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.

Methods
A
E
H
N
P
S
U
Constants
LETTER = '[:alpha:]'
 
DIGIT = '[:digit:]'
 
COMBININGCHAR = ''
 
EXTENDER = ''
 
NCNAME_STR = "[#{LETTER}_:][-[:alnum:]._:#{COMBININGCHAR}#{EXTENDER}]*"
 
NAME_STR = "(?:(#{NCNAME_STR}):)?(#{NCNAME_STR})"
 
UNAME_STR = "(?:#{NCNAME_STR}:)?#{NCNAME_STR}"
 
NAMECHAR = '[\-\w\.:]'
 
NAME = "([\\w:]#{NAMECHAR}*)"
 
NMTOKEN = "(?:#{NAMECHAR})+"
 
NMTOKENS = "#{NMTOKEN}(\\s+#{NMTOKEN})*"
 
REFERENCE = "&(?:#{NAME};|#\\d+;|#x[0-9a-fA-F]+;)"
 
REFERENCE_RE = /#{REFERENCE}/
 
DOCTYPE_START = /\A\s*<!DOCTYPE\s/um
 
DOCTYPE_END = /\A\s*\]\s*>/um
 
DOCTYPE_PATTERN = /\s*<!DOCTYPE\s+(.*?)(\[|>)/um
 
ATTRIBUTE_PATTERN = /\s*(#{NAME_STR})\s*=\s*(["'])(.*?)\4/um
 
COMMENT_START = /\A<!--/u
 
COMMENT_PATTERN = /<!--(.*?)-->/um
 
CDATA_START = /\A<!\[CDATA\[/u
 
CDATA_END = /\A\s*\]\s*>/um
 
CDATA_PATTERN = /<!\[CDATA\[(.*?)\]\]>/um
 
XMLDECL_START = /\A<\?xml\s/u;
 
XMLDECL_PATTERN = /<\?xml\s+(.*?)\?>/um
 
INSTRUCTION_START = /\A<\?/u
 
INSTRUCTION_PATTERN = /<\?(.*?)(\s+.*?)?\?>/um
 
TAG_MATCH = /^<((?>#{NAME_STR}))\s*((?>\s+#{UNAME_STR}\s*=\s*(["']).*?\5)*)\s*(\/)?>/um
 
CLOSE_MATCH = /^\s*<\/(#{NAME_STR})\s*>/um
 
VERSION = /\bversion\s*=\s*["'](.*?)['"]/um
 
ENCODING = /\bencoding\s*=\s*["'](.*?)['"]/um
 
STANDALONE = /\bstandalone\s*=\s*["'](.*?)['"]/um
 
ENTITY_START = /\A\s*<!ENTITY/
 
IDENTITY = /^([!\*\w\-]+)(\s+#{NCNAME_STR})?(\s+["'](.*?)['"])?(\s+['"](.*?)["'])?/u
 
ELEMENTDECL_START = /\A\s*<!ELEMENT/um
 
ELEMENTDECL_PATTERN = /\A\s*(<!ELEMENT.*?)>/um
 
SYSTEMENTITY = /\A\s*(%.*?;)\s*$/um
 
ENUMERATION = "\\(\\s*#{NMTOKEN}(?:\\s*\\|\\s*#{NMTOKEN})*\\s*\\)"
 
NOTATIONTYPE = "NOTATION\\s+\\(\\s*#{NAME}(?:\\s*\\|\\s*#{NAME})*\\s*\\)"
 
ENUMERATEDTYPE = "(?:(?:#{NOTATIONTYPE})|(?:#{ENUMERATION}))"
 
ATTTYPE = "(CDATA|ID|IDREF|IDREFS|ENTITY|ENTITIES|NMTOKEN|NMTOKENS|#{ENUMERATEDTYPE})"
 
ATTVALUE = "(?:\"((?:[^<&\"]|#{REFERENCE})*)\")|(?:'((?:[^<&']|#{REFERENCE})*)')"
 
DEFAULTDECL = "(#REQUIRED|#IMPLIED|(?:(#FIXED\\s+)?#{ATTVALUE}))"
 
ATTDEF = "\\s+#{NAME}\\s+#{ATTTYPE}\\s+#{DEFAULTDECL}"
 
ATTDEF_RE = /#{ATTDEF}/
 
ATTLISTDECL_START = /\A\s*<!ATTLIST/um
 
ATTLISTDECL_PATTERN = /\A\s*<!ATTLIST\s+#{NAME}(?:#{ATTDEF})*\s*>/um
 
NOTATIONDECL_START = /\A\s*<!NOTATION/um
 
PUBLIC = /\A\s*<!NOTATION\s+(\w[\-\w]*)\s+(PUBLIC)\s+(["'])(.*?)\3(?:\s+(["'])(.*?)\5)?\s*>/um
 
