Experimental parser: dfa optimization to remove transitions from keyword lexing

tools/lexer_generator/rule_parser.py

Index: tools/lexer_generator/rule_parser.py
diff --git a/tools/lexer_generator/rule_parser.py b/tools/lexer_generator/rule_parser.py
index 08277435940dcbea302fa94eba77e00fba3971e6..df19a3108bfcfca911512519d49de1861fc5ca5f 100644
--- a/tools/lexer_generator/rule_parser.py
+++ b/tools/lexer_generator/rule_parser.py
@@ -31,6 +31,7 @@ from rule_lexer import RuleLexer
 from regex_parser import RegexParser
 from nfa_builder import NfaBuilder
 from dfa import Dfa
+from dfa_optimizer import DfaOptimizer
 from transition_keys import TransitionKey, KeyEncoding
 
 class RuleParserState:
@@ -293,6 +294,10 @@ class RuleProcessor(object):
         self.__dfa = Dfa(self.nfa().encoding(), start, dfa_nodes)
       return self.__dfa
 
+    def optimize_dfa(self, log = False):
+      assert not self.__dfa
+      self.__dfa = DfaOptimizer.optimize(self.dfa(), log)
+
     def minimal_dfa(self):
       if not self.__minimial_dfa:
         self.__minimial_dfa = self.dfa().minimize()