Lrama v0.6.0

tool/lrama/NEWS.md

@@ -1,5 +1,25 @@
 # NEWS for Lrama
 
+## Lrama 0.6.0 (2023-12-25)
+
+### User defined parameterizing rules
+
+Allow to define parameterizing rule by `%rule` directive.
+
+```
+%rule pair(X, Y): X Y { $$ = $1 + $2; }
+                ;
+
+%%
+
+program: stmt
+       ;
+
+stmt: pair(ODD, EVEN) <num>
+    | pair(EVEN, ODD) <num>
+    ;
+```
+
 ## Lrama 0.5.11 (2023-12-02)
 
 ### Type specification of parameterizing rules

tool/lrama/lib/lrama/grammar.rb

@@ -8,6 +8,10 @@ require "lrama/grammar/printer"
 require "lrama/grammar/reference"
 require "lrama/grammar/rule"
 require "lrama/grammar/rule_builder"
+require "lrama/grammar/parameterizing_rule_builder"
+require "lrama/grammar/parameterizing_rule_resolver"
+require "lrama/grammar/parameterizing_rule_rhs_builder"
+require "lrama/grammar/parameterizing_rule"
 require "lrama/grammar/symbol"
 require "lrama/grammar/type"
 require "lrama/grammar/union"
@@ -36,6 +40,7 @@ module Lrama
       @rule_builders = []
       @rules = []
       @sym_to_rules = {}
+      @parameterizing_resolver = ParameterizingRuleResolver.new
       @empty_symbol = nil
       @eof_symbol = nil
       @error_symbol = nil
@@ -69,7 +74,7 @@ module Lrama
         return sym
       end
 
-      if sym = @symbols.find {|s| s.id == id }
+      if (sym = @symbols.find {|s| s.id == id })
         return sym
       end
 
@@ -129,6 +134,10 @@ module Lrama
       @rule_builders << builder
     end
 
+    def add_parameterizing_rule_builder(builder)
+      @parameterizing_resolver.add_parameterizing_rule_builder(builder)
+    end
+
     def prologue_first_lineno=(prologue_first_lineno)
       @aux.prologue_first_lineno = prologue_first_lineno
     end
@@ -310,7 +319,7 @@ module Lrama
 
     def setup_rules
       @rule_builders.each do |builder|
-        builder.setup_rules
+        builder.setup_rules(@parameterizing_resolver)
       end
     end
 
@@ -350,56 +359,21 @@ module Lrama
       @accept_symbol = term
     end
 
-    # 1. Add $accept rule to the top of rules
-    # 2. Extract action in the middle of RHS into new Empty rule
-    # 3. Append id and extract action then create Rule
-    #
-    # Bison 3.8.2 uses different orders for symbol number and rule number
-    # when a rule has actions in the middle of a rule.
-    #
-    # For example,
-    #
-    # `program: $@1 top_compstmt`
-    #
-    # Rules are ordered like below,
-    #
-    # 1 $@1: ε
-    # 2 program: $@1 top_compstmt
-    #
-    # Symbols are ordered like below,
-    #
-    # 164 program
-    # 165 $@1
-    #
     def normalize_rules
-      # 1. Add $accept rule to the top of rules
+      # Add $accept rule to the top of rules
-      accept = @accept_symbol
-      eof = @eof_symbol
       lineno = @rule_builders.first ? @rule_builders.first.line : 0
-      @rules << Rule.new(id: @rule_counter.increment, _lhs: accept.id, _rhs: [@rule_builders.first.lhs, eof.id], token_code: nil, lineno: lineno)
+      @rules << Rule.new(id: @rule_counter.increment, _lhs: @accept_symbol.id, _rhs: [@rule_builders.first.lhs, @eof_symbol.id], token_code: nil, lineno: lineno)
 
       setup_rules
 
       @rule_builders.each do |builder|
-        # Extract actions in the middle of RHS into new rules.
-        builder.midrule_action_rules.each do |rule|
-          @rules << rule
-        end
-
         builder.rules.each do |rule|
-          add_nterm(id: rule._lhs)
-          @rules << rule
-        end
-
-        builder.parameterizing_rules.each do |rule|
           add_nterm(id: rule._lhs, tag: rule.lhs_tag)
           @rules << rule
         end
+      end
 
