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920dae64 AT |
1 | """Python version compatibility support for minidom.""" |
2 | ||
3 | # This module should only be imported using "import *". | |
4 | # | |
5 | # The following names are defined: | |
6 | # | |
7 | # isinstance -- version of the isinstance() function that accepts | |
8 | # tuples as the second parameter regardless of the | |
9 | # Python version | |
10 | # | |
11 | # NodeList -- lightest possible NodeList implementation | |
12 | # | |
13 | # EmptyNodeList -- lightest possible NodeList that is guarateed to | |
14 | # remain empty (immutable) | |
15 | # | |
16 | # StringTypes -- tuple of defined string types | |
17 | # | |
18 | # GetattrMagic -- base class used to make _get_<attr> be magically | |
19 | # invoked when available | |
20 | # defproperty -- function used in conjunction with GetattrMagic; | |
21 | # using these together is needed to make them work | |
22 | # as efficiently as possible in both Python 2.2+ | |
23 | # and older versions. For example: | |
24 | # | |
25 | # class MyClass(GetattrMagic): | |
26 | # def _get_myattr(self): | |
27 | # return something | |
28 | # | |
29 | # defproperty(MyClass, "myattr", | |
30 | # "return some value") | |
31 | # | |
32 | # For Python 2.2 and newer, this will construct a | |
33 | # property object on the class, which avoids | |
34 | # needing to override __getattr__(). It will only | |
35 | # work for read-only attributes. | |
36 | # | |
37 | # For older versions of Python, inheriting from | |
38 | # GetattrMagic will use the traditional | |
39 | # __getattr__() hackery to achieve the same effect, | |
40 | # but less efficiently. | |
41 | # | |
42 | # defproperty() should be used for each version of | |
43 | # the relevant _get_<property>() function. | |
44 | # | |
45 | # NewStyle -- base class to cause __slots__ to be honored in | |
46 | # the new world | |
47 | # | |
48 | # True, False -- only for Python 2.2 and earlier | |
49 | ||
50 | __all__ = ["NodeList", "EmptyNodeList", "NewStyle", | |
51 | "StringTypes", "defproperty", "GetattrMagic"] | |
52 | ||
53 | import xml.dom | |
54 | ||
55 | try: | |
56 | unicode | |
57 | except NameError: | |
58 | StringTypes = type(''), | |
59 | else: | |
60 | StringTypes = type(''), type(unicode('')) | |
61 | ||
62 | ||
63 | # define True and False only if not defined as built-ins | |
64 | try: | |
65 | True | |
66 | except NameError: | |
67 | True = 1 | |
68 | False = 0 | |
69 | __all__.extend(["True", "False"]) | |
70 | ||
71 | ||
72 | try: | |
73 | isinstance('', StringTypes) | |
74 | except TypeError: | |
75 | # | |
76 | # Wrap isinstance() to make it compatible with the version in | |
77 | # Python 2.2 and newer. | |
78 | # | |
79 | _isinstance = isinstance | |
80 | def isinstance(obj, type_or_seq): | |
81 | try: | |
82 | return _isinstance(obj, type_or_seq) | |
83 | except TypeError: | |
84 | for t in type_or_seq: | |
85 | if _isinstance(obj, t): | |
86 | return 1 | |
87 | return 0 | |
88 | __all__.append("isinstance") | |
89 | ||
90 | ||
91 | if list is type([]): | |
92 | class NodeList(list): | |
93 | __slots__ = () | |
94 | ||
95 | def item(self, index): | |
96 | if 0 <= index < len(self): | |
97 | return self[index] | |
98 | ||
99 | def _get_length(self): | |
100 | return len(self) | |
101 | ||
102 | def _set_length(self, value): | |
103 | raise xml.dom.NoModificationAllowedErr( | |
104 | "attempt to modify read-only attribute 'length'") | |
105 | ||
106 | length = property(_get_length, _set_length, | |
107 | doc="The number of nodes in the NodeList.") | |
108 | ||
109 | def __getstate__(self): | |
110 | return list(self) | |
111 | ||
112 | def __setstate__(self, state): | |
113 | self[:] = state | |
114 | ||
115 | class EmptyNodeList(tuple): | |
116 | __slots__ = () | |
117 | ||
118 | def __add__(self, other): | |
119 | NL = NodeList() | |
120 | NL.extend(other) | |
121 | return NL | |
122 | ||
123 | def __radd__(self, other): | |
124 | NL = NodeList() | |
125 | NL.extend(other) | |
126 | return NL | |
127 | ||
128 | def item(self, index): | |
129 | return None | |
130 | ||
131 | def _get_length(self): | |
132 | return 0 | |
133 | ||
134 | def _set_length(self, value): | |
135 | raise xml.dom.NoModificationAllowedErr( | |
136 | "attempt to modify read-only attribute 'length'") | |
137 | ||
138 | length = property(_get_length, _set_length, | |
139 | doc="The number of nodes in the NodeList.") | |
140 | ||
141 | else: | |
142 | def NodeList(): | |
143 | return [] | |
144 | ||
145 | def EmptyNodeList(): | |
146 | return [] | |
147 | ||
148 | ||
149 | try: | |
150 | property | |
151 | except NameError: | |
152 | def defproperty(klass, name, doc): | |
153 | # taken care of by the base __getattr__() | |
154 | pass | |
155 | ||
156 | class GetattrMagic: | |
157 | def __getattr__(self, key): | |
158 | if key.startswith("_"): | |
159 | raise AttributeError, key | |
160 | ||
161 | try: | |
162 | get = getattr(self, "_get_" + key) | |
163 | except AttributeError: | |
164 | raise AttributeError, key | |
165 | return get() | |
166 | ||
167 | class NewStyle: | |
168 | pass | |
169 | ||
170 | else: | |
171 | def defproperty(klass, name, doc): | |
172 | get = getattr(klass, ("_get_" + name)).im_func | |
173 | def set(self, value, name=name): | |
174 | raise xml.dom.NoModificationAllowedErr( | |
175 | "attempt to modify read-only attribute " + repr(name)) | |
176 | assert not hasattr(klass, "_set_" + name), \ | |
177 | "expected not to find _set_" + name | |
178 | prop = property(get, set, doc=doc) | |
179 | setattr(klass, name, prop) | |
180 | ||
181 | class GetattrMagic: | |
182 | pass | |
183 | ||
184 | NewStyle = object |