class AVLtreeDict(AVL):
'''A AVL-based implementation of a sorted dictionary'''
def __init__(self):
self._items = AVL()
def __getitem__(self, key):
'''Returns the value associated with key or returns None if key does not exist.'''
return self._items.find(key)
def __setitem__(self, key, value):
self._items.add((key, value))
def __contains__(self, key):
return self.__getitem__(key) != None
def __str__(self):
return str(self._items)
def __len__(self):
return len(self._items)
def __iter__(self):
return iter(self._items)
