Lots of small bug fixes and DOM API conformance improvements:

Make Node inherit from xml.dom.Node to pick up the NodeType values
defined by the W3C recommendation.

When raising AttributeError, be sure to provide the name of the attribute
that does not exist.

Node.normalize():  Make sure we do not allow an empty text node to survive
                   as the first child; update the sibling links properly.

_getElementsByTagNameNSHelper():  Make recursive calls using the right
                                  number of parameters.

Attr.__setattr__():  Be sure to update name and nodeName at the same time
                     since they are synonyms for this node type.

AttributeList:  Renamed to NamedNodeMap (AttributeList maintained as an
                alias).  Compute the length attribute dynamically to allow
                the underlying structures to mutate.

AttributeList.item():  Call .keys() on the dictionary rather than using
                       self.keys() for performance.

AttributeList.setNamedItem(), .setNamedItemNS():
        Added methods.

Text.splitText():
        Added method.

DocumentType:
        Added implementation class.

DOMImplementation:
        Added implementation class.

Document.appendChild():  Do not allow a second document element to be added.

Document.documentElement:  Find this dynamically, so that one can be
        removed and another added.

Document.unlink():  Clear the doctype attribute.

_get_StringIO():  Only use the StringIO module; cStringIO does not support
                  Unicode.

Lib/xml/dom/minidom.py

 """\
-minidom.py -- a lightweight DOM implementation based on SAX.
+minidom.py -- a lightweight DOM implementation.
 
 parse( "foo.xml" )
 
@@ -27,21 +27,12 @@ except AttributeError:
     _StringTypes = (types.StringType,)
 del types
 
+import xml.dom
+_Node = xml.dom.Node
+del xml
 
-class Node:
-    ELEMENT_NODE                = 1
-    ATTRIBUTE_NODE              = 2
-    TEXT_NODE                   = 3
-    CDATA_SECTION_NODE          = 4
-    ENTITY_REFERENCE_NODE       = 5
-    ENTITY_NODE                 = 6
-    PROCESSING_INSTRUCTION_NODE = 7
-    COMMENT_NODE                = 8
-    DOCUMENT_NODE               = 9
-    DOCUMENT_TYPE_NODE          = 10
-    DOCUMENT_FRAGMENT_NODE      = 11
-    NOTATION_NODE               = 12
 
+class Node(_Node):
     allnodes = {}
     _debug = 0
     _makeParentNodes = 1
@@ -59,7 +50,7 @@ class Node:
 
     def __getattr__(self, key):
         if key[0:2] == "__":
-            raise AttributeError
+            raise AttributeError, key
         # getattr should never call getattr!
         if self.__dict__.has_key("inGetAttr"):
             del self.inGetAttr
@@ -158,25 +149,36 @@ class Node:
         return oldChild
 
     def normalize(self):
-        if len(self.childNodes) > 1:
-            L = [self.childNodes[0]]
-            for child in self.childNodes[1:]:
-                if (  child.nodeType == Node.TEXT_NODE
-                      and L[-1].nodeType == child.nodeType):
+        L = []
+        for child in self.childNodes:
+            if child.nodeType == Node.TEXT_NODE:
+                data = child.data
+                if data and L and L[-1].nodeType == child.nodeType:
                     # collapse text node
                     node = L[-1]
                     node.data = node.nodeValue = node.data + child.data
                     node.nextSibling = child.nextSibling
                     child.unlink()
+                elif data:
+                    if L:
+                        L[-1].nextSibling = child
+                        child.previousSibling = L[-1]
+                    else:
+                        child.previousSibling = None
+                    L.append(child)
                 else:
+                    # empty text node; discard
+                    child.unlink()
+            else:
+                if L:
                     L[-1].nextSibling = child
                     child.previousSibling = L[-1]
-                    L.append(child)
+                else:
+                    child.previousSibling = None
+                L.append(child)
+                if child.nodeType == Node.ELEMENT_NODE:
                     child.normalize()
-            self.childNodes = L
-        elif self.childNodes:
-            # exactly one child -- just recurse
-            self.childNodes[0].normalize()
+        self.childNodes[:] = L
 
