Experimental parser: better eos handling

tools/lexer_generator/nfa_builder.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 233 matching lines @@
     catch_all = TransitionKey.unique('catch_all')
     transitions = state.transitions()
     if not catch_all in transitions:
       return
     f = lambda acc, state: acc | set(state.epsilon_closure_iter())
     reachable_states = reduce(f, transitions[catch_all], set())
     f = lambda acc, state: acc | set(state.transitions().keys())
     keys = reduce(f, reachable_states, set())
     keys.discard(TransitionKey.epsilon())
     keys.discard(catch_all)
+    keys.discard(TransitionKey.unique('eos'))
     inverse_key = TransitionKey.inverse_key(encoding, keys)
     if inverse_key:
       transitions[inverse_key] = transitions[catch_all]
     del transitions[catch_all]
 
   def nfa(self, graph):
     (start, end, nodes_created) = self.__nfa(graph)
 
     global_end_to_return = self.__global_end_node or end
     assert global_end_to_return
@@ skipping 73 matching lines @@
 
   __modifer_map = {
     '+': 'ONE_OR_MORE',
     '?': 'ZERO_OR_ONE',
     '*': 'ZERO_OR_MORE',
   }
 
   @staticmethod
   def apply_modifier(modifier, graph):
     return (NfaBuilder.__modifer_map[modifier], graph)