-        builder.midrule_action_rules.each do |rule|
+      @rules.sort_by!(&:id)
-          add_nterm(id: rule._lhs)
-        end
-      end
     end
 
     # Collect symbols from rules

tool/lrama/lib/lrama/grammar/code.rb

@@ -1,12 +1,29 @@
 require "forwardable"
+require "lrama/grammar/code/initial_action_code"
+require "lrama/grammar/code/no_reference_code"
+require "lrama/grammar/code/printer_code"
+require "lrama/grammar/code/rule_action"
 
 module Lrama
   class Grammar
-    class Code < Struct.new(:type, :token_code, keyword_init: true)
+    class Code
       extend Forwardable
 
       def_delegators "token_code", :s_value, :line, :column, :references
 
+      attr_reader :type, :token_code
+
+      def initialize(type:, token_code:)
+        @type = type
+        @token_code = token_code
+      end
+
+      def ==(other)
+        self.class == other.class &&
+        self.type == other.type &&
+        self.token_code == other.token_code
+      end
+
       # $$, $n, @$, @n are translated to C code
       def translated_code
         t_code = s_value.dup
@@ -17,7 +34,7 @@ module Lrama
 
           str = reference_to_c(ref)
 
-          t_code[first_column..last_column] = str
+          t_code[first_column...last_column] = str
         end
 
         return t_code
@@ -31,8 +48,3 @@ module Lrama
     end
   end
 end
-
-require "lrama/grammar/code/initial_action_code"
-require "lrama/grammar/code/no_reference_code"
-require "lrama/grammar/code/printer_code"
-require "lrama/grammar/code/rule_action"

tool/lrama/lib/lrama/grammar/code/printer_code.rb

@@ -2,7 +2,7 @@ module Lrama
   class Grammar
     class Code
       class PrinterCode < Code
-        def initialize(type: nil, token_code: nil, tag: nil)
+        def initialize(type:, token_code:, tag:)
           super(type: type, token_code: token_code)
           @tag = tag
         end

tool/lrama/lib/lrama/grammar/code/rule_action.rb

@@ -2,7 +2,7 @@ module Lrama
   class Grammar
     class Code
       class RuleAction < Code
-        def initialize(type: nil, token_code: nil, rule: nil)
+        def initialize(type:, token_code:, rule:)
           super(type: type, token_code: token_code)
           @rule = rule
         end

tool/lrama/lib/lrama/grammar/parameterizing_rule.rb

@@ -0,0 +1,6 @@
+module Lrama
+  class Grammar
+    class ParameterizingRule < Struct.new(:rules, :token, keyword_init: true)
+    end
+  end
+end

tool/lrama/lib/lrama/grammar/parameterizing_rule_builder.rb

@@ -0,0 +1,34 @@
+module Lrama
+  class Grammar
+    class ParameterizingRuleBuilder
+      attr_reader :name, :parameters, :rhs
+
+      def initialize(name, parameters, rhs)
+        @name = name
+        @parameters = parameters
+        @rhs = rhs
+        @required_parameters_count = parameters.count
+      end
+
+      def build_rules(token, actual_args, rule_counter, lhs_tag, line, rule_builders)
+        validate_argument_number!(token)
+        lhs = lhs(actual_args)
+        @rhs.map do |rhs|
+          rhs.build_rules(token, actual_args, parameters, rule_counter, lhs, lhs_tag, line, rule_builders)
+        end.flatten
+      end
+
+      private
+
+      def validate_argument_number!(token)
+        unless @required_parameters_count == token.args.count
+          raise "Invalid number of arguments. expect: #{@required_parameters_count} actual: #{token.args.count}"
+        end
+      end
+
+      def lhs(actual_args)
+        Lrama::Lexer::Token::Ident.new(s_value: "#{name}_#{actual_args.map(&:s_value).join('_')}")
+      end
+    end
+  end
+end

