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simplexml.py

##   simplexml.py based on Mattew Allum's xmlstream.py
##
##   Copyright (C) 2003-2005 Alexey "Snake" Nezhdanov
##
##   This program is free software; you can redistribute it and/or modify
##   it under the terms of the GNU General Public License as published by
##   the Free Software Foundation; either version 2, or (at your option)
##   any later version.
##
##   This program is distributed in the hope that it will be useful,
##   but WITHOUT ANY WARRANTY; without even the implied warranty of
##   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
##   GNU General Public License for more details.

# $Id: simplexml.py,v 1.27 2005/04/30 07:20:27 snakeru Exp $

"""Simplexml module provides xmpppy library with all needed tools to handle XML nodes and XML streams.
I'm personally using it in many other separate projects. It is designed to be as standalone as possible."""

import xml.parsers.expat

def XMLescape(txt):
      """Returns provided string with symbols & < > " replaced by their respective XML entities."""
      # replace also FORM FEED and ESC, because they are not valid XML chars
      return txt.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;").replace('"', "&quot;").replace(u'\x0C', "").replace(u'\x1B', "")

ENCODING='utf-8'
def ustr(what):
      """Converts object "what" to unicode string using it's own __str__ method if accessible or unicode method otherwise."""
      if type(what) == type(u''): return what
      try: r=what.__str__()
      except AttributeError: r=str(what)
      if type(r)<>type(u''): return unicode(r,ENCODING)
      return r

00036 class Node:
      """ Node class describes syntax of separate XML Node. It have a constructor that permits node creation
            from set of "namespace name", attributes and payload of text strings and other nodes.
            It does not natively support building node from text string and uses NodeBuilder class for that purpose.
            After creation node can be mangled in many ways so it can be completely changed.
            Also node can be serialised into string in one of two modes: default (where the textual representation
            of node describes it exactly) and "fancy" - with whitespace added to make indentation and thus make
            result more readable by human.

            Node class have attribute FORCE_NODE_RECREATION that is defaults to False thus enabling fast node
            replication from the some other node. The drawback of the fast way is that new node shares some
            info with the "original" node that is changing the one node may influence the other. Though it is
            rarely needed (in xmpppy it is never needed at all since I'm usually never using original node after
            replication (and using replication only to move upwards on the classes tree).
      """
      FORCE_NODE_RECREATION=0
00052       def __init__(self, tag=None, attrs={}, payload=[], parent=None, node=None):
            """ Takes "tag" argument as the name of node (prepended by namespace, if needed and separated from it
                  by a space), attrs dictionary as the set of arguments, payload list as the set of textual strings
                  and child nodes that this node carries within itself and "parent" argument that is another node
                  that this one will be the child of. Also the __init__ can be provided with "node" argument that is 
                  either a text string containing exactly one node or another Node instance to begin with. If both
                  "node" and other arguments is provided then the node initially created as replica of "node"
                  provided and then modified to be compliant with other arguments."""
            if node:
                  if self.FORCE_NODE_RECREATION and type(node)==type(self): 
                        node=str(node)
                  if type(node)<>type(self): 
                        node=NodeBuilder(node,self)
                  else:
                        self.name,self.namespace,self.attrs,self.data,self.kids,self.parent = node.name,node.namespace,{},[],[],node.parent
                        for key  in node.attrs.keys(): self.attrs[key]=node.attrs[key]
                        for data in node.data: self.data.append(data)
                        for kid  in node.kids: self.kids.append(kid)
            else: self.name,self.namespace,self.attrs,self.data,self.kids,self.parent = 'tag','',{},[],[],None

            if tag: self.namespace, self.name = ([self.namespace]+tag.split())[-2:]
            if parent: self.parent = parent
            if self.parent and not self.namespace: self.namespace=self.parent.namespace
            for attr in attrs.keys():
                  self.attrs[attr]=attrs[attr]
            if type(payload) in (type(''),type(u'')): payload=[payload]
            for i in payload:
                  if type(i)==type(self): self.addChild(node=i)
                  else: self.data.append(ustr(i))

