Rename "following" to "next" - #25

The term "following" could potentially imply an association with the
"follow set", however it was used in a non-closed manner.

lib/propane/parser.rb

@@ -23,10 +23,10 @@ class Propane
           item_set.id = @item_sets.size
           @item_sets << item_set
           @item_sets_set[item_set] = item_set
-          item_set.following_symbols.each do |following_symbol|
+          item_set.next_symbols.each do |next_symbol|
-            unless following_symbol.name == "$EOF"
+            unless next_symbol.name == "$EOF"
-              following_set = item_set.build_following_item_set(following_symbol)
+              next_item_set = item_set.build_next_item_set(next_symbol)
-              eval_item_sets << following_set
+              eval_item_sets << next_item_set
             end
           end
         end
@@ -48,15 +48,15 @@ class Propane
       @shift_table = []
       @reduce_table = []
       @item_sets.each do |item_set|
-        shift_entries = item_set.following_symbols.map do |following_symbol|
+        shift_entries = item_set.next_symbols.map do |next_symbol|
           state_id =
-            if following_symbol.name == "$EOF"
+            if next_symbol.name == "$EOF"
               0
             else
-              item_set.following_item_set[following_symbol].id
+              item_set.next_item_set[next_symbol].id
             end
           {
-            symbol_id: following_symbol.id,
+            symbol_id: next_symbol.id,
             state_id: state_id,
           }
         end
@@ -87,11 +87,11 @@ class Propane
     end
 
     def process_item_set(item_set)
-      item_set.following_symbols.each do |following_symbol|
+      item_set.next_symbols.each do |next_symbol|
-        unless following_symbol.name == "$EOF"
+        unless next_symbol.name == "$EOF"
-          following_set = @item_sets_set[item_set.build_following_item_set(following_symbol)]
+          next_item_set = @item_sets_set[item_set.build_next_item_set(next_symbol)]
-          item_set.following_item_set[following_symbol] = following_set
+          item_set.next_item_set[next_symbol] = next_item_set
-          following_set.in_sets << item_set
+          next_item_set.in_sets << item_set
         end
       end
     end
@@ -183,9 +183,9 @@ class Propane
         # tokens to form the lookahead token set.
         item_sets.each do |item_set|
           item_set.items.each do |item|
-            if item.following_symbol == rule_set
+            if item.next_symbol == rule_set
               (1..).each do |offset|
-                case symbol = item.following_symbol(offset)
+                case symbol = item.next_symbol(offset)
                 when nil
                   rule_set = item.rule.rule_set
                   unless checked_rule_sets.include?(rule_set)
@@ -242,8 +242,8 @@ class Propane
         @log.puts
         @log.puts "  Incoming states: #{incoming_ids.join(", ")}"
         @log.puts "  Outgoing states:"
-        item_set.following_item_set.each do |following_symbol, following_item_set|
+        item_set.next_item_set.each do |next_symbol, next_item_set|
-          @log.puts "    #{following_symbol.name} => #{following_item_set.id}"
+          @log.puts "    #{next_symbol.name} => #{next_item_set.id}"
         end
         @log.puts
         @log.puts "  Reduce actions:"

lib/propane/parser/item.rb

@@ -56,7 +56,7 @@ class Propane
 
       # Return the set of Items obtained by "closing" the current item.
       #
-      # If the following symbol for the current item is another Rule name, then
+      # If the next symbol for the current item is another Rule name, then
       # this method will return all Items for that Rule with a position of 0.
       # Otherwise, an empty Array is returned.
       #
@@ -81,17 +81,17 @@ class Propane
         @position == @rule.components.size
       end
 
-      # Get the following symbol for the Item.
+      # Get the next symbol for the Item.
       #
-      # That is, the symbol which follows the parse position marker in the
+      # That is, the symbol which is after the parse position marker in the
       # current Item.
       #
       # @param offset [Integer]
       #   Offset from current parse position to examine.
       #
       # @return [Token, RuleSet, nil]
-      #   Following symbol for the Item.
+      #   Next symbol for the Item.
-      def following_symbol(offset = 0)
+      def next_symbol(offset = 0)
         @rule.components[@position + offset]
       end
 
@@ -108,25 +108,25 @@ class Propane
         end
       end
 
-      # Get whether this Item is followed by the provided symbol.
+      # Get whether this Item's next symbol is the given symbol.
       #
       # @param symbol [Token, RuleSet]
       #   Symbol to query.
       #
       # @return [Boolean]
-      #   Whether this Item is followed by the provided symbol.
+      #   Whether this Item's next symbol is the given symbol.
-      def followed_by?(symbol)
+      def next_symbol?(symbol)
-        following_symbol == symbol
+        next_symbol == symbol
       end
 
-      # Get the following item for this Item.
+      # Get the next item for this Item.
       #
       # That is, the Item formed by moving the parse position marker one place
       # forward from its position in this Item.
       #
       # @return [Item]
-      #   The following item for this Item.
+      #   The next item for this Item.
-      def following_item
+      def next_item
         Item.new(@rule, @position + 1)
       end
 

lib/propane/parser/item_set.rb

@@ -14,8 +14,8 @@ class Propane
       attr_accessor :id
 
       # @return [Hash]
-      #   Maps a following symbol to its ItemSet.
+      #   Maps a next symbol to its ItemSet.
-      attr_reader :following_item_set
+      attr_reader :next_item_set
 
       # @return [Set<ItemSet>]
       #   ItemSets leading to this item set.
@@ -31,28 +31,28 @@ class Propane
       #   Items in this ItemSet.
       def initialize(items)
         @items = Set.new(items)
-        @following_item_set = {}
+        @next_item_set = {}
         @in_sets = Set.new
         close!
       end
 
-      # Get the set of following symbols for all Items in this ItemSet.
+      # Get the set of next symbols for all Items in this ItemSet.
       #
       # @return [Set<Token, RuleSet>]
-      #   Set of following symbols for all Items in this ItemSet.
+      #   Set of next symbols for all Items in this ItemSet.
-      def following_symbols
+      def next_symbols
-        Set.new(@items.map(&:following_symbol).compact)
+        Set.new(@items.map(&:next_symbol).compact)
       end
 
-      # Build a following ItemSet for the given following symbol.
+      # Build a next ItemSet for the given next symbol.
       #
       # @param symbol [Token, RuleSet]
-      #   Following symbol to build the following ItemSet for.
+      #   Next symbol to build the next ItemSet for.
       #
       # @return [ItemSet]
-      #   Following ItemSet for the given following symbol.
+      #   Next ItemSet for the given next symbol.
-      def build_following_item_set(symbol)
+      def build_next_item_set(symbol)
-        ItemSet.new(items_followed_by(symbol).map(&:following_item))
+        ItemSet.new(items_with_next(symbol).map(&:next_item))
       end
 
       # Hash function.
@@ -137,16 +137,16 @@ class Propane
         end
       end
 
-      # Get the Items followed by the given following symbol.
+      # Get the Items with the given next symbol.
       #
       # @param symbol [Token, RuleSet]
-      #   Following symbol.
+      #   Next symbol.
       #
       # @return [Array<Item>]
-      #   Items followed by the given following symbol.
+      #   Items with the given next symbol.
-      def items_followed_by(symbol)
+      def items_with_next(symbol)
         @items.select do |item|
-          item.followed_by?(symbol)
+          item.next_symbol?(symbol)
         end
       end