+
+// This has the same ingredients as kStringWithMultipleOctalNulls
+// but with \x hex escapes instead of octal escapes.
+const char CUnescapeTest::kStringWithMultipleHexNulls[] =
+    "\\x0\\n"
+    "0\\n"
+    "\\x00\\xa"
+    "\\x000";
+
+const char CUnescapeTest::kStringWithMultipleUnicodeNulls[] =
+    "\\u0000\\n"    // short-form (4-digit) null escape plus newline
+    "0\\n"          // just a number 0 (not a null escape) plus newline
+    "\\U00000000";  // long-form (8-digit) null escape
+
+TEST_F(CUnescapeTest, Unescapes1CharOctalNull) {
+  std::string original_string = "\\0";
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  EXPECT_EQ(std::string("\0", 1), result_string_);
+}
+
+TEST_F(CUnescapeTest, Unescapes2CharOctalNull) {
+  std::string original_string = "\\00";
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  EXPECT_EQ(std::string("\0", 1), result_string_);
+}
+
+TEST_F(CUnescapeTest, Unescapes3CharOctalNull) {
+  std::string original_string = "\\000";
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  EXPECT_EQ(std::string("\0", 1), result_string_);
+}
+
+TEST_F(CUnescapeTest, Unescapes1CharHexNull) {
+  std::string original_string = "\\x0";
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  EXPECT_EQ(std::string("\0", 1), result_string_);
+}
+
+TEST_F(CUnescapeTest, Unescapes2CharHexNull) {
+  std::string original_string = "\\x00";
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  EXPECT_EQ(std::string("\0", 1), result_string_);
+}
+
+TEST_F(CUnescapeTest, Unescapes3CharHexNull) {
+  std::string original_string = "\\x000";
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  EXPECT_EQ(std::string("\0", 1), result_string_);
+}
+
+TEST_F(CUnescapeTest, Unescapes4CharUnicodeNull) {
+  std::string original_string = "\\u0000";
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  EXPECT_EQ(std::string("\0", 1), result_string_);
+}
+
+TEST_F(CUnescapeTest, Unescapes8CharUnicodeNull) {
+  std::string original_string = "\\U00000000";
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  EXPECT_EQ(std::string("\0", 1), result_string_);
+}
+
+TEST_F(CUnescapeTest, UnescapesMultipleOctalNulls) {
+  std::string original_string(kStringWithMultipleOctalNulls);
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  // All escapes, including newlines and null escapes, should have been
+  // converted to the equivalent characters.
+  EXPECT_EQ(std::string("\0\n"
+                        "0\n"
+                        "\0\n"
+                        "\0",
+                        7),
+            result_string_);
+}
+
+
+TEST_F(CUnescapeTest, UnescapesMultipleHexNulls) {
+  std::string original_string(kStringWithMultipleHexNulls);
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  EXPECT_EQ(std::string("\0\n"
+                        "0\n"
+                        "\0\n"
+                        "\0",
+                        7),
+            result_string_);
+}
+
+TEST_F(CUnescapeTest, UnescapesMultipleUnicodeNulls) {
+  std::string original_string(kStringWithMultipleUnicodeNulls);
+  EXPECT_TRUE(absl::CUnescape(original_string, &result_string_));
+  EXPECT_EQ(std::string("\0\n"
+                        "0\n"
+                        "\0",
+                        5),
+            result_string_);
+}
+
+static struct {
+  absl::string_view plaintext;
+  absl::string_view cyphertext;
+} const base64_tests[] = {
+    // Empty string.
+    {{"", 0}, {"", 0}},
+    {{nullptr, 0},
+     {"", 0}},  // if length is zero, plaintext ptr must be ignored!
+
+    // Basic bit patterns;
+    // values obtained with "echo -n '...' | uuencode -m test"
+
+    {{"\000", 1}, "AA=="},
+    {{"\001", 1}, "AQ=="},
+    {{"\002", 1}, "Ag=="},
+    {{"\004", 1}, "BA=="},
+    {{"\010", 1}, "CA=="},
+    {{"\020", 1}, "EA=="},
+    {{"\040", 1}, "IA=="},
+    {{"\100", 1}, "QA=="},
+    {{"\200", 1}, "gA=="},
+
+    {{"\377", 1}, "/w=="},
+    {{"\376", 1}, "/g=="},
+    {{"\375", 1}, "/Q=="},
+    {{"\373", 1}, "+w=="},
+    {{"\367", 1}, "9w=="},
+    {{"\357", 1}, "7w=="},
+    {{"\337", 1}, "3w=="},
+    {{"\277", 1}, "vw=="},
+    {{"\177", 1}, "fw=="},
+    {{"\000\000", 2}, "AAA="},
+    {{"\000\001", 2}, "AAE="},
+    {{"\000\002", 2}, "AAI="},
+    {{"\000\004", 2}, "AAQ="},
+    {{"\000\010", 2}, "AAg="},
+    {{"\000\020", 2}, "ABA="},
+    {{"\000\040", 2}, "ACA="},
+    {{"\000\100", 2}, "AEA="},
+    {{"\000\200", 2}, "AIA="},
+    {{"\001\000", 2}, "AQA="},
+    {{"\002\000", 2}, "AgA="},
+    {{"\004\000", 2}, "BAA="},
+    {{"\010\000", 2}, "CAA="},
+    {{"\020\000", 2}, "EAA="},
+    {{"\040\000", 2}, "IAA="},
+    {{"\100\000", 2}, "QAA="},
+    {{"\200\000", 2}, "gAA="},
+
+    {{"\377\377", 2}, "//8="},
+    {{"\377\376", 2}, "//4="},
+    {{"\377\375", 2}, "//0="},
+    {{"\377\373", 2}, "//s="},
+    {{"\377\367", 2}, "//c="},
+    {{"\377\357", 2}, "/+8="},
+    {{"\377\337", 2}, "/98="},
+    {{"\377\277", 2}, "/78="},
+    {{"\377\177", 2}, "/38="},
+    {{"\376\377", 2}, "/v8="},
+    {{"\375\377", 2}, "/f8="},
+    {{"\373\377", 2}, "+/8="},
+    {{"\367\377", 2}, "9/8="},
+    {{"\357\377", 2}, "7/8="},
+    {{"\337\377", 2}, "3/8="},
+    {{"\277\377", 2}, "v/8="},
+    {{"\177\377", 2}, "f/8="},
+
+    {{"\000\000\000", 3}, "AAAA"},
+    {{"\000\000\001", 3}, "AAAB"},
+    {{"\000\000\002", 3}, "AAAC"},
+    {{"\000\000\004", 3}, "AAAE"},
+    {{"\000\000\010", 3}, "AAAI"},
+    {{"\000\000\020", 3}, "AAAQ"},
+    {{"\000\000\040", 3}, "AAAg"},
+    {{"\000\000\100", 3}, "AABA"},
+    {{"\000\000\200", 3}, "AACA"},
+    {{"\000\001\000", 3}, "AAEA"},
+    {{"\000\002\000", 3}, "AAIA"},
+    {{"\000\004\000", 3}, "AAQA"},
+    {{"\000\010\000", 3}, "AAgA"},
+    {{"\000\020\000", 3}, "ABAA"},
+    {{"\000\040\000", 3}, "ACAA"},
+    {{"\000\100\000", 3}, "AEAA"},
+    {{"\000\200\000", 3}, "AIAA"},
+    {{"\001\000\000", 3}, "AQAA"},
+    {{"\002\000\000", 3}, "AgAA"},
+    {{"\004\000\000", 3}, "BAAA"},
+    {{"\010\000\000", 3}, "CAAA"},
+    {{"\020\000\000", 3}, "EAAA"},
+    {{"\040\000\000", 3}, "IAAA"},
+    {{"\100\000\000", 3}, "QAAA"},
+    {{"\200\000\000", 3}, "gAAA"},
+
+    {{"\377\377\377", 3}, "////"},
+    {{"\377\377\376", 3}, "///+"},
+    {{"\377\377\375", 3}, "///9"},
+    {{"\377\377\373", 3}, "///7"},
+    {{"\377\377\367", 3}, "///3"},
+    {{"\377\377\357", 3}, "///v"},
+    {{"\377\377\337", 3}, "///f"},
+    {{"\377\377\277", 3}, "//+/"},
+    {{"\377\377\177", 3}, "//9/"},
+    {{"\377\376\377", 3}, "//7/"},
+    {{"\377\375\377", 3}, "//3/"},
+    {{"\377\373\377", 3}, "//v/"},
+    {{"\377\367\377", 3}, "//f/"},
+    {{"\377\357\377", 3}, "/+//"},
+    {{"\377\337\377", 3}, "/9//"},
+    {{"\377\277\377", 3}, "/7//"},
+    {{"\377\177\377", 3}, "/3//"},
+    {{"\376\377\377", 3}, "/v//"},
+    {{"\375\377\377", 3}, "/f//"},
+    {{"\373\377\377", 3}, "+///"},
+    {{"\367\377\377", 3}, "9///"},
+    {{"\357\377\377", 3}, "7///"},
+    {{"\337\377\377", 3}, "3///"},
+    {{"\277\377\377", 3}, "v///"},
+    {{"\177\377\377", 3}, "f///"},
+
+    // Random numbers: values obtained with
+    //
+    //  #! /bin/bash
+    //  dd bs=$1 count=1 if=/dev/random of=/tmp/bar.random
+    //  od -N $1 -t o1 /tmp/bar.random
+    //  uuencode -m test < /tmp/bar.random
+    //
+    // where $1 is the number of bytes (2, 3)
+
+    {{"\243\361", 2}, "o/E="},
+    {{"\024\167", 2}, "FHc="},
+    {{"\313\252", 2}, "y6o="},
+    {{"\046\041", 2}, "JiE="},
+    {{"\145\236", 2}, "ZZ4="},
+    {{"\254\325", 2}, "rNU="},
+    {{"\061\330", 2}, "Mdg="},
+    {{"\245\032", 2}, "pRo="},
+    {{"\006\000", 2}, "BgA="},
+    {{"\375\131", 2}, "/Vk="},
+    {{"\303\210", 2}, "w4g="},
+    {{"\040\037", 2}, "IB8="},
+    {{"\261\372", 2}, "sfo="},
+    {{"\335\014", 2}, "3Qw="},
+    {{"\233\217", 2}, "m48="},
+    {{"\373\056", 2}, "+y4="},
+    {{"\247\232", 2}, "p5o="},
+    {{"\107\053", 2}, "Rys="},
+    {{"\204\077", 2}, "hD8="},
+    {{"\276\211", 2}, "vok="},
+    {{"\313\110", 2}, "y0g="},
+    {{"\363\376", 2}, "8/4="},
+    {{"\251\234", 2}, "qZw="},
+    {{"\103\262", 2}, "Q7I="},
+    {{"\142\312", 2}, "Yso="},
+    {{"\067\211", 2}, "N4k="},
+    {{"\220\001", 2}, "kAE="},
+    {{"\152\240", 2}, "aqA="},
+    {{"\367\061", 2}, "9zE="},
+    {{"\133\255", 2}, "W60="},
+    {{"\176\035", 2}, "fh0="},
+    {{"\032\231", 2}, "Gpk="},
+
+    {{"\013\007\144", 3}, "Cwdk"},
+    {{"\030\112\106", 3}, "GEpG"},
+    {{"\047\325\046", 3}, "J9Um"},
+    {{"\310\160\022", 3}, "yHAS"},
+    {{"\131\100\237", 3}, "WUCf"},
+    {{"\064\342\134", 3}, "NOJc"},
+    {{"\010\177\004", 3}, "CH8E"},
+    {{"\345\147\205", 3}, "5WeF"},
+    {{"\300\343\360", 3}, "wOPw"},
+    {{"\061\240\201", 3}, "MaCB"},
+    {{"\225\333\044", 3}, "ldsk"},
+    {{"\215\137\352", 3}, "jV/q"},
+    {{"\371\147\160", 3}, "+Wdw"},
+    {{"\030\320\051", 3}, "GNAp"},
+    {{"\044\174\241", 3}, "JHyh"},
+    {{"\260\127\037", 3}, "sFcf"},
+    {{"\111\045\033", 3}, "SSUb"},
+    {{"\202\114\107", 3}, "gkxH"},
+    {{"\057\371\042", 3}, "L/ki"},
+    {{"\223\247\244", 3}, "k6ek"},
+    {{"\047\216\144", 3}, "J45k"},
+    {{"\203\070\327", 3}, "gzjX"},
+    {{"\247\140\072", 3}, "p2A6"},
+    {{"\124\115\116", 3}, "VE1O"},
+    {{"\157\162\050", 3}, "b3Io"},
+    {{"\357\223\004", 3}, "75ME"},
+    {{"\052\117\156", 3}, "Kk9u"},
+    {{"\347\154\000", 3}, "52wA"},
+    {{"\303\012\142", 3}, "wwpi"},
+    {{"\060\035\362", 3}, "MB3y"},
+    {{"\130\226\361", 3}, "WJbx"},
+    {{"\173\013\071", 3}, "ews5"},
+    {{"\336\004\027", 3}, "3gQX"},
+    {{"\357\366\234", 3}, "7/ac"},
+    {{"\353\304\111", 3}, "68RJ"},
+    {{"\024\264\131", 3}, "FLRZ"},
+    {{"\075\114\251", 3}, "PUyp"},
+    {{"\315\031\225", 3}, "zRmV"},
+    {{"\154\201\276", 3}, "bIG+"},
+    {{"\200\066\072", 3}, "gDY6"},
+    {{"\142\350\267", 3}, "Yui3"},
+    {{"\033\000\166", 3}, "GwB2"},
+    {{"\210\055\077", 3}, "iC0/"},
+    {{"\341\037\124", 3}, "4R9U"},
+    {{"\161\103\152", 3}, "cUNq"},
+    {{"\270\142\131", 3}, "uGJZ"},
+    {{"\337\076\074", 3}, "3z48"},
+    {{"\375\106\362", 3}, "/Uby"},
+    {{"\227\301\127", 3}, "l8FX"},
+    {{"\340\002\234", 3}, "4AKc"},
+    {{"\121\064\033", 3}, "UTQb"},
+    {{"\157\134\143", 3}, "b1xj"},
+    {{"\247\055\327", 3}, "py3X"},
+    {{"\340\142\005", 3}, "4GIF"},
+    {{"\060\260\143", 3}, "MLBj"},
+    {{"\075\203\170", 3}, "PYN4"},
+    {{"\143\160\016", 3}, "Y3AO"},
+    {{"\313\013\063", 3}, "ywsz"},
+    {{"\174\236\135", 3}, "fJ5d"},
+    {{"\103\047\026", 3}, "QycW"},
+    {{"\365\005\343", 3}, "9QXj"},
+    {{"\271\160\223", 3}, "uXCT"},
+    {{"\362\255\172", 3}, "8q16"},
+    {{"\113\012\015", 3}, "SwoN"},
+
+    // various lengths, generated by this python script:
+    //
+    // from std::string import lowercase as lc
+    // for i in range(27):
+    //   print '{ %2d, "%s",%s "%s" },' % (i, lc[:i], ' ' * (26-i),
+    //                                     lc[:i].encode('base64').strip())
+
+    {{"", 0}, {"", 0}},
+    {"a", "YQ=="},
+    {"ab", "YWI="},
+    {"abc", "YWJj"},
+    {"abcd", "YWJjZA=="},
+    {"abcde", "YWJjZGU="},
+    {"abcdef", "YWJjZGVm"},
+    {"abcdefg", "YWJjZGVmZw=="},
+    {"abcdefgh", "YWJjZGVmZ2g="},
+    {"abcdefghi", "YWJjZGVmZ2hp"},
+    {"abcdefghij", "YWJjZGVmZ2hpag=="},
+    {"abcdefghijk", "YWJjZGVmZ2hpams="},
+    {"abcdefghijkl", "YWJjZGVmZ2hpamts"},
+    {"abcdefghijklm", "YWJjZGVmZ2hpamtsbQ=="},
+    {"abcdefghijklmn", "YWJjZGVmZ2hpamtsbW4="},
+    {"abcdefghijklmno", "YWJjZGVmZ2hpamtsbW5v"},
+    {"abcdefghijklmnop", "YWJjZGVmZ2hpamtsbW5vcA=="},
+    {"abcdefghijklmnopq", "YWJjZGVmZ2hpamtsbW5vcHE="},
+    {"abcdefghijklmnopqr", "YWJjZGVmZ2hpamtsbW5vcHFy"},
+    {"abcdefghijklmnopqrs", "YWJjZGVmZ2hpamtsbW5vcHFycw=="},
+    {"abcdefghijklmnopqrst", "YWJjZGVmZ2hpamtsbW5vcHFyc3Q="},
+    {"abcdefghijklmnopqrstu", "YWJjZGVmZ2hpamtsbW5vcHFyc3R1"},
+    {"abcdefghijklmnopqrstuv", "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dg=="},
+    {"abcdefghijklmnopqrstuvw", "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnc="},
+    {"abcdefghijklmnopqrstuvwx", "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4"},
+    {"abcdefghijklmnopqrstuvwxy", "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eQ=="},
+    {"abcdefghijklmnopqrstuvwxyz", "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXo="},
+};
+
+template <typename StringType>
+void TestEscapeAndUnescape() {
+  // Check the short strings; this tests the math (and boundaries)
+  for (const auto& tc : base64_tests) {
+    // Test plain base64.
+    StringType encoded("this junk should be ignored");
+    absl::Base64Escape(tc.plaintext, &encoded);
+    EXPECT_EQ(encoded, tc.cyphertext);
+    EXPECT_EQ(absl::Base64Escape(tc.plaintext), tc.cyphertext);
+
+    StringType decoded("this junk should be ignored");
+    EXPECT_TRUE(absl::Base64Unescape(encoded, &decoded));
+    EXPECT_EQ(decoded, tc.plaintext);
+
+    StringType websafe_with_padding(tc.cyphertext);
+    for (unsigned int c = 0; c < websafe_with_padding.size(); ++c) {
+      if ('+' == websafe_with_padding[c]) websafe_with_padding[c] = '-';
+      if ('/' == websafe_with_padding[c]) websafe_with_padding[c] = '_';
+      // Intentionally keeping padding aka '='.
+    }
+
+    // Test plain websafe (aka without padding).
+    StringType websafe(websafe_with_padding);
+    for (unsigned int c = 0; c < websafe.size(); ++c) {
+      if ('=' == websafe[c]) {
+        websafe.resize(c);
+        break;
+      }
+    }
+    encoded = "this junk should be ignored";
+    absl::WebSafeBase64Escape(tc.plaintext, &encoded);
+    EXPECT_EQ(encoded, websafe);
+    EXPECT_EQ(absl::WebSafeBase64Escape(tc.plaintext), websafe);
+
+    decoded = "this junk should be ignored";
+    EXPECT_TRUE(absl::WebSafeBase64Unescape(websafe, &decoded));
+    EXPECT_EQ(decoded, tc.plaintext);
+  }
+
+  // Now try the long strings, this tests the streaming
+  for (const auto& tc : absl::strings_internal::base64_strings()) {
+    StringType buffer;
+    absl::WebSafeBase64Escape(tc.plaintext, &buffer);
+    EXPECT_EQ(tc.cyphertext, buffer);
+    EXPECT_EQ(absl::WebSafeBase64Escape(tc.plaintext), tc.cyphertext);
+  }
+
+  // Verify the behavior when decoding bad data
+  {
+    absl::string_view data_set[] = {"ab-/", absl::string_view("\0bcd", 4),
+                                    absl::string_view("abc.\0", 5)};
+    for (absl::string_view bad_data : data_set) {
+      StringType buf;
+      EXPECT_FALSE(absl::Base64Unescape(bad_data, &buf));
+      EXPECT_FALSE(absl::WebSafeBase64Unescape(bad_data, &buf));
+      EXPECT_TRUE(buf.empty());
+    }
+  }
+}
+
+TEST(Base64, EscapeAndUnescape) {
+  TestEscapeAndUnescape<std::string>();
+}
+
+TEST(Base64, Padding) {
+  // Padding is optional.
+  // '.' is an acceptable padding character, just like '='.
+  std::initializer_list<absl::string_view> good_padding = {
+    "YQ",
+    "YQ==",
+    "YQ=.",
+    "YQ.=",
+    "YQ..",
+  };
+  for (absl::string_view b64 : good_padding) {
+    std::string decoded;
+    EXPECT_TRUE(absl::Base64Unescape(b64, &decoded));
+    EXPECT_EQ(decoded, "a");
+    std::string websafe_decoded;
+    EXPECT_TRUE(absl::WebSafeBase64Unescape(b64, &websafe_decoded));
+    EXPECT_EQ(websafe_decoded, "a");
+  }
+  std::initializer_list<absl::string_view> bad_padding = {
+    "YQ=",
+    "YQ.",
+    "YQ===",
+    "YQ==.",
+    "YQ=.=",
+    "YQ=..",
+    "YQ.==",
+    "YQ.=.",
+    "YQ..=",
+    "YQ...",
+    "YQ====",
+    "YQ....",
+    "YQ=====",
+    "YQ.....",
+  };
+  for (absl::string_view b64 : bad_padding) {
+    std::string decoded;
+    EXPECT_FALSE(absl::Base64Unescape(b64, &decoded));
+    std::string websafe_decoded;
+    EXPECT_FALSE(absl::WebSafeBase64Unescape(b64, &websafe_decoded));
+  }
+}
+
+TEST(Base64, DISABLED_HugeData) {
+  const size_t kSize = size_t(3) * 1000 * 1000 * 1000;
+  static_assert(kSize % 3 == 0, "kSize must be divisible by 3");
+  const std::string huge(kSize, 'x');
+
+  std::string escaped;
+  absl::Base64Escape(huge, &escaped);
+
+  // Generates the string that should match a base64 encoded "xxx..." string.
+  // "xxx" in base64 is "eHh4".
+  std::string expected_encoding;
+  expected_encoding.reserve(kSize / 3 * 4);
+  for (size_t i = 0; i < kSize / 3; ++i) {
+    expected_encoding.append("eHh4");
+  }
+  EXPECT_EQ(expected_encoding, escaped);
+
+  std::string unescaped;
+  EXPECT_TRUE(absl::Base64Unescape(escaped, &unescaped));
+  EXPECT_EQ(huge, unescaped);
+}
+
+TEST(HexAndBack, HexStringToBytes_and_BytesToHexString) {
+  std::string hex_mixed = "0123456789abcdefABCDEF";
+  std::string bytes_expected = "\x01\x23\x45\x67\x89\xab\xcd\xef\xAB\xCD\xEF";
+  std::string hex_only_lower = "0123456789abcdefabcdef";
+
+  std::string bytes_result = absl::HexStringToBytes(hex_mixed);
+  EXPECT_EQ(bytes_expected, bytes_result);
+
+  std::string prefix_valid = hex_mixed + "?";
+  std::string prefix_valid_result = absl::HexStringToBytes(
+      absl::string_view(prefix_valid.data(), prefix_valid.size() - 1));
+  EXPECT_EQ(bytes_expected, prefix_valid_result);
+
+  std::string infix_valid = "?" + hex_mixed + "???";
+  std::string infix_valid_result = absl::HexStringToBytes(
+      absl::string_view(infix_valid.data() + 1, hex_mixed.size()));
+  EXPECT_EQ(bytes_expected, infix_valid_result);
+
+  std::string hex_result = absl::BytesToHexString(bytes_expected);
+  EXPECT_EQ(hex_only_lower, hex_result);
+}
+
+}  // namespace

weight/_dep/abseil-cpp/absl/strings/has_ostream_operator_test.cc

@@ -0,0 +1,41 @@
+// Copyright 2023 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/has_ostream_operator.h"
+
+#include <ostream>
+#include <string>
+
+#include "gtest/gtest.h"
+#include "absl/types/optional.h"
+
+namespace {
+
+struct TypeWithoutOstreamOp {};
+
+struct TypeWithOstreamOp {
+  friend std::ostream& operator<<(std::ostream& os, const TypeWithOstreamOp&) {
+    return os;
+  }
+};
+
+TEST(HasOstreamOperatorTest, Works) {
+  EXPECT_TRUE(absl::HasOstreamOperator<int>::value);
+  EXPECT_TRUE(absl::HasOstreamOperator<std::string>::value);
+  EXPECT_FALSE(absl::HasOstreamOperator<absl::optional<int>>::value);
+  EXPECT_FALSE(absl::HasOstreamOperator<TypeWithoutOstreamOp>::value);
+  EXPECT_TRUE(absl::HasOstreamOperator<TypeWithOstreamOp>::value);
+}
+
+}  // namespace

