# Pure Python implementation of OrderedDict from the Python 3.5 collections.py from operator import eq as _eq import sys as _sys from _weakref import proxy as _proxy from reprlib import recursive_repr as _recursive_repr from _collections_abc import KeysView, ItemsView, ValuesView, MutableMapping class _OrderedDictKeysView(KeysView): def __reversed__(self): for key in reversed(self._mapping): yield key class _OrderedDictItemsView(ItemsView): def __reversed__(self): for key in reversed(self._mapping): yield (key, self._mapping[key]) class _OrderedDictValuesView(ValuesView): def __reversed__(self): for key in reversed(self._mapping): yield self._mapping[key] class _Link(object): __slots__ = 'prev', 'next', 'key', '__weakref__' class OrderedDict(dict): 'Dictionary that remembers insertion order' # An inherited dict maps keys to values. # The inherited dict provides __getitem__, __len__, __contains__, and get. # The remaining methods are order-aware. # Big-O running times for all methods are the same as regular dictionaries. # The internal self.__map dict maps keys to links in a doubly linked list. # The circular doubly linked list starts and ends with a sentinel element. # The sentinel element never gets deleted (this simplifies the algorithm). # The sentinel is in self.__hardroot with a weakref proxy in self.__root. # The prev links are weakref proxies (to prevent circular references). # Individual links are kept alive by the hard reference in self.__map. # Those hard references disappear when a key is deleted from an OrderedDict. def __init__(*args, **kwds): '''Initialize an ordered dictionary. The signature is the same as regular dictionaries, but keyword arguments are not recommended because their insertion order is arbitrary. ''' if not args: raise TypeError("descriptor '__init__' of 'OrderedDict' object " "needs an argument") self, args = args[0], args[1:] if len(args) > 1: raise TypeError('expected at most 1 arguments, got %d' % len(args)) try: self.__root except AttributeError: self.__hardroot = _Link() self.__root = root = _proxy(self.__hardroot) root.prev = root.next = root self.__map = {} self.__update(*args, **kwds) def __setitem__(self, key, value, dict_setitem=dict.__setitem__, proxy=_proxy, Link=_Link): 'od.__setitem__(i, y) <==> od[i]=y' # Setting a new item creates a new link at the end of the linked list, # and the inherited dictionary is updated with the new key/value pair. if key not in self: self.__map[key] = link = Link() root = self.__root last = root.prev link.prev, link.next, link.key = last, root, key last.next = link root.prev = proxy(link) dict_setitem(self, key, value) def __delitem__(self, key, dict_delitem=dict.__delitem__): 'od.__delitem__(y) <==> del od[y]' # Deleting an existing item uses self.__map to find the link which gets # removed by updating the links in the predecessor and successor nodes. dict_delitem(self, key) link = self.__map.pop(key) link_prev = link.prev link_next = link.next link_prev.next = link_next link_next.prev = link_prev link.prev = None link.next = None def __iter__(self): 'od.__iter__() <==> iter(od)' # Traverse the linked list in order. root = self.__root curr = root.next while curr is not root: yield curr.key curr = curr.next def __reversed__(self): 'od.__reversed__() <==> reversed(od)' # Traverse the linked list in reverse order. root = self.__root curr = root.prev while curr is not root: yield curr.key curr = curr.prev def clear(self): 'od.clear() -> None. Remove all items from od.' root = self.__root root.prev = root.next = root self.__map.clear() dict.clear(self) def popitem(self, last=True): '''od.popitem() -> (k, v), return and remove a (key, value) pair. Pairs are returned in LIFO order if last is true or FIFO order if false. ''' if not self: raise KeyError('dictionary is empty') root = self.__root if last: link = root.prev link_prev = link.prev link_prev.next = root root.prev = link_prev else: link = root.next link_next = link.next root.next = link_next link_next.prev = root key = link.key del self.__map[key] value = dict.pop(self, key) return key, value def move_to_end(self, key, last=True): '''Move an existing element to the end (or beginning if last==False). Raises KeyError if the element does not exist. When last=True, acts like a fast version of self[key]=self.pop(key). ''' link = self.__map[key] link_prev = link.prev link_next = link.next link_prev.next = link_next link_next.prev = link_prev root = self.__root if last: last = root.prev link.prev = last link.next = root last.next = root.prev = link else: first = root.next link.prev = root link.next = first root.next = first.prev = link def __sizeof__(self): sizeof = _sys.getsizeof n = len(self) + 1 # number of links including root size = sizeof(self.__dict__) # instance dictionary size += sizeof(self.__map) * 2 # internal dict and inherited dict size += sizeof(self.__hardroot) * n # link objects size += sizeof(self.__root) * n # proxy objects return size update = __update = MutableMapping.update def keys(self): "D.keys() -> a set-like object providing a view on D's keys" return _OrderedDictKeysView(self) def items(self): "D.items() -> a set-like object providing a view on D's items" return _OrderedDictItemsView(self) def values(self): "D.values() -> an object providing a view on D's values" return _OrderedDictValuesView(self) __ne__ = MutableMapping.__ne__ __marker = object() def pop(self, key, default=__marker): '''od.pop(k[,d]) -> v, remove specified key and return the corresponding value. If key is not found, d is returned if given, otherwise KeyError is raised. ''' if key in self: result = self[key] del self[key] return result if default is self.__marker: raise KeyError(key) return default def setdefault(self, key, default=None): 'od.setdefault(k[,d]) -> od.get(k,d), also set od[k]=d if k not in od' if key in self: return self[key] self[key] = default return default @_recursive_repr() def __repr__(self): 'od.__repr__() <==> repr(od)' if not self: return '%s()' % (self.__class__.__name__,) return '%s(%r)' % (self.__class__.__name__, list(self.items())) def __reduce__(self): 'Return state information for pickling' inst_dict = vars(self).copy() for k in vars(OrderedDict()): inst_dict.pop(k, None) return self.__class__, (), inst_dict or None, None, iter(self.items()) def copy(self): 'od.copy() -> a shallow copy of od' return self.__class__(self) @classmethod def fromkeys(cls, iterable, value=None): '''OD.fromkeys(S[, v]) -> New ordered dictionary with keys from S. If not specified, the value defaults to None. ''' self = cls() for key in iterable: self[key] = value return self def __eq__(self, other): '''od.__eq__(y) <==> od==y. Comparison to another OD is order-sensitive while comparison to a regular mapping is order-insensitive. ''' if isinstance(other, OrderedDict): return dict.__eq__(self, other) and all(map(_eq, self, other)) return dict.__eq__(self, other)