Add type to define OAS responses

aiohttp_pydantic/oas/typing.py

@@ -0,0 +1,47 @@
+"""
+This module provides type to annotate the content of web.Response returned by
+the HTTP handlers.
+
+The type are: r100, r101, ..., r599
+
+Example:
+
+    class PetCollectionView(PydanticView):
+        async def get(self) -> Union[r200[List[Pet]], r404]:
+            ...
+"""
+
+from functools import lru_cache
+from types import new_class
+from typing import Protocol, TypeVar
+
+RespContents = TypeVar("RespContents", covariant=True)
+
+_status_code = frozenset(f"r{code}" for code in range(100, 600))
+
+
+@lru_cache(maxsize=len(_status_code))
+def _make_status_code_type(status_code):
+    if status_code in _status_code:
+        return new_class(status_code, (Protocol[RespContents],))
+
+
+def is_status_code_type(obj):
+    """
+    Return True if obj is a status code type such as _200 or _404.
+    """
+    name = getattr(obj, "__name__", None)
+    if name not in _status_code:
+        return False
+
+    return obj is _make_status_code_type(name)
+
+
+def __getattr__(name):
+    if (status_code_type := _make_status_code_type(name)) is None:
+        raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
+    return status_code_type
+
+
+__all__ = list(_status_code)
+__all__.append("is_status_code_type")