weight/_dep/abseil-cpp/absl/strings/internal/charconv_bigint.h

@@ -0,0 +1,423 @@
+// Copyright 2018 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_STRINGS_INTERNAL_CHARCONV_BIGINT_H_
+#define ABSL_STRINGS_INTERNAL_CHARCONV_BIGINT_H_
+
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <string>
+
+#include "absl/base/config.h"
+#include "absl/strings/ascii.h"
+#include "absl/strings/internal/charconv_parse.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace strings_internal {
+
+// The largest power that 5 that can be raised to, and still fit in a uint32_t.
+constexpr int kMaxSmallPowerOfFive = 13;
+// The largest power that 10 that can be raised to, and still fit in a uint32_t.
+constexpr int kMaxSmallPowerOfTen = 9;
+
+ABSL_DLL extern const uint32_t
+    kFiveToNth[kMaxSmallPowerOfFive + 1];
+ABSL_DLL extern const uint32_t kTenToNth[kMaxSmallPowerOfTen + 1];
+
+// Large, fixed-width unsigned integer.
+//
+// Exact rounding for decimal-to-binary floating point conversion requires very
+// large integer math, but a design goal of absl::from_chars is to avoid
+// allocating memory.  The integer precision needed for decimal-to-binary
+// conversions is large but bounded, so a huge fixed-width integer class
+// suffices.
+//
+// This is an intentionally limited big integer class.  Only needed operations
+// are implemented.  All storage lives in an array data member, and all
+// arithmetic is done in-place, to avoid requiring separate storage for operand
+// and result.
+//
+// This is an internal class.  Some methods live in the .cc file, and are
+// instantiated only for the values of max_words we need.
+template <int max_words>
+class BigUnsigned {
+ public:
+  static_assert(max_words == 4 || max_words == 84,
+                "unsupported max_words value");
+
+  BigUnsigned() : size_(0), words_{} {}
+  explicit constexpr BigUnsigned(uint64_t v)
+      : size_((v >> 32) ? 2 : v ? 1 : 0),
+        words_{static_cast<uint32_t>(v & 0xffffffffu),
+               static_cast<uint32_t>(v >> 32)} {}
+
+  // Constructs a BigUnsigned from the given string_view containing a decimal
+  // value.  If the input string is not a decimal integer, constructs a 0
+  // instead.
+  explicit BigUnsigned(absl::string_view sv) : size_(0), words_{} {
+    // Check for valid input, returning a 0 otherwise.  This is reasonable
+    // behavior only because this constructor is for unit tests.
+    if (std::find_if_not(sv.begin(), sv.end(), ascii_isdigit) != sv.end() ||
+        sv.empty()) {
+      return;
+    }
+    int exponent_adjust =
+        ReadDigits(sv.data(), sv.data() + sv.size(), Digits10() + 1);
+    if (exponent_adjust > 0) {
+      MultiplyByTenToTheNth(exponent_adjust);
+    }
+  }
+
+  // Loads the mantissa value of a previously-parsed float.
+  //
+  // Returns the associated decimal exponent.  The value of the parsed float is
+  // exactly *this * 10**exponent.
+  int ReadFloatMantissa(const ParsedFloat& fp, int significant_digits);
+
+  // Returns the number of decimal digits of precision this type provides.  All
+  // numbers with this many decimal digits or fewer are representable by this
+  // type.
+  //
+  // Analogous to std::numeric_limits<BigUnsigned>::digits10.
+  static constexpr int Digits10() {
+    // 9975007/1035508 is very slightly less than log10(2**32).
+    return static_cast<uint64_t>(max_words) * 9975007 / 1035508;
+  }
+
+  // Shifts left by the given number of bits.
+  void ShiftLeft(int count) {
+    if (count > 0) {
+      const int word_shift = count / 32;
+      if (word_shift >= max_words) {
+        SetToZero();
+        return;
+      }
+      size_ = (std::min)(size_ + word_shift, max_words);
+      count %= 32;
+      if (count == 0) {
+        std::copy_backward(words_, words_ + size_ - word_shift, words_ + size_);
+      } else {
+        for (int i = (std::min)(size_, max_words - 1); i > word_shift; --i) {
+          words_[i] = (words_[i - word_shift] << count) |
+                      (words_[i - word_shift - 1] >> (32 - count));
+        }
+        words_[word_shift] = words_[0] << count;
+        // Grow size_ if necessary.
+        if (size_ < max_words && words_[size_]) {
+          ++size_;
+        }
+      }
+      std::fill_n(words_, word_shift, 0u);
+    }
+  }
+
+
+  // Multiplies by v in-place.
+  void MultiplyBy(uint32_t v) {
+    if (size_ == 0 || v == 1) {
+      return;
+    }
+    if (v == 0) {
+      SetToZero();
+      return;
+    }
+    const uint64_t factor = v;
+    uint64_t window = 0;
+    for (int i = 0; i < size_; ++i) {
+      window += factor * words_[i];
+      words_[i] = window & 0xffffffff;
+      window >>= 32;
+    }
+    // If carry bits remain and there's space for them, grow size_.
+    if (window && size_ < max_words) {
+      words_[size_] = window & 0xffffffff;
+      ++size_;
+    }
+  }
+
+  void MultiplyBy(uint64_t v) {
+    uint32_t words[2];
+    words[0] = static_cast<uint32_t>(v);
+    words[1] = static_cast<uint32_t>(v >> 32);
+    if (words[1] == 0) {
+      MultiplyBy(words[0]);
+    } else {
+      MultiplyBy(2, words);
+    }
+  }
+
+  // Multiplies in place by 5 to the power of n.  n must be non-negative.
+  void MultiplyByFiveToTheNth(int n) {
+    while (n >= kMaxSmallPowerOfFive) {
+      MultiplyBy(kFiveToNth[kMaxSmallPowerOfFive]);
+      n -= kMaxSmallPowerOfFive;
+    }
+    if (n > 0) {
+      MultiplyBy(kFiveToNth[n]);
+    }
+  }
+
+  // Multiplies in place by 10 to the power of n.  n must be non-negative.
+  void MultiplyByTenToTheNth(int n) {
+    if (n > kMaxSmallPowerOfTen) {
+      // For large n, raise to a power of 5, then shift left by the same amount.
+      // (10**n == 5**n * 2**n.)  This requires fewer multiplications overall.
+      MultiplyByFiveToTheNth(n);
+      ShiftLeft(n);
+    } else if (n > 0) {
+      // We can do this more quickly for very small N by using a single
+      // multiplication.
+      MultiplyBy(kTenToNth[n]);
+    }
+  }
+
+  // Returns the value of 5**n, for non-negative n.  This implementation uses
+  // a lookup table, and is faster then seeding a BigUnsigned with 1 and calling
+  // MultiplyByFiveToTheNth().
+  static BigUnsigned FiveToTheNth(int n);
+
+  // Multiplies by another BigUnsigned, in-place.
+  template <int M>
+  void MultiplyBy(const BigUnsigned<M>& other) {
+    MultiplyBy(other.size(), other.words());
+  }
+
+  void SetToZero() {
+    std::fill_n(words_, size_, 0u);
+    size_ = 0;
+  }
+
+  // Returns the value of the nth word of this BigUnsigned.  This is
+  // range-checked, and returns 0 on out-of-bounds accesses.
+  uint32_t GetWord(int index) const {
+    if (index < 0 || index >= size_) {
+      return 0;
+    }
+    return words_[index];
+  }
+
+  // Returns this integer as a decimal string.  This is not used in the decimal-
+  // to-binary conversion; it is intended to aid in testing.
+  std::string ToString() const;
+
+  int size() const { return size_; }
+  const uint32_t* words() const { return words_; }
+
+ private:
+  // Reads the number between [begin, end), possibly containing a decimal point,
+  // into this BigUnsigned.
+  //
+  // Callers are required to ensure [begin, end) contains a valid number, with
+  // one or more decimal digits and at most one decimal point.  This routine
+  // will behave unpredictably if these preconditions are not met.
+  //
+  // Only the first `significant_digits` digits are read.  Digits beyond this
+  // limit are "sticky": If the final significant digit is 0 or 5, and if any
+  // dropped digit is nonzero, then that final significant digit is adjusted up
+  // to 1 or 6.  This adjustment allows for precise rounding.
+  //
+  // Returns `exponent_adjustment`, a power-of-ten exponent adjustment to
+  // account for the decimal point and for dropped significant digits.  After
+  // this function returns,
+  //   actual_value_of_parsed_string ~= *this * 10**exponent_adjustment.
+  int ReadDigits(const char* begin, const char* end, int significant_digits);
+
+  // Performs a step of big integer multiplication.  This computes the full
+  // (64-bit-wide) values that should be added at the given index (step), and
+  // adds to that location in-place.
+  //
+  // Because our math all occurs in place, we must multiply starting from the
+  // highest word working downward.  (This is a bit more expensive due to the
+  // extra carries involved.)
+  //
+  // This must be called in steps, for each word to be calculated, starting from
+  // the high end and working down to 0.  The first value of `step` should be
+  //   `std::min(original_size + other.size_ - 2, max_words - 1)`.
+  // The reason for this expression is that multiplying the i'th word from one
+  // multiplicand and the j'th word of another multiplicand creates a
+  // two-word-wide value to be stored at the (i+j)'th element.  The highest
+  // word indices we will access are `original_size - 1` from this object, and
+  // `other.size_ - 1` from our operand.  Therefore,
+  // `original_size + other.size_ - 2` is the first step we should calculate,
+  // but limited on an upper bound by max_words.
+
+  // Working from high-to-low ensures that we do not overwrite the portions of
+  // the initial value of *this which are still needed for later steps.
+  //
+  // Once called with step == 0, *this contains the result of the
+  // multiplication.
+  //
+  // `original_size` is the size_ of *this before the first call to
+  // MultiplyStep().  `other_words` and `other_size` are the contents of our
+  // operand.  `step` is the step to perform, as described above.
+  void MultiplyStep(int original_size, const uint32_t* other_words,
+                    int other_size, int step);
+
+  void MultiplyBy(int other_size, const uint32_t* other_words) {
+    const int original_size = size_;
+    const int first_step =
+        (std::min)(original_size + other_size - 2, max_words - 1);
+    for (int step = first_step; step >= 0; --step) {
+      MultiplyStep(original_size, other_words, other_size, step);
+    }
+  }
+
+  // Adds a 32-bit value to the index'th word, with carry.
+  void AddWithCarry(int index, uint32_t value) {
+    if (value) {
+      while (index < max_words && value > 0) {
+        words_[index] += value;
+        // carry if we overflowed in this word:
+        if (value > words_[index]) {
+          value = 1;
+          ++index;
+        } else {
+          value = 0;
+        }
+      }
+      size_ = (std::min)(max_words, (std::max)(index + 1, size_));
+    }
+  }
+
+  void AddWithCarry(int index, uint64_t value) {
+    if (value && index < max_words) {
+      uint32_t high = value >> 32;
+      uint32_t low = value & 0xffffffff;
+      words_[index] += low;
+      if (words_[index] < low) {
+        ++high;
+        if (high == 0) {
+          // Carry from the low word caused our high word to overflow.
+          // Short circuit here to do the right thing.
+          AddWithCarry(index + 2, static_cast<uint32_t>(1));
+          return;
+        }
+      }
+      if (high > 0) {
+        AddWithCarry(index + 1, high);
+      } else {
+        // Normally 32-bit AddWithCarry() sets size_, but since we don't call
+        // it when `high` is 0, do it ourselves here.
+        size_ = (std::min)(max_words, (std::max)(index + 1, size_));
+      }
+    }
+  }
+
+  // Divide this in place by a constant divisor.  Returns the remainder of the
+  // division.
+  template <uint32_t divisor>
+  uint32_t DivMod() {
+    uint64_t accumulator = 0;
+    for (int i = size_ - 1; i >= 0; --i) {
+      accumulator <<= 32;
+      accumulator += words_[i];
+      // accumulator / divisor will never overflow an int32_t in this loop
+      words_[i] = static_cast<uint32_t>(accumulator / divisor);
+      accumulator = accumulator % divisor;
+    }
+    while (size_ > 0 && words_[size_ - 1] == 0) {
+      --size_;
+    }
+    return static_cast<uint32_t>(accumulator);
+  }
+
+  // The number of elements in words_ that may carry significant values.
+  // All elements beyond this point are 0.
+  //
+  // When size_ is 0, this BigUnsigned stores the value 0.
+  // When size_ is nonzero, is *not* guaranteed that words_[size_ - 1] is
+  // nonzero.  This can occur due to overflow truncation.
+  // In particular, x.size_ != y.size_ does *not* imply x != y.
+  int size_;
+  uint32_t words_[max_words];
+};
+
+// Compares two big integer instances.
+//
+// Returns -1 if lhs < rhs, 0 if lhs == rhs, and 1 if lhs > rhs.
+template <int N, int M>
+int Compare(const BigUnsigned<N>& lhs, const BigUnsigned<M>& rhs) {
+  int limit = (std::max)(lhs.size(), rhs.size());
+  for (int i = limit - 1; i >= 0; --i) {
+    const uint32_t lhs_word = lhs.GetWord(i);
+    const uint32_t rhs_word = rhs.GetWord(i);
+    if (lhs_word < rhs_word) {
+      return -1;
+    } else if (lhs_word > rhs_word) {
+      return 1;
+    }
+  }
+  return 0;
+}
+
+template <int N, int M>
+bool operator==(const BigUnsigned<N>& lhs, const BigUnsigned<M>& rhs) {
+  int limit = (std::max)(lhs.size(), rhs.size());
+  for (int i = 0; i < limit; ++i) {
+    if (lhs.GetWord(i) != rhs.GetWord(i)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+template <int N, int M>
+bool operator!=(const BigUnsigned<N>& lhs, const BigUnsigned<M>& rhs) {
+  return !(lhs == rhs);
+}
+
+template <int N, int M>
+bool operator<(const BigUnsigned<N>& lhs, const BigUnsigned<M>& rhs) {
+  return Compare(lhs, rhs) == -1;
+}
+
+template <int N, int M>
+bool operator>(const BigUnsigned<N>& lhs, const BigUnsigned<M>& rhs) {
+  return rhs < lhs;
+}
+template <int N, int M>
+bool operator<=(const BigUnsigned<N>& lhs, const BigUnsigned<M>& rhs) {
+  return !(rhs < lhs);
+}
+template <int N, int M>
+bool operator>=(const BigUnsigned<N>& lhs, const BigUnsigned<M>& rhs) {
+  return !(lhs < rhs);
+}
+
+// Output operator for BigUnsigned, for testing purposes only.
+template <int N>
+std::ostream& operator<<(std::ostream& os, const BigUnsigned<N>& num) {
+  return os << num.ToString();
+}
+
+// Explicit instantiation declarations for the sizes of BigUnsigned that we
+// are using.
+//
+// For now, the choices of 4 and 84 are arbitrary; 4 is a small value that is
+// still bigger than an int128, and 84 is a large value we will want to use
+// in the from_chars implementation.
+//
+// Comments justifying the use of 84 belong in the from_chars implementation,
+// and will be added in a follow-up CL.
+extern template class BigUnsigned<4>;
+extern template class BigUnsigned<84>;
+
+}  // namespace strings_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_INTERNAL_CHARCONV_BIGINT_H_

weight/_dep/abseil-cpp/absl/strings/internal/charconv_bigint_test.cc

@@ -0,0 +1,260 @@
+// Copyright 2018 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/internal/charconv_bigint.h"
+
+#include <string>
+
+#include "gtest/gtest.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace strings_internal {
+
+TEST(BigUnsigned, ShiftLeft) {
+  {
+    // Check that 3 * 2**100 is calculated correctly
+    BigUnsigned<4> num(3u);
+    num.ShiftLeft(100);
+    EXPECT_EQ(num, BigUnsigned<4>("3802951800684688204490109616128"));
+  }
+  {
+    // Test that overflow is truncated properly.
+    // 15 is 4 bits long, and BigUnsigned<4> is a 128-bit bigint.
+    // Shifting left by 125 bits should truncate off the high bit, so that
+    //   15 << 125 == 7 << 125
+    // after truncation.
+    BigUnsigned<4> a(15u);
+    BigUnsigned<4> b(7u);
+    BigUnsigned<4> c(3u);
+    a.ShiftLeft(125);
+    b.ShiftLeft(125);
+    c.ShiftLeft(125);
+    EXPECT_EQ(a, b);
+    EXPECT_NE(a, c);
+  }
+  {
+    // Same test, larger bigint:
+    BigUnsigned<84> a(15u);
+    BigUnsigned<84> b(7u);
+    BigUnsigned<84> c(3u);
+    a.ShiftLeft(84 * 32 - 3);
+    b.ShiftLeft(84 * 32 - 3);
+    c.ShiftLeft(84 * 32 - 3);
+    EXPECT_EQ(a, b);
+    EXPECT_NE(a, c);
+  }
+  {
+    // Check that incrementally shifting has the same result as doing it all at
+    // once (attempting to capture corner cases.)
+    const std::string seed = "1234567890123456789012345678901234567890";
+    BigUnsigned<84> a(seed);
+    for (int i = 1; i <= 84 * 32; ++i) {
+      a.ShiftLeft(1);
+      BigUnsigned<84> b(seed);
+      b.ShiftLeft(i);
+      EXPECT_EQ(a, b);
+    }
+    // And we should have fully rotated all bits off by now:
+    EXPECT_EQ(a, BigUnsigned<84>(0u));
+  }
+  {
+    // Bit shifting large and small numbers by large and small offsets.
+    // Intended to exercise bounds-checking corner on ShiftLeft() (directly
+    // and under asan).
+
+    // 2**(32*84)-1
+    const BigUnsigned<84> all_bits_one(
+        "1474444211396924248063325089479706787923460402125687709454567433186613"
+        "6228083464060749874845919674257665016359189106695900028098437021384227"
+        "3285029708032466536084583113729486015826557532750465299832071590813090"
+        "2011853039837649252477307070509704043541368002938784757296893793903797"
+        "8180292336310543540677175225040919704702800559606097685920595947397024"
+        "8303316808753252115729411497720357971050627997031988036134171378490368"
+        "6008000778741115399296162550786288457245180872759047016734959330367829"
+        "5235612397427686310674725251378116268607113017720538636924549612987647"
+        "5767411074510311386444547332882472126067840027882117834454260409440463"
+        "9345147252664893456053258463203120637089916304618696601333953616715125"
+        "2115882482473279040772264257431663818610405673876655957323083702713344"
+        "4201105427930770976052393421467136557055");
+    const BigUnsigned<84> zero(0u);
+    const BigUnsigned<84> one(1u);
+    // in bounds shifts
+    for (int i = 1; i < 84*32; ++i) {
+      // shifting all_bits_one to the left should result in a smaller number,
+      // since the high bits rotate off and the low bits are replaced with
+      // zeroes.
+      BigUnsigned<84> big_shifted = all_bits_one;
+      big_shifted.ShiftLeft(i);
+      EXPECT_GT(all_bits_one, big_shifted);
+      // Shifting 1 to the left should instead result in a larger number.
+      BigUnsigned<84> small_shifted = one;
+      small_shifted.ShiftLeft(i);
+      EXPECT_LT(one, small_shifted);
+    }
+    // Shifting by zero or a negative number has no effect
+    for (int no_op_shift : {0, -1, -84 * 32, std::numeric_limits<int>::min()}) {
+      BigUnsigned<84> big_shifted = all_bits_one;
+      big_shifted.ShiftLeft(no_op_shift);
+      EXPECT_EQ(all_bits_one, big_shifted);
+      BigUnsigned<84> small_shifted = one;
+      big_shifted.ShiftLeft(no_op_shift);
+      EXPECT_EQ(one, small_shifted);
+    }
+    // Shifting by an amount greater than the number of bits should result in
+    // zero.
+    for (int out_of_bounds_shift :
+         {84 * 32, 84 * 32 + 1, std::numeric_limits<int>::max()}) {
+      BigUnsigned<84> big_shifted = all_bits_one;
+      big_shifted.ShiftLeft(out_of_bounds_shift);
+      EXPECT_EQ(zero, big_shifted);
+      BigUnsigned<84> small_shifted = one;
+      small_shifted.ShiftLeft(out_of_bounds_shift);
+      EXPECT_EQ(zero, small_shifted);
+    }
+  }
+}
+
+TEST(BigUnsigned, MultiplyByUint32) {
+  const BigUnsigned<84> factorial_100(
+      "933262154439441526816992388562667004907159682643816214685929638952175999"
+      "932299156089414639761565182862536979208272237582511852109168640000000000"
+      "00000000000000");
+  BigUnsigned<84> a(1u);
+  for (uint32_t i = 1; i <= 100; ++i) {
+    a.MultiplyBy(i);
+  }
+  EXPECT_EQ(a, BigUnsigned<84>(factorial_100));
+}
+
+TEST(BigUnsigned, MultiplyByBigUnsigned) {
+  {
+    // Put the terms of factorial_200 into two bigints, and multiply them
+    // together.
+    const BigUnsigned<84> factorial_200(
+        "7886578673647905035523632139321850622951359776871732632947425332443594"
+        "4996340334292030428401198462390417721213891963883025764279024263710506"
+        "1926624952829931113462857270763317237396988943922445621451664240254033"
+        "2918641312274282948532775242424075739032403212574055795686602260319041"
+        "7032406235170085879617892222278962370389737472000000000000000000000000"
+        "0000000000000000000000000");
+    BigUnsigned<84> evens(1u);
+    BigUnsigned<84> odds(1u);
+    for (uint32_t i = 1; i < 200; i += 2) {
+      odds.MultiplyBy(i);
+      evens.MultiplyBy(i + 1);
+    }
+    evens.MultiplyBy(odds);
+    EXPECT_EQ(evens, factorial_200);
+  }
+  {
+    // Multiply various powers of 10 together.
+    for (int a = 0 ; a < 700; a += 25) {
+      SCOPED_TRACE(a);
+      BigUnsigned<84> a_value("3" + std::string(a, '0'));
+      for (int b = 0; b < (700 - a); b += 25) {
+        SCOPED_TRACE(b);
+        BigUnsigned<84> b_value("2" + std::string(b, '0'));
+        BigUnsigned<84> expected_product("6" + std::string(a + b, '0'));
+        b_value.MultiplyBy(a_value);
+        EXPECT_EQ(b_value, expected_product);
+      }
+    }
+  }
+}
+
+TEST(BigUnsigned, MultiplyByOverflow) {
+  {
+    // Check that multiplcation overflow predictably truncates.
+
+    // A big int with all bits on.
+    BigUnsigned<4> all_bits_on("340282366920938463463374607431768211455");
+    // Modulo 2**128, this is equal to -1.  Therefore the square of this,
+    // modulo 2**128, should be 1.
+    all_bits_on.MultiplyBy(all_bits_on);
+    EXPECT_EQ(all_bits_on, BigUnsigned<4>(1u));
+  }
+  {
+    // Try multiplying a large bigint by 2**50, and compare the result to
+    // shifting.
+    BigUnsigned<4> value_1("12345678901234567890123456789012345678");
+    BigUnsigned<4> value_2("12345678901234567890123456789012345678");
+    BigUnsigned<4> two_to_fiftieth(1u);
+    two_to_fiftieth.ShiftLeft(50);
+
+    value_1.ShiftLeft(50);
+    value_2.MultiplyBy(two_to_fiftieth);
+    EXPECT_EQ(value_1, value_2);
+  }
+}
+
+TEST(BigUnsigned, FiveToTheNth) {
+  {
+    // Sanity check that MultiplyByFiveToTheNth gives consistent answers, up to
+    // and including overflow.
+    for (int i = 0; i < 1160; ++i) {
+      SCOPED_TRACE(i);
+      BigUnsigned<84> value_1(123u);
+      BigUnsigned<84> value_2(123u);
+      value_1.MultiplyByFiveToTheNth(i);
+      for (int j = 0; j < i; j++) {
+        value_2.MultiplyBy(5u);
+      }
+      EXPECT_EQ(value_1, value_2);
+    }
+  }
+  {
+    // Check that the faster, table-lookup-based static method returns the same
+    // result that multiplying in-place would return, up to and including
+    // overflow.
+    for (int i = 0; i < 1160; ++i) {
+      SCOPED_TRACE(i);
+      BigUnsigned<84> value_1(1u);
+      value_1.MultiplyByFiveToTheNth(i);
+      BigUnsigned<84> value_2 = BigUnsigned<84>::FiveToTheNth(i);
+      EXPECT_EQ(value_1, value_2);
+    }
+  }
+}
+
+TEST(BigUnsigned, TenToTheNth) {
+  {
+    // Sanity check MultiplyByTenToTheNth.
+    for (int i = 0; i < 800; ++i) {
+      SCOPED_TRACE(i);
+      BigUnsigned<84> value_1(123u);
+      BigUnsigned<84> value_2(123u);
+      value_1.MultiplyByTenToTheNth(i);
+      for (int j = 0; j < i; j++) {
+        value_2.MultiplyBy(10u);
+      }
+      EXPECT_EQ(value_1, value_2);
+    }
+  }
+  {
+    // Alternate testing approach, taking advantage of the decimal parser.
+    for (int i = 0; i < 200; ++i) {
+      SCOPED_TRACE(i);
+      BigUnsigned<84> value_1(135u);
+      value_1.MultiplyByTenToTheNth(i);
+      BigUnsigned<84> value_2("135" + std::string(i, '0'));
+      EXPECT_EQ(value_1, value_2);
+    }
+  }
+}
+
+
+}  // namespace strings_internal
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/strings/internal/charconv_parse_test.cc

