gistfile1.rb

grammar Promo

  rule root
    empty rules:(trigger_or_effect empty)* {
      def triggers
        rules.elements.select { |r| r.elements.first.respond_to?(:trigger) }.map { |r| r.elements.first.trigger }
      rescue NameError # nil for some object
        []
      end

      def effect
        rules.elements.find { |r| r.elements.first.respond_to?(:effect) }.elements.first.effect
      rescue NameError # nil for some object
        nil
      end
    }
  end

  rule trigger_or_effect
    "spend $" amount_in_cents " on product group " name {
      def trigger
        PromotionTrigger.new(:test_type => "MinimumValueSpendOnProductGroup",
                             :test_data => { :value_in_cents => amount_in_cents.value, :group => name.text_value })
      end
    }
    /
    "spend $" amount_in_cents {
      def trigger
        PromotionTrigger.new(:test_type => "MinimumShoppingCartValue",
                             :test_data => amount_in_cents.value)
      end
    }
    /
    "and get $" amount_in_cents " off" {
      def effect
        PromotionEffect.new(:effect_type => "AddDiscount",
                            :effect_data => amount_in_cents.value)
      end
    }
    /
    "and get free shipping" {
      def effect
        PromotionEffect.new(:effect_type => "SetFreightCost",
                            :effect_data => 1199)
      end
    }
  end

  rule amount_in_cents
    [0-9]+ ("\." [0-9]+)? {
      def value
        (text_value.to_f * 100).round
      end
    }
  end

  rule name
    [a-zA-Z0-9 -_]+
  end

  rule empty
    [\n\t\r]*
  end
end