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1############################################################################## 

2# 

3# Copyright (c) 2003 Zope Corporation and Contributors. 

4# All Rights Reserved. 

5# 

6# This software is subject to the provisions of the Zope Public License, 

7# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution. 

8# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED 

9# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 

10# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS 

11# FOR A PARTICULAR PURPOSE. 

12# 

13############################################################################## 

14 

15 

16def inside(resource1, resource2): 

17 """Is ``resource1`` 'inside' ``resource2``? Return ``True`` if so, else 

18 ``False``. 

19 

20 ``resource1`` is 'inside' ``resource2`` if ``resource2`` is a 

21 :term:`lineage` ancestor of ``resource1``. It is a lineage ancestor 

22 if its parent (or one of its parent's parents, etc.) is an 

23 ancestor. 

24 """ 

25 while resource1 is not None: 

26 if resource1 is resource2: 

27 return True 

28 resource1 = resource1.__parent__ 

29 

30 return False 

31 

32 

33def lineage(resource): 

34 """ 

35 Return a generator representing the :term:`lineage` of the 

36 :term:`resource` object implied by the ``resource`` argument. The 

37 generator first returns ``resource`` unconditionally. Then, if 

38 ``resource`` supplies a ``__parent__`` attribute, return the resource 

39 represented by ``resource.__parent__``. If *that* resource has a 

40 ``__parent__`` attribute, return that resource's parent, and so on, 

41 until the resource being inspected either has no ``__parent__`` 

42 attribute or which has a ``__parent__`` attribute of ``None``. 

43 For example, if the resource tree is:: 

44 

45 thing1 = Thing() 

46 thing2 = Thing() 

47 thing2.__parent__ = thing1 

48 

49 Calling ``lineage(thing2)`` will return a generator. When we turn 

50 it into a list, we will get:: 

51 

52 list(lineage(thing2)) 

53 [ <Thing object at thing2>, <Thing object at thing1> ] 

54 """ 

55 while resource is not None: 

56 yield resource 

57 # The common case is that the AttributeError exception below 

58 # is exceptional as long as the developer is a "good citizen" 

59 # who has a root object with a __parent__ of None. Using an 

60 # exception here instead of a getattr with a default is an 

61 # important micro-optimization, because this function is 

62 # called in any non-trivial application over and over again to 

63 # generate URLs and paths. 

64 try: 

65 resource = resource.__parent__ 

66 except AttributeError: 

67 resource = None