Created
April 13, 2019 10:46
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ordersed set
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| #!/usr/bin/env python3 | |
| from collections import MutableSet | |
| from weakref import proxy | |
| class Node(object): | |
| __slots__ = ["prev", "next", "key", "__weakref__"] | |
| class OrderedSet(MutableSet): | |
| def __init__(self, iterable=None): | |
| root = self.__root = Node() | |
| root.prev = root.next = root | |
| self.__map = {} | |
| if iterable is not None: | |
| self |= iterable | |
| def __len__(self): | |
| return len(self.__map) | |
| def __contains__(self, key): | |
| return key in self.__map | |
| def add(self, key): | |
| if key not in self.__map: | |
| self.__map[key] = node = Node() | |
| root = self.__root | |
| last = root.prev | |
| node.prev, node.next, node.key = last, root, key | |
| last.next = root.prev = proxy(node) | |
| def discard(self, x): | |
| if x in self.__map: | |
| node = self.__map.pop(x) | |
| node.prev.next = node.next | |
| node.next.prev = node.prev | |
| def __iter__(self): | |
| root = self.__root | |
| node = root.next | |
| while node is not root: | |
| yield node.key | |
| node = node.next | |
| def __reversed__(self): | |
| root = self.__root | |
| node = root.prev | |
| while node is not root: | |
| yield node.key | |
| node = node.prev | |
| def pop(self, last=False): | |
| if not self.__map: | |
| raise KeyError("set is empty") | |
| key = next(reversed(self)) if last else next(iter(next)) | |
| return self.discard(key) | |
| def __repr__(self): | |
| cls_name = self.__class__.__name__ | |
| if not self: | |
| return "%s()" % cls_name | |
| return "%s(%r)" % (cls_name, list(self)) | |
| def __eq__(self, other): | |
| if isinstance(other, list): | |
| return len(other) == len(self) and list(other) == list(self) | |
| return not (self ^ other) | |
| if __name__ == "__main__": | |
| # import pdb | |
| # pdb.set_trace() | |
| a = [1, 2, 3] | |
| oset = OrderedSet(iterable=a) | |
| print("ordered set:", oset) | |
| oset.add(4) | |
| print("ordered set:", oset) | |
| print("pop: ", oset.pop(last=True)) | |
| print("ordered set:", oset) | |
| bset = set(a) | |
| print("set comp orderset:", bset == oset, bset, oset) | |
| cset = OrderedSet(iterable=a) | |
| print("orderedset comp orderset:", cset == oset, cset, oset) | |
| a[0] = 0 | |
| cset = OrderedSet(iterable=a) | |
| print("orderedset comp orderset:", cset == oset, cset, oset) | |
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