class Liquid::Lexer

def initialize(input)
  @ss = StringScanner.new(input)
end

def tokenize
  @output = []
  until @ss.eos?
    @ss.skip(WHITESPACE_OR_NOTHING)
    break if @ss.eos?
    tok      = if (t = @ss.scan(COMPARISON_OPERATOR))
      [:comparison, t]
    elsif (t = @ss.scan(STRING_LITERAL))
      [:string, t]
    elsif (t = @ss.scan(NUMBER_LITERAL))
      [:number, t]
    elsif (t = @ss.scan(IDENTIFIER))
      [:id, t]
    elsif (t = @ss.scan(DOTDOT))
      [:dotdot, t]
    else
      c     = @ss.getch
      if (s = SPECIALS[c])
        [s, c]
      else
        raise SyntaxError, "Unexpected character #{c}"
      end
    end
    @output << tok
  end
  @output << [:end_of_string]
end