first add files

1 files changed, 1210 insertions, 0 deletions

diff --git a/lib/sqlalchemy/orm/decl_base.py b/lib/sqlalchemy/orm/decl_base.py
new file mode 100644
index 0000000..6e1c797
--- /dev/null
+++ b/lib/sqlalchemy/orm/decl_base.py
@@ -0,0 +1,1210 @@
+# ext/declarative/base.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
+"""Internal implementation for declarative."""
+from __future__ import absolute_import
+
+import collections
+import weakref
+
+from sqlalchemy.orm import attributes
+from sqlalchemy.orm import instrumentation
+from . import clsregistry
+from . import exc as orm_exc
+from . import mapper as mapperlib
+from .attributes import InstrumentedAttribute
+from .attributes import QueryableAttribute
+from .base import _is_mapped_class
+from .base import InspectionAttr
+from .descriptor_props import CompositeProperty
+from .descriptor_props import SynonymProperty
+from .interfaces import MapperProperty
+from .mapper import Mapper as mapper
+from .properties import ColumnProperty
+from .util import class_mapper
+from .. import event
+from .. import exc
+from .. import util
+from ..sql import expression
+from ..sql.schema import Column
+from ..sql.schema import Table
+from ..util import topological
+
+
+def _declared_mapping_info(cls):
+    # deferred mapping
+    if _DeferredMapperConfig.has_cls(cls):
+        return _DeferredMapperConfig.config_for_cls(cls)
+    # regular mapping
+    elif _is_mapped_class(cls):
+        return class_mapper(cls, configure=False)
+    else:
+        return None
+
+
+def _resolve_for_abstract_or_classical(cls):
+    if cls is object:
+        return None
+
+    if cls.__dict__.get("__abstract__", False):
+        for sup in cls.__bases__:
+            sup = _resolve_for_abstract_or_classical(sup)
+            if sup is not None:
+                return sup
+        else:
+            return None
+    else:
+        clsmanager = _dive_for_cls_manager(cls)
+
+        if clsmanager:
+            return clsmanager.class_
+        else:
+            return cls
+
+
+def _get_immediate_cls_attr(cls, attrname, strict=False):
+    """return an attribute of the class that is either present directly
+    on the class, e.g. not on a superclass, or is from a superclass but
+    this superclass is a non-mapped mixin, that is, not a descendant of
+    the declarative base and is also not classically mapped.
+
+    This is used to detect attributes that indicate something about
+    a mapped class independently from any mapped classes that it may
+    inherit from.
+
+    """
+
+    # the rules are different for this name than others,
+    # make sure we've moved it out.  transitional
+    assert attrname != "__abstract__"
+
+    if not issubclass(cls, object):
+        return None
+
+    if attrname in cls.__dict__:
+        return getattr(cls, attrname)
+
+    for base in cls.__mro__[1:]:
+        _is_classicial_inherits = _dive_for_cls_manager(base)
+
+        if attrname in base.__dict__ and (
+            base is cls
+            or (
+                (base in cls.__bases__ if strict else True)
+                and not _is_classicial_inherits
+            )
+        ):
+            return getattr(base, attrname)
+    else:
+        return None
+
+
+def _dive_for_cls_manager(cls):
+    # because the class manager registration is pluggable,
+    # we need to do the search for every class in the hierarchy,
+    # rather than just a simple "cls._sa_class_manager"
+
+    # python 2 old style class
+    if not hasattr(cls, "__mro__"):
+        return None
+
+    for base in cls.__mro__:
+        manager = attributes.manager_of_class(base)
+        if manager:
+            return manager
+    return None
+
+
+def _as_declarative(registry, cls, dict_):
+
+    # declarative scans the class for attributes.  no table or mapper
+    # args passed separately.
