69 lines
2.1 KiB
Python
69 lines
2.1 KiB
Python
##############################################################################
|
|
#
|
|
# Copyright (c) 2003 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.
|
|
#
|
|
##############################################################################
|
|
"""Compute a resolution order for an object and its bases
|
|
"""
|
|
__docformat__ = 'restructuredtext'
|
|
|
|
|
|
def ro(object):
|
|
"""Compute a "resolution order" for an object
|
|
"""
|
|
return mergeOrderings([_flatten(object)])
|
|
|
|
def mergeOrderings(orderings, seen=None):
|
|
"""Merge multiple orderings so that within-ordering order is preserved
|
|
|
|
Orderings are constrained in such a way that if an object appears
|
|
in two or more orderings, then the suffix that begins with the
|
|
object must be in both orderings.
|
|
|
|
For example:
|
|
|
|
>>> mergeOrderings([
|
|
... ['x', 'y', 'z'],
|
|
... ['q', 'z'],
|
|
... [1, 3, 5],
|
|
... ['z']
|
|
... ])
|
|
['x', 'y', 'q', 1, 3, 5, 'z']
|
|
|
|
"""
|
|
|
|
if seen is None:
|
|
seen = {}
|
|
result = []
|
|
orderings.reverse()
|
|
for ordering in orderings:
|
|
ordering = list(ordering)
|
|
ordering.reverse()
|
|
for o in ordering:
|
|
if o not in seen:
|
|
seen[o] = 1
|
|
result.append(o)
|
|
|
|
result.reverse()
|
|
return result
|
|
|
|
def _flatten(ob):
|
|
result = [ob]
|
|
i = 0
|
|
for ob in iter(result):
|
|
i += 1
|
|
# The recursive calls can be avoided by inserting the base classes
|
|
# into the dynamically growing list directly after the currently
|
|
# considered object; the iterator makes sure this will keep working
|
|
# in the future, since it cannot rely on the length of the list
|
|
# by definition.
|
|
result[i:i] = ob.__bases__
|
|
return result
|