36 lines
1,003 B
Python
36 lines
1,003 B
Python
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import collections
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class LazyChain:
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'''
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You may be familiar with itertools.chain, which chains two iterables into
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one. However, I wanted a data structure where I could add more and more
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generators into the chain without repeatedly calling
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`chain = itertools.chain(chain, more)`.
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'''
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def __init__(self):
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self.iters = collections.deque()
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def __iter__(self):
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return self
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def __next__(self):
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while self.iters:
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try:
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return next(self.iters[0])
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except StopIteration:
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self.iters.popleft()
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raise StopIteration()
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def append(self, item):
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'''
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Add a single item to the chain.
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'''
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self.iters.append(iter((item,)))
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def extend(self, sequence):
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'''
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Add the contents of a list, tuple, generator... to the chain.
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Make sure not to exhaust the generator outside of this chain!
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'''
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self.iters.append(iter(sequence))
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