+
+    return _MapperConfig.setup_mapping(registry, cls, dict_, None, {})
+
+
+def _mapper(registry, cls, table, mapper_kw):
+    _ImperativeMapperConfig(registry, cls, table, mapper_kw)
+    return cls.__mapper__
+
+
+@util.preload_module("sqlalchemy.orm.decl_api")
+def _is_declarative_props(obj):
+    declared_attr = util.preloaded.orm_decl_api.declared_attr
+
+    return isinstance(obj, (declared_attr, util.classproperty))
+
+
+def _check_declared_props_nocascade(obj, name, cls):
+    if _is_declarative_props(obj):
+        if getattr(obj, "_cascading", False):
+            util.warn(
+                "@declared_attr.cascading is not supported on the %s "
+                "attribute on class %s.  This attribute invokes for "
+                "subclasses in any case." % (name, cls)
+            )
+        return True
+    else:
+        return False
+
+
+class _MapperConfig(object):
+    __slots__ = (
+        "cls",
+        "classname",
+        "properties",
+        "declared_attr_reg",
+        "__weakref__",
+    )
+
+    @classmethod
+    def setup_mapping(cls, registry, cls_, dict_, table, mapper_kw):
+        manager = attributes.manager_of_class(cls)
+        if manager and manager.class_ is cls_:
+            raise exc.InvalidRequestError(
+                "Class %r already has been " "instrumented declaratively" % cls
+            )
+
+        if cls_.__dict__.get("__abstract__", False):
+            return
+
+        defer_map = _get_immediate_cls_attr(
+            cls_, "_sa_decl_prepare_nocascade", strict=True
+        ) or hasattr(cls_, "_sa_decl_prepare")
+
+        if defer_map:
+            cfg_cls = _DeferredMapperConfig
+        else:
+            cfg_cls = _ClassScanMapperConfig
+
+        return cfg_cls(registry, cls_, dict_, table, mapper_kw)
+
+    def __init__(self, registry, cls_, mapper_kw):
+        self.cls = util.assert_arg_type(cls_, type, "cls_")
+        self.classname = cls_.__name__
+        self.properties = util.OrderedDict()
+        self.declared_attr_reg = {}
+
+        if not mapper_kw.get("non_primary", False):
+            instrumentation.register_class(
+                self.cls,
+                finalize=False,
+                registry=registry,
+                declarative_scan=self,
+                init_method=registry.constructor,
+            )
+        else:
+            manager = attributes.manager_of_class(self.cls)
+            if not manager or not manager.is_mapped:
+                raise exc.InvalidRequestError(
+                    "Class %s has no primary mapper configured.  Configure "
+                    "a primary mapper first before setting up a non primary "
+                    "Mapper." % self.cls
+                )
+
+    def set_cls_attribute(self, attrname, value):
+
+        manager = instrumentation.manager_of_class(self.cls)
+        manager.install_member(attrname, value)
+        return value
+
+    def _early_mapping(self, mapper_kw):
+        self.map(mapper_kw)
+
+
+class _ImperativeMapperConfig(_MapperConfig):
+    __slots__ = ("dict_", "local_table", "inherits")
+
+    def __init__(
+        self,
+        registry,
+        cls_,
+        table,
+        mapper_kw,
+    ):
+        super(_ImperativeMapperConfig, self).__init__(
+            registry, cls_, mapper_kw
+        )
+
+        self.dict_ = {}
+        self.local_table = self.set_cls_attribute("__table__", table)
+
+        with mapperlib._CONFIGURE_MUTEX:
+            if not mapper_kw.get("non_primary", False):
+                clsregistry.add_class(
+                    self.classname, self.cls, registry._class_registry
+                )
+
+            self._setup_inheritance(mapper_kw)
+
+            self._early_mapping(mapper_kw)
+
+    def map(self, mapper_kw=util.EMPTY_DICT):
+        mapper_cls = mapper
+
+        return self.set_cls_attribute(
+            "__mapper__",
+            mapper_cls(self.cls, self.local_table, **mapper_kw),
+        )
+
+    def _setup_inheritance(self, mapper_kw):
+        cls = self.cls
+
+        inherits = mapper_kw.get("inherits", None)
+
+        if inherits is None:
+            # since we search for classical mappings now, search for
+            # multiple mapped bases as well and raise an error.
+            inherits_search = []
+            for c in cls.__bases__:
+                c = _resolve_for_abstract_or_classical(c)
+                if c is None:
+                    continue
+                if _declared_mapping_info(
+                    c
+                ) is not None and not _get_immediate_cls_attr(
+                    c, "_sa_decl_prepare_nocascade", strict=True
+                ):
+                    inherits_search.append(c)
+
+            if inherits_search:
+                if len(inherits_search) > 1:
+                    raise exc.InvalidRequestError(
+                        "Class %s has multiple mapped bases: %r"
+                        % (cls, inherits_search)
+                    )
+                inherits = inherits_search[0]
+        elif isinstance(inherits, mapper):
+            inherits = inherits.class_
+
+        self.inherits = inherits
+
+
+class _ClassScanMapperConfig(_MapperConfig):
+    __slots__ = (
+        "dict_",
+        "local_table",
+        "persist_selectable",
+        "declared_columns",
+        "column_copies",
+        "table_args",
+        "tablename",
+        "mapper_args",
+        "mapper_args_fn",
+        "inherits",
+    )
+
+    def __init__(
+        self,
+        registry,
+        cls_,
+        dict_,
+        table,
+        mapper_kw,
+    ):
+
+        # grab class dict before the instrumentation manager has been added.
