itercools.py 文件源码

def reuse(func=None, *, cache=lru_cache()):
    """Cache and reuse a generator function across multiple calls."""
    # Allow this decorator to work with or without being called
    if func is None:
        return partial(reuse, cache=cache)

    # Either initialize an empty history and start a new generator, or
    # retrieve an existing history and the already-started generator
    # that produced it
    @cache
    def resume(*args, **kwargs):
        return [], func(*args, **kwargs)

    @wraps(func)
    def reuser(*args, **kwargs):
        history, gen = resume(*args, **kwargs)
        yield from history
        record = history.append  # Avoid inner-loop name lookup
        for x in gen:
            record(x)
            yield x

    return reuser