#!/usr/bin/python

# Demonstrating SAX-based parsing of XML

from xml.sax import parse, SAXParseException, ContentHandler

class TagInfoHandler( ContentHandler ):
  """Custom xml.sax.ContentHandler"""

  def __init__(self, tagName ):
    ContentHandler.__init__(self)
    self.tagName = tagName
    self.depth = 0 #spaces to indent to show structure

  def startElement( self, name, attributes ):
    #check if this is tag name we're looking for
    if name == self.tagName:
      print "\n%s<%s> started" % ( " " * self.depth, name )
      self.depth += 3
      print "%sAttributes: " % (" " * self.depth )
      for attribute in attributes.getNames():
        print "%s%s = %s" % ( " " * self.depth, attribute,
          attributes.getValue( attribute ) )

  def endElement( self, name ) :
    if name == self.tagName:
      self.depth -= 3
      print "%s</%s> ended\n" % ( " " * self.depth, name )

  def characters( self, content ) :
    content = content.strip()
    if content: print content

def main():
  print "Beginning XML processor..."
  file = raw_input( "Enter a file to parse: " )
  tagname = raw_input( "Enter a tag to search for: " )
  try:
    parse ( file, TagInfoHandler( tagname ) )
  except IOError, message:
    print "Error reading file: ", message
  except SAXParseException, message:
    print "Error parsing file: ", message

if __name__ == "__main__":
  main()