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Viewing changes to Lib/xml/dom/minicompat.py

  • Committer: Bazaar Package Importer
  • Author(s): Matthias Klose
  • Date: 2009-03-23 00:01:27 UTC
  • Revision ID: james.westby@ubuntu.com-20090323000127-5fstfxju4ufrhthq
Tags: upstream-3.1~a1+20090322
Import upstream version 3.1~a1+20090322

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Lib/xml/dom/minicompat.py
 
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"""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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#   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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#   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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__all__ = ["NodeList", "EmptyNodeList", "StringTypes", "defproperty"]
 
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import xml.dom
 
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StringTypes = (str,)
 
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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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def defproperty(klass, name, doc):
 
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    get = getattr(klass, ("_get_" + name))
 
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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)