#!/usr/bin/env python3
-class bidict(dict):
+# © Copyright 2021-2022, Scott Gasch
+
+"""Bidirectional Dictionary."""
+
+
+class BiDict(dict):
def __init__(self, *args, **kwargs):
"""
A class that stores both a Mapping between keys and values and
is possible to have several keys with the same value, using
the inverse map returns a sequence of keys.
- >>> d = bidict()
+ >>> d = BiDict()
>>> d['a'] = 1
>>> d['b'] = 2
>>> d['c'] = 2
def __setitem__(self, key, value):
if key in self:
- self.inverse[self[key]].remove(key)
+ old_value = self[key]
+ self.inverse[old_value].remove(key)
super().__setitem__(key, value)
self.inverse.setdefault(value, []).append(key)
def __delitem__(self, key):
- self.inverse.setdefault(self[key], []).remove(key)
- if self[key] in self.inverse and not self.inverse[self[key]]:
- del self.inverse[self[key]]
+ value = self[key]
+ self.inverse.setdefault(value, []).remove(key)
+ if value in self.inverse and not self.inverse[value]:
+ del self.inverse[value]
super().__delitem__(key)
if __name__ == '__main__':
import doctest
+
doctest.testmod()