Experimental parser: fix an assert to be more meaningful.

tools/lexer_generator/dfa.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 171 matching lines @@
     all_keys = [] # Will contain all TransitionKeys in the dfa.
 
     # f fills in initial_partitions, id_to_state and all_keys.
     def f(state, visitor_state):
       state_id = len(id_to_state)
       id_to_state[state_id] = state
       action = state.action()
       all_keys.append(state.key_iter())
       if action:
         if state not in terminal_set:
-          assert action.entry_action()
+          # Match actions are valid only if we have matched the whole token, not
+          # just some sub-part of it.
+          assert not action.match_action()
           key = ("nonterminal action", action)
         else:
           key = ("terminal action", action)
       elif state in terminal_set:
         key = ("terminal set",)
       else:
         key = ("nonterminal set",)
       if not key in initial_partitions:
         initial_partitions[key] = set()
       initial_partitions[key].add(state_id)
@@ skipping 182 matching lines @@
           elif len(intersection) <= len(difference):
             working_set.add(intersection)
           else:
             working_set.add(difference)
         if old_partitions:
           partitions -= old_partitions
         if new_partitions:
           partitions |= new_partitions
     (start_name, mapping) = self.__create_states_from_partitions(partitions)
     return Dfa(self.__dfa.encoding(), start_name, mapping)