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from typing import Callable, Optional, TypeVar, cast
from reactivex import Observable, abc
from reactivex.internal.exceptions import ArgumentOutOfRangeException
_T = TypeVar("_T")
def element_at_or_default_(
index: int, has_default: bool = False, default_value: Optional[_T] = None
) -> Callable[[Observable[_T]], Observable[_T]]:
if index < 0:
raise ArgumentOutOfRangeException()
def element_at_or_default(source: Observable[_T]) -> Observable[_T]:
def subscribe(
observer: abc.ObserverBase[_T],
scheduler: Optional[abc.SchedulerBase] = None,
) -> abc.DisposableBase:
index_ = index
def on_next(x: _T) -> None:
nonlocal index_
found = False
with source.lock:
if index_:
index_ -= 1
else:
found = True
if found:
observer.on_next(x)
observer.on_completed()
def on_completed():
if not has_default:
observer.on_error(ArgumentOutOfRangeException())
else:
observer.on_next(cast(_T, default_value))
observer.on_completed()
return source.subscribe(
on_next, observer.on_error, on_completed, scheduler=scheduler
)
return Observable(subscribe)
return element_at_or_default
__all__ = ["element_at_or_default_"]
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