| 1 | """Python version compatibility support for minidom."""
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| 2 |
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| 3 | # This module should only be imported using "import *".
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| 4 | #
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| 5 | # The following names are defined:
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| 6 | #
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| 7 | # NodeList -- lightest possible NodeList implementation
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| 8 | #
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| 9 | # EmptyNodeList -- lightest possible NodeList that is guarateed to
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| 10 | # remain empty (immutable)
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| 11 | #
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| 12 | # StringTypes -- tuple of defined string types
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| 13 | #
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| 14 | # defproperty -- function used in conjunction with GetattrMagic;
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| 15 | # using these together is needed to make them work
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| 16 | # as efficiently as possible in both Python 2.2+
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| 17 | # and older versions. For example:
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| 18 | #
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| 19 | # class MyClass(GetattrMagic):
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| 20 | # def _get_myattr(self):
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| 21 | # return something
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| 22 | #
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| 23 | # defproperty(MyClass, "myattr",
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| 24 | # "return some value")
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| 25 | #
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| 26 | # For Python 2.2 and newer, this will construct a
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| 27 | # property object on the class, which avoids
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| 28 | # needing to override __getattr__(). It will only
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| 29 | # work for read-only attributes.
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| 30 | #
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| 31 | # For older versions of Python, inheriting from
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| 32 | # GetattrMagic will use the traditional
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| 33 | # __getattr__() hackery to achieve the same effect,
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| 34 | # but less efficiently.
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| 35 | #
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| 36 | # defproperty() should be used for each version of
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| 37 | # the relevant _get_<property>() function.
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| 38 |
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| 39 | __all__ = ["NodeList", "EmptyNodeList", "StringTypes", "defproperty"]
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| 40 |
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| 41 | import xml.dom
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| 42 |
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| 43 | try:
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| 44 | unicode
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| 45 | except NameError:
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| 46 | StringTypes = type(''),
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| 47 | else:
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| 48 | StringTypes = type(''), type(unicode(''))
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| 49 |
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| 50 |
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| 51 | class NodeList(list):
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| 52 | __slots__ = ()
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| 53 |
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| 54 | def item(self, index):
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| 55 | if 0 <= index < len(self):
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| 56 | return self[index]
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| 57 |
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| 58 | def _get_length(self):
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| 59 | return len(self)
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| 60 |
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| 61 | def _set_length(self, value):
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| 62 | raise xml.dom.NoModificationAllowedErr(
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| 63 | "attempt to modify read-only attribute 'length'")
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| 64 |
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| 65 | length = property(_get_length, _set_length,
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| 66 | doc="The number of nodes in the NodeList.")
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| 67 |
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| 68 | def __getstate__(self):
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| 69 | return list(self)
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| 70 |
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| 71 | def __setstate__(self, state):
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| 72 | self[:] = state
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| 73 |
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| 74 |
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| 75 | class EmptyNodeList(tuple):
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| 76 | __slots__ = ()
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| 77 |
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| 78 | def __add__(self, other):
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| 79 | NL = NodeList()
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| 80 | NL.extend(other)
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| 81 | return NL
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| 82 |
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| 83 | def __radd__(self, other):
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| 84 | NL = NodeList()
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| 85 | NL.extend(other)
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| 86 | return NL
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| 87 |
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| 88 | def item(self, index):
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| 89 | return None
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| 90 |
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| 91 | def _get_length(self):
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| 92 | return 0
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| 93 |
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| 94 | def _set_length(self, value):
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| 95 | raise xml.dom.NoModificationAllowedErr(
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| 96 | "attempt to modify read-only attribute 'length'")
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| 97 |
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| 98 | length = property(_get_length, _set_length,
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| 99 | doc="The number of nodes in the NodeList.")
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| 100 |
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| 101 |
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| 102 | def defproperty(klass, name, doc):
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| 103 | get = getattr(klass, ("_get_" + name)).im_func
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| 104 | def set(self, value, name=name):
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| 105 | raise xml.dom.NoModificationAllowedErr(
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| 106 | "attempt to modify read-only attribute " + repr(name))
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| 107 | assert not hasattr(klass, "_set_" + name), \
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| 108 | "expected not to find _set_" + name
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| 109 | prop = property(get, set, doc=doc)
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| 110 | setattr(klass, name, prop)
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