SYSTEM = /\A\s*<!NOTATION\s+(\w[\-\w]*)\s+(SYSTEM)\s+(["'])(.*?)\3\s*>/um
 
TEXT_PATTERN = /\A([^<]*)/um
 
PUBIDCHAR = "\x20\x0D\x0Aa-zA-Z0-9\\-()+,./:=?;!*@$_%#"
 

Entity constants

SYSTEMLITERAL = %Q{((?:"[^"]*")|(?:'[^']*'))}
 
PUBIDLITERAL = %Q{("[#{PUBIDCHAR}']*"|'[#{PUBIDCHAR}]*')}
 
EXTERNALID = "(?:(?:(SYSTEM)\\s+#{SYSTEMLITERAL})|(?:(PUBLIC)\\s+#{PUBIDLITERAL}\\s+#{SYSTEMLITERAL}))"
 
NDATADECL = "\\s+NDATA\\s+#{NAME}"
 
PEREFERENCE = "%#{NAME};"
 
ENTITYVALUE = %Q{((?:"(?:[^%&"]|#{PEREFERENCE}|#{REFERENCE})*")|(?:'([^%&']|#{PEREFERENCE}|#{REFERENCE})*'))}
 
PEDEF = "(?:#{ENTITYVALUE}|#{EXTERNALID})"
 
ENTITYDEF = "(?:#{ENTITYVALUE}|(?:#{EXTERNALID}(#{NDATADECL})?))"
 
PEDECL = "<!ENTITY\\s+(%)\\s+#{NAME}\\s+#{PEDEF}\\s*>"
 
GEDECL = "<!ENTITY\\s+#{NAME}\\s+#{ENTITYDEF}\\s*>"
 
ENTITYDECL = /\s*(?:#{GEDECL})|(?:#{PEDECL})/um
 
EREFERENCE = /&(?!#{NAME};)/
 
DEFAULT_ENTITIES = { 'gt' => [/&gt;/, '&gt;', '>', />/], 'lt' => [/&lt;/, '&lt;', '<', /</], 'quot' => [/&quot;/, '&quot;', '"', /"/], "apos" => [/&apos;/, "&apos;", "'", /'/] }
 
MISSING_ATTRIBUTE_QUOTES = /^<#{NAME_STR}\s+#{NAME_STR}\s*=\s*[^"']/um
 

These are patterns to identify common markup errors, to make the error messages more informative.

Attributes
[R] source
Class Public methods
new( source )
# File lib/rexml/parsers/baseparser.rb, line 117
def initialize( source )
  self.stream = source
  @listeners = []
end
Instance Public methods
add_listener( listener )
# File lib/rexml/parsers/baseparser.rb, line 122
def add_listener( listener )
  @listeners << listener
end
empty?()

Returns true if there are no more events

# File lib/rexml/parsers/baseparser.rb, line 148
def empty?
  return (@source.empty? and @stack.empty?)
end
entity( reference, entities )
# File lib/rexml/parsers/baseparser.rb, line 449
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?()

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

# File lib/rexml/parsers/baseparser.rb, line 153
def has_next?
  return !(@source.empty? and @stack.empty?)
end
normalize( input, entities=nil, entity_filter=nil )

Escapes all possible entities

# File lib/rexml/parsers/baseparser.rb, line 460
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)

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 lib/rexml/parsers/baseparser.rb, line 169
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()
# File lib/rexml/parsers/baseparser.rb, line 138
def position
  if @source.respond_to? :position
    @source.position
  else
    # FIXME
    0
  end
end
pull()

Returns the next event. This is a PullEvent object.

# File lib/rexml/parsers/baseparser.rb, line 184
def pull
  pull_event.tap do |event|
    @listeners.each do |listener|
      listener.receive event
    end
  end
end
stream=( source )
# File lib/rexml/parsers/baseparser.rb, line 128
def stream=( source )
  @source = SourceFactory.create_from( source )
  @closed = nil
  @document_status = nil
  @tags = []
  @stack = []
  @entities = []
  @nsstack = []
end
unnormalize( string, entities=nil, filter=nil )

Unescapes all possible entities

# File lib/rexml/parsers/baseparser.rb, line 476
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)

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

# File lib/rexml/parsers/baseparser.rb, line 159
def unshift token
  @stack.unshift(token)
end