Welcome, guest | Sign In | My Account | Store | Cart
```import collections

class OrderedSet(collections.MutableSet):

def __init__(self, iterable=None):
self.end = end = []
end += [None, end, end]         # sentinel node for doubly linked list
self.map = {}                   # key --> [key, prev, next]
if iterable is not None:
self |= iterable

def __len__(self):
return len(self.map)

def __contains__(self, key):
return key in self.map

if key not in self.map:
end = self.end
curr = end[1]
curr[2] = end[1] = self.map[key] = [key, curr, end]

if key in self.map:
key, prev, next = self.map.pop(key)
prev[2] = next
next[1] = prev

def __iter__(self):
end = self.end
curr = end[2]
while curr is not end:
yield curr[0]
curr = curr[2]

def __reversed__(self):
end = self.end
curr = end[1]
while curr is not end:
yield curr[0]
curr = curr[1]

def pop(self, last=True):
if not self:
raise KeyError('set is empty')
key = self.end[1][0] if last else self.end[2][0]
return key

def __repr__(self):
if not self:
return '%s()' % (self.__class__.__name__,)
return '%s(%r)' % (self.__class__.__name__, list(self))

def __eq__(self, other):
if isinstance(other, OrderedSet):
return len(self) == len(other) and list(self) == list(other)
return set(self) == set(other)

if __name__ == '__main__':
t = OrderedSet('simsalabim')
print(s | t)
print(s & t)
print(s - t)
```

#### Diff to Previous Revision

```--- revision 8 2012-12-18 20:38:26
+++ revision 9 2012-12-19 07:12:32
@@ -1,6 +1,4 @@
import collections
-
-KEY, PREV, NEXT = range(3)

class OrderedSet(collections.MutableSet):

@@ -20,33 +18,33 @@
if key not in self.map:
end = self.end
-            curr = end[PREV]
-            curr[NEXT] = end[PREV] = self.map[key] = [key, curr, end]
+            curr = end[1]
+            curr[2] = end[1] = self.map[key] = [key, curr, end]

if key in self.map:
key, prev, next = self.map.pop(key)
-            prev[NEXT] = next
-            next[PREV] = prev
+            prev[2] = next
+            next[1] = prev

def __iter__(self):
end = self.end
-        curr = end[NEXT]
+        curr = end[2]
while curr is not end:
-            yield curr[KEY]
-            curr = curr[NEXT]
+            yield curr[0]
+            curr = curr[2]

def __reversed__(self):
end = self.end
-        curr = end[PREV]
+        curr = end[1]
while curr is not end:
-            yield curr[KEY]
-            curr = curr[PREV]
+            yield curr[0]
+            curr = curr[1]

def pop(self, last=True):
if not self:
raise KeyError('set is empty')
-        key = next(reversed(self)) if last else next(iter(self))
+        key = self.end[1][0] if last else self.end[2][0]
return key

@@ -62,5 +60,8 @@

if __name__ == '__main__':