Minimal treetop example

treetop_example.rb

require 'treetop'

grammar = Treetop.load_from_string(DATA.read)
parser = MyGrammarParser.new
p parser.parse(" a = 1 \n b = 2 \n").value

__END__
grammar MyGrammar
  rule main
    pair* {
      def value
        elements.map(&:key_value)
      end
    }
  end

  rule pair
    space keyword:(keyword) space '=' space value:(value) space eol {
      def key_value
        [keyword.text_value, value.text_value]
      end
    }
  end

  rule space
    ' '+
  end

  rule keyword
    [a-z]+
  end

  rule value
    [0-9]+
  end

  rule eol
    "\n"+
  end
end