@@ -0,0 +1,357 @@
+// Copyright 2018 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/internal/charconv_parse.h"
+
+#include <string>
+#include <utility>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/log/check.h"
+#include "absl/strings/str_cat.h"
+
+using absl::chars_format;
+using absl::strings_internal::FloatType;
+using absl::strings_internal::ParsedFloat;
+using absl::strings_internal::ParseFloat;
+
+namespace {
+
+// Check that a given string input is parsed to the expected mantissa and
+// exponent.
+//
+// Input string `s` must contain a '$' character.  It marks the end of the
+// characters that should be consumed by the match.  It is stripped from the
+// input to ParseFloat.
+//
+// If input string `s` contains '[' and ']' characters, these mark the region
+// of characters that should be marked as the "subrange".  For NaNs, this is
+// the location of the extended NaN string.  For numbers, this is the location
+// of the full, over-large mantissa.
+template <int base>
+void ExpectParsedFloat(std::string s, absl::chars_format format_flags,
+                       FloatType expected_type, uint64_t expected_mantissa,
+                       int expected_exponent,
+                       int expected_literal_exponent = -999) {
+  SCOPED_TRACE(s);
+
+  int begin_subrange = -1;
+  int end_subrange = -1;
+  // If s contains '[' and ']', then strip these characters and set the subrange
+  // indices appropriately.
+  std::string::size_type open_bracket_pos = s.find('[');
+  if (open_bracket_pos != std::string::npos) {
+    begin_subrange = static_cast<int>(open_bracket_pos);
+    s.replace(open_bracket_pos, 1, "");
+    std::string::size_type close_bracket_pos = s.find(']');
+    CHECK_NE(close_bracket_pos, absl::string_view::npos)
+        << "Test input contains [ without matching ]";
+    end_subrange = static_cast<int>(close_bracket_pos);
+    s.replace(close_bracket_pos, 1, "");
+  }
+  const std::string::size_type expected_characters_matched = s.find('$');
+  CHECK_NE(expected_characters_matched, std::string::npos)
+      << "Input string must contain $";
+  s.replace(expected_characters_matched, 1, "");
+
+  ParsedFloat parsed =
+      ParseFloat<base>(s.data(), s.data() + s.size(), format_flags);
+
+  EXPECT_NE(parsed.end, nullptr);
+  if (parsed.end == nullptr) {
+    return;  // The following tests are not useful if we fully failed to parse
+  }
+  EXPECT_EQ(parsed.type, expected_type);
+  if (begin_subrange == -1) {
+    EXPECT_EQ(parsed.subrange_begin, nullptr);
+    EXPECT_EQ(parsed.subrange_end, nullptr);
+  } else {
+    EXPECT_EQ(parsed.subrange_begin, s.data() + begin_subrange);
+    EXPECT_EQ(parsed.subrange_end, s.data() + end_subrange);
+  }
+  if (parsed.type == FloatType::kNumber) {
+    EXPECT_EQ(parsed.mantissa, expected_mantissa);
+    EXPECT_EQ(parsed.exponent, expected_exponent);
+    if (expected_literal_exponent != -999) {
+      EXPECT_EQ(parsed.literal_exponent, expected_literal_exponent);
+    }
+  }
+  auto characters_matched = static_cast<int>(parsed.end - s.data());
+  EXPECT_EQ(characters_matched, expected_characters_matched);
+}
+
+// Check that a given string input is parsed to the expected mantissa and
+// exponent.
+//
+// Input string `s` must contain a '$' character.  It marks the end of the
+// characters that were consumed by the match.
+template <int base>
+void ExpectNumber(std::string s, absl::chars_format format_flags,
+                  uint64_t expected_mantissa, int expected_exponent,
+                  int expected_literal_exponent = -999) {
+  ExpectParsedFloat<base>(std::move(s), format_flags, FloatType::kNumber,
+                          expected_mantissa, expected_exponent,
+                          expected_literal_exponent);
+}
+
+// Check that a given string input is parsed to the given special value.
+//
+// This tests against both number bases, since infinities and NaNs have
+// identical representations in both modes.
+void ExpectSpecial(const std::string& s, absl::chars_format format_flags,
+                   FloatType type) {
+  ExpectParsedFloat<10>(s, format_flags, type, 0, 0);
+  ExpectParsedFloat<16>(s, format_flags, type, 0, 0);
+}
+
+// Check that a given input string is not matched by Float.
+template <int base>
+void ExpectFailedParse(absl::string_view s, absl::chars_format format_flags) {
+  ParsedFloat parsed =
+      ParseFloat<base>(s.data(), s.data() + s.size(), format_flags);
+  EXPECT_EQ(parsed.end, nullptr);
+}
+
+TEST(ParseFloat, SimpleValue) {
+  // Test that various forms of floating point numbers all parse correctly.
+  ExpectNumber<10>("1.23456789e5$", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("1.23456789e+5$", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("1.23456789E5$", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("1.23456789e05$", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("123.456789e3$", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("0.000123456789e9$", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("123456.789$", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("123456789e-3$", chars_format::general, 123456789, -3);
+
+  ExpectNumber<16>("1.234abcdefp28$", chars_format::general, 0x1234abcdef, -8);
+  ExpectNumber<16>("1.234abcdefp+28$", chars_format::general, 0x1234abcdef, -8);
+  ExpectNumber<16>("1.234ABCDEFp28$", chars_format::general, 0x1234abcdef, -8);
+  ExpectNumber<16>("1.234AbCdEfP0028$", chars_format::general, 0x1234abcdef,
+                   -8);
+  ExpectNumber<16>("123.4abcdefp20$", chars_format::general, 0x1234abcdef, -8);
+  ExpectNumber<16>("0.0001234abcdefp44$", chars_format::general, 0x1234abcdef,
+                   -8);
+  ExpectNumber<16>("1234abcd.ef$", chars_format::general, 0x1234abcdef, -8);
+  ExpectNumber<16>("1234abcdefp-8$", chars_format::general, 0x1234abcdef, -8);
+
+  // ExpectNumber does not attempt to drop trailing zeroes.
+  ExpectNumber<10>("0001.2345678900e005$", chars_format::general, 12345678900,
+                   -5);
+  ExpectNumber<16>("0001.234abcdef000p28$", chars_format::general,
+                   0x1234abcdef000, -20);
+
+  // Ensure non-matching characters after a number are ignored, even when they
+  // look like potentially matching characters.
+  ExpectNumber<10>("1.23456789e5$   ", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("1.23456789e5$e5e5", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("1.23456789e5$.25", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("1.23456789e5$-", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("1.23456789e5$PUPPERS!!!", chars_format::general, 123456789,
+                   -3);
+  ExpectNumber<10>("123456.789$efghij", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("123456.789$e", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("123456.789$p5", chars_format::general, 123456789, -3);
+  ExpectNumber<10>("123456.789$.10", chars_format::general, 123456789, -3);
+
+  ExpectNumber<16>("1.234abcdefp28$   ", chars_format::general, 0x1234abcdef,
+                   -8);
+  ExpectNumber<16>("1.234abcdefp28$p28", chars_format::general, 0x1234abcdef,
+                   -8);
+  ExpectNumber<16>("1.234abcdefp28$.125", chars_format::general, 0x1234abcdef,
+                   -8);
+  ExpectNumber<16>("1.234abcdefp28$-", chars_format::general, 0x1234abcdef, -8);
+  ExpectNumber<16>("1.234abcdefp28$KITTEHS!!!", chars_format::general,
+                   0x1234abcdef, -8);
+  ExpectNumber<16>("1234abcd.ef$ghijk", chars_format::general, 0x1234abcdef,
+                   -8);
+  ExpectNumber<16>("1234abcd.ef$p", chars_format::general, 0x1234abcdef, -8);
+  ExpectNumber<16>("1234abcd.ef$.10", chars_format::general, 0x1234abcdef, -8);
+
+  // Ensure we can read a full resolution mantissa without overflow.
+  ExpectNumber<10>("9999999999999999999$", chars_format::general,
+                   9999999999999999999u, 0);
+  ExpectNumber<16>("fffffffffffffff$", chars_format::general,
+                   0xfffffffffffffffu, 0);
+
+  // Check that zero is consistently read.
+  ExpectNumber<10>("0$", chars_format::general, 0, 0);
+  ExpectNumber<16>("0$", chars_format::general, 0, 0);
+  ExpectNumber<10>("000000000000000000000000000000000000000$",
+                   chars_format::general, 0, 0);
+  ExpectNumber<16>("000000000000000000000000000000000000000$",
+                   chars_format::general, 0, 0);
+  ExpectNumber<10>("0000000000000000000000.000000000000000000$",
+                   chars_format::general, 0, 0);
+  ExpectNumber<16>("0000000000000000000000.000000000000000000$",
+                   chars_format::general, 0, 0);
+  ExpectNumber<10>("0.00000000000000000000000000000000e123456$",
+                   chars_format::general, 0, 0);
+  ExpectNumber<16>("0.00000000000000000000000000000000p123456$",
+                   chars_format::general, 0, 0);
+}
+
+TEST(ParseFloat, LargeDecimalMantissa) {
+  // After 19 significant decimal digits in the mantissa, ParsedFloat will
+  // truncate additional digits.  We need to test that:
+  //   1) the truncation to 19 digits happens
+  //   2) the returned exponent reflects the dropped significant digits
+  //   3) a correct literal_exponent is set
+  //
+  // If and only if a significant digit is found after 19 digits, then the
+  // entirety of the mantissa in case the exact value is needed to make a
+  // rounding decision.  The [ and ] characters below denote where such a
+  // subregion was marked by by ParseFloat.  They are not part of the input.
+
+  // Mark a capture group only if a dropped digit is significant (nonzero).
+  ExpectNumber<10>("100000000000000000000000000$", chars_format::general,
+                   1000000000000000000,
+                   /* adjusted exponent */ 8);
+
+  ExpectNumber<10>("123456789123456789100000000$", chars_format::general,
+                   1234567891234567891,
+                   /* adjusted exponent */ 8);
+
+  ExpectNumber<10>("[123456789123456789123456789]$", chars_format::general,
+                   1234567891234567891,
+                   /* adjusted exponent */ 8,
+                   /* literal exponent */ 0);
+
+  ExpectNumber<10>("[123456789123456789100000009]$", chars_format::general,
+                   1234567891234567891,
+                   /* adjusted exponent */ 8,
+                   /* literal exponent */ 0);
+
+  ExpectNumber<10>("[123456789123456789120000000]$", chars_format::general,
+                   1234567891234567891,
+                   /* adjusted exponent */ 8,
+                   /* literal exponent */ 0);
+
+  // Leading zeroes should not count towards the 19 significant digit limit
+  ExpectNumber<10>("[00000000123456789123456789123456789]$",
+                   chars_format::general, 1234567891234567891,
+                   /* adjusted exponent */ 8,
+                   /* literal exponent */ 0);
+
+  ExpectNumber<10>("00000000123456789123456789100000000$",
+                   chars_format::general, 1234567891234567891,
+                   /* adjusted exponent */ 8);
+
+  // Truncated digits after the decimal point should not cause a further
+  // exponent adjustment.
+  ExpectNumber<10>("1.234567891234567891e123$", chars_format::general,
+                   1234567891234567891, 105);
+  ExpectNumber<10>("[1.23456789123456789123456789]e123$", chars_format::general,
+                   1234567891234567891,
+                   /* adjusted exponent */ 105,
+                   /* literal exponent */ 123);
+
+  // Ensure we truncate, and not round.  (The from_chars algorithm we use
+  // depends on our guess missing low, if it misses, so we need the rounding
+  // error to be downward.)
+  ExpectNumber<10>("[1999999999999999999999]$", chars_format::general,
+                   1999999999999999999,
+                   /* adjusted exponent */ 3,
+                   /* literal exponent */ 0);
+}
+
+TEST(ParseFloat, LargeHexadecimalMantissa) {
+  // After 15 significant hex digits in the mantissa, ParsedFloat will treat
+  // additional digits as sticky,  We need to test that:
+  //   1) The truncation to 15 digits happens
+  //   2) The returned exponent reflects the dropped significant digits
+  //   3) If a nonzero digit is dropped, the low bit of mantissa is set.
+
+  ExpectNumber<16>("123456789abcdef123456789abcdef$", chars_format::general,
+                   0x123456789abcdef, 60);
+
+  // Leading zeroes should not count towards the 15 significant digit limit
+  ExpectNumber<16>("000000123456789abcdef123456789abcdef$",
+                   chars_format::general, 0x123456789abcdef, 60);
+
+  // Truncated digits after the radix point should not cause a further
+  // exponent adjustment.
+  ExpectNumber<16>("1.23456789abcdefp100$", chars_format::general,
+                   0x123456789abcdef, 44);
+  ExpectNumber<16>("1.23456789abcdef123456789abcdefp100$",
+                   chars_format::general, 0x123456789abcdef, 44);
+
+  // test sticky digit behavior.  The low bit should be set iff any dropped
+  // digit is nonzero.
+  ExpectNumber<16>("123456789abcdee123456789abcdee$", chars_format::general,
+                   0x123456789abcdef, 60);
+  ExpectNumber<16>("123456789abcdee000000000000001$", chars_format::general,
+                   0x123456789abcdef, 60);
+  ExpectNumber<16>("123456789abcdee000000000000000$", chars_format::general,
+                   0x123456789abcdee, 60);
+}
+
+TEST(ParseFloat, ScientificVsFixed) {
+  // In fixed mode, an exponent is never matched (but the remainder of the
+  // number will be matched.)
+  ExpectNumber<10>("1.23456789$e5", chars_format::fixed, 123456789, -8);
+  ExpectNumber<10>("123456.789$", chars_format::fixed, 123456789, -3);
+  ExpectNumber<16>("1.234abcdef$p28", chars_format::fixed, 0x1234abcdef, -36);
+  ExpectNumber<16>("1234abcd.ef$", chars_format::fixed, 0x1234abcdef, -8);
+
+  // In scientific mode, numbers don't match *unless* they have an exponent.
+  ExpectNumber<10>("1.23456789e5$", chars_format::scientific, 123456789, -3);
+  ExpectFailedParse<10>("-123456.789$", chars_format::scientific);
+  ExpectNumber<16>("1.234abcdefp28$", chars_format::scientific, 0x1234abcdef,
+                   -8);
+  ExpectFailedParse<16>("1234abcd.ef$", chars_format::scientific);
+}
+
+TEST(ParseFloat, Infinity) {
+  ExpectFailedParse<10>("in", chars_format::general);
+  ExpectFailedParse<16>("in", chars_format::general);
+  ExpectFailedParse<10>("inx", chars_format::general);
+  ExpectFailedParse<16>("inx", chars_format::general);
+  ExpectSpecial("inf$", chars_format::general, FloatType::kInfinity);
+  ExpectSpecial("Inf$", chars_format::general, FloatType::kInfinity);
+  ExpectSpecial("INF$", chars_format::general, FloatType::kInfinity);
+  ExpectSpecial("inf$inite", chars_format::general, FloatType::kInfinity);
+  ExpectSpecial("iNfInItY$", chars_format::general, FloatType::kInfinity);
+  ExpectSpecial("infinity$!!!", chars_format::general, FloatType::kInfinity);
+}
+
+TEST(ParseFloat, NaN) {
+  ExpectFailedParse<10>("na", chars_format::general);
+  ExpectFailedParse<16>("na", chars_format::general);
+  ExpectFailedParse<10>("nah", chars_format::general);
+  ExpectFailedParse<16>("nah", chars_format::general);
+  ExpectSpecial("nan$", chars_format::general, FloatType::kNan);
+  ExpectSpecial("NaN$", chars_format::general, FloatType::kNan);
+  ExpectSpecial("nAn$", chars_format::general, FloatType::kNan);
+  ExpectSpecial("NAN$", chars_format::general, FloatType::kNan);
+  ExpectSpecial("NaN$aNaNaNaNaBatman!", chars_format::general, FloatType::kNan);
+
+  // A parenthesized sequence of the characters [a-zA-Z0-9_] is allowed to
+  // appear after an NaN.  Check that this is allowed, and that the correct
+  // characters are grouped.
+  //
+  // (The characters [ and ] in the pattern below delimit the expected matched
+  // subgroup; they are not part of the input passed to ParseFloat.)
+  ExpectSpecial("nan([0xabcdef])$", chars_format::general, FloatType::kNan);
+  ExpectSpecial("nan([0xabcdef])$...", chars_format::general, FloatType::kNan);
+  ExpectSpecial("nan([0xabcdef])$)...", chars_format::general, FloatType::kNan);
+  ExpectSpecial("nan([])$", chars_format::general, FloatType::kNan);
+  ExpectSpecial("nan([aAzZ09_])$", chars_format::general, FloatType::kNan);
+  // If the subgroup contains illegal characters, don't match it at all.
+  ExpectSpecial("nan$(bad-char)", chars_format::general, FloatType::kNan);
+  // Also cope with a missing close paren.
+  ExpectSpecial("nan$(0xabcdef", chars_format::general, FloatType::kNan);
+}
+
+}  // namespace

weight/_dep/abseil-cpp/absl/strings/internal/cord_data_edge_test.cc

@@ -0,0 +1,130 @@
+// Copyright 2022 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/internal/cord_data_edge.h"
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_test_util.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+namespace {
+
+using ::absl::cordrep_testing::MakeExternal;
+using ::absl::cordrep_testing::MakeFlat;
+using ::absl::cordrep_testing::MakeSubstring;
+
+TEST(CordDataEdgeTest, IsDataEdgeOnFlat) {
+  CordRep* rep = MakeFlat("Lorem ipsum dolor sit amet, consectetur ...");
+  EXPECT_TRUE(IsDataEdge(rep));
+  CordRep::Unref(rep);
+}
+
+TEST(CordDataEdgeTest, IsDataEdgeOnExternal) {
+  CordRep* rep = MakeExternal("Lorem ipsum dolor sit amet, consectetur ...");
+  EXPECT_TRUE(IsDataEdge(rep));
+  CordRep::Unref(rep);
+}
+
+TEST(CordDataEdgeTest, IsDataEdgeOnSubstringOfFlat) {
+  CordRep* rep = MakeFlat("Lorem ipsum dolor sit amet, consectetur ...");
+  CordRep* substr = MakeSubstring(1, 20, rep);
+  EXPECT_TRUE(IsDataEdge(substr));
+  CordRep::Unref(substr);
+}
+
+TEST(CordDataEdgeTest, IsDataEdgeOnSubstringOfExternal) {
+  CordRep* rep = MakeExternal("Lorem ipsum dolor sit amet, consectetur ...");
+  CordRep* substr = MakeSubstring(1, 20, rep);
+  EXPECT_TRUE(IsDataEdge(substr));
+  CordRep::Unref(substr);
+}
+
+TEST(CordDataEdgeTest, IsDataEdgeOnBtree) {
+  CordRep* rep = MakeFlat("Lorem ipsum dolor sit amet, consectetur ...");
+  CordRepBtree* tree = CordRepBtree::New(rep);
+  EXPECT_FALSE(IsDataEdge(tree));
+  CordRep::Unref(tree);
+}
+
+TEST(CordDataEdgeTest, IsDataEdgeOnBadSubstr) {
+  CordRep* rep = MakeFlat("Lorem ipsum dolor sit amet, consectetur ...");
+  CordRep* substr = MakeSubstring(1, 18, MakeSubstring(1, 20, rep));
+  EXPECT_FALSE(IsDataEdge(substr));
+  CordRep::Unref(substr);
+}
+
+TEST(CordDataEdgeTest, EdgeDataOnFlat) {
+  absl::string_view value = "Lorem ipsum dolor sit amet, consectetur ...";
+  CordRep* rep = MakeFlat(value);
+  EXPECT_EQ(EdgeData(rep), value);
+  CordRep::Unref(rep);
+}
+
+TEST(CordDataEdgeTest, EdgeDataOnExternal) {
+  absl::string_view value = "Lorem ipsum dolor sit amet, consectetur ...";
+  CordRep* rep = MakeExternal(value);
+  EXPECT_EQ(EdgeData(rep), value);
+  CordRep::Unref(rep);
+}
+
+TEST(CordDataEdgeTest, EdgeDataOnSubstringOfFlat) {
+  absl::string_view value = "Lorem ipsum dolor sit amet, consectetur ...";
+  CordRep* rep = MakeFlat(value);
+  CordRep* substr = MakeSubstring(1, 20, rep);
+  EXPECT_EQ(EdgeData(substr), value.substr(1, 20));
+  CordRep::Unref(substr);
+}
+
+TEST(CordDataEdgeTest, EdgeDataOnSubstringOfExternal) {
+  absl::string_view value = "Lorem ipsum dolor sit amet, consectetur ...";
+  CordRep* rep = MakeExternal(value);
+  CordRep* substr = MakeSubstring(1, 20, rep);
+  EXPECT_EQ(EdgeData(substr), value.substr(1, 20));
+  CordRep::Unref(substr);
+}
+
+#if defined(GTEST_HAS_DEATH_TEST) && !defined(NDEBUG)
+
+TEST(CordDataEdgeTest, IsDataEdgeOnNullPtr) {
+  EXPECT_DEATH(IsDataEdge(nullptr), ".*");
+}
+
+TEST(CordDataEdgeTest, EdgeDataOnNullPtr) {
+  EXPECT_DEATH(EdgeData(nullptr), ".*");
+}
+
+TEST(CordDataEdgeTest, EdgeDataOnBtree) {
+  CordRep* rep = MakeFlat("Lorem ipsum dolor sit amet, consectetur ...");
+  CordRepBtree* tree = CordRepBtree::New(rep);
+  EXPECT_DEATH(EdgeData(tree), ".*");
+  CordRep::Unref(tree);
+}
+
+TEST(CordDataEdgeTest, EdgeDataOnBadSubstr) {
+  CordRep* rep = MakeFlat("Lorem ipsum dolor sit amet, consectetur ...");
+  CordRep* substr = MakeSubstring(1, 18, MakeSubstring(1, 20, rep));
+  EXPECT_DEATH(EdgeData(substr), ".*");
+  CordRep::Unref(substr);
+}
+
+#endif  // GTEST_HAS_DEATH_TEST && !NDEBUG
+
+}  // namespace
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/strings/internal/cord_rep_btree.cc