00082       def __str__(self,fancy=0):
            """ Method used to dump node into textual representation.
                  if "fancy" argument is set to True produces indented output for readability."""
            s = (fancy-1) * 2 * ' ' + "<" + self.name
            if self.namespace:
                  if not self.parent or self.parent.namespace!=self.namespace:
                        s = s + ' xmlns="%s"'%self.namespace
            for key in self.attrs.keys():
                  val = ustr(self.attrs[key])
                  s = s + ' %s="%s"' % ( key, XMLescape(val) )
            s = s + ">"
            cnt = 0 
            if self.kids:
                  if fancy: s = s + "\n"
                  for a in self.kids:
                        if not fancy and (len(self.data)-1)>=cnt: s=s+XMLescape(self.data[cnt])
                        elif (len(self.data)-1)>=cnt: s=s+XMLescape(self.data[cnt].strip())
                        s = s + a.__str__(fancy and fancy+1)
                        cnt=cnt+1
            if not fancy and (len(self.data)-1) >= cnt: s = s + XMLescape(self.data[cnt])
            elif (len(self.data)-1) >= cnt: s = s + XMLescape(self.data[cnt].strip())
            if not self.kids and s[-1:]=='>':
                  s=s[:-1]+' />'
                  if fancy: s = s + "\n"
            else:
                  if fancy and not self.data: s = s + (fancy-1) * 2 * ' '
                  s = s + "</" + self.name + ">"
                  if fancy: s = s + "\n"
            return s
00111       def addChild(self, name=None, attrs={}, payload=[], namespace=None, node=None):
            """ If "node" argument is provided, adds it as child node. Else creates new node from
                  the other arguments' values and adds it as well."""
            if namespace: name=namespace+' '+name
            if node:
                  newnode=node
                  node.parent = self
            else: newnode=Node(tag=name, parent=self, attrs=attrs, payload=payload)
            self.kids.append(newnode)
            return newnode
00121       def addData(self, data):
            """ Adds some CDATA to node. """
            self.data.append(ustr(data))
00124       def clearData(self):
            """ Removes all CDATA from the node. """
            self.data=[]
00127       def delAttr(self, key):
            """ Deletes an attribute "key" """
            del self.attrs[key]
00130       def delChild(self, node, attrs={}):
            """ Deletes the "node" from the node's childs list, if "node" is an instance.
                  Else deletes the first node that have specified name and (optionally) attributes. """
            if type(node)<>type(self): node=self.getTag(node,attrs)
            self.kids.remove(node)
            return node
00136       def getAttrs(self):
            """ Returns all node's attributes as dictionary. """
            return self.attrs
00139       def getAttr(self, key):
            """ Returns value of specified attribute. """
            try: return self.attrs[key]
            except: return None
00143       def getChildren(self):
            """ Returns all node's child nodes as list. """
            return self.kids
00146       def getData(self):
            """ Returns all node CDATA as string (concatenated). """
            return ''.join(self.data)
00149       def getName(self):
            """ Returns the name of node """
            return self.name
00152       def getNamespace(self):
            """ Returns the namespace of node """
            return self.namespace
00155       def getParent(self):
            """ Returns the parent of node (if present). """
            return self.parent
00158       def getPayload(self):
            """ Return the payload of node i.e. list of child nodes and CDATA entries.
                  F.e. for "<node>text1<nodea/><nodeb/> text2</node>" will be returned list:
                  ['text1', <nodea instance>, <nodeb instance>, ' text2']. """
            ret=[]
            for i in range(len(self.kids)+len(self.data)+1):
                  try:
                        if self.data[i]: ret.append(self.data[i])
                  except IndexError: pass
                  try: ret.append(self.kids[i])
                  except IndexError: pass
            return ret
00170       def getTag(self, name, attrs={}, namespace=None): 
            """ Filters all child nodes using specified arguments as filter.
                  Returns the first found or None if not found. """
            return self.getTags(name, attrs, namespace, one=1)
00174       def getTagAttr(self,tag,attr):
            """ Returns attribute value of the child with specified name (or None if no such attribute)."""
            try: return self.getTag(tag).attrs[attr]
            except: return None
00178       def getTagData(self,tag):
            """ Returns cocatenated CDATA of the child with specified name."""
            try: return self.getTag(tag).getData()
            except: return None
00182       def getTags(self, name, attrs={}, namespace=None, one=0):
            """ Filters all child nodes using specified arguments as filter.
                  Returns the list of nodes found. """
            nodes=[]
            for node in self.kids:
                  if namespace and namespace<>node.getNamespace(): continue
                  if node.getName() == name:
                        for key in attrs.keys():
                           if not node.attrs.has_key(key) or node.attrs[key]<>attrs[key]: break
                        else: nodes.append(node)
                  if one and nodes: return nodes[0]
            if not one: return nodes
00194       def setAttr(self, key, val):
            """ Sets attribute "key" with the value "val". """
            self.attrs[key]=val
00197       def setData(self, data):
            """ Sets node's CDATA to provided string. Resets all previous CDATA!"""
            self.data=[ustr(data)]
00200       def setName(self,val):
            """ Changes the node name. """
            self.name = val
00203       def setNamespace(self, namespace):
            """ Changes the node namespace. """
            self.namespace=namespace
00206       def setParent(self, node): 
            """ Sets node's parent to "node". WARNING: do not checks if the parent already present 
                  and not removes the node from the list of childs of previous parent. """
            self.parent = node
00210       def setPayload(self,payload,add=0):
            """ Sets node payload according to the list specified. WARNING: completely replaces all node's
                  previous content. If you wish just to add child or CDATA - use addData or addChild methods. """
            if type(payload) in (type(''),type(u'')): payload=[payload]
            if add: self.kids+=payload
            else: self.kids=payload
00216       def setTag(self, name, attrs={}, namespace=None):
            """ Same as getTag but if the node with specified namespace/attributes not found, creates such
                  node and returns it. """
            node=self.getTags(name, attrs, namespace=namespace, one=1)
            if node: return node
            else: return self.addChild(name, attrs, namespace=namespace)
00222       def setTagAttr(self,tag,attr,val):
            """ Creates new node (if not already present) with name "tag"
                  and sets it's attribute "attr" to value "val". """
            try: self.getTag(tag).attrs[attr]=val
            except: self.addChild(tag,attrs={attr:val})
00227       def setTagData(self,tag,val,attrs={}):
            """ Creates new node (if not already present) with name "tag" and (optionally) attributes "attrs"
                  and sets it's CDATA to string "val". """
            try: self.getTag(tag,attrs).setData(ustr(val))
            except: self.addChild(tag,attrs,payload=[ustr(val)])
00232       def has_attr(self,key):
            """ Checks if node have attribute "key"."""
            return self.attrs.has_key(key)
00235       def __getitem__(self,item):
            """ Returns node's attribute "item" value. """
            return self.getAttr(item)
00238       def __setitem__(self,item,val):
            """ Sets node's attribute "item" value. """
            return self.setAttr(item,val)
00241       def __delitem__(self,item):
            """ Deletes node's attribute "item". """
            return self.delAttr(item,val)
00244       def __getattr__(self,attr):
            """ Reduce memory usage caused by T/NT classes - use memory only when needed. """
            if attr=='T':
                  self.T=T(self)
                  return self.T
            if attr=='NT':
                  self.NT=NT(self)
                  return self.NT
            raise AttributeError

