##############################################################################

#

# 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 __future__ import absolute_import

from .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