In Files

  • rexml/parsers/baseparser.rb

REXML::Parsers::BaseParser

Using the Pull Parser

This API is experimental, and subject to change.

parser = PullParser.new( "<a>text<b att='val'/>txet</a>" )
while parser.has_next?
  res = parser.next
  puts res[1]['att'] if res.start_tag? and res[0] == 'b'
end

See the PullEvent class for information on the content of the results. The data is identical to the arguments passed for the various events to the StreamListener API.

Notice that:

parser = PullParser.new( "<a>BAD DOCUMENT" )
while parser.has_next?
  res = parser.next
  raise res[1] if res.error?
end

Nat Price gave me some good ideas for the API.

Attributes

source[R]

Public Class Methods

new( source ) click to toggle source
 
               # File rexml/parsers/baseparser.rb, line 122
def initialize( source )
  self.stream = source
end
            

Public Instance Methods

add_listener( listener ) click to toggle source
 
               # File rexml/parsers/baseparser.rb, line 126
def add_listener( listener )
  if !defined?(@listeners) or !@listeners
    @listeners = []
    instance_eval <<-EOL
      alias :_old_pull :pull
      def pull
        event = _old_pull
        @listeners.each do |listener|
          listener.receive event
        end
        event
      end
    EOL
  end
  @listeners << listener
end
            
empty?() click to toggle source

Returns true if there are no more events

 
               # File rexml/parsers/baseparser.rb, line 165
def empty?
  return (@source.empty? and @stack.empty?)
end
            
entity( reference, entities ) click to toggle source
 
               # File rexml/parsers/baseparser.rb, line 453
def entity( reference, entities )
  value = nil
  value = entities[ reference ] if entities
  if not value
    value = DEFAULT_ENTITIES[ reference ]
    value = value[2] if value
  end
  unnormalize( value, entities ) if value
end
            
has_next?() click to toggle source

Returns true if there are more events. Synonymous with !empty?

 
               # File rexml/parsers/baseparser.rb, line 170
def has_next?
  return !(@source.empty? and @stack.empty?)
end
            
normalize( input, entities=nil, entity_filter=nil ) click to toggle source

Escapes all possible entities

 
               # File rexml/parsers/baseparser.rb, line 464
def normalize( input, entities=nil, entity_filter=nil )
  copy = input.clone
  # Doing it like this rather than in a loop improves the speed
  copy.gsub!( EREFERENCE, '&amp;' )
  entities.each do |key, value|
    copy.gsub!( value, "&#{key};" ) unless entity_filter and 
                                entity_filter.include?(entity)
  end if entities
  copy.gsub!( EREFERENCE, '&amp;' )
  DEFAULT_ENTITIES.each do |key, value|
    copy.gsub!( value[3], value[1] )
  end
  copy
end
            
peek(depth=0) click to toggle source

Peek at the depth event in the stack. The first element on the stack is at depth 0. If depth is -1, will parse to the end of the input stream and return the last event, which is always :end_document. Be aware that this causes the stream to be parsed up to the depth event, so you can effectively pre-parse the entire document (pull the entire thing into memory) using this method.

 
               # File rexml/parsers/baseparser.rb, line 186
def peek depth=0
  raise %Q[Illegal argument "#{depth}"] if depth < -1
  temp = []
  if depth == -1
    temp.push(pull()) until empty?
  else
    while @stack.size+temp.size < depth+1
      temp.push(pull())
    end
  end
  @stack += temp if temp.size > 0
  @stack[depth]
end
            
position() click to toggle source
 
               # File rexml/parsers/baseparser.rb, line 155
def position
  if @source.respond_to? :position
    @source.position
  else
    # FIXME
    0
  end
end
            
pull() click to toggle source

Returns the next event. This is a PullEvent object.

