Experimental parser: cleanup

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 38 matching lines @@
 
 class Dfa:
 
   def __init__(self, start_name, mapping, end_names):
     name_map = {}
     offset = 0
     self.__terminal_set = set()
     for name in mapping.keys():
       dfa_state = DfaState(name, offset)
       name_map[name] = dfa_state
-      offset = offset + 1
+      offset += 1
       if name in end_names:
         self.__terminal_set.add(dfa_state)
     for name, values in mapping.items():
       for key, value in values.items():
         name_map[name].add_transition(key, name_map[value])
     self.__start = name_map[start_name]
     assert self.__terminal_set
 
   @staticmethod
-  def __visit_edges(start, function, state):
+  def __visit_edges(start, visitor, state):
     edge = set([start])
     visited = set()
     while edge:
-      next_edge = set()
-      for node in edge:
-        next_edge |= set(node.transitions().values())
-        state = function(node, state)
+      f = lambda (next_edge, state), node: (
+        next_edge | set(node.transitions().values()),
+        visitor(node, state))
+      (next_edge, state) = reduce(f, edge, (set(), state))
       visited |= edge
       edge = next_edge - visited
     return state
 
   def to_dot(self):
 
     def f(node, node_content):
       for key, value in node.transitions().items():
         node_content.append(
           "  S_%s -> S_%s [ label = \"%s\" ];" %
@@ skipping 12 matching lines @@
   rankdir=LR;
   node [shape = %s, style=filled, bgcolor=lightgrey]; S_%s
   node [shape = doublecircle, style=unfilled]; %s
   node [shape = circle];
 %s
 }
     ''' % (start_shape,
            start_number,
            " ".join(terminals),
            "\n".join(node_content))