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184 lines
5.2 KiB
Python
184 lines
5.2 KiB
Python
"""Python version compatibility support for minidom."""
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# This module should only be imported using "import *".
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#
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# The following names are defined:
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#
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# isinstance -- version of the isinstance() function that accepts
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# tuples as the second parameter regardless of the
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# Python version
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#
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# NodeList -- lightest possible NodeList implementation
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#
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# EmptyNodeList -- lightest possible NodeList that is guarateed to
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# remain empty (immutable)
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#
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# StringTypes -- tuple of defined string types
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#
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# GetattrMagic -- base class used to make _get_<attr> be magically
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# invoked when available
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# defproperty -- function used in conjunction with GetattrMagic;
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# using these together is needed to make them work
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# as efficiently as possible in both Python 2.2+
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# and older versions. For example:
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#
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# class MyClass(GetattrMagic):
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# def _get_myattr(self):
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# return something
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#
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# defproperty(MyClass, "myattr",
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# "return some value")
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#
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# For Python 2.2 and newer, this will construct a
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# property object on the class, which avoids
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# needing to override __getattr__(). It will only
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# work for read-only attributes.
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#
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# For older versions of Python, inheriting from
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# GetattrMagic will use the traditional
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# __getattr__() hackery to achieve the same effect,
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# but less efficiently.
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#
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# defproperty() should be used for each version of
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# the relevant _get_<property>() function.
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#
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# NewStyle -- base class to cause __slots__ to be honored in
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# the new world
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#
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# True, False -- only for Python 2.2 and earlier
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__all__ = ["NodeList", "EmptyNodeList", "NewStyle",
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"StringTypes", "defproperty", "GetattrMagic"]
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import xml.dom
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try:
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unicode
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except NameError:
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StringTypes = type(''),
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else:
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StringTypes = type(''), type(unicode(''))
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# define True and False only if not defined as built-ins
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try:
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True
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except NameError:
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True = 1
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False = 0
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__all__.extend(["True", "False"])
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try:
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isinstance('', StringTypes)
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except TypeError:
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#
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# Wrap isinstance() to make it compatible with the version in
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# Python 2.2 and newer.
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#
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_isinstance = isinstance
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def isinstance(obj, type_or_seq):
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try:
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return _isinstance(obj, type_or_seq)
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except TypeError:
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for t in type_or_seq:
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if _isinstance(obj, t):
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return 1
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return 0
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__all__.append("isinstance")
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if list is type([]):
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class NodeList(list):
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__slots__ = ()
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def item(self, index):
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if 0 <= index < len(self):
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return self[index]
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def _get_length(self):
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return len(self)
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def _set_length(self, value):
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raise xml.dom.NoModificationAllowedErr(
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"attempt to modify read-only attribute 'length'")
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length = property(_get_length, _set_length,
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doc="The number of nodes in the NodeList.")
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def __getstate__(self):
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return list(self)
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def __setstate__(self, state):
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self[:] = state
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class EmptyNodeList(tuple):
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__slots__ = ()
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def __add__(self, other):
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NL = NodeList()
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NL.extend(other)
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return NL
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def __radd__(self, other):
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NL = NodeList()
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NL.extend(other)
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return NL
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def item(self, index):
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return None
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def _get_length(self):
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return 0
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def _set_length(self, value):
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raise xml.dom.NoModificationAllowedErr(
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"attempt to modify read-only attribute 'length'")
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length = property(_get_length, _set_length,
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doc="The number of nodes in the NodeList.")
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else:
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def NodeList():
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return []
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def EmptyNodeList():
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return []
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try:
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property
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except NameError:
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def defproperty(klass, name, doc):
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# taken care of by the base __getattr__()
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pass
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class GetattrMagic:
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def __getattr__(self, key):
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if key.startswith("_"):
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raise AttributeError, key
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try:
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get = getattr(self, "_get_" + key)
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except AttributeError:
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raise AttributeError, key
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return get()
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class NewStyle:
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pass
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else:
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def defproperty(klass, name, doc):
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get = getattr(klass, ("_get_" + name)).im_func
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def set(self, value, name=name):
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raise xml.dom.NoModificationAllowedErr(
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"attempt to modify read-only attribute " + repr(name))
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assert not hasattr(klass, "_set_" + name), \
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"expected not to find _set_" + name
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prop = property(get, set, doc=doc)
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setattr(klass, name, prop)
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class GetattrMagic:
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pass
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NewStyle = object
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