@@ -0,0 +1,1241 @@
+// Copyright 2021 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/internal/cord_rep_btree.h"
+
+#include <atomic>
+#include <cassert>
+#include <cstdint>
+#include <iostream>
+#include <ostream>
+#include <string>
+
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/base/optimization.h"
+#include "absl/strings/internal/cord_data_edge.h"
+#include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_consume.h"
+#include "absl/strings/internal/cord_rep_flat.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+
+#ifdef ABSL_INTERNAL_NEED_REDUNDANT_CONSTEXPR_DECL
+constexpr size_t CordRepBtree::kMaxCapacity;
+#endif
+
+namespace {
+
+using NodeStack = CordRepBtree * [CordRepBtree::kMaxDepth];
+using EdgeType = CordRepBtree::EdgeType;
+using OpResult = CordRepBtree::OpResult;
+using CopyResult = CordRepBtree::CopyResult;
+
+constexpr auto kFront = CordRepBtree::kFront;
+constexpr auto kBack = CordRepBtree::kBack;
+
+ABSL_CONST_INIT std::atomic<bool> cord_btree_exhaustive_validation(false);
+
+// Implementation of the various 'Dump' functions.
+// Prints the entire tree structure or 'rep'. External callers should
+// not specify 'depth' and leave it to its default (0) value.
+// Rep may be a CordRepBtree tree, or a SUBSTRING / EXTERNAL / FLAT node.
+void DumpAll(const CordRep* rep,
+             bool include_contents,
+             std::ostream& stream,
+             size_t depth = 0) {
+  // Allow for full height trees + substring -> flat / external nodes.
+  assert(depth <= CordRepBtree::kMaxDepth + 2);
+  std::string sharing = const_cast<CordRep*>(rep)->refcount.IsOne()
+                            ? std::string("Private")
+                            : absl::StrCat("Shared(", rep->refcount.Get(), ")");
+  std::string sptr = absl::StrCat("0x", absl::Hex(rep));
+
+  // Dumps the data contents of `rep` if `include_contents` is true.
+  // Always emits a new line character.
+  auto maybe_dump_data = [&stream, include_contents](const CordRep* r) {
+    if (include_contents) {
+      // Allow for up to 60 wide display of content data, which with some
+      // indentation and prefix / labels keeps us within roughly 80-100 wide.
+      constexpr size_t kMaxDataLength = 60;
+      stream << ", data = \""
+             << EdgeData(r).substr(0, kMaxDataLength)
+             << (r->length > kMaxDataLength ? "\"..." : "\"");
+    }
+    stream << '\n';
+  };
+
+  // For each level, we print the 'shared/private' state and the rep pointer,
+  // indented by two spaces per recursive depth.
+  stream << std::string(depth * 2, ' ') << sharing << " (" << sptr << ") ";
+
+  if (rep->IsBtree()) {
+    const CordRepBtree* node = rep->btree();
+    std::string label =
+        node->height() ? absl::StrCat("Node(", node->height(), ")") : "Leaf";
+    stream << label << ", len = " << node->length
+           << ", begin = " << node->begin() << ", end = " << node->end()
+           << "\n";
+    for (CordRep* edge : node->Edges()) {
+      DumpAll(edge, include_contents, stream, depth + 1);
+    }
+  } else if (rep->tag == SUBSTRING) {
+    const CordRepSubstring* substring = rep->substring();
+    stream << "Substring, len = " << rep->length
+           << ", start = " << substring->start;
+    maybe_dump_data(rep);
+    DumpAll(substring->child, include_contents, stream, depth + 1);
+  } else if (rep->tag >= FLAT) {
+    stream << "Flat, len = " << rep->length
+           << ", cap = " << rep->flat()->Capacity();
+    maybe_dump_data(rep);
+  } else if (rep->tag == EXTERNAL) {
+    stream << "Extn, len = " << rep->length;
+    maybe_dump_data(rep);
+  }
+}
+
+// TODO(b/192061034): add 'bytes to copy' logic to avoid large slop on substring
+// small data out of large reps, and general efficiency of 'always copy small
+// data'. Consider making this a cord rep internal library function.
+CordRepSubstring* CreateSubstring(CordRep* rep, size_t offset, size_t n) {
+  assert(n != 0);
+  assert(offset + n <= rep->length);
+  assert(offset != 0 || n != rep->length);
+
+  if (rep->tag == SUBSTRING) {
+    CordRepSubstring* substring = rep->substring();
+    offset += substring->start;
+    rep = CordRep::Ref(substring->child);
+    CordRep::Unref(substring);
+  }
+  assert(rep->IsExternal() || rep->IsFlat());
+  CordRepSubstring* substring = new CordRepSubstring();
+  substring->length = n;
+  substring->tag = SUBSTRING;
+  substring->start = offset;
+  substring->child = rep;
+  return substring;
+}
+
+// TODO(b/192061034): consider making this a cord rep library function.
+inline CordRep* MakeSubstring(CordRep* rep, size_t offset, size_t n) {
+  if (n == rep->length) return rep;
+  if (n == 0) return CordRep::Unref(rep), nullptr;
+  return CreateSubstring(rep, offset, n);
+}
+
+// TODO(b/192061034): consider making this a cord rep library function.
+inline CordRep* MakeSubstring(CordRep* rep, size_t offset) {
+  if (offset == 0) return rep;
+  return CreateSubstring(rep, offset, rep->length - offset);
+}
+
+// Resizes `edge` to the provided `length`. Adopts a reference on `edge`.
+// This method directly returns `edge` if `length` equals `edge->length`.
+// If `is_mutable` is set to true, this function may return `edge` with
+// `edge->length` set to the new length depending on the type and size of
+// `edge`. Otherwise, this function returns a new CordRepSubstring value.
+// Requires `length > 0 && length <= edge->length`.
+CordRep* ResizeEdge(CordRep* edge, size_t length, bool is_mutable) {
+  assert(length > 0);
+  assert(length <= edge->length);
+  assert(IsDataEdge(edge));
+  if (length >= edge->length) return edge;
+
+  if (is_mutable && (edge->tag >= FLAT || edge->tag == SUBSTRING)) {
+    edge->length = length;
+    return edge;
+  }
+
+  return CreateSubstring(edge, 0, length);
+}
+
+template <EdgeType edge_type>
+inline absl::string_view Consume(absl::string_view s, size_t n) {
+  return edge_type == kBack ? s.substr(n) : s.substr(0, s.size() - n);
+}
+
+template <EdgeType edge_type>
+inline absl::string_view Consume(char* dst, absl::string_view s, size_t n) {
+  if (edge_type == kBack) {
+    memcpy(dst, s.data(), n);
+    return s.substr(n);
+  } else {
+    const size_t offset = s.size() - n;
+    memcpy(dst, s.data() + offset, n);
+    return s.substr(0, offset);
+  }
+}
+
+// Known issue / optimization weirdness: the store associated with the
+// decrement introduces traffic between cpus (even if the result of that
+// traffic does nothing), making this faster than a single call to
+// refcount.Decrement() checking the zero refcount condition.
+template <typename R, typename Fn>
+inline void FastUnref(R* r, Fn&& fn) {
+  if (r->refcount.IsOne()) {
+    fn(r);
+  } else if (!r->refcount.DecrementExpectHighRefcount()) {
+    fn(r);
+  }
+}
+
+
+void DeleteSubstring(CordRepSubstring* substring) {
+  CordRep* rep = substring->child;
+  if (!rep->refcount.Decrement()) {
+    if (rep->tag >= FLAT) {
+      CordRepFlat::Delete(rep->flat());
+    } else {
+      assert(rep->tag == EXTERNAL);
+      CordRepExternal::Delete(rep->external());
+    }
+  }
+  delete substring;
+}
+
+// Deletes a leaf node data edge. Requires `IsDataEdge(rep)`.
+void DeleteLeafEdge(CordRep* rep) {
+  assert(IsDataEdge(rep));
+  if (rep->tag >= FLAT) {
+    CordRepFlat::Delete(rep->flat());
+  } else if (rep->tag == EXTERNAL) {
+    CordRepExternal::Delete(rep->external());
+  } else {
+    DeleteSubstring(rep->substring());
+  }
+}
+
+// StackOperations contains the logic to build a left-most or right-most stack
+// (leg) down to the leaf level of a btree, and 'unwind' / 'Finalize' methods to
+// propagate node changes up the stack.
+template <EdgeType edge_type>
+struct StackOperations {
+  // Returns true if the node at 'depth' is not shared, i.e. has a refcount
+  // of one and all of its parent nodes have a refcount of one.
+  inline bool owned(int depth) const { return depth < share_depth; }
+
+  // Returns the node at 'depth'.
+  inline CordRepBtree* node(int depth) const { return stack[depth]; }
+
+  // Builds a `depth` levels deep stack starting at `tree` recording which nodes
+  // are private in the form of the 'share depth' where nodes are shared.
+  inline CordRepBtree* BuildStack(CordRepBtree* tree, int depth) {
+    assert(depth <= tree->height());
+    int current_depth = 0;
+    while (current_depth < depth && tree->refcount.IsOne()) {
+      stack[current_depth++] = tree;
+      tree = tree->Edge(edge_type)->btree();
+    }
+    share_depth = current_depth + (tree->refcount.IsOne() ? 1 : 0);
+    while (current_depth < depth) {
+      stack[current_depth++] = tree;
+      tree = tree->Edge(edge_type)->btree();
+    }
+    return tree;
+  }
+
+  // Builds a stack with the invariant that all nodes are private owned / not
+  // shared. This is used in iterative updates where a previous propagation
+  // guaranteed all nodes are owned / private.
+  inline void BuildOwnedStack(CordRepBtree* tree, int height) {
+    assert(height <= CordRepBtree::kMaxHeight);
+    int depth = 0;
+    while (depth < height) {
+      assert(tree->refcount.IsOne());
+      stack[depth++] = tree;
+      tree = tree->Edge(edge_type)->btree();
+    }
+    assert(tree->refcount.IsOne());
+    share_depth = depth + 1;
+  }
+
+  // Processes the final 'top level' result action for the tree.
+  // See the 'Action' enum for the various action implications.
+  static inline CordRepBtree* Finalize(CordRepBtree* tree, OpResult result) {
+    switch (result.action) {
+      case CordRepBtree::kPopped:
+        tree = edge_type == kBack ? CordRepBtree::New(tree, result.tree)
+                                  : CordRepBtree::New(result.tree, tree);
+        if (ABSL_PREDICT_FALSE(tree->height() > CordRepBtree::kMaxHeight)) {
+          tree = CordRepBtree::Rebuild(tree);
+          ABSL_RAW_CHECK(tree->height() <= CordRepBtree::kMaxHeight,
+                         "Max height exceeded");
+        }
+        return tree;
+      case CordRepBtree::kCopied:
+        CordRep::Unref(tree);
+        ABSL_FALLTHROUGH_INTENDED;
+      case CordRepBtree::kSelf:
+        return result.tree;
+    }
+    ABSL_UNREACHABLE();
+    return result.tree;
+  }
+
+  // Propagate the action result in 'result' up into all nodes of the stack
+  // starting at depth 'depth'. 'length' contains the extra length of data that
+  // was added at the lowest level, and is updated into all nodes of the stack.
+  // See the 'Action' enum for the various action implications.
+  // If 'propagate' is true, then any copied node values are updated into the
+  // stack, which is used for iterative processing on the same stack.
+  template <bool propagate = false>
+  inline CordRepBtree* Unwind(CordRepBtree* tree, int depth, size_t length,
+                              OpResult result) {
+    // TODO(mvels): revisit the below code to check if 3 loops with 3
+    // (incremental) conditions is faster than 1 loop with a switch.
+    // Benchmarking and perf recordings indicate the loop with switch is
+    // fastest, likely because of indirect jumps on the tight case values and
+    // dense branches. But it's worth considering 3 loops, as the `action`
+    // transitions are mono directional. E.g.:
+    //   while (action == kPopped) {
+    //     ...
+    //   }
+    //   while (action == kCopied) {
+    //     ...
+    //   }
+    //   ...
+    // We also  found that an "if () do {}" loop here seems faster, possibly
+    // because it allows the branch predictor more granular heuristics on
+    // 'single leaf' (`depth` == 0) and 'single depth' (`depth` == 1) cases
+    // which appear to be the most common use cases.
+    if (depth != 0) {
+      do {
+        CordRepBtree* node = stack[--depth];
+        const bool owned = depth < share_depth;
+        switch (result.action) {
+          case CordRepBtree::kPopped:
+            assert(!propagate);
+            result = node->AddEdge<edge_type>(owned, result.tree, length);
+            break;
+          case CordRepBtree::kCopied:
+            result = node->SetEdge<edge_type>(owned, result.tree, length);
+            if (propagate) stack[depth] = result.tree;
+            break;
+          case CordRepBtree::kSelf:
+            node->length += length;
+            while (depth > 0) {
+              node = stack[--depth];
+              node->length += length;
+            }
+            return node;
+        }
+      } while (depth > 0);
+    }
+    return Finalize(tree, result);
+  }
+
+  // Invokes `Unwind` with `propagate=true` to update the stack node values.
+  inline CordRepBtree* Propagate(CordRepBtree* tree, int depth, size_t length,
+                                 OpResult result) {
+    return Unwind</*propagate=*/true>(tree, depth, length, result);
+  }
+
+  // `share_depth` contains the depth at which the nodes in the stack become
+  // shared. I.e., if the top most level is shared (i.e.: `!refcount.IsOne()`),
+  // then `share_depth` is 0. If the 2nd node is shared (and implicitly all
+  // nodes below that) then `share_depth` is 1, etc. A `share_depth` greater
+  // than the depth of the stack indicates that none of the nodes in the stack
+  // are shared.
+  int share_depth;
+
+  NodeStack stack;
+};
+
+}  // namespace
+
+void SetCordBtreeExhaustiveValidation(bool do_exaustive_validation) {
+  cord_btree_exhaustive_validation.store(do_exaustive_validation,
+                                         std::memory_order_relaxed);
+}
+
+bool IsCordBtreeExhaustiveValidationEnabled() {
+  return cord_btree_exhaustive_validation.load(std::memory_order_relaxed);
+}
+
+void CordRepBtree::Dump(const CordRep* rep, absl::string_view label,
+                        bool include_contents, std::ostream& stream) {
+  stream << "===================================\n";
+  if (!label.empty()) {
+    stream << label << '\n';
+    stream << "-----------------------------------\n";
+  }
+  if (rep) {
+    DumpAll(rep, include_contents, stream);
+  } else {
+    stream << "NULL\n";
+  }
+}
+
+void CordRepBtree::Dump(const CordRep* rep, absl::string_view label,
+                        std::ostream& stream) {
+  Dump(rep, label, false, stream);
+}
+
+void CordRepBtree::Dump(const CordRep* rep, std::ostream& stream) {
+  Dump(rep, absl::string_view(), false, stream);
+}
+
+template <size_t size>
+static void DestroyTree(CordRepBtree* tree) {
+  for (CordRep* node : tree->Edges()) {
+    if (node->refcount.Decrement()) continue;
+    for (CordRep* edge : node->btree()->Edges()) {
+      if (edge->refcount.Decrement()) continue;
+      if (size == 1) {
+        DeleteLeafEdge(edge);
+      } else {
+        CordRepBtree::Destroy(edge->btree());
+      }
+    }
+    CordRepBtree::Delete(node->btree());
+  }
+  CordRepBtree::Delete(tree);
+}
+
+void CordRepBtree::Destroy(CordRepBtree* tree) {
+  switch (tree->height()) {
+    case 0:
+      for (CordRep* edge : tree->Edges()) {
+        if (!edge->refcount.Decrement()) {
+          DeleteLeafEdge(edge);
+        }
+      }
+      return CordRepBtree::Delete(tree);
+    case 1:
+      return DestroyTree<1>(tree);
+    default:
+      return DestroyTree<2>(tree);
+  }
+}
+
+bool CordRepBtree::IsValid(const CordRepBtree* tree, bool shallow) {
+#define NODE_CHECK_VALID(x)                                           \
+  if (!(x)) {                                                         \
+    ABSL_RAW_LOG(ERROR, "CordRepBtree::CheckValid() FAILED: %s", #x); \
+    return false;                                                     \
+  }
+#define NODE_CHECK_EQ(x, y)                                                    \
+  if ((x) != (y)) {                                                            \
+    ABSL_RAW_LOG(ERROR,                                                        \
+                 "CordRepBtree::CheckValid() FAILED: %s != %s (%s vs %s)", #x, \
+                 #y, absl::StrCat(x).c_str(), absl::StrCat(y).c_str());        \
+    return false;                                                              \
+  }
+
+  NODE_CHECK_VALID(tree != nullptr);
+  NODE_CHECK_VALID(tree->IsBtree());
+  NODE_CHECK_VALID(tree->height() <= kMaxHeight);
+  NODE_CHECK_VALID(tree->begin() < tree->capacity());
+  NODE_CHECK_VALID(tree->end() <= tree->capacity());
+  NODE_CHECK_VALID(tree->begin() <= tree->end());
+  size_t child_length = 0;
+  for (CordRep* edge : tree->Edges()) {
+    NODE_CHECK_VALID(edge != nullptr);
+    if (tree->height() > 0) {
+      NODE_CHECK_VALID(edge->IsBtree());
+      NODE_CHECK_VALID(edge->btree()->height() == tree->height() - 1);
+    } else {
+      NODE_CHECK_VALID(IsDataEdge(edge));
+    }
+    child_length += edge->length;
+  }
+  NODE_CHECK_EQ(child_length, tree->length);
+  if ((!shallow || IsCordBtreeExhaustiveValidationEnabled()) &&
+      tree->height() > 0) {
+    for (CordRep* edge : tree->Edges()) {
+      if (!IsValid(edge->btree(), shallow)) return false;
+    }
+  }
+  return true;
+
+#undef NODE_CHECK_VALID
+#undef NODE_CHECK_EQ
+}
+
+#ifndef NDEBUG
+
+CordRepBtree* CordRepBtree::AssertValid(CordRepBtree* tree, bool shallow) {
+  if (!IsValid(tree, shallow)) {
+    Dump(tree, "CordRepBtree validation failed:", false, std::cout);
+    ABSL_RAW_LOG(FATAL, "CordRepBtree::CheckValid() FAILED");
+  }
+  return tree;
+}
+
+const CordRepBtree* CordRepBtree::AssertValid(const CordRepBtree* tree,
+                                              bool shallow) {
+  if (!IsValid(tree, shallow)) {
+    Dump(tree, "CordRepBtree validation failed:", false, std::cout);
+    ABSL_RAW_LOG(FATAL, "CordRepBtree::CheckValid() FAILED");
+  }
+  return tree;
+}
+
+#endif  // NDEBUG
+
+template <EdgeType edge_type>
+inline OpResult CordRepBtree::AddEdge(bool owned, CordRep* edge, size_t delta) {
+  if (size() >= kMaxCapacity) return {New(edge), kPopped};
+  OpResult result = ToOpResult(owned);
+  result.tree->Add<edge_type>(edge);
+  result.tree->length += delta;
+  return result;
+}
+
+template <EdgeType edge_type>
+OpResult CordRepBtree::SetEdge(bool owned, CordRep* edge, size_t delta) {
+  OpResult result;
+  const size_t idx = index(edge_type);
+  if (owned) {
+    result = {this, kSelf};
+    CordRep::Unref(edges_[idx]);
+  } else {
+    // Create a copy containing all unchanged edges. Unchanged edges are the
+    // open interval [begin, back) or [begin + 1, end) depending on `edge_type`.
+    // We conveniently cover both case using a constexpr `shift` being 0 or 1
+    // as `end :== back + 1`.
+    result = {CopyRaw(length), kCopied};
+    constexpr int shift = edge_type == kFront ? 1 : 0;
+    for (CordRep* r : Edges(begin() + shift, back() + shift)) {
+      CordRep::Ref(r);
+    }
+  }
+  result.tree->edges_[idx] = edge;
+  result.tree->length += delta;
+  return result;
+}
+
+template <EdgeType edge_type>
+CordRepBtree* CordRepBtree::AddCordRep(CordRepBtree* tree, CordRep* rep) {
+  const int depth = tree->height();
+  const size_t length = rep->length;
+  StackOperations<edge_type> ops;
+  CordRepBtree* leaf = ops.BuildStack(tree, depth);
+  const OpResult result =
+      leaf->AddEdge<edge_type>(ops.owned(depth), rep, length);
+  return ops.Unwind(tree, depth, length, result);
+}
+
+template <>
+CordRepBtree* CordRepBtree::NewLeaf<kBack>(absl::string_view data,
+                                           size_t extra) {
+  CordRepBtree* leaf = CordRepBtree::New(0);
+  size_t length = 0;
+  size_t end = 0;
+  const size_t cap = leaf->capacity();
+  while (!data.empty() && end != cap) {
+    auto* flat = CordRepFlat::New(data.length() + extra);
+    flat->length = (std::min)(data.length(), flat->Capacity());
+    length += flat->length;
+    leaf->edges_[end++] = flat;
+    data = Consume<kBack>(flat->Data(), data, flat->length);
+  }
+  leaf->length = length;
+  leaf->set_end(end);
+  return leaf;
+}
+
+template <>
+CordRepBtree* CordRepBtree::NewLeaf<kFront>(absl::string_view data,
+                                            size_t extra) {
+  CordRepBtree* leaf = CordRepBtree::New(0);
+  size_t length = 0;
+  size_t begin = leaf->capacity();
+  leaf->set_end(leaf->capacity());
+  while (!data.empty() && begin != 0) {
+    auto* flat = CordRepFlat::New(data.length() + extra);
+    flat->length = (std::min)(data.length(), flat->Capacity());
+    length += flat->length;
+    leaf->edges_[--begin] = flat;
+    data = Consume<kFront>(flat->Data(), data, flat->length);
+  }
+  leaf->length = length;
+  leaf->set_begin(begin);
+  return leaf;
+}
+
+template <>
+absl::string_view CordRepBtree::AddData<kBack>(absl::string_view data,
+                                               size_t extra) {
+  assert(!data.empty());
+  assert(size() < capacity());
+  AlignBegin();
+  const size_t cap = capacity();
+  do {
+    CordRepFlat* flat = CordRepFlat::New(data.length() + extra);
+    const size_t n = (std::min)(data.length(), flat->Capacity());
+    flat->length = n;
+    edges_[fetch_add_end(1)] = flat;
+    data = Consume<kBack>(flat->Data(), data, n);
+  } while (!data.empty() && end() != cap);
+  return data;
+}
+
+template <>
+absl::string_view CordRepBtree::AddData<kFront>(absl::string_view data,
+                                                size_t extra) {
+  assert(!data.empty());
+  assert(size() < capacity());
+  AlignEnd();
+  do {
+    CordRepFlat* flat = CordRepFlat::New(data.length() + extra);
+    const size_t n = (std::min)(data.length(), flat->Capacity());
+    flat->length = n;
+    edges_[sub_fetch_begin(1)] = flat;
+    data = Consume<kFront>(flat->Data(), data, n);
+  } while (!data.empty() && begin() != 0);
+  return data;
+}
+
+template <EdgeType edge_type>
+CordRepBtree* CordRepBtree::AddData(CordRepBtree* tree, absl::string_view data,
+                                    size_t extra) {
+  if (ABSL_PREDICT_FALSE(data.empty())) return tree;
+
+  const size_t original_data_size = data.size();
+  int depth = tree->height();
+  StackOperations<edge_type> ops;
+  CordRepBtree* leaf = ops.BuildStack(tree, depth);
+
+  // If there is capacity in the last edge, append as much data
+  // as possible into this last edge.
+  if (leaf->size() < leaf->capacity()) {
+    OpResult result = leaf->ToOpResult(ops.owned(depth));
+    data = result.tree->AddData<edge_type>(data, extra);
+    if (data.empty()) {
+      result.tree->length += original_data_size;
+      return ops.Unwind(tree, depth, original_data_size, result);
+    }
+
+    // We added some data into this leaf, but not all. Propagate the added
+    // length to the top most node, and rebuild the stack with any newly copied
+    // or updated nodes. From this point on, the path (leg) from the top most
+    // node to the right-most node towards the leaf node is privately owned.
+    size_t delta = original_data_size - data.size();
+    assert(delta > 0);
+    result.tree->length += delta;
+    tree = ops.Propagate(tree, depth, delta, result);
+    ops.share_depth = depth + 1;
+  }
+
+  // We were unable to append all data into the existing right-most leaf node.
+  // This means all remaining data must be put into (a) new leaf node(s) which
+  // we append to the tree. To make this efficient, we iteratively build full
+  // leaf nodes from `data` until the created leaf contains all remaining data.
+  // We utilize the `Unwind` method to merge the created leaf into the first
+  // level towards root that has capacity. On each iteration with remaining
+  // data, we rebuild the stack in the knowledge that right-most nodes are
+  // privately owned after the first `Unwind` completes.
+  for (;;) {
+    OpResult result = {CordRepBtree::NewLeaf<edge_type>(data, extra), kPopped};
+    if (result.tree->length == data.size()) {
+      return ops.Unwind(tree, depth, result.tree->length, result);
+    }
+    data = Consume<edge_type>(data, result.tree->length);
+    tree = ops.Unwind(tree, depth, result.tree->length, result);
+    depth = tree->height();
+    ops.BuildOwnedStack(tree, depth);
+  }
+}
+
+template <EdgeType edge_type>
+CordRepBtree* CordRepBtree::Merge(CordRepBtree* dst, CordRepBtree* src) {
+  assert(dst->height() >= src->height());
+
+  // Capture source length as we may consume / destroy `src`.
+  const size_t length = src->length;
+
+  // We attempt to merge `src` at its corresponding height in `dst`.
+  const int depth = dst->height() - src->height();
+  StackOperations<edge_type> ops;
+  CordRepBtree* merge_node = ops.BuildStack(dst, depth);
+
+  // If there is enough space in `merge_node` for all edges from `src`, add all
+  // edges to this node, making a fresh copy as needed if not privately owned.
+  // If `merge_node` does not have capacity for `src`, we rely on `Unwind` and
+  // `Finalize` to merge `src` into the first level towards `root` where there
+  // is capacity for another edge, or create a new top level node.
+  OpResult result;
+  if (merge_node->size() + src->size() <= kMaxCapacity) {
+    result = merge_node->ToOpResult(ops.owned(depth));
+    result.tree->Add<edge_type>(src->Edges());
+    result.tree->length += src->length;
+    if (src->refcount.IsOne()) {
+      Delete(src);
+    } else {
+      for (CordRep* edge : src->Edges()) CordRep::Ref(edge);
+      CordRepBtree::Unref(src);
+    }
+  } else {
+    result = {src, kPopped};
+  }
+
+  // Unless we merged at the top level (i.e.: src and dst are equal height),
+  // unwind the result towards the top level, and finalize the result.
+  if (depth) {
+    return ops.Unwind(dst, depth, length, result);
+  }
+  return ops.Finalize(dst, result);
+}
+
+CopyResult CordRepBtree::CopySuffix(size_t offset) {
+  assert(offset < this->length);
+
+  // As long as `offset` starts inside the last edge, we can 'drop' the current
+  // depth. For the most extreme example: if offset references the last data
+  // edge in the tree, there is only a single edge / path from the top of the
+  // tree to that last edge, so we can drop all the nodes except that edge.
+  // The fast path check for this is `back->length >= length - offset`.
+  int height = this->height();
+  CordRepBtree* node = this;
+  size_t len = node->length - offset;
+  CordRep* back = node->Edge(kBack);
+  while (back->length >= len) {
+    offset = back->length - len;
+    if (--height < 0) {
+      return {MakeSubstring(CordRep::Ref(back), offset), height};
+    }
+    node = back->btree();
+    back = node->Edge(kBack);
+  }
+  if (offset == 0) return {CordRep::Ref(node), height};
+
+  // Offset does not point into the last edge, so we span at least two edges.
+  // Find the index of offset with `IndexBeyond` which provides us the edge
+  // 'beyond' the offset if offset is not a clean starting point of an edge.
+  Position pos = node->IndexBeyond(offset);
+  CordRepBtree* sub = node->CopyToEndFrom(pos.index, len);
+  const CopyResult result = {sub, height};
+
+  // `pos.n` contains a non zero value if the offset is not an exact starting
+  // point of an edge. In this case, `pos.n` contains the 'trailing' amount of
+  // bytes of the edge preceding that in `pos.index`. We need to iteratively
+  // adjust the preceding edge with the 'broken' offset until we have a perfect
+  // start of the edge.
+  while (pos.n != 0) {
+    assert(pos.index >= 1);
+    const size_t begin = pos.index - 1;
+    sub->set_begin(begin);
+    CordRep* const edge = node->Edge(begin);
+
+    len = pos.n;
+    offset = edge->length - len;
+
+    if (--height < 0) {
+      sub->edges_[begin] = MakeSubstring(CordRep::Ref(edge), offset, len);
+      return result;
+    }
+
+    node = edge->btree();
+    pos = node->IndexBeyond(offset);
+
+    CordRepBtree* nsub = node->CopyToEndFrom(pos.index, len);
+    sub->edges_[begin] = nsub;
+    sub = nsub;
+  }
+  sub->set_begin(pos.index);
+  return result;
+}
+
+CopyResult CordRepBtree::CopyPrefix(size_t n, bool allow_folding) {
+  assert(n > 0);
+  assert(n <= this->length);
+
+  // As long as `n` does not exceed the length of the first edge, we can 'drop'
+  // the current depth. For the most extreme example: if we'd copy a 1 byte
+  // prefix from a tree, there is only a single edge / path from the top of the
+  // tree to the single data edge containing this byte, so we can drop all the
+  // nodes except the data node.
+  int height = this->height();
+  CordRepBtree* node = this;
+  CordRep* front = node->Edge(kFront);
+  if (allow_folding) {
+    while (front->length >= n) {
+      if (--height < 0) return {MakeSubstring(CordRep::Ref(front), 0, n), -1};
+      node = front->btree();
+      front = node->Edge(kFront);
+    }
+  }
+  if (node->length == n) return {CordRep::Ref(node), height};
+
+  // `n` spans at least two nodes, find the end point of the span.
+  Position pos = node->IndexOf(n);
+
+  // Create a partial copy of the node up to `pos.index`, with a defined length
+  // of `n`. Any 'partial last edge' is added further below as needed.
+  CordRepBtree* sub = node->CopyBeginTo(pos.index, n);
+  const CopyResult result = {sub, height};
+
+  // `pos.n` contains the 'offset inside the edge for IndexOf(n)'. As long as
+  // this is not zero, we don't have a 'clean cut', so we need to make a
+  // (partial) copy of that last edge, and repeat this until pos.n is zero.
+  while (pos.n != 0) {
+    size_t end = pos.index;
+    n = pos.n;
+
+    CordRep* edge = node->Edge(pos.index);
+    if (--height < 0) {
+      sub->edges_[end++] = MakeSubstring(CordRep::Ref(edge), 0, n);
+      sub->set_end(end);
+      AssertValid(result.edge->btree());
+      return result;
+    }
+
+    node = edge->btree();
+    pos = node->IndexOf(n);
+    CordRepBtree* nsub = node->CopyBeginTo(pos.index, n);
+    sub->edges_[end++] = nsub;
+    sub->set_end(end);
+    sub = nsub;
+  }
+  sub->set_end(pos.index);
+  AssertValid(result.edge->btree());
+  return result;
+}
+
+CordRep* CordRepBtree::ExtractFront(CordRepBtree* tree) {
+  CordRep* front = tree->Edge(tree->begin());
+  if (tree->refcount.IsOne()) {
+    Unref(tree->Edges(tree->begin() + 1, tree->end()));
+    CordRepBtree::Delete(tree);
+  } else {
+    CordRep::Ref(front);
+    CordRep::Unref(tree);
+  }
+  return front;
+}
+
+CordRepBtree* CordRepBtree::ConsumeBeginTo(CordRepBtree* tree, size_t end,
+                                           size_t new_length) {
+  assert(end <= tree->end());
+  if (tree->refcount.IsOne()) {
+    Unref(tree->Edges(end, tree->end()));
+    tree->set_end(end);
+    tree->length = new_length;
+  } else {
+    CordRepBtree* old = tree;
+    tree = tree->CopyBeginTo(end, new_length);
+    CordRep::Unref(old);
+  }
+  return tree;
+}
+
+CordRep* CordRepBtree::RemoveSuffix(CordRepBtree* tree, size_t n) {
+  // Check input and deal with trivial cases 'Remove all/none'
+  assert(tree != nullptr);
+  assert(n <= tree->length);
+  const size_t len = tree->length;
+  if (ABSL_PREDICT_FALSE(n == 0)) {
+    return tree;
+  }
+  if (ABSL_PREDICT_FALSE(n >= len)) {
+    CordRepBtree::Unref(tree);
+    return nullptr;
+  }
+
+  size_t length = len - n;
+  int height = tree->height();
+  bool is_mutable = tree->refcount.IsOne();
+
+  // Extract all top nodes which are reduced to size = 1
+  Position pos = tree->IndexOfLength(length);
+  while (pos.index == tree->begin()) {
+    CordRep* edge = ExtractFront(tree);
+    is_mutable &= edge->refcount.IsOne();
+    if (height-- == 0) return ResizeEdge(edge, length, is_mutable);
+    tree = edge->btree();
+    pos = tree->IndexOfLength(length);
+  }
+
+  // Repeat the following sequence traversing down the tree:
+  // - Crop the top node to the 'last remaining edge' adjusting length.
+  // - Set the length for down edges to the partial length in that last edge.
+  // - Repeat this until the last edge is 'included in full'
+  // - If we hit the data edge level, resize and return the last data edge
+  CordRepBtree* top = tree = ConsumeBeginTo(tree, pos.index + 1, length);
+  CordRep* edge = tree->Edge(pos.index);
+  length = pos.n;
+  while (length != edge->length) {
+    // ConsumeBeginTo guarantees `tree` is a clean, privately owned copy.
+    assert(tree->refcount.IsOne());
+    const bool edge_is_mutable = edge->refcount.IsOne();
+
+    if (height-- == 0) {
+      tree->edges_[pos.index] = ResizeEdge(edge, length, edge_is_mutable);
+      return AssertValid(top);
+    }
+
+    if (!edge_is_mutable) {
+      // We can't 'in place' remove any suffixes down this edge.
+      // Replace this edge with a prefix copy instead.
+      tree->edges_[pos.index] = edge->btree()->CopyPrefix(length, false).edge;
+      CordRep::Unref(edge);
+      return AssertValid(top);
+    }
+
+    // Move down one level, rinse repeat.
+    tree = edge->btree();
+    pos = tree->IndexOfLength(length);
+    tree = ConsumeBeginTo(edge->btree(), pos.index + 1, length);
+    edge = tree->Edge(pos.index);
+    length = pos.n;
+  }
+
+  return AssertValid(top);
+}
+
+CordRep* CordRepBtree::SubTree(size_t offset, size_t n) {
+  assert(n <= this->length);
+  assert(offset <= this->length - n);
+  if (ABSL_PREDICT_FALSE(n == 0)) return nullptr;
+
+  CordRepBtree* node = this;
+  int height = node->height();
+  Position front = node->IndexOf(offset);
+  CordRep* left = node->edges_[front.index];
+  while (front.n + n <= left->length) {
+    if (--height < 0) return MakeSubstring(CordRep::Ref(left), front.n, n);
+    node = left->btree();
+    front = node->IndexOf(front.n);
+    left = node->edges_[front.index];
+  }
+
+  const Position back = node->IndexBefore(front, n);
+  CordRep* const right = node->edges_[back.index];
+  assert(back.index > front.index);
+
+  // Get partial suffix and prefix entries.
+  CopyResult prefix;
+  CopyResult suffix;
+  if (height > 0) {
+    // Copy prefix and suffix of the boundary nodes.
+    prefix = left->btree()->CopySuffix(front.n);
+    suffix = right->btree()->CopyPrefix(back.n);
+
+    // If there is an edge between the prefix and suffix edges, then the tree
+    // must remain at its previous (full) height. If we have no edges between
+    // prefix and suffix edges, then the tree must be as high as either the
+    // suffix or prefix edges (which are collapsed to their minimum heights).
+    if (front.index + 1 == back.index) {
+      height = (std::max)(prefix.height, suffix.height) + 1;
+    }
+
+    // Raise prefix and suffixes to the new tree height.
+    for (int h = prefix.height + 1; h < height; ++h) {
+      prefix.edge = CordRepBtree::New(prefix.edge);
+    }
+    for (int h = suffix.height + 1; h < height; ++h) {
+      suffix.edge = CordRepBtree::New(suffix.edge);
+    }
+  } else {
+    // Leaf node, simply take substrings for prefix and suffix.
+    prefix = CopyResult{MakeSubstring(CordRep::Ref(left), front.n), -1};
+    suffix = CopyResult{MakeSubstring(CordRep::Ref(right), 0, back.n), -1};
+  }
+
+  // Compose resulting tree.
+  CordRepBtree* sub = CordRepBtree::New(height);
+  size_t end = 0;
+  sub->edges_[end++] = prefix.edge;
+  for (CordRep* r : node->Edges(front.index + 1, back.index)) {
+    sub->edges_[end++] = CordRep::Ref(r);
+  }
+  sub->edges_[end++] = suffix.edge;
+  sub->set_end(end);
+  sub->length = n;
+  return AssertValid(sub);
+}
+
+CordRepBtree* CordRepBtree::MergeTrees(CordRepBtree* left,
+                                       CordRepBtree* right) {
+  return left->height() >= right->height() ? Merge<kBack>(left, right)
+                                           : Merge<kFront>(right, left);
+}
+
+bool CordRepBtree::IsFlat(absl::string_view* fragment) const {
+  if (height() == 0 && size() == 1) {
+    if (fragment) *fragment = Data(begin());
+    return true;
+  }
+  return false;
+}
+
+bool CordRepBtree::IsFlat(size_t offset, const size_t n,
+                          absl::string_view* fragment) const {
+  assert(n <= this->length);
+  assert(offset <= this->length - n);
+  if (ABSL_PREDICT_FALSE(n == 0)) return false;
+  int height = this->height();
+  const CordRepBtree* node = this;
+  for (;;) {
+    const Position front = node->IndexOf(offset);
+    const CordRep* edge = node->Edge(front.index);
+    if (edge->length < front.n + n) return false;
+    if (--height < 0) {
+      if (fragment) *fragment = EdgeData(edge).substr(front.n, n);
+      return true;
+    }
+    offset = front.n;
+    node = node->Edge(front.index)->btree();
+  }
+}
+
+char CordRepBtree::GetCharacter(size_t offset) const {
+  assert(offset < length);
+  const CordRepBtree* node = this;
+  int height = node->height();
+  for (;;) {
+    Position front = node->IndexOf(offset);
+    if (--height < 0) return node->Data(front.index)[front.n];
+    offset = front.n;
+    node = node->Edge(front.index)->btree();
+  }
+}
+
+Span<char> CordRepBtree::GetAppendBufferSlow(size_t size) {
+  // The inlined version in `GetAppendBuffer()` deals with all heights <= 3.
+  assert(height() >= 4);
+  assert(refcount.IsOne());
+
+  // Build a stack of nodes we may potentially need to update if we find a
+  // non-shared FLAT with capacity at the leaf level.
+  const int depth = height();
+  CordRepBtree* node = this;
+  CordRepBtree* stack[kMaxDepth];
+  for (int i = 0; i < depth; ++i) {
+    node = node->Edge(kBack)->btree();
+    if (!node->refcount.IsOne()) return {};
+    stack[i] = node;
+  }
+
+  // Must be a privately owned, mutable flat.
+  CordRep* const edge = node->Edge(kBack);
+  if (!edge->refcount.IsOne() || edge->tag < FLAT) return {};
+
+  // Must have capacity.
+  const size_t avail = edge->flat()->Capacity() - edge->length;
+  if (avail == 0) return {};
+
+  // Build span on remaining capacity.
+  size_t delta = (std::min)(size, avail);
+  Span<char> span = {edge->flat()->Data() + edge->length, delta};
+  edge->length += delta;
+  this->length += delta;
+  for (int i = 0; i < depth; ++i) {
+    stack[i]->length += delta;
+  }
+  return span;
+}
+
+CordRepBtree* CordRepBtree::CreateSlow(CordRep* rep) {
+  if (rep->IsBtree()) return rep->btree();
+
+  CordRepBtree* node = nullptr;
+  auto consume = [&node](CordRep* r, size_t offset, size_t length) {
+    r = MakeSubstring(r, offset, length);
+    if (node == nullptr) {
+      node = New(r);
+    } else {
+      node = CordRepBtree::AddCordRep<kBack>(node, r);
+    }
+  };
+  Consume(rep, consume);
+  return node;
+}
+
+CordRepBtree* CordRepBtree::AppendSlow(CordRepBtree* tree, CordRep* rep) {
+  if (ABSL_PREDICT_TRUE(rep->IsBtree())) {
+    return MergeTrees(tree, rep->btree());
+  }
+  auto consume = [&tree](CordRep* r, size_t offset, size_t length) {
+    r = MakeSubstring(r, offset, length);
+    tree = CordRepBtree::AddCordRep<kBack>(tree, r);
+  };
+  Consume(rep, consume);
+  return tree;
+}
+
+CordRepBtree* CordRepBtree::PrependSlow(CordRepBtree* tree, CordRep* rep) {
+  if (ABSL_PREDICT_TRUE(rep->IsBtree())) {
+    return MergeTrees(rep->btree(), tree);
+  }
+  auto consume = [&tree](CordRep* r, size_t offset, size_t length) {
+    r = MakeSubstring(r, offset, length);
+    tree = CordRepBtree::AddCordRep<kFront>(tree, r);
+  };
+  ReverseConsume(rep, consume);
+  return tree;
+}
+
+CordRepBtree* CordRepBtree::Append(CordRepBtree* tree, absl::string_view data,
+                                   size_t extra) {
+  return CordRepBtree::AddData<kBack>(tree, data, extra);
+}
+
+CordRepBtree* CordRepBtree::Prepend(CordRepBtree* tree, absl::string_view data,
+                                    size_t extra) {
+  return CordRepBtree::AddData<kFront>(tree, data, extra);
+}
+
+template CordRepBtree* CordRepBtree::AddCordRep<kFront>(CordRepBtree* tree,
+                                                        CordRep* rep);
+template CordRepBtree* CordRepBtree::AddCordRep<kBack>(CordRepBtree* tree,
+                                                       CordRep* rep);
+template CordRepBtree* CordRepBtree::AddData<kFront>(CordRepBtree* tree,
+                                                     absl::string_view data,
+                                                     size_t extra);
+template CordRepBtree* CordRepBtree::AddData<kBack>(CordRepBtree* tree,
+                                                    absl::string_view data,
+                                                    size_t extra);
+
+void CordRepBtree::Rebuild(CordRepBtree** stack, CordRepBtree* tree,
+                           bool consume) {
+  bool owned = consume && tree->refcount.IsOne();
+  if (tree->height() == 0) {
+    for (CordRep* edge : tree->Edges()) {
+      if (!owned) edge = CordRep::Ref(edge);
+      size_t height = 0;
+      size_t length = edge->length;
+      CordRepBtree* node = stack[0];
+      OpResult result = node->AddEdge<kBack>(true, edge, length);
+      while (result.action == CordRepBtree::kPopped) {
+        stack[height] = result.tree;
+        if (stack[++height] == nullptr) {
+          result.action = CordRepBtree::kSelf;
+          stack[height] = CordRepBtree::New(node, result.tree);
+        } else {
+          node = stack[height];
+          result = node->AddEdge<kBack>(true, result.tree, length);
+        }
+      }
+      while (stack[++height] != nullptr) {
+        stack[height]->length += length;
+      }
+    }
+  } else {
+    for (CordRep* rep : tree->Edges()) {
+      Rebuild(stack, rep->btree(), owned);
+    }
+  }
+  if (consume) {
+    if (owned) {
+      CordRepBtree::Delete(tree);
+    } else {
+      CordRepBtree::Unref(tree);
+    }
+  }
+}
+
+CordRepBtree* CordRepBtree::Rebuild(CordRepBtree* tree) {
+  // Set up initial stack with empty leaf node.
+  CordRepBtree* node = CordRepBtree::New();
+  CordRepBtree* stack[CordRepBtree::kMaxDepth + 1] = {node};
+
+  // Recursively build the tree, consuming the input tree.
+  Rebuild(stack, tree, /* consume reference */ true);
+
+  // Return top most node
+  for (CordRepBtree* parent : stack) {
+    if (parent == nullptr) return node;
+    node = parent;
+  }
+
+  // Unreachable
+  assert(false);
+  return nullptr;
+}
+
+CordRepBtree::ExtractResult CordRepBtree::ExtractAppendBuffer(
+    CordRepBtree* tree, size_t extra_capacity) {
+  int depth = 0;
+  NodeStack stack;
+
+  // Set up default 'no success' result which is {tree, nullptr}.
+  ExtractResult result;
+  result.tree = tree;
+  result.extracted = nullptr;
+
+  // Dive down the right side of the tree, making sure no edges are shared.
+  while (tree->height() > 0) {
+    if (!tree->refcount.IsOne()) return result;
+    stack[depth++] = tree;
+    tree = tree->Edge(kBack)->btree();
+  }
+  if (!tree->refcount.IsOne()) return result;
+
+  // Validate we ended on a non shared flat.
+  CordRep* rep = tree->Edge(kBack);
+  if (!(rep->IsFlat() && rep->refcount.IsOne())) return result;
+
+  // Verify it has at least the requested extra capacity.
+  CordRepFlat* flat = rep->flat();
+  const size_t length = flat->length;
+  const size_t avail = flat->Capacity() - flat->length;
+  if (extra_capacity > avail) return result;
+
+  // Set the extracted flat in the result.
+  result.extracted = flat;
+
+  // Cascading delete all nodes that become empty.
+  while (tree->size() == 1) {
+    CordRepBtree::Delete(tree);
+    if (--depth < 0) {
+      // We consumed the entire tree: return nullptr for new tree.
+      result.tree = nullptr;
+      return result;
+    }
+    rep = tree;
+    tree = stack[depth];
+  }
+
+  // Remove the edge or cascaded up parent node.
+  tree->set_end(tree->end() - 1);
+  tree->length -= length;
+
+  // Adjust lengths up the tree.
+  while (depth > 0) {
+    tree = stack[--depth];
+    tree->length -= length;
+  }
+
+  // Remove unnecessary top nodes with size = 1. This may iterate all the way
+  // down to the leaf node in which case we simply return the remaining last
+  // edge in that node and the extracted flat.
+  while (tree->size() == 1) {
+    int height = tree->height();
+    rep = tree->Edge(kBack);
+    Delete(tree);
+    if (height == 0) {
+      // We consumed the leaf: return the sole data edge as the new tree.
+      result.tree = rep;
+      return result;
+    }
+    tree = rep->btree();
+  }
+
+  // Done: return the (new) top level node and extracted flat.
+  result.tree = tree;
+  return result;
+}
+
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/strings/internal/cord_rep_btree_navigator.cc