tool/lrama/lib/lrama/grammar/parameterizing_rule_resolver.rb

@@ -0,0 +1,30 @@
+module Lrama
+  class Grammar
+    class ParameterizingRuleResolver
+      def initialize
+        @parameterizing_rule_builders = []
+      end
+
+      def add_parameterizing_rule_builder(builder)
+        @parameterizing_rule_builders << builder
+      end
+
+      def defined?(name)
+        !rule_builders(name).empty?
+      end
+
+      def build_rules(token, rule_counter, lhs_tag, line)
+        builder = rule_builders(token.s_value).last
+        raise "Unknown parameterizing rule #{token.s_value} at line #{token.line}" unless builder
+
+        builder.build_rules(token, token.args, rule_counter, lhs_tag, line, @parameterizing_rule_builders)
+      end
+
+      private
+
+      def rule_builders(name)
+        @parameterizing_rule_builders.select { |builder| builder.name == name }
+      end
+    end
+  end
+end

tool/lrama/lib/lrama/grammar/parameterizing_rule_rhs_builder.rb

@@ -0,0 +1,53 @@
+module Lrama
+  class Grammar
+    class ParameterizingRuleRhsBuilder
+      attr_accessor :symbols, :user_code, :precedence_sym
+
+      def initialize
+        @symbols = []
+        @user_code = nil
+        @precedence_sym = nil
+      end
+
+      def build_rules(token, actual_args, parameters, rule_counter, lhs, lhs_tag, line, rule_builders)
+        nested_rules = build_nested_rules(token, actual_args, parameters, rule_counter, lhs_tag, line, rule_builders)
+        rule = Rule.new(id: rule_counter.increment, _lhs: lhs, _rhs: rhs(token, actual_args, parameters, nested_rules.last), lhs_tag: lhs_tag, token_code: user_code, precedence_sym: precedence_sym, lineno: line)
+        ParameterizingRule.new(rules: nested_rules.map(&:rules) + [rule], token: lhs)
+      end
+
+      private
+
+      def build_nested_rules(token, actual_args, parameters, rule_counter, lhs_tag, line, rule_builders)
+        symbols.each_with_index.map do |sym, i|
+          next unless sym.is_a?(Lexer::Token::InstantiateRule)
+
+          builder = rule_builders.select { |builder| builder.name == sym.s_value }.last
+          raise "Unknown parameterizing rule #{token.s_value} at line #{token.line}" unless builder
+
+          builder.build_rules(sym, nested_actual_args(actual_args, parameters, i), rule_counter, lhs_tag, line, rule_builders)
+        end.flatten.compact
+      end
+
+      def nested_actual_args(actual_args, parameters, idx)
+        symbols[idx].args.map do |arg|
+          i = parameters.index { |parameter| parameter.s_value == arg.s_value }
+          i.nil? ? arg : actual_args[i]
+        end
+      end
+
+      def rhs(token, actual_args, parameters, nested_rule)
+        symbols.map do |sym|
+          if sym.is_a?(Lexer::Token::InstantiateRule)
+            sym.args.map do |arg|
+              idx = parameters.index { |parameter| parameter.s_value == arg.s_value }
+              idx.nil? ? sym : nested_rule&.token
+            end
+          else
+            idx = parameters.index { |parameter| parameter.s_value == sym.s_value }
+            idx.nil? ? sym : actual_args[idx]
+          end
+        end.flatten
+      end
+    end
+  end
+end

tool/lrama/lib/lrama/grammar/rule_builder.rb

@@ -51,22 +51,14 @@ module Lrama
         freeze_rhs
       end
 
-      def setup_rules
+      def setup_rules(parameterizing_resolver)
         preprocess_references unless @skip_preprocess_references
-        process_rhs
+        process_rhs(parameterizing_resolver)
         build_rules
       end
 
