Experimental parser: use sentinal values for actions

tools/lexer_generator/code_generator.py

Index: tools/lexer_generator/code_generator.py
diff --git a/tools/lexer_generator/code_generator.py b/tools/lexer_generator/code_generator.py
index 6bc44eb8da20905171050a6d350727dd3ed122da..96a26f473d52c1024265af92d0bbafc934f49d18 100644
--- a/tools/lexer_generator/code_generator.py
+++ b/tools/lexer_generator/code_generator.py
@@ -61,8 +61,8 @@ class CodeGenerator:
   def __transform_state(encoding, state):
     # action data
     action = state.action()
-    entry_action = None if not action else action.entry_action()
-    match_action = None if not action else action.match_action()
+    entry_action = action.entry_action()
+    match_action = action.match_action()
     # generate ordered transitions
     transitions = map(lambda (k, v) : (k, v.node_number()),
                       state.transitions().items())
@@ -297,8 +297,7 @@ class CodeGenerator:
     goto_map = {}
     states = self.__dfa_states
     for state in states:
-      if (state['match_action'] and
-          state['match_action'].name() == 'do_stored_token'):
+      if (state['match_action'].name() == 'do_stored_token'):
         assert not state['match_action'].args()[0] in goto_map
         goto_map[state['match_action'].args()[0]] = state['node_number']
     mapped_actions = set([