     def cloneNode(self, deep):
         import new
@@ -224,7 +226,8 @@ def _getElementsByTagNameNSHelper(parent, nsURI, localName, rc):
             if ((localName == "*" or node.tagName == localName) and
                 (nsURI == "*" or node.namespaceURI == nsURI)):
                 rc.append(node)
-            _getElementsByTagNameNSHelper(node, name, rc)
+            _getElementsByTagNameNSHelper(node, nsURI, localName, rc)
+    return rc
 
 class Attr(Node):
     nodeType = Node.ATTRIBUTE_NODE
@@ -242,10 +245,13 @@ class Attr(Node):
         # nodeValue and value are set elsewhere
 
     def __setattr__(self, name, value):
+        d = self.__dict__
         if name in ("value", "nodeValue"):
-            self.__dict__["value"] = self.__dict__["nodeValue"] = value
+            d["value"] = d["nodeValue"] = value
+        elif name in ("name", "nodeName"):
+            d["name"] = d["nodeName"] = value
         else:
-            self.__dict__[name] = value
+            d[name] = value
 
     def cloneNode(self, deep):
         clone = Node.cloneNode(self, deep)
@@ -253,19 +259,28 @@ class Attr(Node):
             del clone.ownerElement
         return clone
 
-class AttributeList:
+
+class NamedNodeMap:
     """The attribute list is a transient interface to the underlying
     dictionaries.  Mutations here will change the underlying element's
-    dictionary"""
+    dictionary.
+
+    Ordering is imposed artificially and does not reflect the order of
+    attributes as found in an input document.
+    """
 
     def __init__(self, attrs, attrsNS):
         self._attrs = attrs
         self._attrsNS = attrsNS
-        self.length = len(self._attrs)
+
+    def __getattr__(self, name):
+        if name == "length":
+            return len(self._attrs)
+        raise AttributeError, name
 
     def item(self, index):
         try:
-            return self[self.keys()[index]]
+            return self[self._attrs.keys()[index]]
         except IndexError:
             return None
 
@@ -315,17 +330,28 @@ class AttributeList:
             if not isinstance(value, Attr):
                 raise TypeError, "value must be a string or Attr object"
             node = value
-        old = self._attrs.get(attname, None)
+        self.setNamedItem(node)
+
+    def setNamedItem(self, node):
+        old = self._attrs.get(node.name)
         if old:
             old.unlink()
         self._attrs[node.name] = node
         self._attrsNS[(node.namespaceURI, node.localName)] = node
+        return old
+
+    def setNamedItemNS(self, node):
+        return self.setNamedItem(node)
 
     def __delitem__(self, attname_or_tuple):
         node = self[attname_or_tuple]
         node.unlink()
         del self._attrs[node.name]
         del self._attrsNS[(node.namespaceURI, node.localName)]
+        self.length = len(self._attrs)
+
+AttributeList = NamedNodeMap
+
 
 class Element(Node):
     nodeType = Node.ELEMENT_NODE
@@ -495,6 +521,19 @@ class Text(Node):
             dotdotdot = ""
         return "<DOM Text node \"%s%s\">" % (self.data[0:10], dotdotdot)
 
+    def splitText(self, offset):
+        if offset < 0 or offset > len(self.data):
+            raise ValueError, "illegal offset value for splitText()"
+        newText = Text(self.data[offset:])
+        next = self.nextSibling
+        if self.parentNode and self in self.parentNode.childNodes:
+            if next is None:
+                self.parentNode.appendChild(newText)
+            else:
+                self.parentNode.insertBefore(newText, next)
+        self.data = self.data[:offset]
+        return newText
+
     def writexml(self, writer):
         _write_data(writer, self.data)
 
@@ -505,21 +544,84 @@ def _nssplit(qualifiedName):
     elif len(fields) == 1:
         return ('', fields[0])
 
