1  """Python version compatibility support for minidom.
       2  
       3  This module contains internal implementation details and
       4  should not be imported; use xml.dom.minidom instead.
       5  """
       6  
       7  # This module should only be imported using "import *".
       8  #
       9  # The following names are defined:
      10  #
      11  #   NodeList      -- lightest possible NodeList implementation
      12  #
      13  #   EmptyNodeList -- lightest possible NodeList that is guaranteed to
      14  #                    remain empty (immutable)
      15  #
      16  #   StringTypes   -- tuple of defined string types
      17  #
      18  #   defproperty   -- function used in conjunction with GetattrMagic;
      19  #                    using these together is needed to make them work
      20  #                    as efficiently as possible in both Python 2.2+
      21  #                    and older versions.  For example:
      22  #
      23  #                        class MyClass(GetattrMagic):
      24  #                            def _get_myattr(self):
      25  #                                return something
      26  #
      27  #                        defproperty(MyClass, "myattr",
      28  #                                    "return some value")
      29  #
      30  #                    For Python 2.2 and newer, this will construct a
      31  #                    property object on the class, which avoids
      32  #                    needing to override __getattr__().  It will only
      33  #                    work for read-only attributes.
      34  #
      35  #                    For older versions of Python, inheriting from
      36  #                    GetattrMagic will use the traditional
      37  #                    __getattr__() hackery to achieve the same effect,
      38  #                    but less efficiently.
      39  #
      40  #                    defproperty() should be used for each version of
      41  #                    the relevant _get_<property>() function.
      42  
      43  __all__ = ["NodeList", "EmptyNodeList", "StringTypes", "defproperty"]
      44  
      45  import xml.dom
      46  
      47  StringTypes = (str,)
      48  
      49  
      50  class ESC[4;38;5;81mNodeList(ESC[4;38;5;149mlist):
      51      __slots__ = ()
      52  
      53      def item(self, index):
      54          if 0 <= index < len(self):
      55              return self[index]
      56  
      57      def _get_length(self):
      58          return len(self)
      59  
      60      def _set_length(self, value):
      61          raise xml.dom.NoModificationAllowedErr(
      62              "attempt to modify read-only attribute 'length'")
      63  
      64      length = property(_get_length, _set_length,
      65                        doc="The number of nodes in the NodeList.")
      66  
      67      # For backward compatibility
      68      def __setstate__(self, state):
      69          if state is None:
      70              state = []
      71          self[:] = state
      72  
      73  
      74  class ESC[4;38;5;81mEmptyNodeList(ESC[4;38;5;149mtuple):
      75      __slots__ = ()
      76  
      77      def __add__(self, other):
      78          NL = NodeList()
      79          NL.extend(other)
      80          return NL
      81  
      82      def __radd__(self, other):
      83          NL = NodeList()
      84          NL.extend(other)
      85          return NL
      86  
      87      def item(self, index):
      88          return None
      89  
      90      def _get_length(self):
      91          return 0
      92  
      93      def _set_length(self, value):
      94          raise xml.dom.NoModificationAllowedErr(
      95              "attempt to modify read-only attribute 'length'")
      96  
      97      length = property(_get_length, _set_length,
      98                        doc="The number of nodes in the NodeList.")
      99  
     100  
     101  def defproperty(klass, name, doc):
     102      get = getattr(klass, ("_get_" + name))
     103      def set(self, value, name=name):
     104          raise xml.dom.NoModificationAllowedErr(
     105              "attempt to modify read-only attribute " + repr(name))
     106      assert not hasattr(klass, "_set_" + name), \
     107             "expected not to find _set_" + name
     108      prop = property(get, set, doc=doc)
     109      setattr(klass, name, prop)