item_vertex.rb in rley-0.3.00

- old
+ new
@@ -1,26 +1,72 @@
-require_relative 'vertex'
-
-module Rley # This module is used as a namespace
-  module GFG # This module is used as a namespace
-    # TODO: modify definition
-    # Represents a specialized vertex in a grammar flow graph 
-    # that is associated to a given dotted item.
-    # Responsibilities (in addition to inherited ones):
-    # - Know its related non-terminal symbol
-    class ItemVertex < Vertex
-        attr_reader :dotted_item
-      
-      def initialize(aDottedItem)
-        super()
-        @dotted_item = aDottedItem
-      end
-      
-      def label()
-        return "#{dotted_item}"
-      end
-
-    end # class
-  end # module
-end # module
-
+require_relative '../syntax/non_terminal'
+require_relative 'vertex'
+
+
+module Rley # This module is used as a namespace
+  module GFG # This module is used as a namespace
+    # TODO: modify definition
+    # Represents a specialized vertex in a grammar flow graph
+    # that is associated to a given dotted item.
+    # Responsibilities (in addition to inherited ones):
+    # - Know its related non-terminal symbol
+    class ItemVertex < Vertex
+        # Link to the dotted item object
+        attr_reader :dotted_item
+
+        # Optional link to a "shortcut" edge.
+        # Applicable only if the dotted expects a non-terminal symbol.
+        attr_reader :shortcut
+
+      def initialize(aDottedItem)
+        super()
+        @dotted_item = aDottedItem
+      end
+      
+      # Set the "shortcut" edge.
+      def shortcut=(aShortcut)
+        unless aShortcut.kind_of?(ShortcutEdge)
+          fail StandardError, 'Invalid shortcut argument'
+        end
+=begin
+        unless next_symbol && next_symbol.kind_of?(Syntax::NonTerminal)
+          fail StandardError, 'Invalid shortcut usage'
+        end
+        
+        shortcut_d_item = aShortcut.successor.dotted_item
+        unless (dotted_item.production == shortcut_d_item.production) &&
+          (dotted_item.position == shortcut_d_item.prev_position)
+          fail StandardError, 'Shortcut refers to wrong vertex'
+        end
+=end        
+        @shortcut = aShortcut
+      end
+
+      def label()
+        return "#{dotted_item}"
+      end
+
+      # Returns true if the dotted item has a dot at the end of the production.
+      def complete?()
+        return dotted_item.reduce_item?
+      end
+
+      # Return the symbol before the dot else nil.
+      def prev_symbol()
+        return dotted_item.prev_symbol
+      end      
+      
+      # Return the symbol after the dot else nil.
+      def next_symbol()
+        return dotted_item.next_symbol
+      end
+      
+      # Return the non-terminal symbol at the left-hand side of the production
+      def lhs()
+        return dotted_item.lhs
+      end
+
+    end # class
+  end # module
+end # module
+
 # End of file
\ No newline at end of file