Ruby command line diff based on Diff::LCS

diff.rb

#!/usr/bin/ruby -Ku

DEBUG = false

require 'rubygems'
require 'diff/lcs'

class OO
	def green; "\e[42m\e[1;37m" end
	def red; "\e[41m\e[1;37m" end
	def rst; "\e[0m" end

	def initialize(a,b)
		@a = a.chars.to_a
		@ha = @a.map { false }
		@b = b.chars.to_a
		@hb = @b.map { false }
	end
	
	def match(e)
		# good to know...
		puts "ERROR" if e.action != '='
		puts "M: #{e.inspect}" if DEBUG
	end
	
	def discard_a(e)
		puts "ERROR" if e.action != '-'
		@ha[e.old_position] = true
		puts "A: #{e.inspect}" if DEBUG
	end
	
	def discard_b(e)
		puts "ERROR" if e.action != '+'
		@hb[e.new_position] = true
		puts "B: #{e.inspect}" if DEBUG
	end
	
	def change(e)
		puts "ERROR" if e.action != '!'
		@ha[e.old_position] = true
		@hb[e.new_position] = true
		puts "C: #{e.inspect}" if DEBUG
	end
	
	def debug
		i = 0
		@a.each do |a|
			print red,a,rst if @ha[i]
			print a if not @ha[i]
			i += 1
		end
		puts
		i = 0
		@b.each do |b|
			print green,b,rst if @hb[i]
			print b if not @hb[i]
			i += 1
		end
		puts
	end

end

a = ARGV[0] || "old string"
b = ARGV[1] || "new string"
o = OO.new(a,b)

Diff::LCS.traverse_balanced a, b, o

o.debug