+        # reduces cycles
+        self.dict_ = dict(dict_) if dict_ else {}
+
+        super(_ClassScanMapperConfig, self).__init__(registry, cls_, mapper_kw)
+
+        self.persist_selectable = None
+        self.declared_columns = set()
+        self.column_copies = {}
+        self._setup_declared_events()
+
+        self._scan_attributes()
+
+        with mapperlib._CONFIGURE_MUTEX:
+            clsregistry.add_class(
+                self.classname, self.cls, registry._class_registry
+            )
+
+            self._extract_mappable_attributes()
+
+            self._extract_declared_columns()
+
+            self._setup_table(table)
+
+            self._setup_inheritance(mapper_kw)
+
+            self._early_mapping(mapper_kw)
+
+    def _setup_declared_events(self):
+        if _get_immediate_cls_attr(self.cls, "__declare_last__"):
+
+            @event.listens_for(mapper, "after_configured")
+            def after_configured():
+                self.cls.__declare_last__()
+
+        if _get_immediate_cls_attr(self.cls, "__declare_first__"):
+
+            @event.listens_for(mapper, "before_configured")
+            def before_configured():
+                self.cls.__declare_first__()
+
+    def _cls_attr_override_checker(self, cls):
+        """Produce a function that checks if a class has overridden an
+        attribute, taking SQLAlchemy-enabled dataclass fields into account.
+
+        """
+        sa_dataclass_metadata_key = _get_immediate_cls_attr(
+            cls, "__sa_dataclass_metadata_key__", None
+        )
+
+        if sa_dataclass_metadata_key is None:
+
+            def attribute_is_overridden(key, obj):
+                return getattr(cls, key) is not obj
+
+        else:
+
+            all_datacls_fields = {
+                f.name: f.metadata[sa_dataclass_metadata_key]
+                for f in util.dataclass_fields(cls)
+                if sa_dataclass_metadata_key in f.metadata
+            }
+            local_datacls_fields = {
+                f.name: f.metadata[sa_dataclass_metadata_key]
+                for f in util.local_dataclass_fields(cls)
+                if sa_dataclass_metadata_key in f.metadata
+            }
+
+            absent = object()
+
+            def attribute_is_overridden(key, obj):
+                if _is_declarative_props(obj):
+                    obj = obj.fget
+
+                # this function likely has some failure modes still if
+                # someone is doing a deep mixing of the same attribute
+                # name as plain Python attribute vs. dataclass field.
+
+                ret = local_datacls_fields.get(key, absent)
+                if _is_declarative_props(ret):
+                    ret = ret.fget
+
+                if ret is obj:
+                    return False
+                elif ret is not absent:
+                    return True
+
+                all_field = all_datacls_fields.get(key, absent)
+
+                ret = getattr(cls, key, obj)
+
+                if ret is obj:
+                    return False
+
+                # for dataclasses, this could be the
+                # 'default' of the field.  so filter more specifically
+                # for an already-mapped InstrumentedAttribute
+                if ret is not absent and isinstance(
+                    ret, InstrumentedAttribute
+                ):
+                    return True
+
+                if all_field is obj:
+                    return False
+                elif all_field is not absent:
+                    return True
+
+                # can't find another attribute
+                return False
+
+        return attribute_is_overridden
+
+    def _cls_attr_resolver(self, cls):
+        """produce a function to iterate the "attributes" of a class,
+        adjusting for SQLAlchemy fields embedded in dataclass fields.
+
+        """
+        sa_dataclass_metadata_key = _get_immediate_cls_attr(
+            cls, "__sa_dataclass_metadata_key__", None
+        )
+
+        if sa_dataclass_metadata_key is None:
+
+            def local_attributes_for_class():
+                for name, obj in vars(cls).items():
+                    yield name, obj, False
+
+        else:
+            field_names = set()
+
+            def local_attributes_for_class():
+                for field in util.local_dataclass_fields(cls):
+                    if sa_dataclass_metadata_key in field.metadata:
+                        field_names.add(field.name)
+                        yield field.name, _as_dc_declaredattr(
+                            field.metadata, sa_dataclass_metadata_key
+                        ), True
+                for name, obj in vars(cls).items():
+                    if name not in field_names:
+                        yield name, obj, False
+
+        return local_attributes_for_class
+
+    def _scan_attributes(self):
+        cls = self.cls
+        dict_ = self.dict_
+        column_copies = self.column_copies
+        mapper_args_fn = None
+        table_args = inherited_table_args = None
+        tablename = None
+
+        attribute_is_overridden = self._cls_attr_override_checker(self.cls)
+
+        bases = []
+
+        for base in cls.__mro__:
+            # collect bases and make sure standalone columns are copied
+            # to be the column they will ultimately be on the class,
+            # so that declared_attr functions use the right columns.
+            # need to do this all the way up the hierarchy first
+            # (see #8190)
+
+            class_mapped = (
+                base is not cls
+                and _declared_mapping_info(base) is not None
+                and not _get_immediate_cls_attr(
+                    base, "_sa_decl_prepare_nocascade", strict=True
+                )
+            )
+
+            local_attributes_for_class = self._cls_attr_resolver(base)
+
+            if not class_mapped and base is not cls:
+                locally_collected_columns = self._produce_column_copies(
+                    local_attributes_for_class,
+                    attribute_is_overridden,
+                )
+            else:
+                locally_collected_columns = {}
+
+            bases.append(
+                (
+                    base,
+                    class_mapped,
+                    local_attributes_for_class,
+                    locally_collected_columns,
+                )
+            )
+
+        for (
+            base,
+            class_mapped,
+            local_attributes_for_class,
+            locally_collected_columns,
+        ) in bases:
+
+            # this transfer can also take place as we scan each name
+            # for finer-grained control of how collected_attributes is
+            # populated, as this is what impacts column ordering.