00254 class T:
      """ Auxiliary class used to quick access to node's child nodes. """
      def __init__(self,node): self.__dict__['node']=node
      def __getattr__(self,attr): return self.node.setTag(attr)
      def __setattr__(self,attr,val):
            if isinstance(val,Node): Node.__init__(self.node.setTag(attr),node=val)
            else: return self.node.setTagData(attr,val)
      def __delattr__(self,attr): return self.node.delChild(attr)

00263 class NT(T):
      """ Auxiliary class used to quick create node's child nodes. """
      def __getattr__(self,attr): return self.node.addChild(attr)
      def __setattr__(self,attr,val):
            if isinstance(val,Node): self.node.addChild(attr,node=val)
            else: return self.node.addChild(attr,payload=[val])

DBG_NODEBUILDER = 'nodebuilder'
00271 class NodeBuilder:
      """ Builds a Node class minidom from data parsed to it. This class used for two purposes:
            1. Creation an XML Node from a textual representation. F.e. reading a config file. See an XML2Node method.
            2. Handling an incoming XML stream. This is done by mangling 
               the __dispatch_depth parameter and redefining the dispatch method.
            You do not need to use this class directly if you do not designing your own XML handler."""
00277       def __init__(self,data=None,initial_node=None):
            """ Takes two optional parameters: "data" and "initial_node".
                  By default class initialised with empty Node class instance.
                  Though, if "initial_node" is provided it used as "starting point".
                  You can think about it as of "node upgrade".
                  "data" (if provided) feeded to parser immidiatedly after instance init.
                  """
            self.DEBUG(DBG_NODEBUILDER, "Preparing to handle incoming XML stream.", 'start')
            self._parser = xml.parsers.expat.ParserCreate(namespace_separator=' ')
            self._parser.StartElementHandler       = self.starttag
            self._parser.EndElementHandler         = self.endtag
            self._parser.StartNamespaceDeclHandler = self.handle_namespace_start
            self._parser.CharacterDataHandler    = self.handle_cdata
            self.Parse = self._parser.Parse

            self.__depth = 0
            self._dispatch_depth = 1
            self._document_attrs = None
            self._mini_dom=initial_node
            self.last_is_data = 1
            self._ptr=None
            self.data_buffer = None
            self.namespaces={"http://www.w3.org/XML/1998/namespace":'xml:'}
            self.xmlns="http://www.w3.org/XML/1998/namespace"

            if data: 
                  self._parser.Parse(data,1)
      
      def check_data_buffer(self):
            if self.data_buffer:
                  self._ptr.data.append(''.join(self.data_buffer))
                  del self.data_buffer[:]
                  self.data_buffer = None
      
