| // 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. | |
| namespace absl { | |
| ABSL_NAMESPACE_BEGIN | |
| // Workalike compatibility version of std::chars_format from C++17. | |
| // | |
| // This is an bitfield enumerator which can be passed to absl::from_chars to | |
| // configure the string-to-float conversion. | |
| enum class chars_format { | |
| scientific = 1, | |
| fixed = 2, | |
| hex = 4, | |
| general = fixed | scientific, | |
| }; | |
| // The return result of a string-to-number conversion. | |
| // | |
| // `ec` will be set to `invalid_argument` if a well-formed number was not found | |
| // at the start of the input range, `result_out_of_range` if a well-formed | |
| // number was found, but it was out of the representable range of the requested | |
| // type, or to std::errc() otherwise. | |
| // | |
| // If a well-formed number was found, `ptr` is set to one past the sequence of | |
| // characters that were successfully parsed. If none was found, `ptr` is set | |
| // to the `first` argument to from_chars. | |
| struct from_chars_result { | |
| absl::Nonnull<const char*> ptr; | |
| std::errc ec; | |
| }; | |
| // Workalike compatibility version of std::from_chars from C++17. Currently | |
| // this only supports the `double` and `float` types. | |
| // | |
| // This interface incorporates the proposed resolutions for library issues | |
| // DR 3080 and DR 3081. If these are adopted with different wording, | |
| // Abseil's behavior will change to match the standard. (The behavior most | |
| // likely to change is for DR 3081, which says what `value` will be set to in | |
| // the case of overflow and underflow. Code that wants to avoid possible | |
| // breaking changes in this area should not depend on `value` when the returned | |
| // from_chars_result indicates a range error.) | |
| // | |
| // Searches the range [first, last) for the longest matching pattern beginning | |
| // at `first` that represents a floating point number. If one is found, store | |
| // the result in `value`. | |
| // | |
| // The matching pattern format is almost the same as that of strtod(), except | |
| // that (1) C locale is not respected, (2) an initial '+' character in the | |
| // input range will never be matched, and (3) leading whitespaces are not | |
| // ignored. | |
| // | |
| // If `fmt` is set, it must be one of the enumerator values of the chars_format. | |
| // (This is despite the fact that chars_format is a bitmask type.) If set to | |
| // `scientific`, a matching number must contain an exponent. If set to `fixed`, | |
| // then an exponent will never match. (For example, the string "1e5" will be | |
| // parsed as "1".) If set to `hex`, then a hexadecimal float is parsed in the | |
| // format that strtod() accepts, except that a "0x" prefix is NOT matched. | |
| // (In particular, in `hex` mode, the input "0xff" results in the largest | |
| // matching pattern "0".) | |
| absl::from_chars_result from_chars(absl::Nonnull<const char*> first, | |
| absl::Nonnull<const char*> last, | |
| double& value, // NOLINT | |
| chars_format fmt = chars_format::general); | |
| absl::from_chars_result from_chars(absl::Nonnull<const char*> first, | |
| absl::Nonnull<const char*> last, | |
| float& value, // NOLINT | |
| chars_format fmt = chars_format::general); | |
| // std::chars_format is specified as a bitmask type, which means the following | |
| // operations must be provided: | |
| inline constexpr chars_format operator&(chars_format lhs, chars_format rhs) { | |
| return static_cast<chars_format>(static_cast<int>(lhs) & | |
| static_cast<int>(rhs)); | |
| } | |
| inline constexpr chars_format operator|(chars_format lhs, chars_format rhs) { | |
| return static_cast<chars_format>(static_cast<int>(lhs) | | |
| static_cast<int>(rhs)); | |
| } | |
| inline constexpr chars_format operator^(chars_format lhs, chars_format rhs) { | |
| return static_cast<chars_format>(static_cast<int>(lhs) ^ | |
| static_cast<int>(rhs)); | |
| } | |
| inline constexpr chars_format operator~(chars_format arg) { | |
| return static_cast<chars_format>(~static_cast<int>(arg)); | |
| } | |
| inline chars_format& operator&=(chars_format& lhs, chars_format rhs) { | |
| lhs = lhs & rhs; | |
| return lhs; | |
| } | |
| inline chars_format& operator|=(chars_format& lhs, chars_format rhs) { | |
| lhs = lhs | rhs; | |
| return lhs; | |
| } | |
| inline chars_format& operator^=(chars_format& lhs, chars_format rhs) { | |
| lhs = lhs ^ rhs; | |
| return lhs; | |
| } | |
| ABSL_NAMESPACE_END | |
| } // namespace absl | |