first add files

1 files changed, 441 insertions, 0 deletions

diff --git a/lib/sqlalchemy/orm/clsregistry.py b/lib/sqlalchemy/orm/clsregistry.py
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+++ b/lib/sqlalchemy/orm/clsregistry.py
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+# ext/declarative/clsregistry.py
+# Copyright (C) 2005-2022 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
+"""Routines to handle the string class registry used by declarative.
+
+This system allows specification of classes and expressions used in
+:func:`_orm.relationship` using strings.
+
+"""
+import weakref
+
+from . import attributes
+from . import interfaces
+from .descriptor_props import SynonymProperty
+from .properties import ColumnProperty
+from .util import class_mapper
+from .. import exc
+from .. import inspection
+from .. import util
+from ..sql.schema import _get_table_key
+
+# strong references to registries which we place in
+# the _decl_class_registry, which is usually weak referencing.
+# the internal registries here link to classes with weakrefs and remove
+# themselves when all references to contained classes are removed.
+_registries = set()
+
+
+def add_class(classname, cls, decl_class_registry):
+    """Add a class to the _decl_class_registry associated with the
+    given declarative class.
+
+    """
+    if classname in decl_class_registry:
+        # class already exists.
+        existing = decl_class_registry[classname]
+        if not isinstance(existing, _MultipleClassMarker):
+            existing = decl_class_registry[classname] = _MultipleClassMarker(
+                [cls, existing]
+            )
+    else:
+        decl_class_registry[classname] = cls
+
+    try:
+        root_module = decl_class_registry["_sa_module_registry"]
+    except KeyError:
+        decl_class_registry[
+            "_sa_module_registry"
+        ] = root_module = _ModuleMarker("_sa_module_registry", None)
+
+    tokens = cls.__module__.split(".")
+
+    # build up a tree like this:
+    # modulename:  myapp.snacks.nuts
+    #
+    # myapp->snack->nuts->(classes)
+    # snack->nuts->(classes)
+    # nuts->(classes)
+    #
+    # this allows partial token paths to be used.
+    while tokens:
+        token = tokens.pop(0)
+        module = root_module.get_module(token)
+        for token in tokens:
+            module = module.get_module(token)
+        module.add_class(classname, cls)
+
+
+def remove_class(classname, cls, decl_class_registry):
+    if classname in decl_class_registry:
+        existing = decl_class_registry[classname]
+        if isinstance(existing, _MultipleClassMarker):
+            existing.remove_item(cls)
+        else:
+            del decl_class_registry[classname]
+
+    try:
+        root_module = decl_class_registry["_sa_module_registry"]
+    except KeyError:
+        return
+
+    tokens = cls.__module__.split(".")
+
+    while tokens:
+        token = tokens.pop(0)
+        module = root_module.get_module(token)
+        for token in tokens:
+            module = module.get_module(token)
+        module.remove_class(classname, cls)
+
+
+def _key_is_empty(key, decl_class_registry, test):
+    """test if a key is empty of a certain object.
+
+    used for unit tests against the registry to see if garbage collection
+    is working.
+
+    "test" is a callable that will be passed an object should return True
+    if the given object is the one we were looking for.
+
+    We can't pass the actual object itself b.c. this is for testing garbage
+    collection; the caller will have to have removed references to the
+    object itself.
+
+    """
+    if key not in decl_class_registry:
+        return True
+
+    thing = decl_class_registry[key]
+    if isinstance(thing, _MultipleClassMarker):
+        for sub_thing in thing.contents:
+            if test(sub_thing):
+                return False
+    else:
+        return not test(thing)
+
+
+class _MultipleClassMarker(object):
+    """refers to multiple classes of the same name
+    within _decl_class_registry.
+
+    """
+
+    __slots__ = "on_remove", "contents", "__weakref__"
+
+    def __init__(self, classes, on_remove=None):
+        self.on_remove = on_remove
+        self.contents = set(
+            [weakref.ref(item, self._remove_item) for item in classes]
+        )
+        _registries.add(self)
+
+    def remove_item(self, cls):
+        self._remove_item(weakref.ref(cls))
+
+    def __iter__(self):
+        return (ref() for ref in self.contents)
+
+    def attempt_get(self, path, key):
+        if len(self.contents) > 1:
+            raise exc.InvalidRequestError(
+                'Multiple classes found for path "%s" '
+                "in the registry of this declarative "
+                "base. Please use a fully module-qualified path."
