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Diffstat (limited to 'lib/python2.7/xml/dom/minicompat.py')
-rw-r--r-- | lib/python2.7/xml/dom/minicompat.py | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/lib/python2.7/xml/dom/minicompat.py b/lib/python2.7/xml/dom/minicompat.py new file mode 100644 index 0000000..266a7f4 --- /dev/null +++ b/lib/python2.7/xml/dom/minicompat.py @@ -0,0 +1,110 @@ +"""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) |