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+# sqlalchemy/sql/events.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
+
+from .base import SchemaEventTarget
+from .. import event
+
+
+class DDLEvents(event.Events):
+    """
+    Define event listeners for schema objects,
+    that is, :class:`.SchemaItem` and other :class:`.SchemaEventTarget`
+    subclasses, including :class:`_schema.MetaData`, :class:`_schema.Table`,
+    :class:`_schema.Column`.
+
+    :class:`_schema.MetaData` and :class:`_schema.Table` support events
+    specifically regarding when CREATE and DROP
+    DDL is emitted to the database.
+
+    Attachment events are also provided to customize
+    behavior whenever a child schema element is associated
+    with a parent, such as, when a :class:`_schema.Column` is associated
+    with its :class:`_schema.Table`, when a
+    :class:`_schema.ForeignKeyConstraint`
+    is associated with a :class:`_schema.Table`, etc.
+
+    Example using the ``after_create`` event::
+
+        from sqlalchemy import event
+        from sqlalchemy import Table, Column, Metadata, Integer
+
+        m = MetaData()
+        some_table = Table('some_table', m, Column('data', Integer))
+
+        def after_create(target, connection, **kw):
+            connection.execute(text(
+                "ALTER TABLE %s SET name=foo_%s" % (target.name, target.name)
+            ))
+
+        event.listen(some_table, "after_create", after_create)
+
+    DDL events integrate closely with the
+    :class:`.DDL` class and the :class:`.DDLElement` hierarchy
+    of DDL clause constructs, which are themselves appropriate
+    as listener callables::
+
+        from sqlalchemy import DDL
+        event.listen(
+            some_table,
+            "after_create",
+            DDL("ALTER TABLE %(table)s SET name=foo_%(table)s")
+        )
+
+    The methods here define the name of an event as well
+    as the names of members that are passed to listener
+    functions.
+
+    For all :class:`.DDLEvent` events, the ``propagate=True`` keyword argument
+    will ensure that a given event handler is propagated to copies of the
+    object, which are made when using the :meth:`_schema.Table.to_metadata`
+    method::
+
+        from sqlalchemy import DDL
+        event.listen(
+            some_table,
+            "after_create",
+            DDL("ALTER TABLE %(table)s SET name=foo_%(table)s"),
+            propagate=True
+        )
+
+        new_table = some_table.to_metadata(new_metadata)
+
+    The above :class:`.DDL` object will also be associated with the
+    :class:`_schema.Table` object represented by ``new_table``.
+
+    .. seealso::
+
+        :ref:`event_toplevel`
+
+        :class:`.DDLElement`
+
+        :class:`.DDL`
+
+        :ref:`schema_ddl_sequences`
+
+    """
+
+    _target_class_doc = "SomeSchemaClassOrObject"
+    _dispatch_target = SchemaEventTarget
+
+    def before_create(self, target, connection, **kw):
+        r"""Called before CREATE statements are emitted.
+
+        :param target: the :class:`_schema.MetaData` or :class:`_schema.Table`
+         object which is the target of the event.
+        :param connection: the :class:`_engine.Connection` where the
+         CREATE statement or statements will be emitted.
+        :param \**kw: additional keyword arguments relevant
+         to the event.  The contents of this dictionary
+         may vary across releases, and include the
+         list of tables being generated for a metadata-level
+         event, the checkfirst flag, and other
+         elements used by internal events.
+
+        :func:`.event.listen` accepts the ``propagate=True``
+        modifier for this event; when True, the listener function will
+        be established for any copies made of the target object,
+        i.e. those copies that are generated when
+        :meth:`_schema.Table.to_metadata` is used.
+
+        :func:`.event.listen` accepts the ``insert=True``
+        modifier for this event; when True, the listener function will
+        be prepended to the internal list of events upon discovery, and execute
+        before registered listener functions that do not pass this argument.
+
+        """
+
+    def after_create(self, target, connection, **kw):
+        r"""Called after CREATE statements are emitted.
