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from typing import Callable, List, Optional, TypeVar
from reactivex import Observable, abc
_T = TypeVar("_T")
def skip_last_(count: int) -> Callable[[Observable[_T]], Observable[_T]]:
def skip_last(source: Observable[_T]) -> Observable[_T]:
"""Bypasses a specified number of elements at the end of an
observable sequence.
This operator accumulates a queue with a length enough to store
the first `count` elements. As more elements are received,
elements are taken from the front of the queue and produced on
the result sequence. This causes elements to be delayed.
Args:
count: Number of elements to bypass at the end of the
source sequence.
Returns:
An observable sequence containing the source sequence
elements except for the bypassed ones at the end.
"""
def subscribe(
observer: abc.ObserverBase[_T],
scheduler: Optional[abc.SchedulerBase] = None,
):
q: List[_T] = []
def on_next(value: _T) -> None:
front = None
with source.lock:
q.append(value)
if len(q) > count:
front = q.pop(0)
if front is not None:
observer.on_next(front)
return source.subscribe(
on_next, observer.on_error, observer.on_completed, scheduler=scheduler
)
return Observable(subscribe)
return skip_last
__all__ = ["skip_last_"]
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