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firestar5683
56 lines
1.6 KiB
Python
56 lines
1.6 KiB
Python
from typing import Callable, List, Optional, TypeVar
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from reactivex import Observable, abc
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_T = TypeVar("_T")
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def take_last_(count: int) -> Callable[[Observable[_T]], Observable[_T]]:
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def take_last(source: Observable[_T]) -> Observable[_T]:
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"""Returns a specified number of contiguous elements from the end of an
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observable sequence.
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Example:
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>>> res = take_last(source)
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This operator accumulates a buffer with a length enough to store
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elements count elements. Upon completion of the source sequence, this
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buffer is drained on the result sequence. This causes the elements to be
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delayed.
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Args:
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source: Number of elements to take from the end of the source
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sequence.
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Returns:
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An observable sequence containing the specified number of elements
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from the end of the source sequence.
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"""
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def subscribe(
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observer: abc.ObserverBase[_T],
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scheduler: Optional[abc.SchedulerBase] = None,
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) -> abc.DisposableBase:
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q: List[_T] = []
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def on_next(x: _T) -> None:
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q.append(x)
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if len(q) > count:
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q.pop(0)
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def on_completed():
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while q:
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observer.on_next(q.pop(0))
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observer.on_completed()
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return source.subscribe(
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on_next, observer.on_error, on_completed, scheduler=scheduler
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)
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return Observable(subscribe)
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return take_last
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__all__ = ["take_last_"]
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