collect/bidict.py

   1 #!/usr/bin/env python3
   2
   3 class bidict(dict):
   4     def __init__(self, *args, **kwargs):
   5         super(bidict, self).__init__(*args, **kwargs)
   6         self.inverse = {}
   7         for key, value in self.items():
   8             self.inverse.setdefault(value, []).append(key)
   9
  10     def __setitem__(self, key, value):
  11         if key in self:
  12             self.inverse[self[key]].remove(key)
  13         super(bidict, self).__setitem__(key, value)
  14         self.inverse.setdefault(value, []).append(key)
  15
  16     def __delitem__(self, key):
  17         self.inverse.setdefault(self[key], []).remove(key)
  18         if self[key] in self.inverse and not self.inverse[self[key]]:
  19             del self.inverse[self[key]]
  20         super(bidict, self).__delitem__(key)