Adding upstream version 1.2+20240521.

Signed-off-by: Daniel Baumann <daniel@debian.org>

src/aristaproto/enum.py

@@ -0,0 +1,195 @@
+from __future__ import annotations
+
+import sys
+from enum import (
+    EnumMeta,
+    IntEnum,
+)
+from types import MappingProxyType
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Dict,
+    Optional,
+    Tuple,
+)
+
+
+if TYPE_CHECKING:
+    from collections.abc import (
+        Generator,
+        Mapping,
+    )
+
+    from typing_extensions import (
+        Never,
+        Self,
+    )
+
+
+def _is_descriptor(obj: object) -> bool:
+    return (
+        hasattr(obj, "__get__") or hasattr(obj, "__set__") or hasattr(obj, "__delete__")
+    )
+
+
+class EnumType(EnumMeta if TYPE_CHECKING else type):
+    _value_map_: Mapping[int, Enum]
+    _member_map_: Mapping[str, Enum]
+
+    def __new__(
+        mcs, name: str, bases: Tuple[type, ...], namespace: Dict[str, Any]
+    ) -> Self:
+        value_map = {}
+        member_map = {}
+
+        new_mcs = type(
+            f"{name}Type",
+            tuple(
+                dict.fromkeys(
+                    [base.__class__ for base in bases if base.__class__ is not type]
+                    + [EnumType, type]
+                )
+            ),  # reorder the bases so EnumType and type are last to avoid conflicts
+            {"_value_map_": value_map, "_member_map_": member_map},
+        )
+
+        members = {
+            name: value
+            for name, value in namespace.items()
+            if not _is_descriptor(value) and not name.startswith("__")
+        }
+
+        cls = type.__new__(
+            new_mcs,
+            name,
+            bases,
+            {key: value for key, value in namespace.items() if key not in members},
+        )
+        # this allows us to disallow member access from other members as
+        # members become proper class variables
+
+        for name, value in members.items():
+            member = value_map.get(value)
+            if member is None:
+                member = cls.__new__(cls, name=name, value=value)  # type: ignore
+                value_map[value] = member
+            member_map[name] = member
+            type.__setattr__(new_mcs, name, member)
+
+        return cls
+
+    if not TYPE_CHECKING:
+
+        def __call__(cls, value: int) -> Enum:
+            try:
+                return cls._value_map_[value]
+            except (KeyError, TypeError):
+                raise ValueError(f"{value!r} is not a valid {cls.__name__}") from None
+
+        def __iter__(cls) -> Generator[Enum, None, None]:
+            yield from cls._member_map_.values()
+
+        def __reversed__(cls) -> Generator[Enum, None, None]:
+            yield from reversed(cls._member_map_.values())
+
+        def __getitem__(cls, key: str) -> Enum:
+            return cls._member_map_[key]
+
+        @property
+        def __members__(cls) -> MappingProxyType[str, Enum]:
+            return MappingProxyType(cls._member_map_)
+
+    def __repr__(cls) -> str:
+        return f"<enum {cls.__name__!r}>"
+
+    def __len__(cls) -> int:
+        return len(cls._member_map_)
+
+    def __setattr__(cls, name: str, value: Any) -> Never:
+        raise AttributeError(f"{cls.__name__}: cannot reassign Enum members.")
+
+    def __delattr__(cls, name: str) -> Never:
+        raise AttributeError(f"{cls.__name__}: cannot delete Enum members.")
+
+    def __contains__(cls, member: object) -> bool:
+        return isinstance(member, cls) and member.name in cls._member_map_
+
+
+class Enum(IntEnum if TYPE_CHECKING else int, metaclass=EnumType):
+    """
+    The base class for protobuf enumerations, all generated enumerations will
+    inherit from this. Emulates `enum.IntEnum`.
+    """
+
+    name: Optional[str]
+    value: int
+
+    if not TYPE_CHECKING:
+
+        def __new__(cls, *, name: Optional[str], value: int) -> Self:
+            self = super().__new__(cls, value)
+            super().__setattr__(self, "name", name)
+            super().__setattr__(self, "value", value)
+            return self
+
+    def __str__(self) -> str:
+        return self.name or "None"
+
+    def __repr__(self) -> str:
+        return f"{self.__class__.__name__}.{self.name}"
+
+    def __setattr__(self, key: str, value: Any) -> Never:
+        raise AttributeError(
+            f"{self.__class__.__name__} Cannot reassign a member's attributes."
+        )
+
+    def __delattr__(self, item: Any) -> Never:
+        raise AttributeError(
+            f"{self.__class__.__name__} Cannot delete a member's attributes."
+        )
+
+    def __copy__(self) -> Self:
+        return self
+
+    def __deepcopy__(self, memo: Any) -> Self:
+        return self
+
+    @classmethod
+    def try_value(cls, value: int = 0) -> Self:
+        """Return the value which corresponds to the value.
+
+        Parameters
+        -----------
+        value: :class:`int`
+            The value of the enum member to get.
+
+        Returns
+        -------
+        :class:`Enum`
+            The corresponding member or a new instance of the enum if
+            ``value`` isn't actually a member.
+        """
+        try:
+            return cls._value_map_[value]
+        except (KeyError, TypeError):
+            return cls.__new__(cls, name=None, value=value)
+
+    @classmethod
+    def from_string(cls, name: str) -> Self:
+        """Return the value which corresponds to the string name.
+
+        Parameters
+        -----------
+        name: :class:`str`
+            The name of the enum member to get.
+
+        Raises
+        -------
+        :exc:`ValueError`
+            The member was not found in the Enum.
+        """
+        try:
+            return cls._member_map_[name]
+        except KeyError as e:
+            raise ValueError(f"Unknown value {name} for enum {cls.__name__}") from e