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+"""Python version compatibility support for minidom."""
+
+# This module should only be imported using "import *".
+#
+# The following names are defined:
+#
+# NodeList -- lightest possible NodeList implementation
+#
+# EmptyNodeList -- lightest possible NodeList that is guaranteed to
+# remain empty (immutable)
+#
+# StringTypes -- tuple of defined string types
+#
+# defproperty -- function used in conjunction with GetattrMagic;
+# using these together is needed to make them work
+# as efficiently as possible in both Python 2.2+
+# and older versions. For example:
+#
+# class MyClass(GetattrMagic):
+# def _get_myattr(self):
+# return something
+#
+# defproperty(MyClass, "myattr",
+# "return some value")
+#
+# For Python 2.2 and newer, this will construct a
+# property object on the class, which avoids
+# needing to override __getattr__(). It will only
+# work for read-only attributes.
+#
+# For older versions of Python, inheriting from
+# GetattrMagic will use the traditional
+# __getattr__() hackery to achieve the same effect,
+# but less efficiently.
+#
+# defproperty() should be used for each version of
+# the relevant _get_<property>() function.
+
+__all__ = ["NodeList", "EmptyNodeList", "StringTypes", "defproperty"]
+
+import xml.dom
+
+try:
+ unicode
+except NameError:
+ StringTypes = type(''),
+else:
+ StringTypes = type(''), type(unicode(''))
+
+
+class NodeList(list):
+ __slots__ = ()
+
+ def item(self, index):
+ if 0 <= index < len(self):
+ return self[index]
+
+ def _get_length(self):
+ return len(self)
+
+ def _set_length(self, value):
+ raise xml.dom.NoModificationAllowedErr(
+ "attempt to modify read-only attribute 'length'")
+
+ length = property(_get_length, _set_length,
+ doc="The number of nodes in the NodeList.")
+
+ # For backward compatibility
+ def __setstate__(self, state):
+ if state is None:
+ state = []
+ self[:] = state
+
+
+class EmptyNodeList(tuple):
+ __slots__ = ()
+
+ def __add__(self, other):
+ NL = NodeList()
+ NL.extend(other)
+ return NL
+
+ def __radd__(self, other):
+ NL = NodeList()
+ NL.extend(other)
+ return NL
+
+ def item(self, index):
+ return None
+
+ def _get_length(self):
+ return 0
+
+ def _set_length(self, value):
+ raise xml.dom.NoModificationAllowedErr(
+ "attempt to modify read-only attribute 'length'")
+
+ length = property(_get_length, _set_length,
+ doc="The number of nodes in the NodeList.")
+
+
+def defproperty(klass, name, doc):
+ get = getattr(klass, ("_get_" + name)).im_func
+ def set(self, value, name=name):
+ raise xml.dom.NoModificationAllowedErr(
+ "attempt to modify read-only attribute " + repr(name))
+ assert not hasattr(klass, "_set_" + name), \
+ "expected not to find _set_" + name
+ prop = property(get, set, doc=doc)
+ setattr(klass, name, prop)