@@ -0,0 +1,187 @@
+// Copyright 2021 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/internal/cord_rep_btree_navigator.h"
+
+#include <cassert>
+
+#include "absl/strings/internal/cord_data_edge.h"
+#include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_btree.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+
+using ReadResult = CordRepBtreeNavigator::ReadResult;
+
+namespace {
+
+// Returns a `CordRepSubstring` from `rep` starting at `offset` of size `n`.
+// If `rep` is already a `CordRepSubstring` instance, an adjusted instance is
+// created based on the old offset and new offset.
+// Adopts a reference on `rep`. Rep must be a valid data edge. Returns
+// nullptr if `n == 0`, `rep` if `n == rep->length`.
+// Requires `offset < rep->length` and `offset + n <= rep->length`.
+// TODO(192061034): move to utility library in internal and optimize for small
+// substrings of larger reps.
+inline CordRep* Substring(CordRep* rep, size_t offset, size_t n) {
+  assert(n <= rep->length);
+  assert(offset < rep->length);
+  assert(offset <= rep->length - n);
+  assert(IsDataEdge(rep));
+
+  if (n == 0) return nullptr;
+  if (n == rep->length) return CordRep::Ref(rep);
+
+  if (rep->tag == SUBSTRING) {
+    offset += rep->substring()->start;
+    rep = rep->substring()->child;
+  }
+
+  assert(rep->IsExternal() || rep->IsFlat());
+  CordRepSubstring* substring = new CordRepSubstring();
+  substring->length = n;
+  substring->tag = SUBSTRING;
+  substring->start = offset;
+  substring->child = CordRep::Ref(rep);
+  return substring;
+}
+
+inline CordRep* Substring(CordRep* rep, size_t offset) {
+  return Substring(rep, offset, rep->length - offset);
+}
+
+}  // namespace
+
+CordRepBtreeNavigator::Position CordRepBtreeNavigator::Skip(size_t n) {
+  int height = 0;
+  size_t index = index_[0];
+  CordRepBtree* node = node_[0];
+  CordRep* edge = node->Edge(index);
+
+  // Overall logic: Find an edge of at least the length we need to skip.
+  // We consume all edges which are smaller (i.e., must be 100% skipped).
+  // If we exhausted all edges on the current level, we move one level
+  // up the tree, and repeat until we either find the edge, or until we hit
+  // the top of the tree meaning the skip exceeds tree->length.
+  while (n >= edge->length) {
+    n -= edge->length;
+    while (++index == node->end()) {
+      if (++height > height_) return {nullptr, n};
+      node = node_[height];
+      index = index_[height];
+    }
+    edge = node->Edge(index);
+  }
+
+  // If we moved up the tree, descend down to the leaf level, consuming all
+  // edges that must be skipped.
+  while (height > 0) {
+    node = edge->btree();
+    index_[height] = static_cast<uint8_t>(index);
+    node_[--height] = node;
+    index = node->begin();
+    edge = node->Edge(index);
+    while (n >= edge->length) {
+      n -= edge->length;
+      ++index;
+      assert(index != node->end());
+      edge = node->Edge(index);
+    }
+  }
+  index_[0] = static_cast<uint8_t>(index);
+  return {edge, n};
+}
+
+ReadResult CordRepBtreeNavigator::Read(size_t edge_offset, size_t n) {
+  int height = 0;
+  size_t length = edge_offset + n;
+  size_t index = index_[0];
+  CordRepBtree* node = node_[0];
+  CordRep* edge = node->Edge(index);
+  assert(edge_offset < edge->length);
+
+  if (length < edge->length) {
+    return {Substring(edge, edge_offset, n), length};
+  }
+
+  // Similar to 'Skip', we consume all edges that are inside the 'length' of
+  // data that needs to be read. If we exhaust the current level, we move one
+  // level up the tree and repeat until we hit the final edge that must be
+  // (partially) read. We consume all edges into `subtree`.
+  CordRepBtree* subtree = CordRepBtree::New(Substring(edge, edge_offset));
+  size_t subtree_end = 1;
+  do {
+    length -= edge->length;
+    while (++index == node->end()) {
+      index_[height] = static_cast<uint8_t>(index);
+      if (++height > height_) {
+        subtree->set_end(subtree_end);
+        if (length == 0) return {subtree, 0};
+        CordRep::Unref(subtree);
+        return {nullptr, length};
+      }
+      if (length != 0) {
+        subtree->set_end(subtree_end);
+        subtree = CordRepBtree::New(subtree);
+        subtree_end = 1;
+      }
+      node = node_[height];
+      index = index_[height];
+    }
+    edge = node->Edge(index);
+    if (length >= edge->length) {
+      subtree->length += edge->length;
+      subtree->edges_[subtree_end++] = CordRep::Ref(edge);
+    }
+  } while (length >= edge->length);
+  CordRepBtree* tree = subtree;
+  subtree->length += length;
+
+  // If we moved up the tree, descend down to the leaf level, consuming all
+  // edges that must be read, adding 'down' nodes to `subtree`.
+  while (height > 0) {
+    node = edge->btree();
+    index_[height] = static_cast<uint8_t>(index);
+    node_[--height] = node;
+    index = node->begin();
+    edge = node->Edge(index);
+
+    if (length != 0) {
+      CordRepBtree* right = CordRepBtree::New(height);
+      right->length = length;
+      subtree->edges_[subtree_end++] = right;
+      subtree->set_end(subtree_end);
+      subtree = right;
+      subtree_end = 0;
+      while (length >= edge->length) {
+        subtree->edges_[subtree_end++] = CordRep::Ref(edge);
+        length -= edge->length;
+        edge = node->Edge(++index);
+      }
+    }
+  }
+  // Add any (partial) edge still remaining at the leaf level.
+  if (length != 0) {
+    subtree->edges_[subtree_end++] = Substring(edge, 0, length);
+  }
+  subtree->set_end(subtree_end);
+  index_[0] = static_cast<uint8_t>(index);
+  return {tree, length};
+}
+
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/strings/internal/cord_rep_btree_navigator.h

@@ -0,0 +1,267 @@
+// Copyright 2021 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_STRINGS_INTERNAL_CORD_REP_BTREE_NAVIGATOR_H_
+#define ABSL_STRINGS_INTERNAL_CORD_REP_BTREE_NAVIGATOR_H_
+
+#include <cassert>
+#include <iostream>
+
+#include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_btree.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+
+// CordRepBtreeNavigator is a bi-directional navigator allowing callers to
+// navigate all the (leaf) data edges in a CordRepBtree instance.
+//
+// A CordRepBtreeNavigator instance is by default empty. Callers initialize a
+// navigator instance by calling one of `InitFirst()`, `InitLast()` or
+// `InitOffset()`, which establishes a current position. Callers can then
+// navigate using the `Next`, `Previous`, `Skip` and `Seek` methods.
+//
+// The navigator instance does not take or adopt a reference on the provided
+// `tree` on any of the initialization calls. Callers are responsible for
+// guaranteeing the lifecycle of the provided tree. A navigator instance can
+// be reset to the empty state by calling `Reset`.
+//
+// A navigator only keeps positional state on the 'current data edge', it does
+// explicitly not keep any 'offset' state. The class does accept and return
+// offsets in the `Read()`, `Skip()` and 'Seek()` methods as these would
+// otherwise put a big burden on callers. Callers are expected to maintain
+// (returned) offset info if they require such granular state.
+class CordRepBtreeNavigator {
+ public:
+  // The logical position as returned by the Seek() and Skip() functions.
+  // Returns the current leaf edge for the desired seek or skip position and
+  // the offset of that position inside that edge.
+  struct Position {
+    CordRep* edge;
+    size_t offset;
+  };
+
+  // The read result as returned by the Read() function.
+  // `tree` contains the resulting tree which is identical to the result
+  // of calling CordRepBtree::SubTree(...) on the tree being navigated.
+  // `n` contains the number of bytes used from the last navigated to
+  // edge of the tree.
+  struct ReadResult {
+    CordRep* tree;
+    size_t n;
+  };
+
+  // Returns true if this instance is not empty.
+  explicit operator bool() const;
+
+  // Returns the tree for this instance or nullptr if empty.
+  CordRepBtree* btree() const;
+
+  // Returns the data edge of the current position.
+  // Requires this instance to not be empty.
+  CordRep* Current() const;
+
+  // Resets this navigator to `tree`, returning the first data edge in the tree.
+  CordRep* InitFirst(CordRepBtree* tree);
+
+  // Resets this navigator to `tree`, returning the last data edge in the tree.
+  CordRep* InitLast(CordRepBtree* tree);
+
+  // Resets this navigator to `tree` returning the data edge at position
+  // `offset` and the relative offset of `offset` into that data edge.
+  // Returns `Position.edge = nullptr` if the provided offset is greater
+  // than or equal to the length of the tree, in which case the state of
+  // the navigator instance remains unchanged.
+  Position InitOffset(CordRepBtree* tree, size_t offset);
+
+  // Navigates to the next data edge.
+  // Returns the next data edge or nullptr if there is no next data edge, in
+  // which case the current position remains unchanged.
+  CordRep* Next();
+
+  // Navigates to the previous data edge.
+  // Returns the previous data edge or nullptr if there is no previous data
+  // edge, in which case the current position remains unchanged.
+  CordRep* Previous();
+
+  // Navigates to the data edge at position `offset`. Returns the navigated to
+  // data edge in `Position.edge` and the relative offset of `offset` into that
+  // data edge in `Position.offset`. Returns `Position.edge = nullptr` if the
+  // provide offset is greater than or equal to the tree's length.
+  Position Seek(size_t offset);
+
+  // Reads `n` bytes of data starting at offset `edge_offset` of the current
+  // data edge, and returns the result in `ReadResult.tree`. `ReadResult.n`
+  // contains the 'bytes used` from the last / current data edge in the tree.
+  // This allows users that mix regular navigation (using string views) and
+  // 'read into cord' navigation to keep track of the current state, and which
+  // bytes have been consumed from a navigator.
+  // This function returns `ReadResult.tree = nullptr` if the requested length
+  // exceeds the length of the tree starting at the current data edge.
+  ReadResult Read(size_t edge_offset, size_t n);
+
+  // Skips `n` bytes forward from the current data edge, returning the navigated
+  // to data edge in `Position.edge` and `Position.offset` containing the offset
+  // inside that data edge. Note that the state of the navigator is left
+  // unchanged if `n` is smaller than the length of the current data edge.
+  Position Skip(size_t n);
+
+  // Resets this instance to the default / empty state.
+  void Reset();
+
+ private:
+  // Slow path for Next() if Next() reached the end of a leaf node. Backtracks
+  // up the stack until it finds a node that has a 'next' position available,
+  // and then does a 'front dive' towards the next leaf node.
+  CordRep* NextUp();
+
+  // Slow path for Previous() if Previous() reached the beginning of a leaf
+  // node. Backtracks up the stack until it finds a node that has a 'previous'
+  // position available, and then does a 'back dive' towards the previous leaf
+  // node.
+  CordRep* PreviousUp();
+
+  // Generic implementation of InitFirst() and InitLast().
+  template <CordRepBtree::EdgeType edge_type>
+  CordRep* Init(CordRepBtree* tree);
+
+  // `height_` contains the height of the current tree, or -1 if empty.
+  int height_ = -1;
+
+  // `index_` and `node_` contain the navigation state as the 'path' to the
+  // current data edge which is at `node_[0]->Edge(index_[0])`. The contents
+  // of these are undefined until the instance is initialized (`height_ >= 0`).
+  uint8_t index_[CordRepBtree::kMaxDepth];
+  CordRepBtree* node_[CordRepBtree::kMaxDepth];
+};
+
+// Returns true if this instance is not empty.
+inline CordRepBtreeNavigator::operator bool() const { return height_ >= 0; }
+
+inline CordRepBtree* CordRepBtreeNavigator::btree() const {
+  return height_ >= 0 ? node_[height_] : nullptr;
+}
+
+inline CordRep* CordRepBtreeNavigator::Current() const {
+  assert(height_ >= 0);
+  return node_[0]->Edge(index_[0]);
+}
+
+inline void CordRepBtreeNavigator::Reset() { height_ = -1; }
+
+inline CordRep* CordRepBtreeNavigator::InitFirst(CordRepBtree* tree) {
+  return Init<CordRepBtree::kFront>(tree);
+}
+
+inline CordRep* CordRepBtreeNavigator::InitLast(CordRepBtree* tree) {
+  return Init<CordRepBtree::kBack>(tree);
+}
+
+template <CordRepBtree::EdgeType edge_type>
+inline CordRep* CordRepBtreeNavigator::Init(CordRepBtree* tree) {
+  assert(tree != nullptr);
+  assert(tree->size() > 0);
+  assert(tree->height() <= CordRepBtree::kMaxHeight);
+  int height = height_ = tree->height();
+  size_t index = tree->index(edge_type);
+  node_[height] = tree;
+  index_[height] = static_cast<uint8_t>(index);
+  while (--height >= 0) {
+    tree = tree->Edge(index)->btree();
+    node_[height] = tree;
+    index = tree->index(edge_type);
+    index_[height] = static_cast<uint8_t>(index);
+  }
+  return node_[0]->Edge(index);
+}
+
+inline CordRepBtreeNavigator::Position CordRepBtreeNavigator::Seek(
+    size_t offset) {
+  assert(btree() != nullptr);
+  int height = height_;
+  CordRepBtree* edge = node_[height];
+  if (ABSL_PREDICT_FALSE(offset >= edge->length)) return {nullptr, 0};
+  CordRepBtree::Position index = edge->IndexOf(offset);
+  index_[height] = static_cast<uint8_t>(index.index);
+  while (--height >= 0) {
+    edge = edge->Edge(index.index)->btree();
+    node_[height] = edge;
+    index = edge->IndexOf(index.n);
+    index_[height] = static_cast<uint8_t>(index.index);
+  }
+  return {edge->Edge(index.index), index.n};
+}
+
+inline CordRepBtreeNavigator::Position CordRepBtreeNavigator::InitOffset(
+    CordRepBtree* tree, size_t offset) {
+  assert(tree != nullptr);
+  assert(tree->height() <= CordRepBtree::kMaxHeight);
+  if (ABSL_PREDICT_FALSE(offset >= tree->length)) return {nullptr, 0};
+  height_ = tree->height();
+  node_[height_] = tree;
+  return Seek(offset);
+}
+
+inline CordRep* CordRepBtreeNavigator::Next() {
+  CordRepBtree* edge = node_[0];
+  return index_[0] == edge->back() ? NextUp() : edge->Edge(++index_[0]);
+}
+
+inline CordRep* CordRepBtreeNavigator::Previous() {
+  CordRepBtree* edge = node_[0];
+  return index_[0] == edge->begin() ? PreviousUp() : edge->Edge(--index_[0]);
+}
+
+inline CordRep* CordRepBtreeNavigator::NextUp() {
+  assert(index_[0] == node_[0]->back());
+  CordRepBtree* edge;
+  size_t index;
+  int height = 0;
+  do {
+    if (++height > height_) return nullptr;
+    edge = node_[height];
+    index = index_[height] + 1;
+  } while (index == edge->end());
+  index_[height] = static_cast<uint8_t>(index);
+  do {
+    node_[--height] = edge = edge->Edge(index)->btree();
+    index_[height] = static_cast<uint8_t>(index = edge->begin());
+  } while (height > 0);
+  return edge->Edge(index);
+}
+
+inline CordRep* CordRepBtreeNavigator::PreviousUp() {
+  assert(index_[0] == node_[0]->begin());
+  CordRepBtree* edge;
+  size_t index;
+  int height = 0;
+  do {
+    if (++height > height_) return nullptr;
+    edge = node_[height];
+    index = index_[height];
+  } while (index == edge->begin());
+  index_[height] = static_cast<uint8_t>(--index);
+  do {
+    node_[--height] = edge = edge->Edge(index)->btree();
+    index_[height] = static_cast<uint8_t>(index = edge->back());
+  } while (height > 0);
+  return edge->Edge(index);
+}
+
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_INTERNAL_CORD_REP_BTREE_NAVIGATOR_H_

weight/_dep/abseil-cpp/absl/strings/internal/cord_rep_btree_reader.cc

@@ -0,0 +1,69 @@
+// Copyright 2021 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/internal/cord_rep_btree_reader.h"
+
+#include <cassert>
+
+#include "absl/base/config.h"
+#include "absl/strings/internal/cord_data_edge.h"
+#include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_btree.h"
+#include "absl/strings/internal/cord_rep_btree_navigator.h"
+#include "absl/strings/internal/cord_rep_flat.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+
+absl::string_view CordRepBtreeReader::Read(size_t n, size_t chunk_size,
+                                           CordRep*& tree) {
+  assert(chunk_size <= navigator_.Current()->length);
+
+  // If chunk_size is non-zero, we need to start inside last returned edge.
+  // Else we start reading at the next data edge of the tree.
+  CordRep* edge = chunk_size ? navigator_.Current() : navigator_.Next();
+  const size_t offset = chunk_size ? edge->length - chunk_size : 0;
+
+  // Read the sub tree and verify we got what we wanted.
+  ReadResult result = navigator_.Read(offset, n);
+  tree = result.tree;
+
+  // If the data returned in `tree` was covered entirely by `chunk_size`, i.e.,
+  // read from the 'previous' edge, we did not consume any additional data, and
+  // can directly return the substring into the current data edge as the next
+  // chunk. We can easily establish from the above code that `navigator_.Next()`
+  // has not been called as that requires `chunk_size` to be zero.
+  if (n < chunk_size) return EdgeData(edge).substr(result.n);
+
+  // The amount of data taken from the last edge is `chunk_size` and `result.n`
+  // contains the offset into the current edge trailing the read data (which can
+  // be 0). As the call to `navigator_.Read()` could have consumed all remaining
+  // data, calling `navigator_.Current()` is not safe before checking if we
+  // already consumed all remaining data.
+  const size_t consumed_by_read = n - chunk_size - result.n;
+  if (consumed_by_read >= remaining_) {
+    remaining_ = 0;
+    return {};
+  }
+
+  // We did not read all data, return remaining data from current edge.
+  edge = navigator_.Current();
+  remaining_ -= consumed_by_read + edge->length;
+  return EdgeData(edge).substr(result.n);
+}
+
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/strings/internal/cord_rep_btree_reader.h

@@ -0,0 +1,212 @@
+// Copyright 2021 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_STRINGS_INTERNAL_CORD_REP_BTREE_READER_H_
+#define ABSL_STRINGS_INTERNAL_CORD_REP_BTREE_READER_H_
+
+#include <cassert>
+
+#include "absl/base/config.h"
+#include "absl/strings/internal/cord_data_edge.h"
+#include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_btree.h"
+#include "absl/strings/internal/cord_rep_btree_navigator.h"
+#include "absl/strings/internal/cord_rep_flat.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+
+// CordRepBtreeReader implements logic to iterate over cord btrees.
+// References to the underlying data are returned as absl::string_view values.
+// The most typical use case is a forward only iteration over tree data.
+// The class also provides `Skip()`, `Seek()` and `Read()` methods similar to
+// CordRepBtreeNavigator that allow more advanced navigation.
+//
+// Example: iterate over all data inside a cord btree:
+//
+//   CordRepBtreeReader reader;
+//   for (string_view sv = reader.Init(tree); !sv.Empty(); sv = sv.Next()) {
+//     DoSomethingWithDataIn(sv);
+//   }
+//
+// All navigation methods always return the next 'chunk' of data. The class
+// assumes that all data is directly 'consumed' by the caller. For example:
+// invoking `Skip()` will skip the desired number of bytes, and directly
+// read and return the next chunk of data directly after the skipped bytes.
+//
+// Example: iterate over all data inside a btree skipping the first 100 bytes:
+//
+//   CordRepBtreeReader reader;
+//   absl::string_view sv = reader.Init(tree);
+//   if (sv.length() > 100) {
+//     sv.RemovePrefix(100);
+//   } else {
+//     sv = reader.Skip(100 - sv.length());
+//   }
+//   while (!sv.empty()) {
+//     DoSomethingWithDataIn(sv);
+//     absl::string_view sv = reader.Next();
+//   }
+//
+// It is important to notice that `remaining` is based on the end position of
+// the last data edge returned to the caller, not the cumulative data returned
+// to the caller which can be less in cases of skipping or seeking over data.
+//
+// For example, consider a cord btree with five data edges: "abc", "def", "ghi",
+// "jkl" and "mno":
+//
+//   absl::string_view sv;
+//   CordRepBtreeReader reader;
+//
+//   sv = reader.Init(tree); // sv = "abc", remaining = 12
+//   sv = reader.Skip(4);    // sv = "hi",  remaining = 6
+//   sv = reader.Skip(2);    // sv = "l",   remaining = 3
+//   sv = reader.Next();     // sv = "mno", remaining = 0
+//   sv = reader.Seek(1);    // sv = "bc", remaining = 12
+//
+class CordRepBtreeReader {
+ public:
+  using ReadResult = CordRepBtreeNavigator::ReadResult;
+  using Position = CordRepBtreeNavigator::Position;
+
+  // Returns true if this instance is not empty.
+  explicit operator bool() const { return navigator_.btree() != nullptr; }
+
+  // Returns the tree referenced by this instance or nullptr if empty.
+  CordRepBtree* btree() const { return navigator_.btree(); }
+
+  // Returns the current data edge inside the referenced btree.
+  // Requires that the current instance is not empty.
+  CordRep* node() const { return navigator_.Current(); }
+
+  // Returns the length of the referenced tree.
+  // Requires that the current instance is not empty.
+  size_t length() const;
+
+  // Returns the number of remaining bytes available for iteration, which is the
+  // number of bytes directly following the end of the last chunk returned.
+  // This value will be zero if we iterated over the last edge in the bound
+  // tree, in which case any call to Next() or Skip() will return an empty
+  // string_view reflecting the EOF state.
+  // Note that a call to `Seek()` resets `remaining` to a value based on the
+  // end position of the chunk returned by that call.
+  size_t remaining() const { return remaining_; }
+
+  // Resets this instance to an empty value.
+  void Reset() { navigator_.Reset(); }
+
+  // Initializes this instance with `tree`. `tree` must not be null.
+  // Returns a reference to the first data edge of the provided tree.
+  absl::string_view Init(CordRepBtree* tree);
+
+  // Navigates to and returns the next data edge of the referenced tree.
+  // Returns an empty string_view if an attempt is made to read beyond the end
+  // of the tree, i.e.: if `remaining()` is zero indicating an EOF condition.
+  // Requires that the current instance is not empty.
+  absl::string_view Next();
+
+  // Skips the provided amount of bytes and returns a reference to the data
+  // directly following the skipped bytes.
+  absl::string_view Skip(size_t skip);
+
+  // Reads `n` bytes into `tree`.
+  // If `chunk_size` is zero, starts reading at the next data edge. If
+  // `chunk_size` is non zero, the read starts at the last `chunk_size` bytes of
+  // the last returned data edge. Effectively, this means that the read starts
+  // at offset `consumed() - chunk_size`.
+  // Requires that `chunk_size` is less than or equal to the length of the
+  // last returned data edge. The purpose of `chunk_size` is to simplify code
+  // partially consuming a returned chunk and wanting to include the remaining
+  // bytes in the Read call. For example, the below code will read 1000 bytes of
+  // data into a cord tree if the first chunk starts with "big:":
+  //
+  //   CordRepBtreeReader reader;
+  //   absl::string_view sv = reader.Init(tree);
+  //   if (absl::StartsWith(sv, "big:")) {
+  //     CordRepBtree tree;
+  //     sv = reader.Read(1000, sv.size() - 4 /* "big:" */, &tree);
+  //   }
+  //
+  // This method will return an empty string view if all remaining data was
+  // read. If `n` exceeded the amount of remaining data this function will
+  // return an empty string view and `tree` will be set to nullptr.
+  // In both cases, `consumed` will be set to `length`.
+  absl::string_view Read(size_t n, size_t chunk_size, CordRep*& tree);
+
+  // Navigates to the chunk at offset `offset`.
+  // Returns a reference into the navigated to chunk, adjusted for the relative
+  // position of `offset` into that chunk. For example, calling `Seek(13)` on a
+  // cord tree containing 2 chunks of 10 and 20 bytes respectively will return
+  // a string view into the second chunk starting at offset 3 with a size of 17.
+  // Returns an empty string view if `offset` is equal to or greater than the
+  // length of the referenced tree.
+  absl::string_view Seek(size_t offset);
+
+ private:
+  size_t remaining_ = 0;
+  CordRepBtreeNavigator navigator_;
+};
+
+inline size_t CordRepBtreeReader::length() const {
+  assert(btree() != nullptr);
+  return btree()->length;
+}
+
+inline absl::string_view CordRepBtreeReader::Init(CordRepBtree* tree) {
+  assert(tree != nullptr);
+  const CordRep* edge = navigator_.InitFirst(tree);
+  remaining_ = tree->length - edge->length;
+  return EdgeData(edge);
+}
+
+inline absl::string_view CordRepBtreeReader::Next() {
+  if (remaining_ == 0) return {};
+  const CordRep* edge = navigator_.Next();
+  assert(edge != nullptr);
+  remaining_ -= edge->length;
+  return EdgeData(edge);
+}
+
+inline absl::string_view CordRepBtreeReader::Skip(size_t skip) {
+  // As we are always positioned on the last 'consumed' edge, we
+  // need to skip the current edge as well as `skip`.
+  const size_t edge_length = navigator_.Current()->length;
+  CordRepBtreeNavigator::Position pos = navigator_.Skip(skip + edge_length);
+  if (ABSL_PREDICT_FALSE(pos.edge == nullptr)) {
+    remaining_ = 0;
+    return {};
+  }
+  // The combined length of all edges skipped before `pos.edge` is `skip -
+  // pos.offset`, all of which are 'consumed', as well as the current edge.
+  remaining_ -= skip - pos.offset + pos.edge->length;
+  return EdgeData(pos.edge).substr(pos.offset);
+}
+
+inline absl::string_view CordRepBtreeReader::Seek(size_t offset) {
+  const CordRepBtreeNavigator::Position pos = navigator_.Seek(offset);
+  if (ABSL_PREDICT_FALSE(pos.edge == nullptr)) {
+    remaining_ = 0;
+    return {};
+  }
+  absl::string_view chunk = EdgeData(pos.edge).substr(pos.offset);
+  remaining_ = length() - offset - chunk.length();
+  return chunk;
+}
+
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_INTERNAL_CORD_REP_BTREE_READER_H_

