##############################################################################
#
# Copyright (c) 2002 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Adapter-style interface registry

See Adapter class.
"""
from zope.interface import Declaration

def _flatten(implements, include_None=0):

try:
r = implements.flattened()
except AttributeError:
if implements is None:
r=()
else:
r = Declaration(implements).flattened()

if not include_None:
return r

r = list(r)
r.append(None)
return r