Experimental lexer generator: random refactoring + comments.

tools/lexer_generator/dfa.py

Index: tools/lexer_generator/dfa.py
diff --git a/tools/lexer_generator/dfa.py b/tools/lexer_generator/dfa.py
index d191e0518550f014d15076cf259b102dfd77786b..545fe84b6ee5d5e5531b89eabfdc84cc72c1dc23 100644
--- a/tools/lexer_generator/dfa.py
+++ b/tools/lexer_generator/dfa.py
@@ -55,14 +55,17 @@ class DfaState(AutomatonState):
 
   # TODO abstract state matching
   def __matches(self, match_func, value):
-    f = lambda acc, (k, vs): acc | set([vs]) if match_func(k, value) else acc
+    # f collects states whose corresponding TransitionKey matches 'value'.
+    f = (lambda acc, (key, state):
+           acc | set([state]) if match_func(key, value) else acc)
     matches = reduce(f, self.__transitions.items(), set())
+    # Since this is a dfa, we should have at most one such state. Return it.
     if not matches:
       return None
     assert len(matches) == 1
     return iter(matches).next()
 
-  def char_matches(self, value):
+  def next_state_with_char(self, value):
     return self.__matches(lambda k, v : k.matches_char(v), value)
 
   def key_matches(self, value):