+                % (".".join(path + [key]))
+            )
+        else:
+            ref = list(self.contents)[0]
+            cls = ref()
+            if cls is None:
+                raise NameError(key)
+            return cls
+
+    def _remove_item(self, ref):
+        self.contents.discard(ref)
+        if not self.contents:
+            _registries.discard(self)
+            if self.on_remove:
+                self.on_remove()
+
+    def add_item(self, item):
+        # protect against class registration race condition against
+        # asynchronous garbage collection calling _remove_item,
+        # [ticket:3208]
+        modules = set(
+            [
+                cls.__module__
+                for cls in [ref() for ref in self.contents]
+                if cls is not None
+            ]
+        )
+        if item.__module__ in modules:
+            util.warn(
+                "This declarative base already contains a class with the "
+                "same class name and module name as %s.%s, and will "
+                "be replaced in the string-lookup table."
+                % (item.__module__, item.__name__)
+            )
+        self.contents.add(weakref.ref(item, self._remove_item))
+
+
+class _ModuleMarker(object):
+    """Refers to a module name within
+    _decl_class_registry.
+
+    """
+
+    __slots__ = "parent", "name", "contents", "mod_ns", "path", "__weakref__"
+
+    def __init__(self, name, parent):
+        self.parent = parent
+        self.name = name
+        self.contents = {}
+        self.mod_ns = _ModNS(self)
+        if self.parent:
+            self.path = self.parent.path + [self.name]
+        else:
+            self.path = []
+        _registries.add(self)
+
+    def __contains__(self, name):
+        return name in self.contents
+
+    def __getitem__(self, name):
+        return self.contents[name]
+
+    def _remove_item(self, name):
+        self.contents.pop(name, None)
+        if not self.contents and self.parent is not None:
+            self.parent._remove_item(self.name)
+            _registries.discard(self)
+
+    def resolve_attr(self, key):
+        return getattr(self.mod_ns, key)
+
+    def get_module(self, name):
+        if name not in self.contents:
+            marker = _ModuleMarker(name, self)
+            self.contents[name] = marker
+        else:
+            marker = self.contents[name]
+        return marker
+
+    def add_class(self, name, cls):
+        if name in self.contents:
+            existing = self.contents[name]
+            existing.add_item(cls)
+        else:
+            existing = self.contents[name] = _MultipleClassMarker(
+                [cls], on_remove=lambda: self._remove_item(name)
+            )
+
+    def remove_class(self, name, cls):
+        if name in self.contents:
+            existing = self.contents[name]
+            existing.remove_item(cls)
+
+
+class _ModNS(object):
+    __slots__ = ("__parent",)
+
+    def __init__(self, parent):
+        self.__parent = parent
+
+    def __getattr__(self, key):
+        try:
+            value = self.__parent.contents[key]
+        except KeyError:
+            pass
+        else:
+            if value is not None:
+                if isinstance(value, _ModuleMarker):
+                    return value.mod_ns
+                else:
+                    assert isinstance(value, _MultipleClassMarker)
+                    return value.attempt_get(self.__parent.path, key)
+        raise NameError(
+            "Module %r has no mapped classes "
+            "registered under the name %r" % (self.__parent.name, key)
+        )
+
+
+class _GetColumns(object):
+    __slots__ = ("cls",)
+
+    def __init__(self, cls):
+        self.cls = cls
+
+    def __getattr__(self, key):
+        mp = class_mapper(self.cls, configure=False)
+        if mp:
+            if key not in mp.all_orm_descriptors:
+                raise AttributeError(
+                    "Class %r does not have a mapped column named %r"
+                    % (self.cls, key)
+                )
+
+            desc = mp.all_orm_descriptors[key]
+            if desc.extension_type is interfaces.NOT_EXTENSION:
+                prop = desc.property
+                if isinstance(prop, SynonymProperty):
+                    key = prop.name
+                elif not isinstance(prop, ColumnProperty):
+                    raise exc.InvalidRequestError(
+                        "Property %r is not an instance of"