+
+        :param target: the :class:`_schema.MetaData` or :class:`_schema.Table`
+         object which is the target of the event.
+        :param connection: the :class:`_engine.Connection` where the
+         CREATE statement or statements have been emitted.
+        :param \**kw: additional keyword arguments relevant
+         to the event.  The contents of this dictionary
+         may vary across releases, and include the
+         list of tables being generated for a metadata-level
+         event, the checkfirst flag, and other
+         elements used by internal events.
+
+        :func:`.event.listen` also accepts the ``propagate=True``
+        modifier for this event; when True, the listener function will
+        be established for any copies made of the target object,
+        i.e. those copies that are generated when
+        :meth:`_schema.Table.to_metadata` is used.
+
+        """
+
+    def before_drop(self, target, connection, **kw):
+        r"""Called before DROP statements are emitted.
+
+        :param target: the :class:`_schema.MetaData` or :class:`_schema.Table`
+         object which is the target of the event.
+        :param connection: the :class:`_engine.Connection` where the
+         DROP statement or statements will be emitted.
+        :param \**kw: additional keyword arguments relevant
+         to the event.  The contents of this dictionary
+         may vary across releases, and include the
+         list of tables being generated for a metadata-level
+         event, the checkfirst flag, and other
+         elements used by internal events.
+
+        :func:`.event.listen` also accepts the ``propagate=True``
+        modifier for this event; when True, the listener function will
+        be established for any copies made of the target object,
+        i.e. those copies that are generated when
+        :meth:`_schema.Table.to_metadata` is used.
+
+        """
+
+    def after_drop(self, target, connection, **kw):
+        r"""Called after DROP statements are emitted.
+
+        :param target: the :class:`_schema.MetaData` or :class:`_schema.Table`
+         object which is the target of the event.
+        :param connection: the :class:`_engine.Connection` where the
+         DROP statement or statements have been emitted.
+        :param \**kw: additional keyword arguments relevant
+         to the event.  The contents of this dictionary
+         may vary across releases, and include the
+         list of tables being generated for a metadata-level
+         event, the checkfirst flag, and other
+         elements used by internal events.
+
+        :func:`.event.listen` also accepts the ``propagate=True``
+        modifier for this event; when True, the listener function will
+        be established for any copies made of the target object,
+        i.e. those copies that are generated when
+        :meth:`_schema.Table.to_metadata` is used.
+
+        """
+
+    def before_parent_attach(self, target, parent):
+        """Called before a :class:`.SchemaItem` is associated with
+        a parent :class:`.SchemaItem`.
+
+        :param target: the target object
+        :param parent: the parent to which the target is being attached.
+
+        :func:`.event.listen` also accepts the ``propagate=True``
+        modifier for this event; when True, the listener function will
+        be established for any copies made of the target object,
+        i.e. those copies that are generated when
+        :meth:`_schema.Table.to_metadata` is used.
+
+        """
+
+    def after_parent_attach(self, target, parent):
+        """Called after a :class:`.SchemaItem` is associated with
+        a parent :class:`.SchemaItem`.
+
+        :param target: the target object
+        :param parent: the parent to which the target is being attached.
+
+        :func:`.event.listen` also accepts the ``propagate=True``
+        modifier for this event; when True, the listener function will
+        be established for any copies made of the target object,
+        i.e. those copies that are generated when
+        :meth:`_schema.Table.to_metadata` is used.
+
+        """
+
+    def _sa_event_column_added_to_pk_constraint(self, const, col):
+        """internal event hook used for primary key naming convention
+        updates.
+
+        """
+
+    def column_reflect(self, inspector, table, column_info):
+        """Called for each unit of 'column info' retrieved when
+        a :class:`_schema.Table` is being reflected.