 
               # File rexml/parsers/baseparser.rb, line 201
def pull
  if @closed
    x, @closed = @closed, nil
    return [ :end_element, x ]
  end
  return [ :end_document ] if empty?
  return @stack.shift if @stack.size > 0
  #STDERR.puts @source.encoding
  @source.read if @source.buffer.size<2
  #STDERR.puts "BUFFER = #{@source.buffer.inspect}"
  if @document_status == nil
    #@source.consume( /^\s*/um )
    word = @source.match( /^((?:\s+)|(?:<[^>]*>))/um )
    word = word[1] unless word.nil?
    #STDERR.puts "WORD = #{word.inspect}"
    case word
    when COMMENT_START
      return [ :comment, @source.match( COMMENT_PATTERN, true )[1] ]
    when XMLDECL_START
      #STDERR.puts "XMLDECL"
      results = @source.match( XMLDECL_PATTERN, true )[1]
      version = VERSION.match( results )
      version = version[1] unless version.nil?
      encoding = ENCODING.match(results)
      encoding = encoding[1] unless encoding.nil?
      @source.encoding = encoding
      standalone = STANDALONE.match(results)
      standalone = standalone[1] unless standalone.nil?
      return [ :xmldecl, version, encoding, standalone ]
    when INSTRUCTION_START
      return [ :processing_instruction, *@source.match(INSTRUCTION_PATTERN, true)[1,2] ]
    when DOCTYPE_START
      md = @source.match( DOCTYPE_PATTERN, true )
      @nsstack.unshift(curr_ns=Set.new)
      identity = md[1]
      close = md[2]
      identity =~ IDENTITY
      name = $1
      raise REXML::ParseException.new("DOCTYPE is missing a name") if name.nil?
      pub_sys = $2.nil? ? nil : $2.strip
      long_name = $4.nil? ? nil : $4.strip
      uri = $6.nil? ? nil : $6.strip
      args = [ :start_doctype, name, pub_sys, long_name, uri ]
      if close == ">"
        @document_status = :after_doctype
        @source.read if @source.buffer.size<2
        md = @source.match(/^\s*/um, true)
        @stack << [ :end_doctype ]
      else
        @document_status = :in_doctype
      end
      return args
    when /^\s+/
    else
      @document_status = :after_doctype
      @source.read if @source.buffer.size<2
      md = @source.match(/\s*/um, true)
      if @source.encoding == "UTF-8"
        if @source.buffer.respond_to? :force_encoding
          @source.buffer.force_encoding(Encoding::UTF_8)
        end
      end
    end
  end
  if @document_status == :in_doctype
    md = @source.match(/\s*(.*?>)/um)
    case md[1]
    when SYSTEMENTITY 
      match = @source.match( SYSTEMENTITY, true )[1]
      return [ :externalentity, match ]

    when ELEMENTDECL_START
      return [ :elementdecl, @source.match( ELEMENTDECL_PATTERN, true )[1] ]

    when ENTITY_START
      match = @source.match( ENTITYDECL, true ).to_a.compact
      match[0] = :entitydecl
      ref = false
      if match[1] == '%'
        ref = true
        match.delete_at 1
      end
      # Now we have to sort out what kind of entity reference this is
      if match[2] == 'SYSTEM'
        # External reference
        match[3] = match[3][1..-2] # PUBID
        match.delete_at(4) if match.size > 4 # Chop out NDATA decl
        # match is [ :entity, name, SYSTEM, pubid(, ndata)? ]
      elsif match[2] == 'PUBLIC'
        # External reference
        match[3] = match[3][1..-2] # PUBID
        match[4] = match[4][1..-2] # HREF
        # match is [ :entity, name, PUBLIC, pubid, href ]
      else
        match[2] = match[2][1..-2]
        match.pop if match.size == 4
        # match is [ :entity, name, value ]
      end
      match << '%' if ref
      return match
    when ATTLISTDECL_START
      md = @source.match( ATTLISTDECL_PATTERN, true )
      raise REXML::ParseException.new( "Bad ATTLIST declaration!", @source ) if md.nil?
      element = md[1]
      contents = md[0]

      pairs = {}
      values = md[0].scan( ATTDEF_RE )
      values.each do |attdef|
        unless attdef[3] == "#IMPLIED"
          attdef.compact!
          val = attdef[3]
          val = attdef[4] if val == "#FIXED "
          pairs[attdef[0]] = val
          if attdef[0] =~ /^xmlns:(.*)/
            @nsstack[0] << $1
          end
        end
      end
      return [ :attlistdecl, element, pairs, contents ]
    when NOTATIONDECL_START
      md = nil
      if @source.match( PUBLIC )
        md = @source.match( PUBLIC, true )
        vals = [md[1],md[2],md[4],md[6]]
      elsif @source.match( SYSTEM )
        md = @source.match( SYSTEM, true )
        vals = [md[1],md[2],nil,md[4]]
      else
        raise REXML::ParseException.new( "error parsing notation: no matching pattern", @source )
      end
      return [ :notationdecl, *vals ]
    when CDATA_END
      @document_status = :after_doctype
      @source.match( CDATA_END, true )
      return [ :end_doctype ]
    end
  end
  begin
    if @source.buffer[0] == ?<
      if @source.buffer[1] == ?/
        @nsstack.shift
        last_tag = @tags.pop
        #md = @source.match_to_consume( '>', CLOSE_MATCH)
        md = @source.match( CLOSE_MATCH, true )
        raise REXML::ParseException.new( "Missing end tag for "+
          "'#{last_tag}' (got \"#{md[1]}\")", 
          @source) unless last_tag == md[1]
        return [ :end_element, last_tag ]
      elsif @source.buffer[1] == ?!
        md = @source.match(/\A(\s*[^>]*>)/um)
        #STDERR.puts "SOURCE BUFFER = #{source.buffer}, #{source.buffer.size}"
        raise REXML::ParseException.new("Malformed node", @source) unless md
        if md[0][2] == ?-
          md = @source.match( COMMENT_PATTERN, true )

          case md[1]
          when /--/, /-$/
            raise REXML::ParseException.new("Malformed comment", @source)
          end

