Source Code for Module advene.util.itertools

 1  from heapq import heapify, heapreplace, heappop 
 2   
 3 -class _IterHead(object): 
 4      __slots__ = ["head", "iter"] 
 5   
 6 -    def __init__(self, iter): 
 7          self.iter = iter 
 8          self.fetch_next() 
 9   
10 -    def fetch_next(self): 
11          try: 
12              self.head = self.iter.next() 
13          except StopIteration: 
14              self.head = None 
15   
16 -    def __cmp__(self, other): 
17          return cmp(self.head, other.head) 
18   
19 -def interclass(*iterables): 
20      """ 
21      Takes a number of sorted iterables, and inteclass them, suppressing  
22      doublons. 
23      """ 
24      h = [ _IterHead(iter(i)) for i in iterables ] 
25      h = [ ih for ih in h if ih.head is not None ] # remove empty iterators 
26      heapify(h) 
27      prev = None 
28   
29      while h: 
30          ih = h[0] 
31          ihh = ih.head 
32          if prev is None or ihh != prev: 
33              yield ihh 
34              prev = ihh 
35          ih.fetch_next() 
36          # ih.head has probably changed with fetch_next, don't use ihh anymore: 
37          if ih.head is not None: 
38              heapreplace(h, ih) 
39          else: 
40              heappop(h) 
41