gistfile1

require 'rubygems'
require 'parse_tree'
require 'sexp_processor'
require 'logger'

class ParseError < RuntimeError; end

class Parser
  def initialize
    @logger = Logger.new(STDOUT)
    $rules = Hash.new
    @start = nil
    @tokens = ["+", "-", "*", "/"]
    @input = Array.new
    @output = Array.new
  end

  def tokenize(string)
    @input = string.clone
    tokens = Array.new
    @input.strip.to_a
    puts @input
    until string.empty?
      @input.each do |lex| 
      raise ParseError,  "unable to lex #{string}" unless lex.match(/\w+/)
      @output << string[/\+|\-|\/|\*/]
      string.gsub(/\+|\-|\/|\*/, '')
      end
      string = ""
    end
    puts tokens
  end
end

parser = Parser.new
parser.tokenize('1 + 2')