          return [ :comment, md[1] ] if md
        else
          md = @source.match( CDATA_PATTERN, true )
          return [ :cdata, md[1] ] if md
        end
        raise REXML::ParseException.new( "Declarations can only occur "+
          "in the doctype declaration.", @source)
      elsif @source.buffer[1] == ??
        md = @source.match( INSTRUCTION_PATTERN, true )
        return [ :processing_instruction, md[1], md[2] ] if md
        raise REXML::ParseException.new( "Bad instruction declaration",
          @source)
      else
        # Get the next tag
        md = @source.match(TAG_MATCH, true)
        unless md
          # Check for missing attribute quotes
          raise REXML::ParseException.new("missing attribute quote", @source) if @source.match(MISSING_ATTRIBUTE_QUOTES )
          raise REXML::ParseException.new("malformed XML: missing tag start", @source) 
        end
        attributes = {}
        prefixes = Set.new
        prefixes << md[2] if md[2]
        @nsstack.unshift(curr_ns=Set.new)
        if md[4].size > 0
          attrs = md[4].scan( ATTRIBUTE_PATTERN )
          raise REXML::ParseException.new( "error parsing attributes: [#{attrs.join ', '}], excess = \"#$'\"", @source) if $' and $'.strip.size > 0
          attrs.each { |a,b,c,d,e| 
            if b == "xmlns"
              if c == "xml"
                if d != "http://www.w3.org/XML/1998/namespace"
                  msg = "The 'xml' prefix must not be bound to any other namespace "+
                  "(http://www.w3.org/TR/REC-xml-names/#ns-decl)"
                  raise REXML::ParseException.new( msg, @source, self )
                end
              elsif c == "xmlns"
                msg = "The 'xmlns' prefix must not be declared "+
                "(http://www.w3.org/TR/REC-xml-names/#ns-decl)"
                raise REXML::ParseException.new( msg, @source, self)
              end
              curr_ns << c
            elsif b
              prefixes << b unless b == "xml"
            end

            if attributes.has_key? a
              msg = "Duplicate attribute #{a.inspect}"
              raise REXML::ParseException.new( msg, @source, self)
            end

            attributes[a] = e 
          }
        end
  
        # Verify that all of the prefixes have been defined
        for prefix in prefixes
          unless @nsstack.find{|k| k.member?(prefix)}
            raise UndefinedNamespaceException.new(prefix,@source,self)
          end
        end

        if md[6]
          @closed = md[1]
          @nsstack.shift
        else
          @tags.push( md[1] )
        end
        return [ :start_element, md[1], attributes ]
      end
    else
      md = @source.match( TEXT_PATTERN, true )
      if md[0].length == 0
        @source.match( /(\s+)/, true )
      end
      #STDERR.puts "GOT #{md[1].inspect}" unless md[0].length == 0
      #return [ :text, "" ] if md[0].length == 0
      # unnormalized = Text::unnormalize( md[1], self )
      # return PullEvent.new( :text, md[1], unnormalized )
      return [ :text, md[1] ]
    end
  rescue REXML::UndefinedNamespaceException
    raise
  rescue REXML::ParseException
    raise
  rescue Exception, NameError => error
    raise REXML::ParseException.new( "Exception parsing",
      @source, self, (error ? error : $!) )
  end
  return [ :dummy ]
end
            
stream=( source ) click to toggle source
 
               # File rexml/parsers/baseparser.rb, line 145
def stream=( source )
  @source = SourceFactory.create_from( source )
  @closed = nil
  @document_status = nil
  @tags = []
  @stack = []
  @entities = []
  @nsstack = []
end
            
unnormalize( string, entities=nil, filter=nil ) click to toggle source

Unescapes all possible entities

 
               # File rexml/parsers/baseparser.rb, line 480
def unnormalize( string, entities=nil, filter=nil )
  rv = string.clone
  rv.gsub!( /\r\n?/, "\n" )
  matches = rv.scan( REFERENCE_RE )
  return rv if matches.size == 0
  rv.gsub!( /&#0*((?:\d+)|(?:x[a-fA-F0-9]+));/ ) {
    m=$1
    m = "0#{m}" if m[0] == ?x
    [Integer(m)].pack('U*')
  }
  matches.collect!{|x|x[0]}.compact!
  if matches.size > 0
    matches.each do |entity_reference|
      unless filter and filter.include?(entity_reference)
        entity_value = entity( entity_reference, entities )
        if entity_value
          re = /&#{entity_reference};/
          rv.gsub!( re, entity_value )
        else
          er = DEFAULT_ENTITIES[entity_reference]
          rv.gsub!( er[0], er[2] ) if er
        end
      end
    end
    rv.gsub!( /&amp;/, '&' )
  end
  rv
end
            
unshift(token) click to toggle source

Push an event back on the head of the stream. This method has (theoretically) infinite depth.

 
               # File rexml/parsers/baseparser.rb, line 176
def unshift token
  @stack.unshift(token)
end
            

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