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#! /usr/bin/env ruby
#
# Copyright (c) 2001 by Jim Menard <jimm@io.com>
#
# Released under the same license as Ruby. See
# http://www.ruby-lang.org/en/LICENSE.txt.
#
# Using the tree parser, this script prints an XML document with all
# tags under the root tag in reverse order. We achieve this by adding a
# method to the NQXML::Document class that traverses the node tree
# depth-first but reversed.
#
# usage:
#
# reverseTags.rb <file.xml>
#
# Start looking for NQXML classes in the directory above this one.
# This forces us to use the local copy of NQXML, even if there is
# a previously installed version out there somewhere.
$LOAD_PATH[0, 0] = '..'
require 'nqxml/info' # For version string
require 'nqxml/treeparser'
# Modify the Text class for our own nefarious purposes.
module NQXML
class Document
# This method, called by each_depthfirst_reversed(), calls a proc
# for the entity in this node and then for all of its children in
# reverse order. If the node's entity is a tag, call the proc again
# after temporarily making the entity an end tag.
def recurse(node, proc)
return if node.nil?
e = node.entity
proc.call(e)
node.children.reverse.each { | n | recurse(n, proc) }
# If it's a tag, print the tag end.
if e.instance_of?(Tag)
e.makeTagEnd(true)
proc.call(e)
e.makeTagEnd(false)
end
end
# Yield each entity, starting at the root, with all children
# in reverse order.
def each_depthfirst_reversed(&block)
node = @rootNode
recurse(node, block)
end
end
class Tag
# Allow tags to change their end state.
def makeTagEnd(bool)
@isTagEnd = bool
end
# If this tag is an end tag, return the normalized end tag version.
def to_s
return "</#{@name}>" if @isTagEnd
return super
end
end
class Text
# Instead of returning the text with entities substituted,
# return the original source if we have it.
def to_s
return @source if @source
return NQXML.encode(@text)
end
end
end
# Fail with usage message if there is no command line argument.
if ARGV.length == 0
$stderr.puts "usage: #$0 <file.xml>"
exit(1)
end
# Print the current version of NQXML.
puts "NQXML version #{NQXML::Version}"
doc = nil
begin
# Create the tree parser (which reads and parses the XML) and retrieve
# the document object.
doc = NQXML::TreeParser.new(File.new(ARGV[0])).document
# First print the prolog in order.
doc.prolog.each { | entity |
print entity.to_s
}
# Now print each body tag with its children in reverse order.
doc.each_depthfirst_reversed { | entity |
print entity.to_s
}
puts
rescue NQXML::ParserError => ex
# Handle parser errors by printing the input line number and error
# message.
puts "\n NQXML parser error, line #{ex.line} column #{ex.column}: #{$!}"
end
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