weight/_dep/abseil-cpp/absl/strings/internal/cord_rep_btree_reader_test.cc

@@ -0,0 +1,293 @@
+// Copyright 2021 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/internal/cord_rep_btree_reader.h"
+
+#include <iostream>
+#include <random>
+#include <string>
+#include <vector>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/base/config.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/strings/cord.h"
+#include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_btree.h"
+#include "absl/strings/internal/cord_rep_test_util.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+namespace {
+
+using ::testing::Eq;
+using ::testing::IsEmpty;
+using ::testing::Ne;
+using ::testing::Not;
+
+using ::absl::cordrep_testing::CordRepBtreeFromFlats;
+using ::absl::cordrep_testing::MakeFlat;
+using ::absl::cordrep_testing::CordToString;
+using ::absl::cordrep_testing::CreateFlatsFromString;
+using ::absl::cordrep_testing::CreateRandomString;
+
+using ReadResult = CordRepBtreeReader::ReadResult;
+
+TEST(CordRepBtreeReaderTest, Next) {
+  constexpr size_t kChars = 3;
+  const size_t cap = CordRepBtree::kMaxCapacity;
+  size_t counts[] = {1, 2, cap, cap * cap, cap * cap + 1, cap * cap * 2 + 17};
+
+  for (size_t count : counts) {
+    std::string data = CreateRandomString(count * kChars);
+    std::vector<CordRep*> flats = CreateFlatsFromString(data, kChars);
+    CordRepBtree* node = CordRepBtreeFromFlats(flats);
+
+    CordRepBtreeReader reader;
+    size_t remaining = data.length();
+    absl::string_view chunk = reader.Init(node);
+    EXPECT_THAT(chunk, Eq(data.substr(0, chunk.length())));
+
+    remaining -= chunk.length();
+    EXPECT_THAT(reader.remaining(), Eq(remaining));
+
+    while (remaining > 0) {
+      const size_t offset = data.length() - remaining;
+      chunk = reader.Next();
+      EXPECT_THAT(chunk, Eq(data.substr(offset, chunk.length())));
+
+      remaining -= chunk.length();
+      EXPECT_THAT(reader.remaining(), Eq(remaining));
+    }
+
+    EXPECT_THAT(reader.remaining(), Eq(0u));
+
+    // Verify trying to read beyond EOF returns empty string_view
+    EXPECT_THAT(reader.Next(), testing::IsEmpty());
+
+    CordRep::Unref(node);
+  }
+}
+
+TEST(CordRepBtreeReaderTest, Skip) {
+  constexpr size_t kChars = 3;
+  const size_t cap = CordRepBtree::kMaxCapacity;
+  size_t counts[] = {1, 2, cap, cap * cap, cap * cap + 1, cap * cap * 2 + 17};
+
+  for (size_t count : counts) {
+    std::string data = CreateRandomString(count * kChars);
+    std::vector<CordRep*> flats = CreateFlatsFromString(data, kChars);
+    CordRepBtree* node = CordRepBtreeFromFlats(flats);
+
+    for (size_t skip1 = 0; skip1 < data.length() - kChars; ++skip1) {
+      for (size_t skip2 = 0; skip2 < data.length() - kChars; ++skip2) {
+        CordRepBtreeReader reader;
+        size_t remaining = data.length();
+        absl::string_view chunk = reader.Init(node);
+        remaining -= chunk.length();
+
+        chunk = reader.Skip(skip1);
+        size_t offset = data.length() - remaining;
+        ASSERT_THAT(chunk, Eq(data.substr(offset + skip1, chunk.length())));
+        remaining -= chunk.length() + skip1;
+        ASSERT_THAT(reader.remaining(), Eq(remaining));
+
+        if (remaining == 0) continue;
+
+        size_t skip = std::min(remaining - 1, skip2);
+        chunk = reader.Skip(skip);
+        offset = data.length() - remaining;
+        ASSERT_THAT(chunk, Eq(data.substr(offset + skip, chunk.length())));
+      }
+    }
+
+    CordRep::Unref(node);
+  }
+}
+
+TEST(CordRepBtreeReaderTest, SkipBeyondLength) {
+  CordRepBtree* tree = CordRepBtree::Create(MakeFlat("abc"));
+  tree = CordRepBtree::Append(tree, MakeFlat("def"));
+  CordRepBtreeReader reader;
+  reader.Init(tree);
+  EXPECT_THAT(reader.Skip(100), IsEmpty());
+  EXPECT_THAT(reader.remaining(), Eq(0u));
+  CordRep::Unref(tree);
+}
+
+TEST(CordRepBtreeReaderTest, Seek) {
+  constexpr size_t kChars = 3;
+  const size_t cap = CordRepBtree::kMaxCapacity;
+  size_t counts[] = {1, 2, cap, cap * cap, cap * cap + 1, cap * cap * 2 + 17};
+
+  for (size_t count : counts) {
+    std::string data = CreateRandomString(count * kChars);
+    std::vector<CordRep*> flats = CreateFlatsFromString(data, kChars);
+    CordRepBtree* node = CordRepBtreeFromFlats(flats);
+
+    for (size_t seek = 0; seek < data.length() - 1; ++seek) {
+      CordRepBtreeReader reader;
+      reader.Init(node);
+      absl::string_view chunk = reader.Seek(seek);
+      ASSERT_THAT(chunk, Not(IsEmpty()));
+      ASSERT_THAT(chunk, Eq(data.substr(seek, chunk.length())));
+      ASSERT_THAT(reader.remaining(),
+                  Eq(data.length() - seek - chunk.length()));
+    }
+
+    CordRep::Unref(node);
+  }
+}
+
+TEST(CordRepBtreeReaderTest, SeekBeyondLength) {
+  CordRepBtree* tree = CordRepBtree::Create(MakeFlat("abc"));
+  tree = CordRepBtree::Append(tree, MakeFlat("def"));
+  CordRepBtreeReader reader;
+  reader.Init(tree);
+  EXPECT_THAT(reader.Seek(6), IsEmpty());
+  EXPECT_THAT(reader.remaining(), Eq(0u));
+  EXPECT_THAT(reader.Seek(100), IsEmpty());
+  EXPECT_THAT(reader.remaining(), Eq(0u));
+  CordRep::Unref(tree);
+}
+
+TEST(CordRepBtreeReaderTest, Read) {
+  std::string data = "abcdefghijklmno";
+  std::vector<CordRep*> flats = CreateFlatsFromString(data, 5);
+  CordRepBtree* node = CordRepBtreeFromFlats(flats);
+
+  CordRep* tree;
+  CordRepBtreeReader reader;
+  absl::string_view chunk;
+
+  // Read zero bytes
+  chunk = reader.Init(node);
+  chunk = reader.Read(0, chunk.length(), tree);
+  EXPECT_THAT(tree, Eq(nullptr));
+  EXPECT_THAT(chunk, Eq("abcde"));
+  EXPECT_THAT(reader.remaining(), Eq(10u));
+  EXPECT_THAT(reader.Next(), Eq("fghij"));
+
+  // Read in full
+  chunk = reader.Init(node);
+  chunk = reader.Read(15, chunk.length(), tree);
+  EXPECT_THAT(tree, Ne(nullptr));
+  EXPECT_THAT(CordToString(tree), Eq("abcdefghijklmno"));
+  EXPECT_THAT(chunk, Eq(""));
+  EXPECT_THAT(reader.remaining(), Eq(0u));
+  CordRep::Unref(tree);
+
+  // Read < chunk bytes
+  chunk = reader.Init(node);
+  chunk = reader.Read(3, chunk.length(), tree);
+  ASSERT_THAT(tree, Ne(nullptr));
+  EXPECT_THAT(CordToString(tree), Eq("abc"));
+  EXPECT_THAT(chunk, Eq("de"));
+  EXPECT_THAT(reader.remaining(), Eq(10u));
+  EXPECT_THAT(reader.Next(), Eq("fghij"));
+  CordRep::Unref(tree);
+
+  // Read < chunk bytes at offset
+  chunk = reader.Init(node);
+  chunk = reader.Read(2, chunk.length() - 2, tree);
+  ASSERT_THAT(tree, Ne(nullptr));
+  EXPECT_THAT(CordToString(tree), Eq("cd"));
+  EXPECT_THAT(chunk, Eq("e"));
+  EXPECT_THAT(reader.remaining(), Eq(10u));
+  EXPECT_THAT(reader.Next(), Eq("fghij"));
+  CordRep::Unref(tree);
+
+  // Read from consumed chunk
+  chunk = reader.Init(node);
+  chunk = reader.Read(3, 0, tree);
+  ASSERT_THAT(tree, Ne(nullptr));
+  EXPECT_THAT(CordToString(tree), Eq("fgh"));
+  EXPECT_THAT(chunk, Eq("ij"));
+  EXPECT_THAT(reader.remaining(), Eq(5u));
+  EXPECT_THAT(reader.Next(), Eq("klmno"));
+  CordRep::Unref(tree);
+
+  // Read across chunks
+  chunk = reader.Init(node);
+  chunk = reader.Read(12, chunk.length() - 2, tree);
+  ASSERT_THAT(tree, Ne(nullptr));
+  EXPECT_THAT(CordToString(tree), Eq("cdefghijklmn"));
+  EXPECT_THAT(chunk, Eq("o"));
+  EXPECT_THAT(reader.remaining(), Eq(0u));
+  CordRep::Unref(tree);
+
+  // Read across chunks landing on exact edge boundary
+  chunk = reader.Init(node);
+  chunk = reader.Read(10 - 2, chunk.length() - 2, tree);
+  ASSERT_THAT(tree, Ne(nullptr));
+  EXPECT_THAT(CordToString(tree), Eq("cdefghij"));
+  EXPECT_THAT(chunk, Eq("klmno"));
+  EXPECT_THAT(reader.remaining(), Eq(0u));
+  CordRep::Unref(tree);
+
+  CordRep::Unref(node);
+}
+
+TEST(CordRepBtreeReaderTest, ReadExhaustive) {
+  constexpr size_t kChars = 3;
+  const size_t cap = CordRepBtree::kMaxCapacity;
+  size_t counts[] = {1, 2, cap, cap * cap + 1, cap * cap * cap * 2 + 17};
+
+  for (size_t count : counts) {
+    std::string data = CreateRandomString(count * kChars);
+    std::vector<CordRep*> flats = CreateFlatsFromString(data, kChars);
+    CordRepBtree* node = CordRepBtreeFromFlats(flats);
+
+    for (size_t read_size : {kChars - 1, kChars, kChars + 7, cap * cap}) {
+      CordRepBtreeReader reader;
+      absl::string_view chunk = reader.Init(node);
+
+      // `consumed` tracks the end of last consumed chunk which is the start of
+      // the next chunk: we always read with `chunk_size = chunk.length()`.
+      size_t consumed = 0;
+      size_t remaining = data.length();
+      while (remaining > 0) {
+        CordRep* tree;
+        size_t n = (std::min)(remaining, read_size);
+        chunk = reader.Read(n, chunk.length(), tree);
+        EXPECT_THAT(tree, Ne(nullptr));
+        if (tree) {
+          EXPECT_THAT(CordToString(tree), Eq(data.substr(consumed, n)));
+          CordRep::Unref(tree);
+        }
+
+        consumed += n;
+        remaining -= n;
+        EXPECT_THAT(reader.remaining(), Eq(remaining - chunk.length()));
+
+        if (remaining > 0) {
+          ASSERT_FALSE(chunk.empty());
+          ASSERT_THAT(chunk, Eq(data.substr(consumed, chunk.length())));
+        } else {
+          ASSERT_TRUE(chunk.empty()) << chunk;
+        }
+      }
+    }
+
+    CordRep::Unref(node);
+  }
+}
+
+}  // namespace
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/strings/internal/cord_rep_btree_test.cc

