Experimental parser: easier to read rules and default rule

tools/lexer_generator/nfa.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 339 matching lines @@
     dfa_nodes = {}
     start_name = self.__to_dfa(set([self.__start]), dfa_nodes, self.__end)
     return (start_name, dfa_nodes)
 
   def to_dot(self):
 
     def f(node, node_content):
       for key, values in node.transitions().items():
         if key == TransitionKey.epsilon():
           key = "ε"
+        key = str(key).replace('\\', '\\\\')
         for value in values:
           if value[1]:
             node_content.append(
                 "  S_%d -> S_%d [ label = \"%s {%s} -> %s\" ];" %
                 (node.node_number(), value[0].node_number(), key, value[1][0],
                  value[1][1]))
           else:
             node_content.append(
                 "  S_%d -> S_%d [ label = \"%s\" ];" %
                 (node.node_number(), value[0].node_number(), key))
       return node_content
 
     node_content = self.__visit_all_edges(f, [])
 
     return '''
 digraph finite_state_machine {
   rankdir=LR;
   node [shape = circle, style=filled, bgcolor=lightgrey]; S_%s
   node [shape = doublecircle, style=unfilled]; S_%s
   node [shape = circle];
 %s
 }
     ''' % (self.__start.node_number(),
            self.__end.node_number(),
            "\n".join(node_content))