Validator,
    lenient_issubclass,
)
from fastapi.datastructures import DefaultPlaceholder, DefaultType
from pydantic import BaseModel, create_model
from pydantic.fields import FieldInfo
from typing_extensions import Literal

if TYPE_CHECKING:  # pragma: nocover
    from .routing import APIRoute

# Cache for `create_cloned_field`
_CLONED_TYPES_CACHE: MutableMapping[
    Type[BaseModel], Type[BaseModel]
] = WeakKeyDictionary()