##############################################################################
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#
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# Copyright (c) 2003 Zope Corporation and Contributors.
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# All Rights Reserved.
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#
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# This software is subject to the provisions of the Zope Public License,
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# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
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# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
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# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
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# FOR A PARTICULAR PURPOSE.
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#
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##############################################################################
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def inside(resource1, resource2):
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"""Is ``resource1`` 'inside' ``resource2``? Return ``True`` if so, else
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``False``.
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``resource1`` is 'inside' ``resource2`` if ``resource2`` is a
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:term:`lineage` ancestor of ``resource1``. It is a lineage ancestor
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if its parent (or one of its parent's parents, etc.) is an
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ancestor.
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"""
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while resource1 is not None:
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if resource1 is resource2:
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return True
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resource1 = resource1.__parent__
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return False
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def lineage(resource):
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"""
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Return a generator representing the :term:`lineage` of the
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:term:`resource` object implied by the ``resource`` argument. The
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generator first returns ``resource`` unconditionally. Then, if
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``resource`` supplies a ``__parent__`` attribute, return the resource
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represented by ``resource.__parent__``. If *that* resource has a
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``__parent__`` attribute, return that resource's parent, and so on,
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until the resource being inspected either has no ``__parent__``
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attribute or which has a ``__parent__`` attribute of ``None``.
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For example, if the resource tree is::
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thing1 = Thing()
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thing2 = Thing()
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thing2.__parent__ = thing1
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Calling ``lineage(thing2)`` will return a generator. When we turn
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it into a list, we will get::
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list(lineage(thing2))
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[ <Thing object at thing2>, <Thing object at thing1> ]
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"""
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while resource is not None:
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yield resource
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# The common case is that the AttributeError exception below
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# is exceptional as long as the developer is a "good citizen"
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# who has a root object with a __parent__ of None. Using an
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# exception here instead of a getattr with a default is an
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# important micro-optimization, because this function is
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# called in any non-trivial application over and over again to
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# generate URLs and paths.
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try:
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resource = resource.__parent__
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except AttributeError:
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resource = None
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