mediawiki_dump_tools/Mediawiki-Utilities/mw/util/iteration/peekable.py

   1 def Peekable(it):
   2     if isinstance(it, PeekableType):
   3         return it
   4     else:
   5         return PeekableType(it)
   6
   7
   8 class PeekableType:
   9     class EMPTY:
  10         pass
  11
  12     def __init__(self, it):
  13         self.it = iter(it)
  14         self.__cycle()
  15
  16     def __iter__(self):
  17         return self
  18
  19     def __cycle(self):
  20         try:
  21             self.lookahead = next(self.it)
  22         except StopIteration:
  23             self.lookahead = self.EMPTY
  24
  25     def __next__(self):
  26         item = self.peek()
  27         self.__cycle()
  28         return item
  29
  30     def peek(self):
  31         if self.empty():
  32             raise StopIteration()
  33         else:
  34             return self.lookahead
  35
  36     def empty(self):
  37         return self.lookahead == self.EMPTY