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1 #!/usr/bin/env python3
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2 # Copyright 2015 Sander
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3 # Permission is hereby granted, free of charge, to any person obtaining a copy
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4 # of this software and associated documentation files (the "Software"), to deal
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5 # in the Software without restriction, including without limitation the rights
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6 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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7 # copies of the Software, and to permit persons to whom the Software is
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8 # furnished to do so, subject to the following conditions:
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9 # The above copyright notice and this permission notice shall be included in
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10 # all copies or substantial portions of the Software.
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11 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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12 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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13 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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14 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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15 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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16 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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17 # SOFTWARE.
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18 import collections
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19
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20 class OrderedSet(collections.MutableSet):
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21
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22 def __init__(self, iterable=None):
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23 self.end = end = []
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24 end += [None, end, end] # sentinel node for doubly linked list
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25 self.map = {} # key --> [key, prev, next]
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26 if iterable is not None:
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27 self |= iterable
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28
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29 def __len__(self):
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30 return len(self.map)
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31
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32 def __contains__(self, key):
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33 return key in self.map
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34
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35 def add(self, key):
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36 if key not in self.map:
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37 end = self.end
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38 curr = end[1]
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39 curr[2] = end[1] = self.map[key] = [key, curr, end]
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40
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41 def discard(self, key):
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42 if key in self.map:
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43 key, prev, next = self.map.pop(key)
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44 prev[2] = next
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45 next[1] = prev
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46
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47 def __iter__(self):
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48 end = self.end
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49 curr = end[2]
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50 while curr is not end:
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51 yield curr[0]
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52 curr = curr[2]
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53
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54 def __reversed__(self):
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55 end = self.end
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56 curr = end[1]
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57 while curr is not end:
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58 yield curr[0]
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59 curr = curr[1]
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60
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61 def pop(self, last=True):
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62 if not self:
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63 raise KeyError('set is empty')
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64 key = self.end[1][0] if last else self.end[2][0]
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65 self.discard(key)
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66 return key
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67
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68 def __repr__(self):
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69 if not self:
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70 return '%s()' % (self.__class__.__name__,)
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71 return '%s(%r)' % (self.__class__.__name__, list(self))
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72
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73 def __eq__(self, other):
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74 if isinstance(other, OrderedSet):
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75 return len(self) == len(other) and list(self) == list(other)
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76 return set(self) == set(other)
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77
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78
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79 if __name__ == '__main__':
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80 s = OrderedSet('abracadaba')
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81 t = OrderedSet('simsalabim')
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82 print(s | t)
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83 print(s & t)
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84 print(s - t)
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