1 files changed, 77 insertions, 0 deletions
diff --git a/tool/lrama/lib/lrama/lexer/token/user_code.rb b/tool/lrama/lib/lrama/lexer/token/user_code.rb
new file mode 100644
index 0000000000..4d487bf01c
--- /dev/null
+++ b/tool/lrama/lib/lrama/lexer/token/user_code.rb
@@ -0,0 +1,77 @@
+require "strscan"
+
+module Lrama
+  class Lexer
+    class Token
+      class UserCode < Token
+        attr_accessor :tag
+
+        def references
+          @references ||= _references
+        end
+
+        private
+
+        def _references
+          scanner = StringScanner.new(s_value)
+          references = []
+
+          while !scanner.eos? do
+            case
+            when reference = scan_reference(scanner)
+              references << reference
+            when scanner.scan(/\/\*/)
+              scanner.scan_until(/\*\//)
+            else
+              scanner.getch
+            end
+          end
+
+          references
+        end
+
+        def scan_reference(scanner)
+          start = scanner.pos
+          case
+          # $ references
+          # It need to wrap an identifier with brackets to use ".-" for identifiers
+          when scanner.scan(/\$(<[a-zA-Z0-9_]+>)?\$/) # $$, $<long>$
+            tag = scanner[1] ? Lrama::Lexer::Token::Tag.new(s_value: scanner[1]) : nil
+            return Lrama::Grammar::Reference.new(type: :dollar, name: "$", ex_tag: tag, first_column: start, last_column: scanner.pos)
+          when scanner.scan(/\$(<[a-zA-Z0-9_]+>)?(\d+)/) # $1, $2, $<long>1
+            tag = scanner[1] ? Lrama::Lexer::Token::Tag.new(s_value: scanner[1]) : nil
+            return Lrama::Grammar::Reference.new(type: :dollar, number: Integer(scanner[2]), index: Integer(scanner[2]), ex_tag: tag, first_column: start, last_column: scanner.pos)
+          when scanner.scan(/\$(<[a-zA-Z0-9_]+>)?([a-zA-Z_][a-zA-Z0-9_]*)/) # $foo, $expr, $<long>program (named reference without brackets)
+            tag = scanner[1] ? Lrama::Lexer::Token::Tag.new(s_value: scanner[1]) : nil
+            return Lrama::Grammar::Reference.new(type: :dollar, name: scanner[2], ex_tag: tag, first_column: start, last_column: scanner.pos)
+          when scanner.scan(/\$(<[a-zA-Z0-9_]+>)?\[([a-zA-Z_.][-a-zA-Z0-9_.]*)\]/) # $[expr.right], $[expr-right], $<long>[expr.right] (named reference with brackets)
+            tag = scanner[1] ? Lrama::Lexer::Token::Tag.new(s_value: scanner[1]) : nil
+            return Lrama::Grammar::Reference.new(type: :dollar, name: scanner[2], ex_tag: tag, first_column: start, last_column: scanner.pos)
+
+          # @ references
+          # It need to wrap an identifier with brackets to use ".-" for identifiers
+          when scanner.scan(/@\$/) # @$
+            return Lrama::Grammar::Reference.new(type: :at, name: "$", first_column: start, last_column: scanner.pos)
+          when scanner.scan(/@(\d+)/) # @1
+            return Lrama::Grammar::Reference.new(type: :at, number: Integer(scanner[1]), index: Integer(scanner[1]), first_column: start, last_column: scanner.pos)
+          when scanner.scan(/@([a-zA-Z][a-zA-Z0-9_]*)/) # @foo, @expr (named reference without brackets)
+            return Lrama::Grammar::Reference.new(type: :at, name: scanner[1], first_column: start, last_column: scanner.pos)
+          when scanner.scan(/@\[([a-zA-Z_.][-a-zA-Z0-9_.]*)\]/) # @[expr.right], @[expr-right]  (named reference with brackets)
+            return Lrama::Grammar::Reference.new(type: :at, name: scanner[1], first_column: start, last_column: scanner.pos)
+
+          # $: references
+          when scanner.scan(/\$:\$/) # $:$
+            return Lrama::Grammar::Reference.new(type: :index, name: "$", first_column: start, last_column: scanner.pos)
+          when scanner.scan(/\$:(\d+)/) # $:1
+            return Lrama::Grammar::Reference.new(type: :index, number: Integer(scanner[1]), first_column: start, last_column: scanner.pos)
+          when scanner.scan(/\$:([a-zA-Z_][a-zA-Z0-9_]*)/) # $:foo, $:expr (named reference without brackets)
+            return Lrama::Grammar::Reference.new(type: :index, name: scanner[1], first_column: start, last_column: scanner.pos)
+          when scanner.scan(/\$:\[([a-zA-Z_.][-a-zA-Z0-9_.]*)\]/) # $:[expr.right], $:[expr-right] (named reference with brackets)
+            return Lrama::Grammar::Reference.new(type: :index, name: scanner[1], first_column: start, last_column: scanner.pos)
+
+          end
+        end
+      end
+    end
+  end
+end