1 files changed, 60 insertions, 0 deletions
diff --git a/tool/lrama/lib/lrama/grammar/rule.rb b/tool/lrama/lib/lrama/grammar/rule.rb
new file mode 100644
index 0000000000..0e06edc80d
--- /dev/null
+++ b/tool/lrama/lib/lrama/grammar/rule.rb
@@ -0,0 +1,60 @@
+module Lrama
+  class Grammar
+    # _rhs holds original RHS element. Use rhs to refer to Symbol.
+    class Rule < Struct.new(:id, :_lhs, :lhs, :lhs_tag, :_rhs, :rhs, :token_code, :position_in_original_rule_rhs, :nullable, :precedence_sym, :lineno, keyword_init: true)
+      attr_accessor :original_rule
+
+      def ==(other)
+        self.class == other.class &&
+        self.lhs == other.lhs &&
+        self.lhs_tag == other.lhs_tag &&
+        self.rhs == other.rhs &&
+        self.token_code == other.token_code &&
+        self.position_in_original_rule_rhs == other.position_in_original_rule_rhs &&
+        self.nullable == other.nullable &&
+        self.precedence_sym == other.precedence_sym &&
+        self.lineno == other.lineno
+      end
+
+      # TODO: Change this to display_name
+      def to_s
+        l = lhs.id.s_value
+        r = empty_rule? ? "ε" : rhs.map {|r| r.id.s_value }.join(" ")
+
+        "#{l} -> #{r}"
+      end
+
+      # Used by #user_actions
+      def as_comment
+        l = lhs.id.s_value
+        r = empty_rule? ? "%empty" : rhs.map(&:display_name).join(" ")
+
+        "#{l}: #{r}"
+      end
+
+      def with_actions
+        "#{to_s} {#{token_code&.s_value}}"
+      end
+
+      # opt_nl: ε     <-- empty_rule
+      #       | '\n'  <-- not empty_rule
+      def empty_rule?
+        rhs.empty?
+      end
+
+      def precedence
+        precedence_sym&.precedence
+      end
+
+      def initial_rule?
+        id == 0
+      end
+
+      def translated_code
+        return nil unless token_code
+
+        Code::RuleAction.new(type: :rule_action, token_code: token_code, rule: self).translated_code
+      end
+    end
+  end
+end