firestar5683
54 lines
1.6 KiB
Python
54 lines
1.6 KiB
Python
from typing import Callable, Optional, Tuple, TypeVar, cast
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from reactivex import Observable, abc
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_T = TypeVar("_T")
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def pairwise_() -> Callable[[Observable[_T]], Observable[Tuple[_T, _T]]]:
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def pairwise(source: Observable[_T]) -> Observable[Tuple[_T, _T]]:
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"""Partially applied pairwise operator.
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Returns a new observable that triggers on the second and
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subsequent triggerings of the input observable. The Nth
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triggering of the input observable passes the arguments from
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the N-1th and Nth triggering as a pair. The argument passed to
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the N-1th triggering is held in hidden internal state until the
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Nth triggering occurs.
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Returns:
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An observable that triggers on successive pairs of
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observations from the input observable as an array.
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"""
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def subscribe(
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observer: abc.ObserverBase[Tuple[_T, _T]],
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scheduler: Optional[abc.SchedulerBase] = None,
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) -> abc.DisposableBase:
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has_previous = False
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previous: _T = cast(_T, None)
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def on_next(x: _T) -> None:
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nonlocal has_previous, previous
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pair = None
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with source.lock:
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if has_previous:
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pair = (previous, x)
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else:
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has_previous = True
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previous = x
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if pair:
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observer.on_next(pair)
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return source.subscribe(on_next, observer.on_error, observer.on_completed)
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return Observable(subscribe)
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return pairwise
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__all__ = ["pairwise_"]
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