+            # however it's simpler to get it out of the way here.
+            dict_.update(locally_collected_columns)
+
+            for name, obj, is_dataclass in local_attributes_for_class():
+                if name == "__mapper_args__":
+                    check_decl = _check_declared_props_nocascade(
+                        obj, name, cls
+                    )
+                    if not mapper_args_fn and (not class_mapped or check_decl):
+                        # don't even invoke __mapper_args__ until
+                        # after we've determined everything about the
+                        # mapped table.
+                        # make a copy of it so a class-level dictionary
+                        # is not overwritten when we update column-based
+                        # arguments.
+                        def mapper_args_fn():
+                            return dict(cls.__mapper_args__)
+
+                elif name == "__tablename__":
+                    check_decl = _check_declared_props_nocascade(
+                        obj, name, cls
+                    )
+                    if not tablename and (not class_mapped or check_decl):
+                        tablename = cls.__tablename__
+                elif name == "__table_args__":
+                    check_decl = _check_declared_props_nocascade(
+                        obj, name, cls
+                    )
+                    if not table_args and (not class_mapped or check_decl):
+                        table_args = cls.__table_args__
+                        if not isinstance(
+                            table_args, (tuple, dict, type(None))
+                        ):
+                            raise exc.ArgumentError(
+                                "__table_args__ value must be a tuple, "
+                                "dict, or None"
+                            )
+                        if base is not cls:
+                            inherited_table_args = True
+                elif class_mapped:
+                    if _is_declarative_props(obj):
+                        util.warn(
+                            "Regular (i.e. not __special__) "
+                            "attribute '%s.%s' uses @declared_attr, "
+                            "but owning class %s is mapped - "
+                            "not applying to subclass %s."
+                            % (base.__name__, name, base, cls)
+                        )
+                    continue
+                elif base is not cls:
+                    # we're a mixin, abstract base, or something that is
+                    # acting like that for now.
+                    if isinstance(obj, Column):
+                        # already copied columns to the mapped class.
+                        continue
+                    elif isinstance(obj, MapperProperty):
+                        raise exc.InvalidRequestError(
+                            "Mapper properties (i.e. deferred,"
+                            "column_property(), relationship(), etc.) must "
+                            "be declared as @declared_attr callables "
+                            "on declarative mixin classes.  For dataclass "
+                            "field() objects, use a lambda:"
+                        )
+                    elif _is_declarative_props(obj):
+                        if obj._cascading:
+                            if name in dict_:
+                                # unfortunately, while we can use the user-
+                                # defined attribute here to allow a clean
+                                # override, if there's another
+                                # subclass below then it still tries to use
+                                # this.  not sure if there is enough
+                                # information here to add this as a feature
+                                # later on.
+                                util.warn(
+                                    "Attribute '%s' on class %s cannot be "
+                                    "processed due to "
+                                    "@declared_attr.cascading; "
+                                    "skipping" % (name, cls)
+                                )
+                            dict_[name] = column_copies[
+                                obj
+                            ] = ret = obj.__get__(obj, cls)
+                            setattr(cls, name, ret)
+                        else:
+                            if is_dataclass:
+                                # access attribute using normal class access
+                                # first, to see if it's been mapped on a
+                                # superclass.   note if the dataclasses.field()
+                                # has "default", this value can be anything.
+                                ret = getattr(cls, name, None)
+
+                                # so, if it's anything that's not ORM
+                                # mapped, assume we should invoke the
+                                # declared_attr
+                                if not isinstance(ret, InspectionAttr):
+                                    ret = obj.fget()
+                            else:
+                                # access attribute using normal class access.
+                                # if the declared attr already took place
+                                # on a superclass that is mapped, then
+                                # this is no longer a declared_attr, it will
+                                # be the InstrumentedAttribute
+                                ret = getattr(cls, name)
+
+                            # correct for proxies created from hybrid_property
+                            # or similar.  note there is no known case that
+                            # produces nested proxies, so we are only
+                            # looking one level deep right now.
+                            if (
+                                isinstance(ret, InspectionAttr)
+                                and ret._is_internal_proxy
+                                and not isinstance(
+                                    ret.original_property, MapperProperty
+                                )
+                            ):
+                                ret = ret.descriptor
+
+                            dict_[name] = column_copies[obj] = ret
+                        if (
+                            isinstance(ret, (Column, MapperProperty))
+                            and ret.doc is None
+                        ):
+                            ret.doc = obj.__doc__
+                    # here, the attribute is some other kind of property that
+                    # we assume is not part of the declarative mapping.