+                        " ColumnProperty (i.e. does not correspond"
+                        " directly to a Column)." % key
+                    )
+        return getattr(self.cls, key)
+
+
+inspection._inspects(_GetColumns)(
+    lambda target: inspection.inspect(target.cls)
+)
+
+
+class _GetTable(object):
+    __slots__ = "key", "metadata"
+
+    def __init__(self, key, metadata):
+        self.key = key
+        self.metadata = metadata
+
+    def __getattr__(self, key):
+        return self.metadata.tables[_get_table_key(key, self.key)]
+
+
+def _determine_container(key, value):
+    if isinstance(value, _MultipleClassMarker):
+        value = value.attempt_get([], key)
+    return _GetColumns(value)
+
+
+class _class_resolver(object):
+    __slots__ = (
+        "cls",
+        "prop",
+        "arg",
+        "fallback",
+        "_dict",
+        "_resolvers",
+        "favor_tables",
+    )
+
+    def __init__(self, cls, prop, fallback, arg, favor_tables=False):
+        self.cls = cls
+        self.prop = prop
+        self.arg = arg
+        self.fallback = fallback
+        self._dict = util.PopulateDict(self._access_cls)
+        self._resolvers = ()
+        self.favor_tables = favor_tables
+
+    def _access_cls(self, key):
+        cls = self.cls
+
+        manager = attributes.manager_of_class(cls)
+        decl_base = manager.registry
+        decl_class_registry = decl_base._class_registry
+        metadata = decl_base.metadata
+
+        if self.favor_tables:
+            if key in metadata.tables:
+                return metadata.tables[key]
+            elif key in metadata._schemas:
+                return _GetTable(key, cls.metadata)
+
+        if key in decl_class_registry:
+            return _determine_container(key, decl_class_registry[key])
+
+        if not self.favor_tables:
+            if key in metadata.tables:
+                return metadata.tables[key]
+            elif key in metadata._schemas:
+                return _GetTable(key, cls.metadata)
+
+        if (
+            "_sa_module_registry" in decl_class_registry
+            and key in decl_class_registry["_sa_module_registry"]
+        ):
+            registry = decl_class_registry["_sa_module_registry"]
+            return registry.resolve_attr(key)
+        elif self._resolvers:
+            for resolv in self._resolvers:
+                value = resolv(key)
+                if value is not None:
+                    return value
+
+        return self.fallback[key]
+
+    def _raise_for_name(self, name, err):
+        util.raise_(
+            exc.InvalidRequestError(
+                "When initializing mapper %s, expression %r failed to "
+                "locate a name (%r). If this is a class name, consider "
+                "adding this relationship() to the %r class after "
+                "both dependent classes have been defined."
+                % (self.prop.parent, self.arg, name, self.cls)
+            ),
+            from_=err,
+        )
+
+    def _resolve_name(self):
+        name = self.arg
+        d = self._dict
+        rval = None
+        try:
+            for token in name.split("."):
+                if rval is None:
+                    rval = d[token]
+                else:
+                    rval = getattr(rval, token)
+        except KeyError as err:
+            self._raise_for_name(name, err)
+        except NameError as n:
+            self._raise_for_name(n.args[0], n)
+        else:
+            if isinstance(rval, _GetColumns):
+                return rval.cls
+            else:
+                return rval
+
+    def __call__(self):
+        try:
+            x = eval(self.arg, globals(), self._dict)
+
+            if isinstance(x, _GetColumns):
+                return x.cls
+            else:
+                return x
+        except NameError as n:
+            self._raise_for_name(n.args[0], n)
+
+
+_fallback_dict = None
+
+
+def _resolver(cls, prop):
+
+    global _fallback_dict
+
+    if _fallback_dict is None:
+        import sqlalchemy
+        from sqlalchemy.orm import foreign, remote
+
+        _fallback_dict = util.immutabledict(sqlalchemy.__dict__).union(
+            {"foreign": foreign, "remote": remote}
+        )
+
+    def resolve_arg(arg, favor_tables=False):
+        return _class_resolver(
+            cls, prop, _fallback_dict, arg, favor_tables=favor_tables
+        )
+
+    def resolve_name(arg):
+        return _class_resolver(cls, prop, _fallback_dict, arg)._resolve_name
+
+    return resolve_name, resolve_arg