Update 2025-04-24_11:44:19

venv/lib/python3.11/site-packages/sqlalchemy/inspection.py

@@ -0,0 +1,174 @@
+# inspection.py
+# Copyright (C) 2005-2025 the SQLAlchemy authors and contributors
+# <see AUTHORS file>
+#
+# This module is part of SQLAlchemy and is released under
+# the MIT License: https://www.opensource.org/licenses/mit-license.php
+
+"""The inspection module provides the :func:`_sa.inspect` function,
+which delivers runtime information about a wide variety
+of SQLAlchemy objects, both within the Core as well as the
+ORM.
+
+The :func:`_sa.inspect` function is the entry point to SQLAlchemy's
+public API for viewing the configuration and construction
+of in-memory objects.   Depending on the type of object
+passed to :func:`_sa.inspect`, the return value will either be
+a related object which provides a known interface, or in many
+cases it will return the object itself.
+
+The rationale for :func:`_sa.inspect` is twofold.  One is that
+it replaces the need to be aware of a large variety of "information
+getting" functions in SQLAlchemy, such as
+:meth:`_reflection.Inspector.from_engine` (deprecated in 1.4),
+:func:`.orm.attributes.instance_state`, :func:`_orm.class_mapper`,
+and others.    The other is that the return value of :func:`_sa.inspect`
+is guaranteed to obey a documented API, thus allowing third party
+tools which build on top of SQLAlchemy configurations to be constructed
+in a forwards-compatible way.
+
+"""
+from __future__ import annotations
+
+from typing import Any
+from typing import Callable
+from typing import Dict
+from typing import Generic
+from typing import Optional
+from typing import overload
+from typing import Type
+from typing import TypeVar
+from typing import Union
+
+from . import exc
+from .util.typing import Literal
+from .util.typing import Protocol
+
+_T = TypeVar("_T", bound=Any)
+_TCov = TypeVar("_TCov", bound=Any, covariant=True)
+_F = TypeVar("_F", bound=Callable[..., Any])
+
+_IN = TypeVar("_IN", bound=Any)
+
+_registrars: Dict[type, Union[Literal[True], Callable[[Any], Any]]] = {}
+
+
+class Inspectable(Generic[_T]):
+    """define a class as inspectable.
+
+    This allows typing to set up a linkage between an object that
+    can be inspected and the type of inspection it returns.
+
+    Unfortunately we cannot at the moment get all classes that are
+    returned by inspection to suit this interface as we get into
+    MRO issues.
+
+    """
+
+    __slots__ = ()
+
+
+class _InspectableTypeProtocol(Protocol[_TCov]):
+    """a protocol defining a method that's used when a type (ie the class
+    itself) is passed to inspect().
+
+    """
+
+    def _sa_inspect_type(self) -> _TCov: ...
+
+
+class _InspectableProtocol(Protocol[_TCov]):
+    """a protocol defining a method that's used when an instance is
+    passed to inspect().
+
+    """
+
+    def _sa_inspect_instance(self) -> _TCov: ...
+
+
+@overload
+def inspect(
+    subject: Type[_InspectableTypeProtocol[_IN]], raiseerr: bool = True
+) -> _IN: ...
+
+
+@overload
+def inspect(
+    subject: _InspectableProtocol[_IN], raiseerr: bool = True
+) -> _IN: ...
+
+
+@overload
+def inspect(subject: Inspectable[_IN], raiseerr: bool = True) -> _IN: ...
+
+
+@overload
+def inspect(subject: Any, raiseerr: Literal[False] = ...) -> Optional[Any]: ...
+
+
+@overload
+def inspect(subject: Any, raiseerr: bool = True) -> Any: ...
+
+
+def inspect(subject: Any, raiseerr: bool = True) -> Any:
+    """Produce an inspection object for the given target.
+
+    The returned value in some cases may be the
+    same object as the one given, such as if a
+    :class:`_orm.Mapper` object is passed.   In other
+    cases, it will be an instance of the registered
+    inspection type for the given object, such as
+    if an :class:`_engine.Engine` is passed, an
+    :class:`_reflection.Inspector` object is returned.
+
+    :param subject: the subject to be inspected.
+    :param raiseerr: When ``True``, if the given subject
+     does not
+     correspond to a known SQLAlchemy inspected type,
+     :class:`sqlalchemy.exc.NoInspectionAvailable`
+     is raised.  If ``False``, ``None`` is returned.
+
+    """
+    type_ = type(subject)
+    for cls in type_.__mro__:
+        if cls in _registrars:
+            reg = _registrars.get(cls, None)
+            if reg is None:
+                continue
+            elif reg is True:
+                return subject
+            ret = reg(subject)
+            if ret is not None:
+                return ret
+    else:
+        reg = ret = None
+
+    if raiseerr and (reg is None or ret is None):
+        raise exc.NoInspectionAvailable(
+            "No inspection system is "
+            "available for object of type %s" % type_
+        )
+    return ret
+
+
+def _inspects(
+    *types: Type[Any],
+) -> Callable[[_F], _F]:
+    def decorate(fn_or_cls: _F) -> _F:
+        for type_ in types:
+            if type_ in _registrars:
+                raise AssertionError("Type %s is already registered" % type_)
+            _registrars[type_] = fn_or_cls
+        return fn_or_cls
+
+    return decorate
+
+
+_TT = TypeVar("_TT", bound="Type[Any]")
+
+
+def _self_inspects(cls: _TT) -> _TT:
+    if cls in _registrars:
+        raise AssertionError("Type %s is already registered" % cls)
+    _registrars[cls] = True
+    return cls