+                    # however, check for some more common mistakes
+                    else:
+                        self._warn_for_decl_attributes(base, name, obj)
+                elif is_dataclass and (
+                    name not in dict_ or dict_[name] is not obj
+                ):
+                    # here, we are definitely looking at the target class
+                    # and not a superclass.   this is currently a
+                    # dataclass-only path.  if the name is only
+                    # a dataclass field and isn't in local cls.__dict__,
+                    # put the object there.
+                    # assert that the dataclass-enabled resolver agrees
+                    # with what we are seeing
+
+                    assert not attribute_is_overridden(name, obj)
+
+                    if _is_declarative_props(obj):
+                        obj = obj.fget()
+
+                    dict_[name] = obj
+
+        if inherited_table_args and not tablename:
+            table_args = None
+
+        self.table_args = table_args
+        self.tablename = tablename
+        self.mapper_args_fn = mapper_args_fn
+
+    def _warn_for_decl_attributes(self, cls, key, c):
+        if isinstance(c, expression.ColumnClause):
+            util.warn(
+                "Attribute '%s' on class %s appears to be a non-schema "
+                "'sqlalchemy.sql.column()' "
+                "object; this won't be part of the declarative mapping"
+                % (key, cls)
+            )
+
+    def _produce_column_copies(
+        self, attributes_for_class, attribute_is_overridden
+    ):
+        cls = self.cls
+        dict_ = self.dict_
+        locally_collected_attributes = {}
+        column_copies = self.column_copies
+        # copy mixin columns to the mapped class
+
+        for name, obj, is_dataclass in attributes_for_class():
+            if isinstance(obj, Column):
+                if attribute_is_overridden(name, obj):
+                    # if column has been overridden
+                    # (like by the InstrumentedAttribute of the
+                    # superclass), skip
+                    continue
+                elif obj.foreign_keys:
+                    raise exc.InvalidRequestError(
+                        "Columns with foreign keys to other columns "
+                        "must be declared as @declared_attr callables "
+                        "on declarative mixin classes.  For dataclass "
+                        "field() objects, use a lambda:."
+                    )
+                elif name not in dict_ and not (
+                    "__table__" in dict_
+                    and (obj.name or name) in dict_["__table__"].c
+                ):
+                    column_copies[obj] = copy_ = obj._copy()
+                    copy_._creation_order = obj._creation_order
+                    setattr(cls, name, copy_)
+                    locally_collected_attributes[name] = copy_
+        return locally_collected_attributes
+
+    def _extract_mappable_attributes(self):
+        cls = self.cls
+        dict_ = self.dict_
+
+        our_stuff = self.properties
+
+        late_mapped = _get_immediate_cls_attr(
+            cls, "_sa_decl_prepare_nocascade", strict=True
+        )
+
+        for k in list(dict_):
+
+            if k in ("__table__", "__tablename__", "__mapper_args__"):
+                continue
+
+            value = dict_[k]
+            if _is_declarative_props(value):
+                if value._cascading:
+                    util.warn(
+                        "Use of @declared_attr.cascading only applies to "
+                        "Declarative 'mixin' and 'abstract' classes.  "
+                        "Currently, this flag is ignored on mapped class "
+                        "%s" % self.cls
+                    )
+
+                value = getattr(cls, k)
+
+            elif (
+                isinstance(value, QueryableAttribute)
+                and value.class_ is not cls
+                and value.key != k
+            ):
+                # detect a QueryableAttribute that's already mapped being
+                # assigned elsewhere in userland, turn into a synonym()
+                value = SynonymProperty(value.key)
+                setattr(cls, k, value)
+
+            if (
+                isinstance(value, tuple)
+                and len(value) == 1
+                and isinstance(value[0], (Column, MapperProperty))
+            ):
+                util.warn(
+                    "Ignoring declarative-like tuple value of attribute "
+                    "'%s': possibly a copy-and-paste error with a comma "
+                    "accidentally placed at the end of the line?" % k
+                )
+                continue
+            elif not isinstance(value, (Column, MapperProperty)):
+                # using @declared_attr for some object that
+                # isn't Column/MapperProperty; remove from the dict_
+                # and place the evaluated value onto the class.
+                if not k.startswith("__"):
+                    dict_.pop(k)
+                    self._warn_for_decl_attributes(cls, k, value)
+                    if not late_mapped:
+                        setattr(cls, k, value)
+                continue
+            # we expect to see the name 'metadata' in some valid cases;
+            # however at this point we see it's assigned to something trying
+            # to be mapped, so raise for that.
+            elif k == "metadata":
+                raise exc.InvalidRequestError(
+                    "Attribute name 'metadata' is reserved "
+                    "for the MetaData instance when using a "
+                    "declarative base class."