00311       def destroy(self):
            """ Method used to allow class instance to be garbage-collected. """
            self.check_data_buffer()
            self._parser.StartElementHandler       = None
            self._parser.EndElementHandler         = None
            self._parser.CharacterDataHandler      = None
            self._parser.StartNamespaceDeclHandler = None

00319       def starttag(self, tag, attrs):
            """XML Parser callback. Used internally"""
            self.check_data_buffer()
            attlist=attrs.keys()       #
            for attr in attlist:       # FIXME: Crude hack. And it also slows down the whole library considerably.
                  sp=attr.rfind(" ")     #
                  if sp==-1: continue    #
                  ns=attr[:sp]           #
                  attrs[self.namespaces[ns]+attr[sp+1:]]=attrs[attr]
                  del attrs[attr]        #
            self.__depth += 1
            self.DEBUG(DBG_NODEBUILDER, "DEPTH -> %i , tag -> %s, attrs -> %s" % (self.__depth, tag, `attrs`), 'down')
            if self.__depth == self._dispatch_depth:
                  if not self._mini_dom : 
                        self._mini_dom = Node(tag=tag, attrs=attrs)
                  else: 
                        Node.__init__(self._mini_dom,tag=tag, attrs=attrs)
                  self._ptr = self._mini_dom
            elif self.__depth > self._dispatch_depth:
                  self._ptr.kids.append(Node(tag=tag,parent=self._ptr,attrs=attrs))
                  self._ptr = self._ptr.kids[-1]
            if self.__depth == 1:
                  self._document_attrs = attrs
                  ns, name = (['']+tag.split())[-2:]
                  self.stream_header_received(ns, name, attrs)
            if not self.last_is_data and self._ptr.parent: 
                  self._ptr.parent.data.append('')
            self.last_is_data = 0
00347       def endtag(self, tag ):
            """XML Parser callback. Used internally"""
            self.DEBUG(DBG_NODEBUILDER, "DEPTH -> %i , tag -> %s" % (self.__depth, tag), 'up')
            self.check_data_buffer()
            if self.__depth == self._dispatch_depth:
                  self.dispatch(self._mini_dom)
            elif self.__depth > self._dispatch_depth:
                  self._ptr = self._ptr.parent
            else:
                  self.DEBUG(DBG_NODEBUILDER, "Got higher than dispatch level. Stream terminated?", 'stop')
            self.__depth -= 1
            self.last_is_data = 0
            if self.__depth == 0: self.stream_footer_received()
      
      def handle_cdata(self, data):
            if self.last_is_data:
                  if self.data_buffer:
                        self.data_buffer.append(data)
            else:
                  self.data_buffer = [data]
                  self.last_is_data = 1
      
00369       def handle_namespace_start(self, prefix, uri):
            """XML Parser callback. Used internally"""
            self.check_data_buffer()
            if prefix: self.namespaces[uri]=prefix+':'
            else: self.xmlns=uri
00374       def DEBUG(self, level, text, comment=None):
            """ Gets all NodeBuilder walking events. Can be used for debugging if redefined."""
00376       def getDom(self):
            """ Returns just built Node. """
            self.check_data_buffer()
            return self._mini_dom
00380       def dispatch(self,stanza):
            """ Gets called when the NodeBuilder reaches some level of depth on it's way up with the built
                  node as argument. Can be redefined to convert incoming XML stanzas to program events. """
00383       def stream_header_received(self,ns,tag,attrs):
            """ Method called when stream just opened. """
            self.check_data_buffer()
00386       def stream_footer_received(self):
            """ Method called when stream just closed. """
            self.check_data_buffer()

def XML2Node(xml):
      """ Converts supplied textual string into XML node. Handy f.e. for reading configuration file.
            Raises xml.parser.expat.parsererror if provided string is not well-formed XML. """
      return NodeBuilder(xml).getDom()

def BadXML2Node(xml):
      """ Converts supplied textual string into XML node. Survives if xml data is cutted half way round.
            I.e. "<html>some text <br>some more text". Will raise xml.parser.expat.parsererror on misplaced
            tags though. F.e. "<b>some text <br>some more text</b>" will not work."""
      return NodeBuilder(xml).getDom()

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