Create base.py

3rdparty/densepose/converters/base.py

@@ -0,0 +1,90 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+
+from typing import Any, Tuple, Type
+import torch
+
+
+class BaseConverter:
+    """
+    Converter base class to be reused by various converters.
+    Converter allows one to convert data from various source types to a particular
+    destination type. Each source type needs to register its converter. The
+    registration for each source type is valid for all descendants of that type.
+    """
+
+    @classmethod
+    def register(cls, from_type: Type, converter: Any = None):
+        """
+        Registers a converter for the specified type.
+        Can be used as a decorator (if converter is None), or called as a method.
+        Args:
+            from_type (type): type to register the converter for;
+                all instances of this type will use the same converter
+            converter (callable): converter to be registered for the given
+                type; if None, this method is assumed to be a decorator for the converter
+        """
+
+        if converter is not None:
+            cls._do_register(from_type, converter)
+
+        def wrapper(converter: Any) -> Any:
+            cls._do_register(from_type, converter)
+            return converter
+
+        return wrapper
+
+    @classmethod
+    def _do_register(cls, from_type: Type, converter: Any):
+        cls.registry[from_type] = converter  # pyre-ignore[16]
+
+    @classmethod
+    def _lookup_converter(cls, from_type: Type) -> Any:
+        """
+        Perform recursive lookup for the given type
+        to find registered converter. If a converter was found for some base
+        class, it gets registered for this class to save on further lookups.
+        Args:
+            from_type: type for which to find a converter
+        Return:
+            callable or None - registered converter or None
+                if no suitable entry was found in the registry
+        """
+        if from_type in cls.registry:  # pyre-ignore[16]
+            return cls.registry[from_type]
+        for base in from_type.__bases__:
+            converter = cls._lookup_converter(base)
+            if converter is not None:
+                cls._do_register(from_type, converter)
+                return converter
+        return None
+
+    @classmethod
+    def convert(cls, instance: Any, *args, **kwargs):
+        """
+        Convert an instance to the destination type using some registered
+        converter. Does recursive lookup for base classes, so there's no need
+        for explicit registration for derived classes.
+        Args:
+            instance: source instance to convert to the destination type
+        Return:
+            An instance of the destination type obtained from the source instance
+            Raises KeyError, if no suitable converter found
+        """
+        instance_type = type(instance)
+        converter = cls._lookup_converter(instance_type)
+        if converter is None:
+            if cls.dst_type is None:  # pyre-ignore[16]
+                output_type_str = "itself"
+            else:
+                output_type_str = cls.dst_type
+            raise KeyError(f"Could not find converter from {instance_type} to {output_type_str}")
+        return converter(instance, *args, **kwargs)
+
+
+IntTupleBox = Tuple[int, int, int, int]
+
+
+def make_int_box(box: torch.Tensor) -> IntTupleBox:
+    int_box = [0, 0, 0, 0]
+    int_box[0], int_box[1], int_box[2], int_box[3] = tuple(box.long().tolist())
+    return int_box[0], int_box[1], int_box[2], int_box[3]