+                )
+            our_stuff[k] = value
+
+    def _extract_declared_columns(self):
+        our_stuff = self.properties
+
+        # set up attributes in the order they were created
+        util.sort_dictionary(
+            our_stuff, key=lambda key: our_stuff[key]._creation_order
+        )
+
+        # extract columns from the class dict
+        declared_columns = self.declared_columns
+        name_to_prop_key = collections.defaultdict(set)
+        for key, c in list(our_stuff.items()):
+            if isinstance(c, (ColumnProperty, CompositeProperty)):
+                for col in c.columns:
+                    if isinstance(col, Column) and col.table is None:
+                        _undefer_column_name(key, col)
+                        if not isinstance(c, CompositeProperty):
+                            name_to_prop_key[col.name].add(key)
+                        declared_columns.add(col)
+            elif isinstance(c, Column):
+                _undefer_column_name(key, c)
+                name_to_prop_key[c.name].add(key)
+                declared_columns.add(c)
+                # if the column is the same name as the key,
+                # remove it from the explicit properties dict.
+                # the normal rules for assigning column-based properties
+                # will take over, including precedence of columns
+                # in multi-column ColumnProperties.
+                if key == c.key:
+                    del our_stuff[key]
+
+        for name, keys in name_to_prop_key.items():
+            if len(keys) > 1:
+                util.warn(
+                    "On class %r, Column object %r named "
+                    "directly multiple times, "
+                    "only one will be used: %s. "
+                    "Consider using orm.synonym instead"
+                    % (self.classname, name, (", ".join(sorted(keys))))
+                )
+
+    def _setup_table(self, table=None):
+        cls = self.cls
+        tablename = self.tablename
+        table_args = self.table_args
+        dict_ = self.dict_
+        declared_columns = self.declared_columns
+
+        manager = attributes.manager_of_class(cls)
+
+        declared_columns = self.declared_columns = sorted(
+            declared_columns, key=lambda c: c._creation_order
+        )
+
+        if "__table__" not in dict_ and table is None:
+            if hasattr(cls, "__table_cls__"):
+                table_cls = util.unbound_method_to_callable(cls.__table_cls__)
+            else:
+                table_cls = Table
+
+            if tablename is not None:
+
+                args, table_kw = (), {}
+                if table_args:
+                    if isinstance(table_args, dict):
+                        table_kw = table_args
+                    elif isinstance(table_args, tuple):
+                        if isinstance(table_args[-1], dict):
+                            args, table_kw = table_args[0:-1], table_args[-1]
+                        else:
+                            args = table_args
+
+                autoload_with = dict_.get("__autoload_with__")
+                if autoload_with:
+                    table_kw["autoload_with"] = autoload_with
+
+                autoload = dict_.get("__autoload__")
+                if autoload:
+                    table_kw["autoload"] = True
+
+                table = self.set_cls_attribute(
+                    "__table__",
+                    table_cls(
+                        tablename,
+                        self._metadata_for_cls(manager),
+                        *(tuple(declared_columns) + tuple(args)),
+                        **table_kw
+                    ),
+                )
+        else:
+            if table is None:
+                table = cls.__table__
+            if declared_columns:
+                for c in declared_columns:
+                    if not table.c.contains_column(c):
+                        raise exc.ArgumentError(
+                            "Can't add additional column %r when "
+                            "specifying __table__" % c.key
+                        )
+        self.local_table = table
+
+    def _metadata_for_cls(self, manager):
+        if hasattr(self.cls, "metadata"):
+            return self.cls.metadata
+        else:
+            return manager.registry.metadata
+
+    def _setup_inheritance(self, mapper_kw):
+        table = self.local_table
+        cls = self.cls
+        table_args = self.table_args
+        declared_columns = self.declared_columns
+
+        inherits = mapper_kw.get("inherits", None)
+
+        if inherits is None:
+            # since we search for classical mappings now, search for
+            # multiple mapped bases as well and raise an error.
+            inherits_search = []
+            for c in cls.__bases__:
+                c = _resolve_for_abstract_or_classical(c)
+                if c is None:
+                    continue
+                if _declared_mapping_info(
+                    c
+                ) is not None and not _get_immediate_cls_attr(
+                    c, "_sa_decl_prepare_nocascade", strict=True
+                ):
+                    if c not in inherits_search:
+                        inherits_search.append(c)
+
+            if inherits_search:
+                if len(inherits_search) > 1:
+                    raise exc.InvalidRequestError(
+                        "Class %s has multiple mapped bases: %r"
+                        % (cls, inherits_search)
+                    )
+                inherits = inherits_search[0]
+        elif isinstance(inherits, mapper):
+            inherits = inherits.class_
+
+        self.inherits = inherits
+
+        if (
+            table is None
+            and self.inherits is None
+            and not _get_immediate_cls_attr(cls, "__no_table__")
+        ):
+
+            raise exc.InvalidRequestError(
+                "Class %r does not have a __table__ or __tablename__ "
+                "specified and does not inherit from an existing "
+                "table-mapped class." % cls
+            )
+        elif self.inherits:
+            inherited_mapper = _declared_mapping_info(self.inherits)
+            inherited_table = inherited_mapper.local_table
+            inherited_persist_selectable = inherited_mapper.persist_selectable
+
+            if table is None:
+                # single table inheritance.
