parser.rb

module Babylon

  ##
  # This is the XML SAX Parser that accepts "pushed" content
  class XmppParser < Nokogiri::XML::SAX::Document
    
    attr_accessor :elem, :doc, :parser
    
    ##
    # Initialize the parser and adds the callback that will be called upon stanza completion
    def initialize(callback)
      super()
      reset
    end
    
    ## 
    # Resets the Pushed SAX Parser.
    def reset
      @parser = Nokogiri::XML::SAX::PushParser.new(self, "UTF-8")
      @elem = @doc = nil
    end
    
    ##
    # Pushes the received data to the parser. The parser will then callback the document's methods (start_tag, end_tag... etc)
    def push(data)
      @parser << data
    end
    
    ##
    # Adds characters to the current element (being parsed)
    def characters(string)
    end
    
    ##
    # Instantiate a new current Element, adds the corresponding attributes and namespaces.
    # The new element is eventually added to a parent element (if present).
    # If no element is being parsed, then, we create a new document, to which we add this new element as root. (we create one document per stanza to avoid memory problems)
    def start_element(qname, attributes = [])
      @doc ||= Nokogiri::XML::Document.new
      @elem ||= @doc # If we have no current element, then, we take the doc
      @elem = @elem.add_child(Nokogiri::XML::Element.new(qname, @doc))
      
      if @elem.name == "stream:stream"
        # We activate the callback since this element  will never end.
        @doc = @elem = nil # Let's prepare for the next stanza
      end
    end
    
    ##
    # Terminates the current element and calls the callback
    def end_element(name)
      if @elem
        if @elem.parent == @doc
          # If we're actually finishing the stanza (a stanza is always a document's root)
          # We delete the current element and the doc (1 doc per stanza policy)
          @elem = @doc = nil 
          @parser = Nokogiri::XML::SAX::PushParser.new(self, "UTF-8")
        else
          @elem = @elem.parent 
        end 
      else 
        # Not sure what to do since it seems we're not processing any element at this time, so how can one end?
      end 
    end 
    
  end 
end