Experimental lexer generator: parse {} in regexps.

tools/lexer_generator/transition_keys.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 177 matching lines @@
         else:
           ranges.append((left, v))
           left = v + 1
       if to_push:
         current = range_map[i + 1]
         range_map[i + 1] = (current[0], sort(current[1] + to_push))
     return ranges
 
   @staticmethod
   def disjoint_keys(key_set):
+    key_set.discard(TransitionKey.epsilon())
     if not key_set:
       return []
     range_map = {}
     for x in key_set:
       for r in x.__ranges:
         if not r[0] in range_map:
           range_map[r[0]] = []
         range_map[r[0]].append(r[1])
     ranges = TransitionKey.__disjoint_keys(range_map)
     TransitionKey.__verify_ranges(ranges, False)
@@ skipping 54 matching lines @@
       elif last[1] + 1 < r[0]:
         inverted.append((last[1] + 1, r[0] - 1))
       last = r
     if last != None and last[1] < TransitionKey.__latin_1_upper_bound:
       inverted.append((last[1] + 1, TransitionKey.__latin_1_upper_bound))
     if not contains_whitespace:
       inverted.append(TransitionKey.__unicode_whitespace_bounds)
     if not contains_literal:
       inverted.append(TransitionKey.__unicode_literal_bounds)
     return inverted