+                # ensure no table args
+                if table_args:
+                    raise exc.ArgumentError(
+                        "Can't place __table_args__ on an inherited class "
+                        "with no table."
+                    )
+                # add any columns declared here to the inherited table.
+                for c in declared_columns:
+                    if c.name in inherited_table.c:
+                        if inherited_table.c[c.name] is c:
+                            continue
+                        raise exc.ArgumentError(
+                            "Column '%s' on class %s conflicts with "
+                            "existing column '%s'"
+                            % (c, cls, inherited_table.c[c.name])
+                        )
+                    if c.primary_key:
+                        raise exc.ArgumentError(
+                            "Can't place primary key columns on an inherited "
+                            "class with no table."
+                        )
+                    inherited_table.append_column(c)
+                    if (
+                        inherited_persist_selectable is not None
+                        and inherited_persist_selectable is not inherited_table
+                    ):
+                        inherited_persist_selectable._refresh_for_new_column(c)
+
+    def _prepare_mapper_arguments(self, mapper_kw):
+        properties = self.properties
+
+        if self.mapper_args_fn:
+            mapper_args = self.mapper_args_fn()
+        else:
+            mapper_args = {}
+
+        if mapper_kw:
+            mapper_args.update(mapper_kw)
+
+        if "properties" in mapper_args:
+            properties = dict(properties)
+            properties.update(mapper_args["properties"])
+
+        # make sure that column copies are used rather
+        # than the original columns from any mixins
+        for k in ("version_id_col", "polymorphic_on"):
+            if k in mapper_args:
+                v = mapper_args[k]
+                mapper_args[k] = self.column_copies.get(v, v)
+
+        if "inherits" in mapper_args:
+            inherits_arg = mapper_args["inherits"]
+            if isinstance(inherits_arg, mapper):
+                inherits_arg = inherits_arg.class_
+
+            if inherits_arg is not self.inherits:
+                raise exc.InvalidRequestError(
+                    "mapper inherits argument given for non-inheriting "
+                    "class %s" % (mapper_args["inherits"])
+                )
+
+        if self.inherits:
+            mapper_args["inherits"] = self.inherits
+
+        if self.inherits and not mapper_args.get("concrete", False):
+            # single or joined inheritance
+            # exclude any cols on the inherited table which are
+            # not mapped on the parent class, to avoid
+            # mapping columns specific to sibling/nephew classes
+            inherited_mapper = _declared_mapping_info(self.inherits)
+            inherited_table = inherited_mapper.local_table
+
+            if "exclude_properties" not in mapper_args:
+                mapper_args["exclude_properties"] = exclude_properties = set(
+                    [
+                        c.key
+                        for c in inherited_table.c
+                        if c not in inherited_mapper._columntoproperty
+                    ]
+                ).union(inherited_mapper.exclude_properties or ())
+                exclude_properties.difference_update(
+                    [c.key for c in self.declared_columns]
+                )
+
+            # look through columns in the current mapper that
+            # are keyed to a propname different than the colname
+            # (if names were the same, we'd have popped it out above,
+            # in which case the mapper makes this combination).
+            # See if the superclass has a similar column property.
+            # If so, join them together.
+            for k, col in list(properties.items()):
+                if not isinstance(col, expression.ColumnElement):
+                    continue
+                if k in inherited_mapper._props:
+                    p = inherited_mapper._props[k]
+                    if isinstance(p, ColumnProperty):
+                        # note here we place the subclass column
+                        # first.  See [ticket:1892] for background.
+                        properties[k] = [col] + p.columns
+        result_mapper_args = mapper_args.copy()
+        result_mapper_args["properties"] = properties
+        self.mapper_args = result_mapper_args
+
+    def map(self, mapper_kw=util.EMPTY_DICT):
+        self._prepare_mapper_arguments(mapper_kw)
+        if hasattr(self.cls, "__mapper_cls__"):
+            mapper_cls = util.unbound_method_to_callable(
+                self.cls.__mapper_cls__
+            )
+        else:
+            mapper_cls = mapper
+
+        return self.set_cls_attribute(
+            "__mapper__",
+            mapper_cls(self.cls, self.local_table, **self.mapper_args),
+        )
+
+
+@util.preload_module("sqlalchemy.orm.decl_api")
+def _as_dc_declaredattr(field_metadata, sa_dataclass_metadata_key):
+    # wrap lambdas inside dataclass fields inside an ad-hoc declared_attr.