-      def parameterizing_rules
-        @parameterizing_rules
-      end
-
-      def midrule_action_rules
-        @midrule_action_rules
-      end
-
       def rules
-        @rules
+        @parameterizing_rules + @midrule_action_rules + @rules
       end
 
       private
@@ -95,9 +87,9 @@ module Lrama
         end
       end
 
-      # rhs is a mixture of variety type of tokens like `Ident`, `Parameterizing`, `UserCode` and so on.
+      # rhs is a mixture of variety type of tokens like `Ident`, `InstantiateRule`, `UserCode` and so on.
       # `#process_rhs` replaces some kind of tokens to `Ident` so that all `@replaced_rhs` are `Ident` or `Char`.
-      def process_rhs
+      def process_rhs(parameterizing_resolver)
         return if @replaced_rhs
 
         @replaced_rhs = []
@@ -109,12 +101,17 @@ module Lrama
             @replaced_rhs << token
           when Lrama::Lexer::Token::Ident
             @replaced_rhs << token
-          when Lrama::Lexer::Token::Parameterizing
+          when Lrama::Lexer::Token::InstantiateRule
+            if parameterizing_resolver.defined?(token.rule_name)
+              parameterizing = parameterizing_resolver.build_rules(token, @rule_counter, @lhs_tag, line)
+              @parameterizing_rules = @parameterizing_rules + parameterizing.map(&:rules).flatten
+              @replaced_rhs = @replaced_rhs + parameterizing.map(&:token).flatten.uniq
+            else
+              # TODO: Delete when the standard library will defined as a grammar file.
               parameterizing = ParameterizingRules::Builder.new(token, @rule_counter, @lhs_tag, user_code, precedence_sym, line)
-            parameterizing.build.each do |r|
+              @parameterizing_rules = @parameterizing_rules + parameterizing.build
-              @parameterizing_rules << r
-            end
               @replaced_rhs << parameterizing.build_token
+            end
           when Lrama::Lexer::Token::UserCode
             prefix = token.referred ? "@" : "$@"
             new_token = Lrama::Lexer::Token::Ident.new(s_value: prefix + @midrule_action_counter.increment.to_s)
@@ -124,7 +121,7 @@ module Lrama
             rule_builder.lhs = new_token
             rule_builder.user_code = token
             rule_builder.complete_input
-            rule_builder.setup_rules
+            rule_builder.setup_rules(parameterizing_resolver)
 
             @rule_builders_for_derived_rules << rule_builder
           else
@@ -146,8 +143,15 @@ module Lrama
               else
                 candidates = rhs.each_with_index.select {|token, i| token.referred_by?(ref_name) }
 
-                raise "Referring symbol `#{ref_name}` is duplicated. #{token}" if candidates.size >= 2
+                if candidates.size >= 2
-                raise "Referring symbol `#{ref_name}` is not found. #{token}" unless referring_symbol = candidates.first
+                  location = token.location.partial_location(ref.first_column, ref.last_column)
+                  raise location.generate_error_message("Referring symbol `#{ref_name}` is duplicated.")
+                end
+
+                unless (referring_symbol = candidates.first)
+                  location = token.location.partial_location(ref.first_column, ref.last_column)
+                  raise location.generate_error_message("Referring symbol `#{ref_name}` is not found.")
+                end
 
                 ref.index = referring_symbol[1] + 1
               end
@@ -167,7 +171,7 @@ module Lrama
       end
 
       def flush_user_code
-        if c = @user_code
+        if (c = @user_code)
           @rhs << c
           @user_code = nil
         end

tool/lrama/lib/lrama/lexer.rb

@@ -1,4 +1,5 @@
 require "strscan"
+require "lrama/lexer/grammar_file"
 require "lrama/lexer/location"
 require "lrama/lexer/token"
 
@@ -28,10 +29,12 @@ module Lrama
       %error-token
       %empty
       %code
+      %rule
     )
 
-    def initialize(text)
+    def initialize(grammar_file)
-      @scanner = StringScanner.new(text)
+      @grammar_file = grammar_file
+      @scanner = StringScanner.new(grammar_file.text)
       @head_column = @head = @scanner.pos
       @head_line = @line = 1
       @status = :initial
@@ -57,8 +60,9 @@ module Lrama
 
     def location
       Location.new(
+        grammar_file: @grammar_file,
         first_line: @head_line, first_column: @head_column,
-        last_line: @line, last_column: column
+        last_line: line, last_column: column
       )
     end
 
