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