sfa/util/defaultdict.py

   1 # from http://code.activestate.com/recipes/523034/
   2 try:
   3     from collections import defaultdict
   4 except:
   5     class defaultdict(dict):
   6         def __init__(self, default_factory=None, *a, **kw):
   7             if (default_factory is not None and
   8                 not hasattr(default_factory, '__call__')):
   9                 raise TypeError('first argument must be callable')
  10             dict.__init__(self, *a, **kw)
  11             self.default_factory = default_factory
  12         def __getitem__(self, key):
  13             try:
  14                 return dict.__getitem__(self, key)
  15             except KeyError:
  16                 return self.__missing__(key)
  17         def __missing__(self, key):
  18             if self.default_factory is None:
  19                 raise KeyError(key)
  20             self[key] = value = self.default_factory()
  21             return value
  22         def __reduce__(self):
  23             if self.default_factory is None:
  24                 args = tuple()
  25             else:
  26                 args = self.default_factory,
  27             return type(self), args, None, None, self.items()
  28         def copy(self):
  29             return self.__copy__()
  30         def __copy__(self):
  31             return type(self)(self.default_factory, self)
  32         def __deepcopy__(self, memo):
  33             import copy
  34             return type(self)(self.default_factory,
  35                               copy.deepcopy(self.items()))
  36         def __repr__(self):
  37             return 'defaultdict(%s, %s)' % (self.default_factory,
  38                                             dict.__repr__(self))