@@ -78,8 +82,7 @@ module Lrama
         end
       end
 
-      @head_line = line
+      reset_first_position
-      @head_column = column
 
       case
       when @scanner.eos?
@@ -117,6 +120,8 @@ module Lrama
     def lex_c_code
       nested = 0
       code = ''
+      reset_first_position
+
       while !@scanner.eos? do
         case
         when @scanner.scan(/{/)
@@ -140,14 +145,14 @@ module Lrama
           @line += @scanner.matched.count("\n")
         when @scanner.scan(/'.*?'/)
           code += %Q(#{@scanner.matched})
-        else
+        when @scanner.scan(/[^\"'\{\}\n]+/)
-          if @scanner.scan(/[^\"'\{\}\n#{@end_symbol}]+/)
+          code += @scanner.matched
+        when @scanner.scan(/#{Regexp.escape(@end_symbol)}/)
           code += @scanner.matched
         else
           code += @scanner.getch
         end
       end
-      end
       raise ParseError, "Unexpected code: #{code}."
     end
 
@@ -166,9 +171,14 @@ module Lrama
       end
     end
 
+    def reset_first_position
+      @head_line = line
+      @head_column = column
+    end
+
     def newline
       @line += 1
-      @head = @scanner.pos + 1
+      @head = @scanner.pos
     end
   end
 end

tool/lrama/lib/lrama/lexer/grammar_file.rb

@@ -0,0 +1,21 @@
+module Lrama
+  class Lexer
+    class GrammarFile
+      attr_reader :path, :text
+
+      def initialize(path, text)
+        @path = path
+        @text = text
+      end
+
+      def ==(other)
+        self.class == other.class &&
+        self.path == other.path
+      end
+
+      def lines
+        @lines ||= text.split("\n")
+      end
+    end
+  end
+end

tool/lrama/lib/lrama/lexer/location.rb

@@ -1,9 +1,10 @@
 module Lrama
   class Lexer
     class Location
-      attr_reader :first_line, :first_column, :last_line, :last_column
+      attr_reader :grammar_file, :first_line, :first_column, :last_line, :last_column
 
-      def initialize(first_line:, first_column:, last_line:, last_column:)
+      def initialize(grammar_file:, first_line:, first_column:, last_line:, last_column:)
+        @grammar_file = grammar_file
         @first_line = first_line
         @first_column = first_column
         @last_line = last_line
@@ -12,11 +13,85 @@ module Lrama
 
       def ==(other)
         self.class == other.class &&
+        self.grammar_file == other.grammar_file &&
         self.first_line == other.first_line &&
         self.first_column == other.first_column &&
         self.last_line == other.last_line &&
         self.last_column == other.last_column
       end
+
+      def partial_location(left, right)
+        offset = -first_column
+        new_first_line = -1
+        new_first_column = -1
+        new_last_line = -1
+        new_last_column = -1
+
+        _text.each.with_index do |line, index|
+          new_offset = offset + line.length + 1
+
+          if offset <= left && left <= new_offset
+            new_first_line = first_line + index
+            new_first_column = left - offset
+          end
+
+          if offset <= right && right <= new_offset
+            new_last_line = first_line + index
+            new_last_column = right - offset
+          end
+
+          offset = new_offset
+        end
+
+        Location.new(
+          grammar_file: grammar_file,
+          first_line: new_first_line, first_column: new_first_column,
+          last_line: new_last_line, last_column: new_last_column
+        )
+      end
+
+      def to_s
+        "#{path} (#{first_line},#{first_column})-(#{last_line},#{last_column})"
+      end
+
+      def generate_error_message(error_message)
+        <<~ERROR.chomp
+          #{path}:#{first_line}:#{first_column}: #{error_message}
+          #{line_with_carets}
+        ERROR
+      end
+
+      def line_with_carets
+        <<~TEXT
+          #{text}
+          #{carets}
+        TEXT
+      end
+
+      private
+
+      def path
+        grammar_file.path
+      end
+
+      def blanks
+        (text[0...first_column] or raise "#{first_column} is invalid").gsub(/[^\t]/, ' ')
+      end
+
+      def carets
+        blanks + '^' * (last_column - first_column)
+      end
+
+      def text
+        @text ||= _text.join("\n")
+      end
+
+      def _text
+        @_text ||=begin
+          range = (first_line - 1)...last_line
+          grammar_file.lines[range] or raise "#{range} is invalid"
+        end
+      end
     end
   end
 end

