require 'forwardable'
require 'rexml/parseexception'
require 'rexml/parsers/baseparser'
require 'rexml/xmltokens'
module REXML
module Parsers
# = Using the Pull Parser
# <em>This API is experimental, and subject to change.</em>
# 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.
class PullParser
include XMLTokens
extend Forwardable
def_delegators( :@parser, :has_next? )
def_delegators( :@parser, :entity )
def_delegators( :@parser, :empty? )
def_delegators( :@parser, :source )
def initialize stream
@entities = {}
@listeners = nil
@parser = BaseParser.new( stream )
@my_stack = []
end
def add_listener( listener )
@listeners = [] unless @listeners
@listeners << listener
end
def each
while has_next?
yield self.pull
end
end
def peek depth=0
if @my_stack.length <= depth
(depth - @my_stack.length + 1).times {
e = PullEvent.new(@parser.pull)
@my_stack.push(e)
}
end
@my_stack[depth]
end
def pull
return @my_stack.shift if @my_stack.length > 0
event = @parser.pull
case event[0]
when :entitydecl
@entities[ event[1] ] =
event[2] unless event[2] =~ /PUBLIC|SYSTEM/
when :text
unnormalized = @parser.unnormalize( event[1], @entities )
event << unnormalized
end
PullEvent.new( event )
end
def unshift token
@my_stack.unshift token
end
end
# A parsing event. The contents of the event are accessed as an +Array?,
# and the type is given either by the ...? methods, or by accessing the
# +type+ accessor. The contents of this object vary from event to event,
# but are identical to the arguments passed to +StreamListener+s for each
# event.
class PullEvent
# The type of this event. Will be one of :tag_start, :tag_end, :text,
# :processing_instruction, :comment, :doctype, :attlistdecl, :entitydecl,
# :notationdecl, :entity, :cdata, :xmldecl, or :error.
def initialize(arg)
@contents = arg
end
def []( start, endd=nil)
if start.kind_of? Range
@contents.slice( start.begin+1 .. start.end )
elsif start.kind_of? Numeric
if endd.nil?
@contents.slice( start+1 )
else
@contents.slice( start+1, endd )
end
else
raise "Illegal argument #{start.inspect} (#{start.class})"
end
end
def event_type
@contents[0]
end
# Content: [ String tag_name, Hash attributes ]
def start_element?
@contents[0] == :start_element
end
# Content: [ String tag_name ]
def end_element?
@contents[0] == :end_element
end
# Content: [ String raw_text, String unnormalized_text ]
def text?
@contents[0] == :text
end
# Content: [ String text ]
def instruction?
@contents[0] == :processing_instruction
end
# Content: [ String text ]
def comment?
@contents[0] == :comment
end
# Content: [ String name, String pub_sys, String long_name, String uri ]
def doctype?
@contents[0] == :start_doctype
end
# Content: [ String text ]
def attlistdecl?
@contents[0] == :attlistdecl
end
# Content: [ String text ]
def elementdecl?
@contents[0] == :elementdecl
end
# Due to the wonders of DTDs, an entity declaration can be just about
# anything. There's no way to normalize it; you'll have to interpret the
# content yourself. However, the following is true:
#
# * If the entity declaration is an internal entity:
# [ String name, String value ]
# Content: [ String text ]
def entitydecl?
@contents[0] == :entitydecl
end
# Content: [ String text ]
def notationdecl?
@contents[0] == :notationdecl
end
# Content: [ String text ]
def entity?
@contents[0] == :entity
end
# Content: [ String text ]
def cdata?
@contents[0] == :cdata
end
# Content: [ String version, String encoding, String standalone ]
def xmldecl?
@contents[0] == :xmldecl
end
def error?
@contents[0] == :error
end
def inspect
@contents[0].to_s + ": " + @contents[1..-1].inspect
end
end
end
end
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