@@ -0,0 +1,1568 @@
+// Copyright 2021 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/internal/cord_rep_btree.h"
+
+#include <cmath>
+#include <deque>
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/base/config.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/cleanup/cleanup.h"
+#include "absl/strings/internal/cord_data_edge.h"
+#include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_test_util.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+
+class CordRepBtreeTestPeer {
+ public:
+  static void SetEdge(CordRepBtree* node, size_t idx, CordRep* edge) {
+    node->edges_[idx] = edge;
+  }
+  static void AddEdge(CordRepBtree* node, CordRep* edge) {
+    node->edges_[node->fetch_add_end(1)] = edge;
+  }
+};
+
+namespace {
+
+using ::absl::cordrep_testing::AutoUnref;
+using ::absl::cordrep_testing::CordCollectRepsIf;
+using ::absl::cordrep_testing::CordToString;
+using ::absl::cordrep_testing::CordVisitReps;
+using ::absl::cordrep_testing::CreateFlatsFromString;
+using ::absl::cordrep_testing::CreateRandomString;
+using ::absl::cordrep_testing::MakeExternal;
+using ::absl::cordrep_testing::MakeFlat;
+using ::absl::cordrep_testing::MakeSubstring;
+using ::testing::_;
+using ::testing::AllOf;
+using ::testing::AnyOf;
+using ::testing::Conditional;
+using ::testing::ElementsAre;
+using ::testing::ElementsAreArray;
+using ::testing::Eq;
+using ::testing::HasSubstr;
+using ::testing::Le;
+using ::testing::Ne;
+using ::testing::Not;
+using ::testing::SizeIs;
+using ::testing::TypedEq;
+
+MATCHER_P(EqFlatHolding, data, "Equals flat holding data") {
+  if (arg->tag < FLAT) {
+    *result_listener << "Expected FLAT, got tag " << static_cast<int>(arg->tag);
+    return false;
+  }
+  std::string actual = CordToString(arg);
+  if (actual != data) {
+    *result_listener << "Expected flat holding \"" << data
+                     << "\", got flat holding \"" << actual << "\"";
+    return false;
+  }
+  return true;
+}
+
+MATCHER_P(IsNode, height, absl::StrCat("Is a valid node of height ", height)) {
+  if (arg == nullptr) {
+    *result_listener << "Expected NODE, got nullptr";
+    return false;
+  }
+  if (arg->tag != BTREE) {
+    *result_listener << "Expected NODE, got " << static_cast<int>(arg->tag);
+    return false;
+  }
+  if (!CordRepBtree::IsValid(arg->btree())) {
+    CordRepBtree::Dump(arg->btree(), "Expected valid NODE, got:", false,
+                       *result_listener->stream());
+    return false;
+  }
+  if (arg->btree()->height() != height) {
+    *result_listener << "Expected NODE of height " << height << ", got "
+                     << arg->btree()->height();
+    return false;
+  }
+  return true;
+}
+
+MATCHER_P2(IsSubstring, start, length,
+           absl::StrCat("Is a substring(start = ", start, ", length = ", length,
+                        ")")) {
+  if (arg == nullptr) {
+    *result_listener << "Expected substring, got nullptr";
+    return false;
+  }
+  if (arg->tag != SUBSTRING) {
+    *result_listener << "Expected SUBSTRING, got "
+                     << static_cast<int>(arg->tag);
+    return false;
+  }
+  const CordRepSubstring* const substr = arg->substring();
+  if (substr->start != start || substr->length != length) {
+    *result_listener << "Expected substring(" << start << ", " << length
+                     << "), got substring(" << substr->start << ", "
+                     << substr->length << ")";
+    return false;
+  }
+  return true;
+}
+
+MATCHER_P2(EqExtractResult, tree, rep, "Equals ExtractResult") {
+  if (arg.tree != tree || arg.extracted != rep) {
+    *result_listener << "Expected {" << static_cast<const void*>(tree) << ", "
+                     << static_cast<const void*>(rep) << "}, got {" << arg.tree
+                     << ", " << arg.extracted << "}";
+    return false;
+  }
+  return true;
+}
+
+// DataConsumer is a simple helper class used by tests to 'consume' string
+// fragments from the provided input in forward or backward direction.
+class DataConsumer {
+ public:
+  // Starts consumption of `data`. Caller must make sure `data` outlives this
+  // instance. Consumes data starting at the front if `forward` is true, else
+  // consumes data from the back.
+  DataConsumer(absl::string_view data, bool forward)
+      : data_(data), forward_(forward) {}
+
+  // Return the next `n` bytes from referenced data.
+  absl::string_view Next(size_t n) {
+    assert(n <= data_.size() - consumed_);
+    consumed_ += n;
+    return data_.substr(forward_ ? consumed_ - n : data_.size() - consumed_, n);
+  }
+
+  // Returns all data consumed so far.
+  absl::string_view Consumed() const {
+    return forward_ ? data_.substr(0, consumed_)
+                    : data_.substr(data_.size() - consumed_);
+  }
+
+ private:
+  absl::string_view data_;
+  size_t consumed_ = 0;
+  bool forward_;
+};
+
+// BtreeAdd returns either CordRepBtree::Append or CordRepBtree::Prepend.
+CordRepBtree* BtreeAdd(CordRepBtree* node, bool append,
+                       absl::string_view data) {
+  return append ? CordRepBtree::Append(node, data)
+                : CordRepBtree::Prepend(node, data);
+}
+
+// Recursively collects all leaf edges from `tree` and appends them to `edges`.
+void GetLeafEdges(const CordRepBtree* tree, std::vector<CordRep*>& edges) {
+  if (tree->height() == 0) {
+    for (CordRep* edge : tree->Edges()) {
+      edges.push_back(edge);
+    }
+  } else {
+    for (CordRep* edge : tree->Edges()) {
+      GetLeafEdges(edge->btree(), edges);
+    }
+  }
+}
+
+// Recursively collects and returns all leaf edges from `tree`.
+std::vector<CordRep*> GetLeafEdges(const CordRepBtree* tree) {
+  std::vector<CordRep*> edges;
+  GetLeafEdges(tree, edges);
+  return edges;
+}
+
+// Creates a flat containing the hexadecimal value of `i` zero padded
+// to at least 4 digits prefixed with "0x", e.g.: "0x04AC".
+CordRepFlat* MakeHexFlat(size_t i) {
+  return MakeFlat(absl::StrCat("0x", absl::Hex(i, absl::kZeroPad4)));
+}
+
+CordRepBtree* MakeLeaf(size_t size = CordRepBtree::kMaxCapacity) {
+  assert(size <= CordRepBtree::kMaxCapacity);
+  CordRepBtree* leaf = CordRepBtree::Create(MakeHexFlat(0));
+  for (size_t i = 1; i < size; ++i) {
+    leaf = CordRepBtree::Append(leaf, MakeHexFlat(i));
+  }
+  return leaf;
+}
+
+CordRepBtree* MakeTree(size_t size, bool append = true) {
+  CordRepBtree* tree = CordRepBtree::Create(MakeHexFlat(0));
+  for (size_t i = 1; i < size; ++i) {
+    tree = append ? CordRepBtree::Append(tree, MakeHexFlat(i))
+                  : CordRepBtree::Prepend(tree, MakeHexFlat(i));
+  }
+  return tree;
+}
+
+CordRepBtree* CreateTree(absl::Span<CordRep* const> reps) {
+  auto it = reps.begin();
+  CordRepBtree* tree = CordRepBtree::Create(*it);
+  while (++it != reps.end()) tree = CordRepBtree::Append(tree, *it);
+  return tree;
+}
+
+CordRepBtree* CreateTree(absl::string_view data, size_t chunk_size) {
+  return CreateTree(CreateFlatsFromString(data, chunk_size));
+}
+
+CordRepBtree* CreateTreeReverse(absl::string_view data, size_t chunk_size) {
+  std::vector<CordRep*> flats = CreateFlatsFromString(data, chunk_size);
+  auto rit = flats.rbegin();
+  CordRepBtree* tree = CordRepBtree::Create(*rit);
+  while (++rit != flats.rend()) tree = CordRepBtree::Prepend(tree, *rit);
+  return tree;
+}
+
+class CordRepBtreeTest : public testing::TestWithParam<bool> {
+ public:
+  bool shared() const { return GetParam(); }
+
+  static std::string ToString(testing::TestParamInfo<bool> param) {
+    return param.param ? "Shared" : "Private";
+  }
+};
+
+INSTANTIATE_TEST_SUITE_P(WithParam, CordRepBtreeTest, testing::Bool(),
+                         CordRepBtreeTest::ToString);
+
+class CordRepBtreeHeightTest : public testing::TestWithParam<int> {
+ public:
+  int height() const { return GetParam(); }
+
+  static std::string ToString(testing::TestParamInfo<int> param) {
+    return absl::StrCat(param.param);
+  }
+};
+
+INSTANTIATE_TEST_SUITE_P(WithHeights, CordRepBtreeHeightTest,
+                         testing::Range(0, CordRepBtree::kMaxHeight),
+                         CordRepBtreeHeightTest::ToString);
+
+using TwoBools = testing::tuple<bool, bool>;
+
+class CordRepBtreeDualTest : public testing::TestWithParam<TwoBools> {
+ public:
+  bool first_shared() const { return std::get<0>(GetParam()); }
+  bool second_shared() const { return std::get<1>(GetParam()); }
+
+  static std::string ToString(testing::TestParamInfo<TwoBools> param) {
+    if (std::get<0>(param.param)) {
+      return std::get<1>(param.param) ? "BothShared" : "FirstShared";
+    }
+    return std::get<1>(param.param) ? "SecondShared" : "Private";
+  }
+};
+
+INSTANTIATE_TEST_SUITE_P(WithParam, CordRepBtreeDualTest,
+                         testing::Combine(testing::Bool(), testing::Bool()),
+                         CordRepBtreeDualTest::ToString);
+
+TEST(CordRepBtreeTest, SizeIsMultipleOf64) {
+  // Only enforce for fully 64-bit platforms.
+  if (sizeof(size_t) == 8 && sizeof(void*) == 8) {
+    EXPECT_THAT(sizeof(CordRepBtree) % 64, Eq(0u))
+        << "Should be multiple of 64";
+  }
+}
+
+TEST(CordRepBtreeTest, NewDestroyEmptyTree) {
+  auto* tree = CordRepBtree::New();
+  EXPECT_THAT(tree->size(), Eq(0u));
+  EXPECT_THAT(tree->height(), Eq(0));
+  EXPECT_THAT(tree->Edges(), ElementsAre());
+  CordRepBtree::Destroy(tree);
+}
+
+TEST(CordRepBtreeTest, NewDestroyEmptyTreeAtHeight) {
+  auto* tree = CordRepBtree::New(3);
+  EXPECT_THAT(tree->size(), Eq(0u));
+  EXPECT_THAT(tree->height(), Eq(3));
+  EXPECT_THAT(tree->Edges(), ElementsAre());
+  CordRepBtree::Destroy(tree);
+}
+
+TEST(CordRepBtreeTest, Btree) {
+  CordRep* rep = CordRepBtree::New();
+  EXPECT_THAT(rep->btree(), Eq(rep));
+  EXPECT_THAT(static_cast<const CordRep*>(rep)->btree(), Eq(rep));
+  CordRep::Unref(rep);
+#if defined(GTEST_HAS_DEATH_TEST) && !defined(NDEBUG)
+  rep = MakeFlat("Hello world");
+  EXPECT_DEATH(rep->btree(), ".*");
+  EXPECT_DEATH(static_cast<const CordRep*>(rep)->btree(), ".*");
+  CordRep::Unref(rep);
+#endif
+}
+
+TEST(CordRepBtreeTest, EdgeData) {
+  CordRepFlat* flat = MakeFlat("Hello world");
+  CordRepExternal* external = MakeExternal("Hello external");
+  CordRep* substr1 = MakeSubstring(1, 6, CordRep::Ref(flat));
+  CordRep* substr2 = MakeSubstring(1, 6, CordRep::Ref(external));
+  CordRep* bad_substr = MakeSubstring(1, 2, CordRep::Ref(substr1));
+
+  EXPECT_TRUE(IsDataEdge(flat));
+  EXPECT_THAT(EdgeData(flat).data(), TypedEq<const void*>(flat->Data()));
+  EXPECT_THAT(EdgeData(flat), Eq("Hello world"));
+
+  EXPECT_TRUE(IsDataEdge(external));
+  EXPECT_THAT(EdgeData(external).data(), TypedEq<const void*>(external->base));
+  EXPECT_THAT(EdgeData(external), Eq("Hello external"));
+
+  EXPECT_TRUE(IsDataEdge(substr1));
+  EXPECT_THAT(EdgeData(substr1).data(), TypedEq<const void*>(flat->Data() + 1));
+  EXPECT_THAT(EdgeData(substr1), Eq("ello w"));
+
+  EXPECT_TRUE(IsDataEdge(substr2));
+  EXPECT_THAT(EdgeData(substr2).data(),
+              TypedEq<const void*>(external->base + 1));
+  EXPECT_THAT(EdgeData(substr2), Eq("ello e"));
+
+  EXPECT_FALSE(IsDataEdge(bad_substr));
+#if defined(GTEST_HAS_DEATH_TEST) && !defined(NDEBUG)
+  EXPECT_DEATH(EdgeData(bad_substr), ".*");
+#endif
+
+  CordRep::Unref(bad_substr);
+  CordRep::Unref(substr2);
+  CordRep::Unref(substr1);
+  CordRep::Unref(external);
+  CordRep::Unref(flat);
+}
+
+TEST(CordRepBtreeTest, CreateUnrefLeaf) {
+  auto* flat = MakeFlat("a");
+  auto* leaf = CordRepBtree::Create(flat);
+  EXPECT_THAT(leaf->size(), Eq(1u));
+  EXPECT_THAT(leaf->height(), Eq(0));
+  EXPECT_THAT(leaf->Edges(), ElementsAre(flat));
+  CordRepBtree::Unref(leaf);
+}
+
+TEST(CordRepBtreeTest, NewUnrefNode) {
+  auto* leaf = CordRepBtree::Create(MakeFlat("a"));
+  CordRepBtree* tree = CordRepBtree::New(leaf);
+  EXPECT_THAT(tree->size(), Eq(1u));
+  EXPECT_THAT(tree->height(), Eq(1));
+  EXPECT_THAT(tree->Edges(), ElementsAre(leaf));
+  CordRepBtree::Unref(tree);
+}
+
+TEST_P(CordRepBtreeTest, AppendToLeafToCapacity) {
+  AutoUnref refs;
+  std::vector<CordRep*> flats;
+  flats.push_back(MakeHexFlat(0));
+  auto* leaf = CordRepBtree::Create(flats.back());
+
+  for (size_t i = 1; i < CordRepBtree::kMaxCapacity; ++i) {
+    refs.RefIf(shared(), leaf);
+    flats.push_back(MakeHexFlat(i));
+    auto* result = CordRepBtree::Append(leaf, flats.back());
+    EXPECT_THAT(result->height(), Eq(0));
+    EXPECT_THAT(result, Conditional(shared(), Ne(leaf), Eq(leaf)));
+    EXPECT_THAT(result->Edges(), ElementsAreArray(flats));
+    leaf = result;
+  }
+  CordRep::Unref(leaf);
+}
+
+TEST_P(CordRepBtreeTest, PrependToLeafToCapacity) {
+  AutoUnref refs;
+  std::deque<CordRep*> flats;
+  flats.push_front(MakeHexFlat(0));
+  auto* leaf = CordRepBtree::Create(flats.front());
+
+  for (size_t i = 1; i < CordRepBtree::kMaxCapacity; ++i) {
+    refs.RefIf(shared(), leaf);
+    flats.push_front(MakeHexFlat(i));
+    auto* result = CordRepBtree::Prepend(leaf, flats.front());
+    EXPECT_THAT(result->height(), Eq(0));
+    EXPECT_THAT(result, Conditional(shared(), Ne(leaf), Eq(leaf)));
+    EXPECT_THAT(result->Edges(), ElementsAreArray(flats));
+    leaf = result;
+  }
+  CordRep::Unref(leaf);
+}
+
+// This test specifically aims at code aligning data at either the front or the
+// back of the contained `edges[]` array, alternating Append and Prepend will
+// move `begin()` and `end()` values as needed for each added value.
+TEST_P(CordRepBtreeTest, AppendPrependToLeafToCapacity) {
+  AutoUnref refs;
+  std::deque<CordRep*> flats;
+  flats.push_front(MakeHexFlat(0));
+  auto* leaf = CordRepBtree::Create(flats.front());
+
+  for (size_t i = 1; i < CordRepBtree::kMaxCapacity; ++i) {
+    refs.RefIf(shared(), leaf);
+    CordRepBtree* result;
+    if (i % 2 != 0) {
+      flats.push_front(MakeHexFlat(i));
+      result = CordRepBtree::Prepend(leaf, flats.front());
+    } else {
+      flats.push_back(MakeHexFlat(i));
+      result = CordRepBtree::Append(leaf, flats.back());
+    }
+    EXPECT_THAT(result->height(), Eq(0));
+    EXPECT_THAT(result, Conditional(shared(), Ne(leaf), Eq(leaf)));
+    EXPECT_THAT(result->Edges(), ElementsAreArray(flats));
+    leaf = result;
+  }
+  CordRep::Unref(leaf);
+}
+
+TEST_P(CordRepBtreeTest, AppendToLeafBeyondCapacity) {
+  AutoUnref refs;
+  auto* leaf = MakeLeaf();
+  refs.RefIf(shared(), leaf);
+  CordRep* flat = MakeFlat("abc");
+  auto* result = CordRepBtree::Append(leaf, flat);
+  ASSERT_THAT(result, IsNode(1));
+  EXPECT_THAT(result, Ne(leaf));
+  absl::Span<CordRep* const> edges = result->Edges();
+  ASSERT_THAT(edges, ElementsAre(leaf, IsNode(0)));
+  EXPECT_THAT(edges[1]->btree()->Edges(), ElementsAre(flat));
+  CordRep::Unref(result);
+}
+
+TEST_P(CordRepBtreeTest, PrependToLeafBeyondCapacity) {
+  AutoUnref refs;
+  auto* leaf = MakeLeaf();
+  refs.RefIf(shared(), leaf);
+  CordRep* flat = MakeFlat("abc");
+  auto* result = CordRepBtree::Prepend(leaf, flat);
+  ASSERT_THAT(result, IsNode(1));
+  EXPECT_THAT(result, Ne(leaf));
+  absl::Span<CordRep* const> edges = result->Edges();
+  ASSERT_THAT(edges, ElementsAre(IsNode(0), leaf));
+  EXPECT_THAT(edges[0]->btree()->Edges(), ElementsAre(flat));
+  CordRep::Unref(result);
+}
+
+TEST_P(CordRepBtreeTest, AppendToTreeOneDeep) {
+  constexpr size_t max_cap = CordRepBtree::kMaxCapacity;
+  AutoUnref refs;
+  std::vector<CordRep*> flats;
+  flats.push_back(MakeHexFlat(0));
+  CordRepBtree* tree = CordRepBtree::Create(flats.back());
+  for (size_t i = 1; i <= max_cap; ++i) {
+    flats.push_back(MakeHexFlat(i));
+    tree = CordRepBtree::Append(tree, flats.back());
+  }
+  ASSERT_THAT(tree, IsNode(1));
+
+  for (size_t i = max_cap + 1; i < max_cap * max_cap; ++i) {
+    // Ref top level tree based on param.
+    // Ref leaf node once every 4 iterations, which should not have an
+    // observable effect other than that the leaf itself is copied.
+    refs.RefIf(shared(), tree);
+    refs.RefIf(i % 4 == 0, tree->Edges().back());
+
+    flats.push_back(MakeHexFlat(i));
+    CordRepBtree* result = CordRepBtree::Append(tree, flats.back());
+    ASSERT_THAT(result, IsNode(1));
+    ASSERT_THAT(result, Conditional(shared(), Ne(tree), Eq(tree)));
+    std::vector<CordRep*> edges = GetLeafEdges(result);
+    ASSERT_THAT(edges, ElementsAreArray(flats));
+    tree = result;
+  }
+  CordRep::Unref(tree);
+}
+
+TEST_P(CordRepBtreeTest, AppendToTreeTwoDeep) {
+  constexpr size_t max_cap = CordRepBtree::kMaxCapacity;
+  AutoUnref refs;
+  std::vector<CordRep*> flats;
+  flats.push_back(MakeHexFlat(0));
+  CordRepBtree* tree = CordRepBtree::Create(flats.back());
+  for (size_t i = 1; i <= max_cap * max_cap; ++i) {
+    flats.push_back(MakeHexFlat(i));
+    tree = CordRepBtree::Append(tree, flats.back());
+  }
+  ASSERT_THAT(tree, IsNode(2));
+  for (size_t i = max_cap * max_cap + 1; i < max_cap * max_cap * max_cap; ++i) {
+    // Ref top level tree based on param.
+    // Ref child node once every 16 iterations, and leaf node every 4
+    // iterations which  which should not have an observable effect other than
+    //  the node and/or the leaf below it being copied.
+    refs.RefIf(shared(), tree);
+    refs.RefIf(i % 16 == 0, tree->Edges().back());
+    refs.RefIf(i % 4 == 0, tree->Edges().back()->btree()->Edges().back());
+
+    flats.push_back(MakeHexFlat(i));
+    CordRepBtree* result = CordRepBtree::Append(tree, flats.back());
+    ASSERT_THAT(result, IsNode(2));
+    ASSERT_THAT(result, Conditional(shared(), Ne(tree), Eq(tree)));
+    std::vector<CordRep*> edges = GetLeafEdges(result);
+    ASSERT_THAT(edges, ElementsAreArray(flats));
+    tree = result;
+  }
+  CordRep::Unref(tree);
+}
+
+TEST_P(CordRepBtreeTest, PrependToTreeOneDeep) {
+  constexpr size_t max_cap = CordRepBtree::kMaxCapacity;
+  AutoUnref refs;
+  std::deque<CordRep*> flats;
+  flats.push_back(MakeHexFlat(0));
+  CordRepBtree* tree = CordRepBtree::Create(flats.back());
+  for (size_t i = 1; i <= max_cap; ++i) {
+    flats.push_front(MakeHexFlat(i));
+    tree = CordRepBtree::Prepend(tree, flats.front());
+  }
+  ASSERT_THAT(tree, IsNode(1));
+
+  for (size_t i = max_cap + 1; i < max_cap * max_cap; ++i) {
+    // Ref top level tree based on param.
+    // Ref leaf node once every 4 iterations which should not have an observable
+    // effect other than than the leaf itself is copied.
+    refs.RefIf(shared(), tree);
+    refs.RefIf(i % 4 == 0, tree->Edges().back());
+
+    flats.push_front(MakeHexFlat(i));
+    CordRepBtree* result = CordRepBtree::Prepend(tree, flats.front());
+    ASSERT_THAT(result, IsNode(1));
+    ASSERT_THAT(result, Conditional(shared(), Ne(tree), Eq(tree)));
+    std::vector<CordRep*> edges = GetLeafEdges(result);
+    ASSERT_THAT(edges, ElementsAreArray(flats));
+    tree = result;
+  }
+  CordRep::Unref(tree);
+}
+
+TEST_P(CordRepBtreeTest, PrependToTreeTwoDeep) {
+  constexpr size_t max_cap = CordRepBtree::kMaxCapacity;
+  AutoUnref refs;
+  std::deque<CordRep*> flats;
+  flats.push_back(MakeHexFlat(0));
+  CordRepBtree* tree = CordRepBtree::Create(flats.back());
+  for (size_t i = 1; i <= max_cap * max_cap; ++i) {
+    flats.push_front(MakeHexFlat(i));
+    tree = CordRepBtree::Prepend(tree, flats.front());
+  }
+  ASSERT_THAT(tree, IsNode(2));
+  for (size_t i = max_cap * max_cap + 1; i < max_cap * max_cap * max_cap; ++i) {
+    // Ref top level tree based on param.
+    // Ref child node once every 16 iterations, and leaf node every 4
+    // iterations which  which should not have an observable effect other than
+    //  the node and/or the leaf below it being copied.
+    refs.RefIf(shared(), tree);
+    refs.RefIf(i % 16 == 0, tree->Edges().back());
+    refs.RefIf(i % 4 == 0, tree->Edges().back()->btree()->Edges().back());
+
+    flats.push_front(MakeHexFlat(i));
+    CordRepBtree* result = CordRepBtree::Prepend(tree, flats.front());
+    ASSERT_THAT(result, IsNode(2));
+    ASSERT_THAT(result, Conditional(shared(), Ne(tree), Eq(tree)));
+    std::vector<CordRep*> edges = GetLeafEdges(result);
+    ASSERT_THAT(edges, ElementsAreArray(flats));
+    tree = result;
+  }
+  CordRep::Unref(tree);
+}
+
+TEST_P(CordRepBtreeDualTest, MergeLeafsNotExceedingCapacity) {
+  for (bool use_append : {false, true}) {
+    SCOPED_TRACE(use_append ? "Using Append" : "Using Prepend");
+
+    AutoUnref refs;
+    std::vector<CordRep*> flats;
+
+    // Build `left` side leaf appending all contained flats to `flats`
+    CordRepBtree* left = MakeLeaf(3);
+    GetLeafEdges(left, flats);
+    refs.RefIf(first_shared(), left);
+
+    // Build `right` side leaf appending all contained flats to `flats`
+    CordRepBtree* right = MakeLeaf(2);
+    GetLeafEdges(right, flats);
+    refs.RefIf(second_shared(), right);
+
+    CordRepBtree* tree = use_append ? CordRepBtree::Append(left, right)
+                                    : CordRepBtree::Prepend(right, left);
+    EXPECT_THAT(tree, IsNode(0));
+
+    // `tree` contains all flats originally belonging to `left` and `right`.
+    EXPECT_THAT(tree->Edges(), ElementsAreArray(flats));
+    CordRepBtree::Unref(tree);
+  }
+}
+
+TEST_P(CordRepBtreeDualTest, MergeLeafsExceedingCapacity) {
+  for (bool use_append : {false, true}) {
+    SCOPED_TRACE(use_append ? "Using Append" : "Using Prepend");
+
+    AutoUnref refs;
+
+    // Build `left` side tree appending all contained flats to `flats`
+    CordRepBtree* left = MakeLeaf(CordRepBtree::kMaxCapacity - 2);
+    refs.RefIf(first_shared(), left);
+
+    // Build `right` side tree appending all contained flats to `flats`
+    CordRepBtree* right = MakeLeaf(CordRepBtree::kMaxCapacity - 1);
+    refs.RefIf(second_shared(), right);
+
+    CordRepBtree* tree = use_append ? CordRepBtree::Append(left, right)
+                                    : CordRepBtree::Prepend(right, left);
+    EXPECT_THAT(tree, IsNode(1));
+    EXPECT_THAT(tree->Edges(), ElementsAre(left, right));
+    CordRepBtree::Unref(tree);
+  }
+}
+
+TEST_P(CordRepBtreeDualTest, MergeEqualHeightTrees) {
+  for (bool use_append : {false, true}) {
+    SCOPED_TRACE(use_append ? "Using Append" : "Using Prepend");
+
+    AutoUnref refs;
+    std::vector<CordRep*> flats;
+
+    // Build `left` side tree appending all contained flats to `flats`
+    CordRepBtree* left = MakeTree(CordRepBtree::kMaxCapacity * 3);
+    GetLeafEdges(left, flats);
+    refs.RefIf(first_shared(), left);
+
+    // Build `right` side tree appending all contained flats to `flats`
+    CordRepBtree* right = MakeTree(CordRepBtree::kMaxCapacity * 2);
+    GetLeafEdges(right, flats);
+    refs.RefIf(second_shared(), right);
+
+    CordRepBtree* tree = use_append ? CordRepBtree::Append(left, right)
+                                    : CordRepBtree::Prepend(right, left);
+    EXPECT_THAT(tree, IsNode(1));
+    EXPECT_THAT(tree->Edges(), SizeIs(5u));
+
+    // `tree` contains all flats originally belonging to `left` and `right`.
+    EXPECT_THAT(GetLeafEdges(tree), ElementsAreArray(flats));
+    CordRepBtree::Unref(tree);
+  }
+}
+
+TEST_P(CordRepBtreeDualTest, MergeLeafWithTreeNotExceedingLeafCapacity) {
+  for (bool use_append : {false, true}) {
+    SCOPED_TRACE(use_append ? "Using Append" : "Using Prepend");
+
+    AutoUnref refs;
+    std::vector<CordRep*> flats;
+
+    // Build `left` side tree appending all added flats to `flats`
+    CordRepBtree* left = MakeTree(CordRepBtree::kMaxCapacity * 2 + 2);
+    GetLeafEdges(left, flats);
+    refs.RefIf(first_shared(), left);
+
+    // Build `right` side tree appending all added flats to `flats`
+    CordRepBtree* right = MakeTree(3);
+    GetLeafEdges(right, flats);
+    refs.RefIf(second_shared(), right);
+
+    CordRepBtree* tree = use_append ? CordRepBtree::Append(left, right)
+                                    : CordRepBtree::Prepend(right, left);
+    EXPECT_THAT(tree, IsNode(1));
+    EXPECT_THAT(tree->Edges(), SizeIs(3u));
+
+    // `tree` contains all flats originally belonging to `left` and `right`.
+    EXPECT_THAT(GetLeafEdges(tree), ElementsAreArray(flats));
+    CordRepBtree::Unref(tree);
+  }
+}
+
+TEST_P(CordRepBtreeDualTest, MergeLeafWithTreeExceedingLeafCapacity) {
+  for (bool use_append : {false, true}) {
+    SCOPED_TRACE(use_append ? "Using Append" : "Using Prepend");
+
+    AutoUnref refs;
+    std::vector<CordRep*> flats;
+
+    // Build `left` side tree appending all added flats to `flats`
+    CordRepBtree* left = MakeTree(CordRepBtree::kMaxCapacity * 3 - 2);
+    GetLeafEdges(left, flats);
+    refs.RefIf(first_shared(), left);
+
+    // Build `right` side tree appending all added flats to `flats`
+    CordRepBtree* right = MakeTree(3);
+    GetLeafEdges(right, flats);
+    refs.RefIf(second_shared(), right);
+
+    CordRepBtree* tree = use_append ? CordRepBtree::Append(left, right)
+                                    : CordRepBtree::Prepend(right, left);
+    EXPECT_THAT(tree, IsNode(1));
+    EXPECT_THAT(tree->Edges(), SizeIs(4u));
+
+    // `tree` contains all flats originally belonging to `left` and `right`.
+    EXPECT_THAT(GetLeafEdges(tree), ElementsAreArray(flats));
+    CordRepBtree::Unref(tree);
+  }
+}
+
+void RefEdgesAt(size_t depth, AutoUnref& refs, CordRepBtree* tree) {
+  absl::Span<CordRep* const> edges = tree->Edges();
+  if (depth == 0) {
+    refs.Ref(edges.front());
+    refs.Ref(edges.back());
+  } else {
+    assert(tree->height() > 0);
+    RefEdgesAt(depth - 1, refs, edges.front()->btree());
+    RefEdgesAt(depth - 1, refs, edges.back()->btree());
+  }
+}
+
+TEST(CordRepBtreeTest, MergeFuzzTest) {
+  constexpr size_t max_cap = CordRepBtree::kMaxCapacity;
+  std::minstd_rand rnd;
+  std::uniform_int_distribution<int> coin_flip(0, 1);
+  std::uniform_int_distribution<int> dice_throw(1, 6);
+
+  auto random_leaf_count = [&]() {
+    std::uniform_int_distribution<int> dist_height(0, 3);
+    std::uniform_int_distribution<int> dist_leaf(0, max_cap - 1);
+    const int height = dist_height(rnd);
+    return (height ? pow(max_cap, height) : 0) + dist_leaf(rnd);
+  };
+
+  for (int i = 0; i < 10000; ++i) {
+    AutoUnref refs;
+    std::vector<CordRep*> flats;
+
+    CordRepBtree* left = MakeTree(random_leaf_count(), coin_flip(rnd));
+    GetLeafEdges(left, flats);
+    if (dice_throw(rnd) == 1) {
+      std::uniform_int_distribution<size_t> dist(
+          0, static_cast<size_t>(left->height()));
+      RefEdgesAt(dist(rnd), refs, left);
+    }
+
+    CordRepBtree* right = MakeTree(random_leaf_count(), coin_flip(rnd));
+    GetLeafEdges(right, flats);
+    if (dice_throw(rnd) == 1) {
+      std::uniform_int_distribution<size_t> dist(
+          0, static_cast<size_t>(right->height()));
+      RefEdgesAt(dist(rnd), refs, right);
+    }
+
+    CordRepBtree* tree = CordRepBtree::Append(left, right);
+    EXPECT_THAT(GetLeafEdges(tree), ElementsAreArray(flats));
+    CordRepBtree::Unref(tree);
+  }
+}
+
+TEST_P(CordRepBtreeTest, RemoveSuffix) {
+  // Create tree of 1, 2 and 3 levels high
+  constexpr size_t max_cap = CordRepBtree::kMaxCapacity;
+  for (size_t cap : {max_cap - 1, max_cap * 2, max_cap * max_cap * 2}) {
+    const std::string data = CreateRandomString(cap * 512);
+
+    {
+      // Verify RemoveSuffix(<all>)
+      AutoUnref refs;
+      CordRepBtree* node = refs.RefIf(shared(), CreateTree(data, 512));
+      EXPECT_THAT(CordRepBtree::RemoveSuffix(node, data.length()), Eq(nullptr));
+
+      // Verify RemoveSuffix(<none>)
+      node = refs.RefIf(shared(), CreateTree(data, 512));
+      EXPECT_THAT(CordRepBtree::RemoveSuffix(node, 0), Eq(node));
+      CordRep::Unref(node);
+    }
+
+    for (size_t n = 1; n < data.length(); ++n) {
+      AutoUnref refs;
+      auto flats = CreateFlatsFromString(data, 512);
+      CordRepBtree* node = refs.RefIf(shared(), CreateTree(flats));
+      CordRep* rep = refs.Add(CordRepBtree::RemoveSuffix(node, n));
+      EXPECT_THAT(CordToString(rep), Eq(data.substr(0, data.length() - n)));
+
+      // Collect all flats
+      auto is_flat = [](CordRep* rep) { return rep->tag >= FLAT; };
+      std::vector<CordRep*> edges = CordCollectRepsIf(is_flat, rep);
+      ASSERT_THAT(edges.size(), Le(flats.size()));
+
+      // Isolate last edge
+      CordRep* last_edge = edges.back();
+      edges.pop_back();
+      const size_t last_length = rep->length - edges.size() * 512;
+
+      // All flats except the last edge must be kept or copied 'as is'
+      size_t index = 0;
+      for (CordRep* edge : edges) {
+        ASSERT_THAT(edge, Eq(flats[index++]));
+        ASSERT_THAT(edge->length, Eq(512u));
+      }
+
+      // CordRepBtree may optimize small substrings to avoid waste, so only
+      // check for flat sharing / updates where the code should always do this.
+      if (last_length >= 500) {
+        EXPECT_THAT(last_edge, Eq(flats[index++]));
+        if (shared()) {
+          EXPECT_THAT(last_edge->length, Eq(512u));
+        } else {
+          EXPECT_TRUE(last_edge->refcount.IsOne());
+          EXPECT_THAT(last_edge->length, Eq(last_length));
+        }
+      }
+    }
+  }
+}
+
+TEST(CordRepBtreeTest, SubTree) {
+  // Create tree of at least 2 levels high
+  constexpr size_t max_cap = CordRepBtree::kMaxCapacity;
+  const size_t n = max_cap * max_cap * 2;
+  const std::string data = CreateRandomString(n * 3);
+  std::vector<CordRep*> flats;
+  for (absl::string_view s = data; !s.empty(); s.remove_prefix(3)) {
+    flats.push_back(MakeFlat(s.substr(0, 3)));
+  }
+  CordRepBtree* node = CordRepBtree::Create(CordRep::Ref(flats[0]));
+  for (size_t i = 1; i < flats.size(); ++i) {
+    node = CordRepBtree::Append(node, CordRep::Ref(flats[i]));
+  }
+
+  for (size_t offset = 0; offset < data.length(); ++offset) {
+    for (size_t length = 1; length <= data.length() - offset; ++length) {
+      CordRep* rep = node->SubTree(offset, length);
+      EXPECT_THAT(CordToString(rep), Eq(data.substr(offset, length)));
+      CordRep::Unref(rep);
+    }
+  }
+  CordRepBtree::Unref(node);
+  for (CordRep* rep : flats) {
+    CordRep::Unref(rep);
+  }
+}
+
+TEST(CordRepBtreeTest, SubTreeOnExistingSubstring) {
+  // This test verifies that a SubTree call on a pre-existing (large) substring
+  // adjusts the existing substring if not shared, and else rewrites the
+  // existing substring.
+  AutoUnref refs;
+  std::string data = CreateRandomString(1000);
+  CordRepBtree* leaf = CordRepBtree::Create(MakeFlat("abc"));
+  CordRep* flat = MakeFlat(data);
+  leaf = CordRepBtree::Append(leaf, flat);
+
+  // Setup tree containing substring.
+  CordRep* result = leaf->SubTree(0, 3 + 990);
+  ASSERT_THAT(result->tag, Eq(BTREE));
+  CordRep::Unref(leaf);
+  leaf = result->btree();
+  ASSERT_THAT(leaf->Edges(), ElementsAre(_, IsSubstring(0u, 990u)));
+  EXPECT_THAT(leaf->Edges()[1]->substring()->child, Eq(flat));
+
+  // Verify substring of substring.
+  result = leaf->SubTree(3 + 5, 970);
+  ASSERT_THAT(result, IsSubstring(5u, 970u));
+  EXPECT_THAT(result->substring()->child, Eq(flat));
+  CordRep::Unref(result);
+
+  CordRep::Unref(leaf);
+}
+
+TEST_P(CordRepBtreeTest, AddDataToLeaf) {
+  const size_t n = CordRepBtree::kMaxCapacity;
+  const std::string data = CreateRandomString(n * 3);
+
+  for (bool append : {true, false}) {
+    AutoUnref refs;
+    DataConsumer consumer(data, append);
+    SCOPED_TRACE(append ? "Append" : "Prepend");
+
+    CordRepBtree* leaf = CordRepBtree::Create(MakeFlat(consumer.Next(3)));
+    for (size_t i = 1; i < n; ++i) {
+      refs.RefIf(shared(), leaf);
+      CordRepBtree* result = BtreeAdd(leaf, append, consumer.Next(3));
+      EXPECT_THAT(result, Conditional(shared(), Ne(leaf), Eq(leaf)));
+      EXPECT_THAT(CordToString(result), Eq(consumer.Consumed()));
+      leaf = result;
+    }
+    CordRep::Unref(leaf);
+  }
+}
+
+TEST_P(CordRepBtreeTest, AppendDataToTree) {
+  AutoUnref refs;
+  size_t n = CordRepBtree::kMaxCapacity + CordRepBtree::kMaxCapacity / 2;
+  std::string data = CreateRandomString(n * 3);
+  CordRepBtree* tree = refs.RefIf(shared(), CreateTree(data, 3));
+  CordRepBtree* leaf0 = tree->Edges()[0]->btree();
+  CordRepBtree* leaf1 = tree->Edges()[1]->btree();
+  CordRepBtree* result = CordRepBtree::Append(tree, "123456789");
+  EXPECT_THAT(result, Conditional(shared(), Ne(tree), Eq(tree)));
+  EXPECT_THAT(result->Edges(),
+              ElementsAre(leaf0, Conditional(shared(), Ne(leaf1), Eq(leaf1))));
+  EXPECT_THAT(CordToString(result), Eq(data + "123456789"));
+  CordRep::Unref(result);
+}
+
+TEST_P(CordRepBtreeTest, PrependDataToTree) {
+  AutoUnref refs;
+  size_t n = CordRepBtree::kMaxCapacity + CordRepBtree::kMaxCapacity / 2;
+  std::string data = CreateRandomString(n * 3);
+  CordRepBtree* tree = refs.RefIf(shared(), CreateTreeReverse(data, 3));
+  CordRepBtree* leaf0 = tree->Edges()[0]->btree();
+  CordRepBtree* leaf1 = tree->Edges()[1]->btree();
+  CordRepBtree* result = CordRepBtree::Prepend(tree, "123456789");
+  EXPECT_THAT(result, Conditional(shared(), Ne(tree), Eq(tree)));
+  EXPECT_THAT(result->Edges(),
+              ElementsAre(Conditional(shared(), Ne(leaf0), Eq(leaf0)), leaf1));
+  EXPECT_THAT(CordToString(result), Eq("123456789" + data));
+  CordRep::Unref(result);
+}
+
+TEST_P(CordRepBtreeTest, AddDataToTreeThreeLevelsDeep) {
+  constexpr size_t max_cap = CordRepBtree::kMaxCapacity;
+  const size_t n = max_cap * max_cap * max_cap;
+  const std::string data = CreateRandomString(n * 3);
+
+  for (bool append : {true, false}) {
+    AutoUnref refs;
+    DataConsumer consumer(data, append);
+    SCOPED_TRACE(append ? "Append" : "Prepend");
+
+    // Fill leaf
+    CordRepBtree* tree = CordRepBtree::Create(MakeFlat(consumer.Next(3)));
+    for (size_t i = 1; i < max_cap; ++i) {
+      tree = BtreeAdd(tree, append, consumer.Next(3));
+    }
+    ASSERT_THAT(CordToString(tree), Eq(consumer.Consumed()));
+
+    // Fill to maximum at one deep
+    refs.RefIf(shared(), tree);
+    CordRepBtree* result = BtreeAdd(tree, append, consumer.Next(3));
+    ASSERT_THAT(result, IsNode(1));
+    ASSERT_THAT(result, Ne(tree));
+    ASSERT_THAT(CordToString(result), Eq(consumer.Consumed()));
+    tree = result;
+    for (size_t i = max_cap + 1; i < max_cap * max_cap; ++i) {
+      refs.RefIf(shared(), tree);
+      result = BtreeAdd(tree, append, consumer.Next(3));
+      ASSERT_THAT(result, Conditional(shared(), Ne(tree), Eq(tree)));
+      ASSERT_THAT(CordToString(result), Eq(consumer.Consumed()));
+      tree = result;
+    }
+
+    // Fill to maximum at two deep
+    refs.RefIf(shared(), tree);
+    result = BtreeAdd(tree, append, consumer.Next(3));
+    ASSERT_THAT(result, IsNode(2));
+    ASSERT_THAT(result, Ne(tree));
+    ASSERT_THAT(CordToString(result), Eq(consumer.Consumed()));
+    tree = result;
+    for (size_t i = max_cap * max_cap + 1; i < max_cap * max_cap * max_cap;
+         ++i) {
+      refs.RefIf(shared(), tree);
+      result = BtreeAdd(tree, append, consumer.Next(3));
+      ASSERT_THAT(result, Conditional(shared(), Ne(tree), Eq(tree)));
+      ASSERT_THAT(CordToString(result), Eq(consumer.Consumed()));
+      tree = result;
+    }
+
+    CordRep::Unref(tree);
+  }
+}
+
+TEST_P(CordRepBtreeTest, AddLargeDataToLeaf) {
+  const size_t max_cap = CordRepBtree::kMaxCapacity;
+  const size_t n = max_cap * max_cap * max_cap * 3 + 2;
+  const std::string data = CreateRandomString(n * kMaxFlatLength);
+
+  for (bool append : {true, false}) {
+    AutoUnref refs;
+    SCOPED_TRACE(append ? "Append" : "Prepend");
+
+    CordRepBtree* leaf = CordRepBtree::Create(MakeFlat("abc"));
+    refs.RefIf(shared(), leaf);
+    CordRepBtree* result = BtreeAdd(leaf, append, data);
+    EXPECT_THAT(CordToString(result), Eq(append ? "abc" + data : data + "abc"));
+    CordRep::Unref(result);
+  }
+}
+
+TEST_P(CordRepBtreeTest, CreateFromTreeReturnsTree) {
+  AutoUnref refs;
+  CordRepBtree* leaf = CordRepBtree::Create(MakeFlat("Hello world"));
+  refs.RefIf(shared(), leaf);
+  CordRepBtree* result = CordRepBtree::Create(leaf);
+  EXPECT_THAT(result, Eq(leaf));
+  CordRep::Unref(result);
+}
+
+TEST(CordRepBtreeTest, GetCharacter) {
+  size_t n = CordRepBtree::kMaxCapacity * CordRepBtree::kMaxCapacity + 2;
+  std::string data = CreateRandomString(n * 3);
+  CordRepBtree* tree = CreateTree(data, 3);
+  // Add a substring node for good measure.
+  tree = tree->Append(tree, MakeSubstring(4, 5, MakeFlat("abcdefghijklm")));
+  data += "efghi";
+  for (size_t i = 0; i < data.length(); ++i) {
+    ASSERT_THAT(tree->GetCharacter(i), Eq(data[i]));
+  }
+  CordRep::Unref(tree);
+}
+
+TEST_P(CordRepBtreeTest, IsFlatSingleFlat) {
+  CordRepBtree* leaf = CordRepBtree::Create(MakeFlat("Hello world"));
+
+  absl::string_view fragment;
+  EXPECT_TRUE(leaf->IsFlat(nullptr));
+  EXPECT_TRUE(leaf->IsFlat(&fragment));
+  EXPECT_THAT(fragment, Eq("Hello world"));
+  fragment = "";
+  EXPECT_TRUE(leaf->IsFlat(0, 11, nullptr));
+  EXPECT_TRUE(leaf->IsFlat(0, 11, &fragment));
+  EXPECT_THAT(fragment, Eq("Hello world"));
+
+  // Arbitrary ranges must check true as well.
+  EXPECT_TRUE(leaf->IsFlat(1, 4, &fragment));
+  EXPECT_THAT(fragment, Eq("ello"));
+  EXPECT_TRUE(leaf->IsFlat(6, 5, &fragment));
+  EXPECT_THAT(fragment, Eq("world"));
+
+  CordRep::Unref(leaf);
+}
+
+TEST(CordRepBtreeTest, IsFlatMultiFlat) {
+  size_t n = CordRepBtree::kMaxCapacity * CordRepBtree::kMaxCapacity + 2;
+  std::string data = CreateRandomString(n * 3);
+  CordRepBtree* tree = CreateTree(data, 3);
+  // Add substring nodes for good measure.
+  tree = tree->Append(tree, MakeSubstring(4, 3, MakeFlat("abcdefghijklm")));
+  tree = tree->Append(tree, MakeSubstring(8, 3, MakeFlat("abcdefghijklm")));
+  data += "efgijk";
+
+  EXPECT_FALSE(tree->IsFlat(nullptr));
+  absl::string_view fragment = "Can't touch this";
+  EXPECT_FALSE(tree->IsFlat(&fragment));
+  EXPECT_THAT(fragment, Eq("Can't touch this"));
+
+  for (size_t offset = 0; offset < data.size(); offset += 3) {
+    EXPECT_TRUE(tree->IsFlat(offset, 3, nullptr));
+    EXPECT_TRUE(tree->IsFlat(offset, 3, &fragment));
+    EXPECT_THAT(fragment, Eq(data.substr(offset, 3)));
+
+    fragment = "Can't touch this";
+    if (offset > 0) {
+      EXPECT_FALSE(tree->IsFlat(offset - 1, 4, nullptr));
+      EXPECT_FALSE(tree->IsFlat(offset - 1, 4, &fragment));
+      EXPECT_THAT(fragment, Eq("Can't touch this"));
+    }
+    if (offset < data.size() - 4) {
+      EXPECT_FALSE(tree->IsFlat(offset, 4, nullptr));
+      EXPECT_FALSE(tree->IsFlat(offset, 4, &fragment));
+      EXPECT_THAT(fragment, Eq("Can't touch this"));
+    }
+  }
+
+  CordRep::Unref(tree);
+}
+
+#if defined(GTEST_HAS_DEATH_TEST) && !defined(NDEBUG)
+
+TEST_P(CordRepBtreeHeightTest, GetAppendBufferNotPrivate) {
+  CordRepBtree* tree = CordRepBtree::Create(MakeExternal("Foo"));
+  CordRepBtree::Ref(tree);
+  EXPECT_DEATH(tree->GetAppendBuffer(1), ".*");
+  CordRepBtree::Unref(tree);
+  CordRepBtree::Unref(tree);
+}
+
+#endif  // defined(GTEST_HAS_DEATH_TEST) && !defined(NDEBUG)
+
+TEST_P(CordRepBtreeHeightTest, GetAppendBufferNotFlat) {
+  CordRepBtree* tree = CordRepBtree::Create(MakeExternal("Foo"));
+  for (int i = 1; i <= height(); ++i) {
+    tree = CordRepBtree::New(tree);
+  }
+  EXPECT_THAT(tree->GetAppendBuffer(1), SizeIs(0u));
+  CordRepBtree::Unref(tree);
+}
+
+TEST_P(CordRepBtreeHeightTest, GetAppendBufferFlatNotPrivate) {
+  CordRepFlat* flat = MakeFlat("abc");
+  CordRepBtree* tree = CordRepBtree::Create(CordRep::Ref(flat));
+  for (int i = 1; i <= height(); ++i) {
+    tree = CordRepBtree::New(tree);
+  }
+  EXPECT_THAT(tree->GetAppendBuffer(1), SizeIs(0u));
+  CordRepBtree::Unref(tree);
+  CordRep::Unref(flat);
+}
+
+TEST_P(CordRepBtreeHeightTest, GetAppendBufferTreeNotPrivate) {
+  if (height() == 0) return;
+  AutoUnref refs;
+  CordRepFlat* flat = MakeFlat("abc");
+  CordRepBtree* tree = CordRepBtree::Create(CordRep::Ref(flat));
+  for (int i = 1; i <= height(); ++i) {
+    if (i == (height() + 1) / 2) refs.Ref(tree);
+    tree = CordRepBtree::New(tree);
+  }
+  EXPECT_THAT(tree->GetAppendBuffer(1), SizeIs(0u));
+  CordRepBtree::Unref(tree);
+  CordRep::Unref(flat);
+}
+
+TEST_P(CordRepBtreeHeightTest, GetAppendBufferFlatNoCapacity) {
+  CordRepFlat* flat = MakeFlat("abc");
+  flat->length = flat->Capacity();
+  CordRepBtree* tree = CordRepBtree::Create(flat);
+  for (int i = 1; i <= height(); ++i) {
+    tree = CordRepBtree::New(tree);
+  }
+  EXPECT_THAT(tree->GetAppendBuffer(1), SizeIs(0u));
+  CordRepBtree::Unref(tree);
+}
+
+TEST_P(CordRepBtreeHeightTest, GetAppendBufferFlatWithCapacity) {
+  CordRepFlat* flat = MakeFlat("abc");
+  CordRepBtree* tree = CordRepBtree::Create(flat);
+  for (int i = 1; i <= height(); ++i) {
+    tree = CordRepBtree::New(tree);
+  }
+  absl::Span<char> span = tree->GetAppendBuffer(2);
+  EXPECT_THAT(span, SizeIs(2u));
+  EXPECT_THAT(span.data(), TypedEq<void*>(flat->Data() + 3));
+  EXPECT_THAT(tree->length, Eq(5u));
+
+  size_t avail = flat->Capacity() - 5;
+  span = tree->GetAppendBuffer(avail + 100);
+  EXPECT_THAT(span, SizeIs(avail));
+  EXPECT_THAT(span.data(), TypedEq<void*>(flat->Data() + 5));
+  EXPECT_THAT(tree->length, Eq(5 + avail));
+
+  CordRepBtree::Unref(tree);
+}
+
+TEST(CordRepBtreeTest, Dump) {
+  // Handles nullptr
+  std::stringstream ss;
+  CordRepBtree::Dump(nullptr, ss);
+  CordRepBtree::Dump(nullptr, "Once upon a label", ss);
+  CordRepBtree::Dump(nullptr, "Once upon a label", false, ss);
+  CordRepBtree::Dump(nullptr, "Once upon a label", true, ss);
+
+  // Cover legal edges
+  CordRepFlat* flat = MakeFlat("Hello world");
+  CordRepExternal* external = MakeExternal("Hello external");
+  CordRep* substr_flat = MakeSubstring(1, 6, CordRep::Ref(flat));
+  CordRep* substr_external = MakeSubstring(2, 7, CordRep::Ref(external));
+
+  // Build tree
+  CordRepBtree* tree = CordRepBtree::Create(flat);
+  tree = CordRepBtree::Append(tree, external);
+  tree = CordRepBtree::Append(tree, substr_flat);
+  tree = CordRepBtree::Append(tree, substr_external);
+
+  // Repeat until we have a tree
+  while (tree->height() == 0) {
+    tree = CordRepBtree::Append(tree, CordRep::Ref(flat));
+    tree = CordRepBtree::Append(tree, CordRep::Ref(external));
+    tree = CordRepBtree::Append(tree, CordRep::Ref(substr_flat));
+    tree = CordRepBtree::Append(tree, CordRep::Ref(substr_external));
+  }
+
+  for (int api = 0; api <= 3; ++api) {
+    absl::string_view api_scope;
+    std::stringstream ss;
+    switch (api) {
+      case 0:
+        api_scope = "Bare";
+        CordRepBtree::Dump(tree, ss);
+        break;
+      case 1:
+        api_scope = "Label only";
+        CordRepBtree::Dump(tree, "Once upon a label", ss);
+        break;
+      case 2:
+        api_scope = "Label no content";
+        CordRepBtree::Dump(tree, "Once upon a label", false, ss);
+        break;
+      default:
+        api_scope = "Label and content";
+        CordRepBtree::Dump(tree, "Once upon a label", true, ss);
+        break;
+    }
+    SCOPED_TRACE(api_scope);
+    std::string str = ss.str();
+
+    // Contains Node(depth) / Leaf and private / shared indicators
+    EXPECT_THAT(str, AllOf(HasSubstr("Node(1)"), HasSubstr("Leaf"),
+                           HasSubstr("Private"), HasSubstr("Shared")));
+
+    // Contains length and start offset of all data edges
+    EXPECT_THAT(str, AllOf(HasSubstr("len = 11"), HasSubstr("len = 14"),
+                           HasSubstr("len = 6"), HasSubstr("len = 7"),
+                           HasSubstr("start = 1"), HasSubstr("start = 2")));
+
+    // Contains address of all data edges
+    EXPECT_THAT(
+        str, AllOf(HasSubstr(absl::StrCat("0x", absl::Hex(flat))),
+                   HasSubstr(absl::StrCat("0x", absl::Hex(external))),
+                   HasSubstr(absl::StrCat("0x", absl::Hex(substr_flat))),
+                   HasSubstr(absl::StrCat("0x", absl::Hex(substr_external)))));
+
+    if (api != 0) {
+      // Contains label
+      EXPECT_THAT(str, HasSubstr("Once upon a label"));
+    }
+
+    if (api != 3) {
+      // Does not contain contents
+      EXPECT_THAT(str, Not(AnyOf((HasSubstr("data = \"Hello world\""),
+                                  HasSubstr("data = \"Hello external\""),
+                                  HasSubstr("data = \"ello w\""),
+                                  HasSubstr("data = \"llo ext\"")))));
+    } else {
+      // Contains contents
+      EXPECT_THAT(str, AllOf((HasSubstr("data = \"Hello world\""),
+                              HasSubstr("data = \"Hello external\""),
+                              HasSubstr("data = \"ello w\""),
+                              HasSubstr("data = \"llo ext\""))));
+    }
+  }
+
+  CordRep::Unref(tree);
+}
+
+TEST(CordRepBtreeTest, IsValid) {
+  EXPECT_FALSE(CordRepBtree::IsValid(nullptr));
+
+  CordRepBtree* empty = CordRepBtree::New(0);
+  EXPECT_TRUE(CordRepBtree::IsValid(empty));
+  CordRep::Unref(empty);
+
+  for (bool as_tree : {false, true}) {
+    CordRepBtree* leaf = CordRepBtree::Create(MakeFlat("abc"));
+    CordRepBtree* tree = as_tree ? CordRepBtree::New(leaf) : nullptr;
+    CordRepBtree* check = as_tree ? tree : leaf;
+
+    ASSERT_TRUE(CordRepBtree::IsValid(check));
+    leaf->length--;
+    EXPECT_FALSE(CordRepBtree::IsValid(check));
+    leaf->length++;
+
+    ASSERT_TRUE(CordRepBtree::IsValid(check));
+    leaf->tag--;
+    EXPECT_FALSE(CordRepBtree::IsValid(check));
+    leaf->tag++;
+
+    // Height
+    ASSERT_TRUE(CordRepBtree::IsValid(check));
+    leaf->storage[0] = static_cast<uint8_t>(CordRepBtree::kMaxHeight + 1);
+    EXPECT_FALSE(CordRepBtree::IsValid(check));
+    leaf->storage[0] = 1;
+    EXPECT_FALSE(CordRepBtree::IsValid(check));
+    leaf->storage[0] = 0;
+
+    // Begin
+    ASSERT_TRUE(CordRepBtree::IsValid(check));
+    const uint8_t begin = leaf->storage[1];
+    leaf->storage[1] = static_cast<uint8_t>(CordRepBtree::kMaxCapacity);
+    EXPECT_FALSE(CordRepBtree::IsValid(check));
+    leaf->storage[1] = 2;
+    EXPECT_FALSE(CordRepBtree::IsValid(check));
+    leaf->storage[1] = begin;
+
+    // End
+    ASSERT_TRUE(CordRepBtree::IsValid(check));
+    const uint8_t end = leaf->storage[2];
+    leaf->storage[2] = static_cast<uint8_t>(CordRepBtree::kMaxCapacity + 1);
+    EXPECT_FALSE(CordRepBtree::IsValid(check));
+    leaf->storage[2] = end;
+
+    // DataEdge tag and value
+    ASSERT_TRUE(CordRepBtree::IsValid(check));
+    CordRep* const edge = leaf->Edges()[0];
+    const uint8_t tag = edge->tag;
+    CordRepBtreeTestPeer::SetEdge(leaf, begin, nullptr);
+    EXPECT_FALSE(CordRepBtree::IsValid(check));
+    CordRepBtreeTestPeer::SetEdge(leaf, begin, edge);
+    edge->tag = BTREE;
+    EXPECT_FALSE(CordRepBtree::IsValid(check));
+    edge->tag = tag;
+
+    if (as_tree) {
+      ASSERT_TRUE(CordRepBtree::IsValid(check));
+      leaf->length--;
+      EXPECT_FALSE(CordRepBtree::IsValid(check));
+      leaf->length++;
+
+      // Height
+      ASSERT_TRUE(CordRepBtree::IsValid(check));
+      tree->storage[0] = static_cast<uint8_t>(2);
+      EXPECT_FALSE(CordRepBtree::IsValid(check));
+      tree->storage[0] = 1;
+
+      // Btree edge
+      ASSERT_TRUE(CordRepBtree::IsValid(check));
+      CordRep* const edge = tree->Edges()[0];
+      const uint8_t tag = edge->tag;
+      edge->tag = FLAT;
+      EXPECT_FALSE(CordRepBtree::IsValid(check));
+      edge->tag = tag;
+    }
+
+    ASSERT_TRUE(CordRepBtree::IsValid(check));
+    CordRep::Unref(check);
+  }
+}
+
+TEST(CordRepBtreeTest, AssertValid) {
+  CordRepBtree* tree = CordRepBtree::Create(MakeFlat("abc"));
+  const CordRepBtree* ctree = tree;
+  EXPECT_THAT(CordRepBtree::AssertValid(tree), Eq(tree));
+  EXPECT_THAT(CordRepBtree::AssertValid(ctree), Eq(ctree));
+
+#if defined(GTEST_HAS_DEATH_TEST)
+  CordRepBtree* nulltree = nullptr;
+  const CordRepBtree* cnulltree = nullptr;
+  EXPECT_DEBUG_DEATH(
+      EXPECT_THAT(CordRepBtree::AssertValid(nulltree), Eq(nulltree)), ".*");
+  EXPECT_DEBUG_DEATH(
+      EXPECT_THAT(CordRepBtree::AssertValid(cnulltree), Eq(cnulltree)), ".*");
+
+  tree->length--;
+  EXPECT_DEBUG_DEATH(EXPECT_THAT(CordRepBtree::AssertValid(tree), Eq(tree)),
+                     ".*");
+  EXPECT_DEBUG_DEATH(EXPECT_THAT(CordRepBtree::AssertValid(ctree), Eq(ctree)),
+                     ".*");
+  tree->length++;
+#endif
+  CordRep::Unref(tree);
+}
+
+TEST(CordRepBtreeTest, CheckAssertValidShallowVsDeep) {
+  // Restore exhaustive validation on any exit.
+  const bool exhaustive_validation = IsCordBtreeExhaustiveValidationEnabled();
+  auto cleanup = absl::MakeCleanup([exhaustive_validation] {
+    SetCordBtreeExhaustiveValidation(exhaustive_validation);
+  });
+
+  // Create a tree of at least 2 levels, and mess with the original flat, which
+  // should go undetected in shallow mode as the flat is too far away, but
+  // should be detected in forced non-shallow mode.
+  CordRep* flat = MakeFlat("abc");
+  CordRepBtree* tree = CordRepBtree::Create(flat);
+  constexpr size_t max_cap = CordRepBtree::kMaxCapacity;
+  const size_t n = max_cap * max_cap * 2;
+  for (size_t i = 0; i < n; ++i) {
+    tree = CordRepBtree::Append(tree, MakeFlat("Hello world"));
+  }
+  flat->length = 100;
+
+  SetCordBtreeExhaustiveValidation(false);
+  EXPECT_FALSE(CordRepBtree::IsValid(tree));
+  EXPECT_TRUE(CordRepBtree::IsValid(tree, true));
+  EXPECT_FALSE(CordRepBtree::IsValid(tree, false));
+  CordRepBtree::AssertValid(tree);
+  CordRepBtree::AssertValid(tree, true);
+#if defined(GTEST_HAS_DEATH_TEST)
+  EXPECT_DEBUG_DEATH(CordRepBtree::AssertValid(tree, false), ".*");
+#endif
+
+  SetCordBtreeExhaustiveValidation(true);
+  EXPECT_FALSE(CordRepBtree::IsValid(tree));
+  EXPECT_FALSE(CordRepBtree::IsValid(tree, true));
+  EXPECT_FALSE(CordRepBtree::IsValid(tree, false));
+#if defined(GTEST_HAS_DEATH_TEST)
+  EXPECT_DEBUG_DEATH(CordRepBtree::AssertValid(tree), ".*");
+  EXPECT_DEBUG_DEATH(CordRepBtree::AssertValid(tree, true), ".*");
+#endif
+
+  flat->length = 3;
+  CordRep::Unref(tree);
+}
+
+TEST_P(CordRepBtreeTest, Rebuild) {
+  for (size_t size : {3u, 8u, 100u, 10000u, 1000000u}) {
+    SCOPED_TRACE(absl::StrCat("Rebuild @", size));
+
+    std::vector<CordRepFlat*> flats;
+    for (size_t i = 0; i < size; ++i) {
+      flats.push_back(CordRepFlat::New(2));
+      flats.back()->Data()[0] = 'x';
+      flats.back()->length = 1;
+    }
+
+    // Build the tree into 'right', and each so many 'split_limit' edges,
+    // combine 'left' + 'right' into a new 'left', and start a new 'right'.
+    // This guarantees we get a reasonable amount of chaos in the tree.
+    size_t split_count = 0;
+    size_t split_limit = 3;
+    auto it = flats.begin();
+    CordRepBtree* left = nullptr;
+    CordRepBtree* right = CordRepBtree::New(*it);
+    while (++it != flats.end()) {
+      if (++split_count >= split_limit) {
+        split_limit += split_limit / 16;
+        left = left ? CordRepBtree::Append(left, right) : right;
+        right = CordRepBtree::New(*it);
+      } else {
+        right = CordRepBtree::Append(right, *it);
+      }
+    }
+
+    // Finalize tree
+    left = left ? CordRepBtree::Append(left, right) : right;
+
+    // Rebuild
+    AutoUnref ref;
+    left = ref.Add(CordRepBtree::Rebuild(ref.RefIf(shared(), left)));
+    ASSERT_TRUE(CordRepBtree::IsValid(left));
+
+    // Verify we have the exact same edges in the exact same order.
+    bool ok = true;
+    it = flats.begin();
+    CordVisitReps(left, [&](CordRep* edge) {
+      if (edge->tag < FLAT) return;
+      ok = ok && (it != flats.end() && *it++ == edge);
+    });
+    EXPECT_TRUE(ok && it == flats.end()) << "Rebuild edges mismatch";
+  }
+}
+
+// Convenience helper for CordRepBtree::ExtractAppendBuffer
+CordRepBtree::ExtractResult ExtractLast(CordRepBtree* input, size_t cap = 1) {
+  return CordRepBtree::ExtractAppendBuffer(input, cap);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferLeafSingleFlat) {
+  CordRep* flat = MakeFlat("Abc");
+  CordRepBtree* leaf = CordRepBtree::Create(flat);
+  EXPECT_THAT(ExtractLast(leaf), EqExtractResult(nullptr, flat));
+  CordRep::Unref(flat);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferNodeSingleFlat) {
+  CordRep* flat = MakeFlat("Abc");
+  CordRepBtree* leaf = CordRepBtree::Create(flat);
+  CordRepBtree* node = CordRepBtree::New(leaf);
+  EXPECT_THAT(ExtractLast(node), EqExtractResult(nullptr, flat));
+  CordRep::Unref(flat);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferLeafTwoFlats) {
+  std::vector<CordRep*> flats = CreateFlatsFromString("abcdef", 3);
+  CordRepBtree* leaf = CreateTree(flats);
+  EXPECT_THAT(ExtractLast(leaf), EqExtractResult(flats[0], flats[1]));
+  CordRep::Unref(flats[0]);
+  CordRep::Unref(flats[1]);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferNodeTwoFlats) {
+  std::vector<CordRep*> flats = CreateFlatsFromString("abcdef", 3);
+  CordRepBtree* leaf = CreateTree(flats);
+  CordRepBtree* node = CordRepBtree::New(leaf);
+  EXPECT_THAT(ExtractLast(node), EqExtractResult(flats[0], flats[1]));
+  CordRep::Unref(flats[0]);
+  CordRep::Unref(flats[1]);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferNodeTwoFlatsInTwoLeafs) {
+  std::vector<CordRep*> flats = CreateFlatsFromString("abcdef", 3);
+  CordRepBtree* leaf1 = CordRepBtree::Create(flats[0]);
+  CordRepBtree* leaf2 = CordRepBtree::Create(flats[1]);
+  CordRepBtree* node = CordRepBtree::New(leaf1, leaf2);
+  EXPECT_THAT(ExtractLast(node), EqExtractResult(flats[0], flats[1]));
+  CordRep::Unref(flats[0]);
+  CordRep::Unref(flats[1]);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferLeafThreeFlats) {
+  std::vector<CordRep*> flats = CreateFlatsFromString("abcdefghi", 3);
+  CordRepBtree* leaf = CreateTree(flats);
+  EXPECT_THAT(ExtractLast(leaf), EqExtractResult(leaf, flats[2]));
+  CordRep::Unref(flats[2]);
+  CordRep::Unref(leaf);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferNodeThreeFlatsRightNoFolding) {
+  CordRep* flat = MakeFlat("Abc");
+  std::vector<CordRep*> flats = CreateFlatsFromString("defghi", 3);
+  CordRepBtree* leaf1 = CordRepBtree::Create(flat);
+  CordRepBtree* leaf2 = CreateTree(flats);
+  CordRepBtree* node = CordRepBtree::New(leaf1, leaf2);
+  EXPECT_THAT(ExtractLast(node), EqExtractResult(node, flats[1]));
+  EXPECT_THAT(node->Edges(), ElementsAre(leaf1, leaf2));
+  EXPECT_THAT(leaf1->Edges(), ElementsAre(flat));
+  EXPECT_THAT(leaf2->Edges(), ElementsAre(flats[0]));
+  CordRep::Unref(node);
+  CordRep::Unref(flats[1]);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferNodeThreeFlatsRightLeafFolding) {
+  CordRep* flat = MakeFlat("Abc");
+  std::vector<CordRep*> flats = CreateFlatsFromString("defghi", 3);
+  CordRepBtree* leaf1 = CreateTree(flats);
+  CordRepBtree* leaf2 = CordRepBtree::Create(flat);
+  CordRepBtree* node = CordRepBtree::New(leaf1, leaf2);
+  EXPECT_THAT(ExtractLast(node), EqExtractResult(leaf1, flat));
+  EXPECT_THAT(leaf1->Edges(), ElementsAreArray(flats));
+  CordRep::Unref(leaf1);
+  CordRep::Unref(flat);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferNoCapacity) {
+  std::vector<CordRep*> flats = CreateFlatsFromString("abcdef", 3);
+  CordRepBtree* leaf = CreateTree(flats);
+  size_t avail = flats[1]->flat()->Capacity() - flats[1]->length;
+  EXPECT_THAT(ExtractLast(leaf, avail + 1), EqExtractResult(leaf, nullptr));
+  EXPECT_THAT(ExtractLast(leaf, avail), EqExtractResult(flats[0], flats[1]));
+  CordRep::Unref(flats[0]);
+  CordRep::Unref(flats[1]);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferNotFlat) {
+  std::vector<CordRep*> flats = CreateFlatsFromString("abcdef", 3);
+  auto substr = MakeSubstring(1, 2, flats[1]);
+  CordRepBtree* leaf = CreateTree({flats[0], substr});
+  EXPECT_THAT(ExtractLast(leaf), EqExtractResult(leaf, nullptr));
+  CordRep::Unref(leaf);
+}
+
+TEST(CordRepBtreeTest, ExtractAppendBufferShared) {
+  std::vector<CordRep*> flats = CreateFlatsFromString("abcdef", 3);
+  CordRepBtree* leaf = CreateTree(flats);
+
+  CordRep::Ref(flats[1]);
+  EXPECT_THAT(ExtractLast(leaf), EqExtractResult(leaf, nullptr));
+  CordRep::Unref(flats[1]);
+
+  CordRep::Ref(leaf);
+  EXPECT_THAT(ExtractLast(leaf), EqExtractResult(leaf, nullptr));
+  CordRep::Unref(leaf);
+
+  CordRepBtree* node = CordRepBtree::New(leaf);
+  CordRep::Ref(node);
+  EXPECT_THAT(ExtractLast(node), EqExtractResult(node, nullptr));
+  CordRep::Unref(node);
+
+  CordRep::Unref(node);
+}
+
+}  // namespace
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl

