constructor.rb in antelope-0.2.2

- old
+ new
@@ -1,126 +1,126 @@
-# encoding: utf-8
-
-require "set"
-require "antelope/generation/constructor/nullable"
-require "antelope/generation/constructor/first"
-require "antelope/generation/constructor/follow"
-
-module Antelope
-  module Generation
-
-    # Constructs the lookahead sets for all of the rules in the
-    # grammar.
-    class Constructor
-
-      include Nullable
-      include First
-      include Follow
-
-      # The grammar.
-      #
-      # @return [Ace::Grammar]
-      attr_reader :grammar
-
-      # The augmented productions generated by the constructor.
-      #
-      # @return [Set<Ace::Production>]
-      attr_reader :productions
-
-      # Initialize.
-      #
-      # @param grammar [Ace::Grammar] the grammar.
-      def initialize(grammar)
-        @productions = Set.new
-        @grammar = grammar
-        super()
-      end
-
-      # Performs the construction.  First, it goes through every state
-      # and augments the state.  It then goes through every rule and
-      # augments it.
-      #
-      # @return [void]
-      # @see #augment_state
-      # @see #augment_rule
-      def call
-        grammar.states.each do |state|
-          augment_state(state)
-        end.each do |state|
-          augment_rules(state)
-        end
-      end
-
-      # Augments the given state.  On every rule within that state
-      # that has a position of zero, it follows the rule throughout
-      # the DFA until the end; it marks every nonterminal it
-      # encounters with the transitions it took on that nonterminal.
-      #
-      # @param state [Recognizer::State] the state to augment.
-      # @return [void]
-      def augment_state(state)
-        state.rules.select { |x| x.position.zero? }.each do |rule|
-          production = rule.production.clone
-          production.items = []
-
-          current_state = state
-          old_state = state
-
-          production.label.from = state
-          production.label.to   = state.transitions[rule.left.name]
-
-          rule.right.each_with_index do |part, pos|
-            transition = current_state.transitions[part.name]
-            new_item = part.dup
-
-            if part.nonterminal?
-              new_item.from = current_state
-              new_item.to   = transition
-            end
-
-            production.items << new_item
-
-            old_state = current_state
-            current_state = transition
-          end
-
-          productions << production
-        end
-      end
-
-      # Augments every final rule.  For every rule in the current
-      # state that has a position of zero, it follows the rule through
-      # the DFA until the ending state; it then modifies the ending
-      # state's lookahead set to be the FOLLOW set of the nonterminal
-      # it reduces to.
-      #
-      # @param state [Recognizer::State]
-      # @return [void]
-      # @see Follow#follow
-      def augment_rules(state)
-        state.rules.select { |x| x.position.zero? }.each do |rule|
-          current_state = state
-
-          label = rule.left.dup
-          label.from = state
-          label.to = state.transitions[label.name]
-
-          rule.right.each do |part|
-            transition = current_state.transitions[part.name]
-            current_state = transition
-          end
-
-          final = current_state.rule_for(rule)
-
-          final.lookahead = Set.new unless final.lookahead
-          final.lookahead.merge follow(label)
-        end
-      end
-
-      private
-
-      def incorrect_argument!(arg, *types)
-        raise ArgumentError, "Expected one of #{types.join(", ")}, got #{arg.class}"
-      end
-    end
-  end
-end
+# encoding: utf-8
+
+require "set"
+require "antelope/generation/constructor/nullable"
+require "antelope/generation/constructor/first"
+require "antelope/generation/constructor/follow"
+
+module Antelope
+  module Generation
+
+    # Constructs the lookahead sets for all of the rules in the
+    # grammar.
+    class Constructor
+
+      include Nullable
+      include First
+      include Follow
+
+      # The grammar.
+      #
+      # @return [Ace::Grammar]
+      attr_reader :grammar
+
+      # The augmented productions generated by the constructor.
+      #
+      # @return [Set<Ace::Production>]
+      attr_reader :productions
+
+      # Initialize.
+      #
+      # @param grammar [Ace::Grammar] the grammar.
+      def initialize(grammar)
+        @productions = Set.new
+        @grammar = grammar
+        super()
+      end
+
+      # Performs the construction.  First, it goes through every state
+      # and augments the state.  It then goes through every rule and
+      # augments it.
+      #
+      # @return [void]
+      # @see #augment_state
+      # @see #augment_rule
+      def call
+        grammar.states.each do |state|
+          augment_state(state)
+        end.each do |state|
+          augment_rules(state)
+        end
+      end
+
+      # Augments the given state.  On every rule within that state
+      # that has a position of zero, it follows the rule throughout
+      # the DFA until the end; it marks every nonterminal it
+      # encounters with the transitions it took on that nonterminal.
+      #
+      # @param state [Recognizer::State] the state to augment.
+      # @return [void]
+      def augment_state(state)
+        state.rules.select { |x| x.position.zero? }.each do |rule|
+          production = rule.production.clone
+          production.items = []
+
+          current_state = state
+          old_state = state
+
+          production.label.from = state
+          production.label.to   = state.transitions[rule.left.name]
+
+          rule.right.each_with_index do |part, pos|
+            transition = current_state.transitions[part.name]
+            new_item = part.dup
+
+            if part.nonterminal?
+              new_item.from = current_state
+              new_item.to   = transition
+            end
+
+            production.items << new_item
+
+            old_state = current_state
+            current_state = transition
+          end
+
+          productions << production
+        end
+      end
+
+      # Augments every final rule.  For every rule in the current
+      # state that has a position of zero, it follows the rule through
+      # the DFA until the ending state; it then modifies the ending
+      # state's lookahead set to be the FOLLOW set of the nonterminal
+      # it reduces to.
+      #
+      # @param state [Recognizer::State]
+      # @return [void]
+      # @see Follow#follow
+      def augment_rules(state)
+        state.rules.select { |x| x.position.zero? }.each do |rule|
+          current_state = state
+
+          label = rule.left.dup
+          label.from = state
+          label.to = state.transitions[label.name]
+
+          rule.right.each do |part|
+            transition = current_state.transitions[part.name]
+            current_state = transition
+          end
+
+          final = current_state.rule_for(rule)
+
+          final.lookahead = Set.new unless final.lookahead
+          final.lookahead.merge follow(label)
+        end
+      end
+
+      private
+
+      def incorrect_argument!(arg, *types)
+        raise ArgumentError, "Expected one of #{types.join(", ")}, got #{arg.class}"
+      end
+    end
+  end
+end