tool/lrama/lib/lrama/lexer/token.rb

@@ -1,6 +1,6 @@
 require 'lrama/lexer/token/char'
 require 'lrama/lexer/token/ident'
-require 'lrama/lexer/token/parameterizing'
+require 'lrama/lexer/token/instantiate_rule'
 require 'lrama/lexer/token/tag'
 require 'lrama/lexer/token/user_code'
 

tool/lrama/lib/lrama/lexer/token/instantiate_rule.rb

@@ -0,0 +1,18 @@
+module Lrama
+  class Lexer
+    class Token
+      class InstantiateRule < Token
+        attr_accessor :args
+
+        def initialize(s_value:, alias_name: nil, location: nil, args: [])
+          super s_value: s_value, alias_name: alias_name, location: location
+          @args = args
+        end
+
+        def rule_name
+          s_value
+        end
+      end
+    end
+  end
+end

tool/lrama/lib/lrama/lexer/token/parameterizing.rb

@@ -1,34 +0,0 @@
-module Lrama
-  class Lexer
-    class Token
-      class Parameterizing < Token
-        attr_accessor :args
-
-        def initialize(s_value:, alias_name: nil, location: nil, args: [])
-          super s_value: s_value, alias_name: alias_name, location: location
-          @args = args
-        end
-
-        def option?
-          %w(option ?).include?(self.s_value)
-        end
-
-        def nonempty_list?
-          %w(nonempty_list +).include?(self.s_value)
-        end
-
-        def list?
-          %w(list *).include?(self.s_value)
-        end
-
-        def separated_nonempty_list?
-          %w(separated_nonempty_list).include?(self.s_value)
-        end
-
-        def separated_list?
-          %w(separated_list).include?(self.s_value)
-        end
-      end
-    end
-  end
-end

tool/lrama/lib/lrama/lexer/token/user_code.rb

@@ -35,27 +35,27 @@ module Lrama
           # 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: "$", ex_tag: tag, first_column: start, last_column: scanner.pos - 1)
+            return Lrama::Grammar::Reference.new(type: :dollar, name: "$", 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, index: Integer(scanner[2]), ex_tag: tag, first_column: start, last_column: scanner.pos - 1)
+            return Lrama::Grammar::Reference.new(type: :dollar, 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 - 1)
+            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>program (named reference with brackets)
+          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 - 1)
+            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: "$", first_column: start, last_column: scanner.pos - 1)
+            return Lrama::Grammar::Reference.new(type: :at, name: "$", first_column: start, last_column: scanner.pos)
           when scanner.scan(/@(\d+)/) # @1
-            return Lrama::Grammar::Reference.new(type: :at, index: Integer(scanner[1]), first_column: start, last_column: scanner.pos - 1)
+            return Lrama::Grammar::Reference.new(type: :at, 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 - 1)
+            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)
+          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 - 1)
+            return Lrama::Grammar::Reference.new(type: :at, name: scanner[1], first_column: start, last_column: scanner.pos)
           end
         end
       end

tool/lrama/lib/lrama/states_reporter.rb

@@ -156,7 +156,7 @@ module Lrama
           nl = true
         end
 
-        if r = state.default_reduction_rule
+        if (r = state.default_reduction_rule)
           nl = true
           s = "$default".ljust(max_len)
 

tool/lrama/lib/lrama/version.rb

@@ -1,3 +1,3 @@
 module Lrama
-  VERSION = "0.5.12".freeze
+  VERSION = "0.6.0".freeze
 end