weight/_dep/abseil-cpp/absl/strings/internal/cord_rep_consume.h

@@ -0,0 +1,47 @@
+// Copyright 2021 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_STRINGS_INTERNAL_CORD_REP_CONSUME_H_
+#define ABSL_STRINGS_INTERNAL_CORD_REP_CONSUME_H_
+
+#include <functional>
+
+#include "absl/functional/function_ref.h"
+#include "absl/strings/internal/cord_internal.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+
+// Consume() and ReverseConsume() consume CONCAT based trees and invoke the
+// provided functor with the contained nodes in the proper forward or reverse
+// order, which is used to convert CONCAT trees into other tree or cord data.
+// All CONCAT and SUBSTRING nodes are processed internally. The 'offset`
+// parameter of the functor is non-zero for any nodes below SUBSTRING nodes.
+// It's up to the caller to form these back into SUBSTRING nodes or otherwise
+// store offset / prefix information. These functions are intended to be used
+// only for migration / transitional code where due to factors such as ODR
+// violations, we can not 100% guarantee that all code respects 'new format'
+// settings and flags, so we need to be able to parse old data on the fly until
+// all old code is deprecated / no longer the default format.
+void Consume(CordRep* rep,
+             FunctionRef<void(CordRep*, size_t, size_t)> consume_fn);
+void ReverseConsume(CordRep* rep,
+                    FunctionRef<void(CordRep*, size_t, size_t)> consume_fn);
+
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_INTERNAL_CORD_REP_CONSUME_H_

weight/_dep/abseil-cpp/absl/strings/internal/cord_rep_crc.cc

@@ -0,0 +1,56 @@
+// Copyright 2021 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/internal/cord_rep_crc.h"
+
+#include <cassert>
+#include <cstdint>
+#include <utility>
+
+#include "absl/base/config.h"
+#include "absl/strings/internal/cord_internal.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+
+CordRepCrc* CordRepCrc::New(CordRep* child, crc_internal::CrcCordState state) {
+  if (child != nullptr && child->IsCrc()) {
+    if (child->refcount.IsOne()) {
+      child->crc()->crc_cord_state = std::move(state);
+      return child->crc();
+    }
+    CordRep* old = child;
+    child = old->crc()->child;
+    CordRep::Ref(child);
+    CordRep::Unref(old);
+  }
+  auto* new_cordrep = new CordRepCrc;
+  new_cordrep->length = child != nullptr ? child->length : 0;
+  new_cordrep->tag = cord_internal::CRC;
+  new_cordrep->child = child;
+  new_cordrep->crc_cord_state = std::move(state);
+  return new_cordrep;
+}
+
+void CordRepCrc::Destroy(CordRepCrc* node) {
+  if (node->child != nullptr) {
+    CordRep::Unref(node->child);
+  }
+  delete node;
+}
+
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl