Experimental parser: dfa optimization to remove transitions from keyword lexing

tools/lexer_generator/transition_keys.py

 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 311 matching lines @@
     self.__ranges = tuple(ranges) # immutable
     self.__cached_hash = None
 
   def to_string(self, encoding):
     if self.__name:
       return self.__name
     strings = [TransitionKey.__range_str(encoding, x) for x in self.__ranges]
     return ', '.join(strings)
 
   def __str__(self):
-    self.to_string(None)
+    return self.to_string(None)
 
   @staticmethod
   def __disjoint_keys(encoding, range_map):
     '''Takes a set of possibly overlapping ranges, returns a list of ranges
     which don't overlap and which cover the same points as the original
     set. range_map is a map from lower bounds to a list of upper bounds.'''
     sort = lambda x : sorted(set(x))
     range_map = sorted(map(lambda (k, v): (k, sort(v)), range_map.items()))
     ranges = []
     upper_bound = encoding.upper_bound() + 1
@@ skipping 182 matching lines @@
         self.class_range('non_primary_whitespace')])
     self.add_predefined_range(
       'letter', [(65, 90), (97, 122), self.class_range('non_primary_letter')])
     self.add_predefined_range(
       'line_terminator',
       [(10, 10), (13, 13), self.class_range('non_primary_line_terminator')])
     self.add_predefined_range(
       'identifier_part_not_letter',
       [(48, 57), (95, 95),
        self.class_range('non_primary_identifier_part_not_letter')])