+
+        This event is most easily used by applying it to a specific
+        :class:`_schema.MetaData` instance, where it will take effect for
+        all :class:`_schema.Table` objects within that
+        :class:`_schema.MetaData` that undergo reflection::
+
+            metadata = MetaData()
+
+            @event.listens_for(metadata, 'column_reflect')
+            def receive_column_reflect(inspector, table, column_info):
+                # receives for all Table objects that are reflected
+                # under this MetaData
+
+
+            # will use the above event hook
+            my_table = Table("my_table", metadata, autoload_with=some_engine)
+
+
+        .. versionadded:: 1.4.0b2 The :meth:`_events.DDLEvents.column_reflect`
+           hook may now be applied to a :class:`_schema.MetaData` object as
+           well as the :class:`_schema.MetaData` class itself where it will
+           take place for all :class:`_schema.Table` objects associated with
+           the targeted :class:`_schema.MetaData`.
+
+        It may also be applied to the :class:`_schema.Table` class across
+        the board::
+
+            from sqlalchemy import Table
+
+            @event.listens_for(Table, 'column_reflect')
+            def receive_column_reflect(inspector, table, column_info):
+                # receives for all Table objects that are reflected
+
+        It can also be applied to a specific :class:`_schema.Table` at the
+        point that one is being reflected using the
+        :paramref:`_schema.Table.listeners` parameter::
+
+            t1 = Table(
+                "my_table",
+                autoload_with=some_engine,
+                listeners=[
+                    ('column_reflect', receive_column_reflect)
+                ]
+            )
+
+        A future release will allow it to be associated with a specific
+        :class:`_schema.MetaData` object as well.
+
+        The dictionary of column information as returned by the
+        dialect is passed, and can be modified.  The dictionary
+        is that returned in each element of the list returned
+        by :meth:`.reflection.Inspector.get_columns`:
+
+            * ``name`` - the column's name, is applied to the
+              :paramref:`_schema.Column.name` parameter
+
+            * ``type`` - the type of this column, which should be an instance
+              of :class:`~sqlalchemy.types.TypeEngine`, is applied to the
+              :paramref:`_schema.Column.type` parameter
+
+            * ``nullable`` - boolean flag if the column is NULL or NOT NULL,
+              is applied to the :paramref:`_schema.Column.nullable` parameter
+
+            * ``default`` - the column's server default value.  This is
+              normally specified as a plain string SQL expression, however the
+              event can pass a :class:`.FetchedValue`, :class:`.DefaultClause`,
+              or :func:`_expression.text` object as well.  Is applied to the
+              :paramref:`_schema.Column.server_default` parameter
+
+        The event is called before any action is taken against
+        this dictionary, and the contents can be modified; the following
+        additional keys may be added to the dictionary to further modify
+        how the :class:`_schema.Column` is constructed:
+
+
+            * ``key`` - the string key that will be used to access this
+              :class:`_schema.Column` in the ``.c`` collection; will be applied
+              to the :paramref:`_schema.Column.key` parameter. Is also used
+              for ORM mapping.  See the section
+              :ref:`mapper_automated_reflection_schemes` for an example.
+
+            * ``quote`` - force or un-force quoting on the column name;
+              is applied to the :paramref:`_schema.Column.quote` parameter.
+
+            * ``info`` - a dictionary of arbitrary data to follow along with
+              the :class:`_schema.Column`, is applied to the
+              :paramref:`_schema.Column.info` parameter.
+
+        :func:`.event.listen` also accepts the ``propagate=True``
+        modifier for this event; when True, the listener function will
+        be established for any copies made of the target object,
+        i.e. those copies that are generated when
+        :meth:`_schema.Table.to_metadata` is used.
+
+        .. seealso::
+
+            :ref:`mapper_automated_reflection_schemes` -
+            in the ORM mapping documentation
+
+            :ref:`automap_intercepting_columns` -
+            in the :ref:`automap_toplevel` documentation
+
+            :ref:`metadata_reflection_dbagnostic_types` - in
+            the :ref:`metadata_reflection_toplevel` documentation
+
+        """