# File lib/expression_parser/parser.rb, line 5
    def parse(input)
      @lexer = Lexer.new(input)

      expression_value = expression
      token = @lexer.get_next_token
      if token.kind == Token::End
        expression_value
      else
        case token.kind
        when Token::GThan
          expression_value > expression ? 1 : 0
        when Token::LThan
          expression_value < expression ? 1 : 0
        when Token::Equal
          expression_value == expression ? 1 : 0
        when Token::NotEqual
          expression_value != expression ? 1 : 0
        when Token::GThanE
          expression_value >= expression ? 1 : 0
        when Token::LThanE
          expression_value <= expression ? 1 : 0
        else
          raise 'End expected'
        end
      end
    end