lib/rley/ptree/token_range.rb in rley-0.2.15 vs lib/rley/ptree/token_range.rb in rley-0.3.00

@@ -1,7 +1,15 @@
 module Rley # This module is used as a namespace
   module PTree # This module is used as a namespace
+    # A token range (also called an extent) represents an interval 
+    # of token positions that is matched by a given grammar symbol.
+    # For instance consider the expression E: 3 + 11,
+    # let's assume that the integer literal '3' is the fifth input token and
+    # that the '+' and '11' tokens are respectively at position 6 and 7;
+    # then the token range associated with E is [5, 7]
+    # While the parse tree/forest is being constructed the boundaries of the token range
+    # can be temporarily undefined (= set to nil)
     class TokenRange
       # The index of the lower bound of token range
       attr_reader(:low)
 
       # The index of the upper bound of token range
@@ -56,10 +64,15 @@
       def to_string(_indentation)
         low_text = low.nil? ? '?' : low.to_s
         high_text = high.nil? ? '?' : high.to_s
         
         return "[#{low_text}, #{high_text}]"
-      end 
+      end
+
+      # Generate a String that represents a value-based identifier 
+      def keystr()
+        return "#{low.object_id}-#{high.object_id}"
+      end
 
       private
 
       def assign_low(aRange)
         case aRange