+    # we can't write it because field.metadata is immutable :( so we have
+    # to go through extra trouble to compare these
+    decl_api = util.preloaded.orm_decl_api
+    obj = field_metadata[sa_dataclass_metadata_key]
+    if callable(obj) and not isinstance(obj, decl_api.declared_attr):
+        return decl_api.declared_attr(obj)
+    else:
+        return obj
+
+
+class _DeferredMapperConfig(_ClassScanMapperConfig):
+    _configs = util.OrderedDict()
+
+    def _early_mapping(self, mapper_kw):
+        pass
+
+    @property
+    def cls(self):
+        return self._cls()
+
+    @cls.setter
+    def cls(self, class_):
+        self._cls = weakref.ref(class_, self._remove_config_cls)
+        self._configs[self._cls] = self
+
+    @classmethod
+    def _remove_config_cls(cls, ref):
+        cls._configs.pop(ref, None)
+
+    @classmethod
+    def has_cls(cls, class_):
+        # 2.6 fails on weakref if class_ is an old style class
+        return isinstance(class_, type) and weakref.ref(class_) in cls._configs
+
+    @classmethod
+    def raise_unmapped_for_cls(cls, class_):
+        if hasattr(class_, "_sa_raise_deferred_config"):
+            class_._sa_raise_deferred_config()
+
+        raise orm_exc.UnmappedClassError(
+            class_,
+            msg="Class %s has a deferred mapping on it.  It is not yet "
+            "usable as a mapped class." % orm_exc._safe_cls_name(class_),
+        )
+
+    @classmethod
+    def config_for_cls(cls, class_):
+        return cls._configs[weakref.ref(class_)]
+
+    @classmethod
+    def classes_for_base(cls, base_cls, sort=True):
+        classes_for_base = [
+            m
+            for m, cls_ in [(m, m.cls) for m in cls._configs.values()]
+            if cls_ is not None and issubclass(cls_, base_cls)
+        ]
+
+        if not sort:
+            return classes_for_base
+
+        all_m_by_cls = dict((m.cls, m) for m in classes_for_base)
+
+        tuples = []
+        for m_cls in all_m_by_cls:
+            tuples.extend(
+                (all_m_by_cls[base_cls], all_m_by_cls[m_cls])
+                for base_cls in m_cls.__bases__
+                if base_cls in all_m_by_cls
+            )
+        return list(topological.sort(tuples, classes_for_base))
+
+    def map(self, mapper_kw=util.EMPTY_DICT):
+        self._configs.pop(self._cls, None)
+        return super(_DeferredMapperConfig, self).map(mapper_kw)
+
+
+def _add_attribute(cls, key, value):
+    """add an attribute to an existing declarative class.
+
+    This runs through the logic to determine MapperProperty,
+    adds it to the Mapper, adds a column to the mapped Table, etc.
+
+    """
+
+    if "__mapper__" in cls.__dict__:
+        if isinstance(value, Column):
+            _undefer_column_name(key, value)
+            cls.__table__.append_column(value, replace_existing=True)
+            cls.__mapper__.add_property(key, value)
+        elif isinstance(value, ColumnProperty):
+            for col in value.columns:
+                if isinstance(col, Column) and col.table is None:
+                    _undefer_column_name(key, col)
+                    cls.__table__.append_column(col, replace_existing=True)
+            cls.__mapper__.add_property(key, value)
+        elif isinstance(value, MapperProperty):
+            cls.__mapper__.add_property(key, value)
+        elif isinstance(value, QueryableAttribute) and value.key != key:
+            # detect a QueryableAttribute that's already mapped being
+            # assigned elsewhere in userland, turn into a synonym()
+            value = SynonymProperty(value.key)
+            cls.__mapper__.add_property(key, value)
+        else:
+            type.__setattr__(cls, key, value)
+            cls.__mapper__._expire_memoizations()
+    else:
+        type.__setattr__(cls, key, value)
+
+
+def _del_attribute(cls, key):
+
+    if (
+        "__mapper__" in cls.__dict__
+        and key in cls.__dict__
+        and not cls.__mapper__._dispose_called
+    ):
+        value = cls.__dict__[key]
+        if isinstance(
+            value, (Column, ColumnProperty, MapperProperty, QueryableAttribute)
+        ):
+            raise NotImplementedError(
+                "Can't un-map individual mapped attributes on a mapped class."
+            )
+        else:
+            type.__delattr__(cls, key)
+            cls.__mapper__._expire_memoizations()
+    else:
+        type.__delattr__(cls, key)
+
+
+def _declarative_constructor(self, **kwargs):
+    """A simple constructor that allows initialization from kwargs.
+
+    Sets attributes on the constructed instance using the names and
+    values in ``kwargs``.
+
+    Only keys that are present as
+    attributes of the instance's class are allowed. These could be,
+    for example, any mapped columns or relationships.
+    """
+    cls_ = type(self)
+    for k in kwargs:
+        if not hasattr(cls_, k):
+            raise TypeError(
+                "%r is an invalid keyword argument for %s" % (k, cls_.__name__)
+            )
+        setattr(self, k, kwargs[k])
+
+
+_declarative_constructor.__name__ = "__init__"
+
+
+def _undefer_column_name(key, column):
+    if column.key is None:
+        column.key = key
+    if column.name is None:
+        column.name = key