BreakWa11
9 years ago
2 changed files with 240 additions and 25 deletions
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import collections |
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################################################################################ |
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### OrderedDict |
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################################################################################ |
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class OrderedDict(dict): |
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'Dictionary that remembers insertion order' |
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# An inherited dict maps keys to values. |
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# The inherited dict provides __getitem__, __len__, __contains__, and get. |
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# The remaining methods are order-aware. |
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# Big-O running times for all methods are the same as regular dictionaries. |
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# The internal self.__map dict maps keys to links in a doubly linked list. |
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# The circular doubly linked list starts and ends with a sentinel element. |
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# The sentinel element never gets deleted (this simplifies the algorithm). |
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# Each link is stored as a list of length three: [PREV, NEXT, KEY]. |
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def __init__(*args, **kwds): |
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'''Initialize an ordered dictionary. The signature is the same as |
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regular dictionaries, but keyword arguments are not recommended because |
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their insertion order is arbitrary. |
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''' |
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if not args: |
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raise TypeError("descriptor '__init__' of 'OrderedDict' object " |
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"needs an argument") |
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self = args[0] |
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args = args[1:] |
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if len(args) > 1: |
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raise TypeError('expected at most 1 arguments, got %d' % len(args)) |
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try: |
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self.__root |
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except AttributeError: |
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self.__root = root = [] # sentinel node |
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root[:] = [root, root, None] |
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self.__map = {} |
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self.__update(*args, **kwds) |
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def __setitem__(self, key, value, dict_setitem=dict.__setitem__): |
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'od.__setitem__(i, y) <==> od[i]=y' |
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# Setting a new item creates a new link at the end of the linked list, |
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# and the inherited dictionary is updated with the new key/value pair. |
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if key not in self: |
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root = self.__root |
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last = root[0] |
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last[1] = root[0] = self.__map[key] = [last, root, key] |
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return dict_setitem(self, key, value) |
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def __delitem__(self, key, dict_delitem=dict.__delitem__): |
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'od.__delitem__(y) <==> del od[y]' |
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# Deleting an existing item uses self.__map to find the link which gets |
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# removed by updating the links in the predecessor and successor nodes. |
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dict_delitem(self, key) |
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link_prev, link_next, _ = self.__map.pop(key) |
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link_prev[1] = link_next # update link_prev[NEXT] |
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link_next[0] = link_prev # update link_next[PREV] |
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def __iter__(self): |
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'od.__iter__() <==> iter(od)' |
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# Traverse the linked list in order. |
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root = self.__root |
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curr = root[1] # start at the first node |
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while curr is not root: |
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yield curr[2] # yield the curr[KEY] |
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curr = curr[1] # move to next node |
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def __reversed__(self): |
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'od.__reversed__() <==> reversed(od)' |
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# Traverse the linked list in reverse order. |
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root = self.__root |
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curr = root[0] # start at the last node |
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while curr is not root: |
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yield curr[2] # yield the curr[KEY] |
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curr = curr[0] # move to previous node |
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def clear(self): |
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'od.clear() -> None. Remove all items from od.' |
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root = self.__root |
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root[:] = [root, root, None] |
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self.__map.clear() |
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dict.clear(self) |
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# -- the following methods do not depend on the internal structure -- |
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def keys(self): |
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'od.keys() -> list of keys in od' |
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return list(self) |
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def values(self): |
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'od.values() -> list of values in od' |
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return [self[key] for key in self] |
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def items(self): |
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'od.items() -> list of (key, value) pairs in od' |
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return [(key, self[key]) for key in self] |
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def iterkeys(self): |
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'od.iterkeys() -> an iterator over the keys in od' |
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return iter(self) |
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def itervalues(self): |
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'od.itervalues -> an iterator over the values in od' |
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for k in self: |
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yield self[k] |
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def iteritems(self): |
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'od.iteritems -> an iterator over the (key, value) pairs in od' |
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for k in self: |
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yield (k, self[k]) |
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update = collections.MutableMapping.update |
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__update = update # let subclasses override update without breaking __init__ |
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__marker = object() |
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def pop(self, key, default=__marker): |
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'''od.pop(k[,d]) -> v, remove specified key and return the corresponding |
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value. If key is not found, d is returned if given, otherwise KeyError |
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is raised. |
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''' |
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if key in self: |
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result = self[key] |
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del self[key] |
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return result |
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if default is self.__marker: |
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raise KeyError(key) |
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return default |
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def setdefault(self, key, default=None): |
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'od.setdefault(k[,d]) -> od.get(k,d), also set od[k]=d if k not in od' |
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if key in self: |
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return self[key] |
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self[key] = default |
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return default |
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def popitem(self, last=True): |
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'''od.popitem() -> (k, v), return and remove a (key, value) pair. |
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Pairs are returned in LIFO order if last is true or FIFO order if false. |
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''' |
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if not self: |
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raise KeyError('dictionary is empty') |
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key = next(reversed(self) if last else iter(self)) |
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value = self.pop(key) |
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return key, value |
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def __repr__(self, _repr_running={}): |
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'od.__repr__() <==> repr(od)' |
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call_key = id(self), _get_ident() |
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if call_key in _repr_running: |
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return '...' |
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_repr_running[call_key] = 1 |
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try: |
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if not self: |
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return '%s()' % (self.__class__.__name__,) |
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return '%s(%r)' % (self.__class__.__name__, self.items()) |
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finally: |
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del _repr_running[call_key] |
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def __reduce__(self): |
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'Return state information for pickling' |
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items = [[k, self[k]] for k in self] |
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inst_dict = vars(self).copy() |
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for k in vars(OrderedDict()): |
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inst_dict.pop(k, None) |
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if inst_dict: |
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return (self.__class__, (items,), inst_dict) |
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return self.__class__, (items,) |
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def copy(self): |
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'od.copy() -> a shallow copy of od' |
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return self.__class__(self) |
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@classmethod |
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def fromkeys(cls, iterable, value=None): |
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'''OD.fromkeys(S[, v]) -> New ordered dictionary with keys from S. |
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If not specified, the value defaults to None. |
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''' |
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self = cls() |
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for key in iterable: |
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self[key] = value |
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return self |
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def __eq__(self, other): |
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'''od.__eq__(y) <==> od==y. Comparison to another OD is order-sensitive |
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while comparison to a regular mapping is order-insensitive. |
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''' |
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if isinstance(other, OrderedDict): |
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return dict.__eq__(self, other) and all(_imap(_eq, self, other)) |
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return dict.__eq__(self, other) |
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def __ne__(self, other): |
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'od.__ne__(y) <==> od!=y' |
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return not self == other |
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# -- the following methods support python 3.x style dictionary views -- |
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def viewkeys(self): |
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"od.viewkeys() -> a set-like object providing a view on od's keys" |
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return KeysView(self) |
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def viewvalues(self): |
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"od.viewvalues() -> an object providing a view on od's values" |
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return ValuesView(self) |
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def viewitems(self): |
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"od.viewitems() -> a set-like object providing a view on od's items" |
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return ItemsView(self) |
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