+
+class DocumentType(Node):
+    nodeType = Node.DOCUMENT_TYPE_NODE
+    nodeValue = None
+    attributes = None
+    name = None
+    publicId = None
+    systemId = None
+    internalSubset = ""
+    entities = None
+    notations = None
+
+    def __init__(self, qualifiedName):
+        Node.__init__(self)
+        if qualifiedName:
+            prefix, localname = _nssplit(qualifiedName)
+            self.name = localname
+
+
+class DOMImplementation:
+    def hasFeature(self, feature, version):
+        if version not in ("1.0", "2.0"):
+            return 0
+        feature = _string.lower(feature)
+        return feature == "core"
+
+    def createDocument(self, namespaceURI, qualifiedName, doctype):
+        if doctype and doctype.parentNode is not None:
+            raise ValueError, "doctype object owned by another DOM tree"
+        doc = Document()
+        if doctype is None:
+            doctype = self.createDocumentType(qualifiedName, None, None)
+        if qualifiedName:
+            prefix, localname = _nssplit(qualifiedName)
+            if prefix == "xml" \
+               and namespaceURI != "http://www.w3.org/XML/1998/namespace":
+                raise ValueError, "illegal use of 'xml' prefix"
+            if prefix and not namespaceURI:
+                raise ValueError, "illegal use of prefix without namespaces"
+        doctype.parentNode = doc
+        doc.doctype = doctype
+        doc.implementation = self
+        return doc
+
+    def createDocumentType(self, qualifiedName, publicId, systemId):
+        doctype = DocumentType(qualifiedName)
+        doctype.publicId = publicId
+        doctype.systemId = systemId
+        return doctype
+
+
 class Document(Node):
     nodeType = Node.DOCUMENT_NODE
     nodeName = "#document"
     nodeValue = None
     attributes = None
-    documentElement = None
+    doctype = None
+    parentNode = None
+
+    implementation = DOMImplementation()
 
     def appendChild(self, node):
-        if node.nodeType == Node.ELEMENT_NODE:
-            if self.documentElement:
-                raise TypeError, "Two document elements disallowed"
-            else:
-                self.documentElement = node
+        if node.nodeType == Node.ELEMENT_NODE \
+           and self._get_documentElement():
+            raise TypeError, "two document elements disallowed"
         return Node.appendChild(self, node)
 
+    def _get_documentElement(self):
+        for node in self.childNodes:
+            if node.nodeType == Node.ELEMENT_NODE:
+                return node
+
+    def unlink(self):
+        if self.doctype is not None:
+            self.doctype.unlink()
+            self.doctype = None
+        Node.unlink(self)
+
     createElement = Element
 
     createTextNode = Text
@@ -543,10 +645,6 @@ class Document(Node):
     def getElementsByTagNameNS(self, namespaceURI, localName):
         _getElementsByTagNameNSHelper(self, namespaceURI, localName)
 
-    def unlink(self):
-        self.documentElement = None
-        Node.unlink(self)
-
     def getElementsByTagName(self, name):
         rc = []
         _getElementsByTagNameHelper(self, name, rc)
@@ -557,10 +655,8 @@ class Document(Node):
             node.writexml(writer)
 
 def _get_StringIO():
-    try:
-        from cStringIO import StringIO
-    except ImportError:
-        from StringIO import StringIO
+    # we can't use cStringIO since it doesn't support Unicode strings
+    from StringIO import StringIO
     return StringIO()
 
 def _doparse(func, args, kwargs):
@@ -570,11 +666,11 @@ def _doparse(func, args, kwargs):
     return rootNode
 
 def parse(*args, **kwargs):
-    "Parse a file into a DOM by filename or file object"
+    """Parse a file into a DOM by filename or file object."""
     from xml.dom import pulldom
     return _doparse(pulldom.parse, args, kwargs)
 
 def parseString(*args, **kwargs):
-    "Parse a file into a DOM from a string"
+    """Parse a file into a DOM from a string."""
     from xml.dom import pulldom
     return _doparse(pulldom.parseString, args, kwargs)