firestar5683
122 lines
3.5 KiB
Python
122 lines
3.5 KiB
Python
from typing import Any, Callable, Optional, TypeVar
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from reactivex import Observable, abc
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from reactivex.typing import Predicate, PredicateIndexed
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_T = TypeVar("_T")
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def take_while_(
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predicate: Predicate[_T], inclusive: bool = False
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) -> Callable[[Observable[_T]], Observable[_T]]:
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def take_while(source: Observable[_T]) -> Observable[_T]:
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"""Returns elements from an observable sequence as long as a
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specified condition is true.
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Example:
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>>> take_while(source)
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Args:
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source: The source observable to take from.
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Returns:
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An observable sequence that contains the elements from the
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input sequence that occur before the element at which the
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test no longer passes.
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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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running = True
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def on_next(value: _T):
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nonlocal running
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with source.lock:
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if not running:
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return
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try:
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running = predicate(value)
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except Exception as exn:
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observer.on_error(exn)
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return
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if running:
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observer.on_next(value)
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else:
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if inclusive:
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observer.on_next(value)
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observer.on_completed()
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return source.subscribe(
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on_next, observer.on_error, observer.on_completed, scheduler=scheduler
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)
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return Observable(subscribe)
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return take_while
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def take_while_indexed_(
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predicate: PredicateIndexed[_T], inclusive: bool = False
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) -> Callable[[Observable[_T]], Observable[_T]]:
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def take_while_indexed(source: Observable[_T]) -> Observable[_T]:
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"""Returns elements from an observable sequence as long as a
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specified condition is true. The element's index is used in the
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logic of the predicate function.
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Example:
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>>> take_while(source)
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Args:
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source: Source observable to take from.
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Returns:
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An observable sequence that contains the elements from the
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input sequence that occur before the element at which the
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test no longer passes.
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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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running = True
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i = 0
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def on_next(value: Any) -> None:
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nonlocal running, i
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with source.lock:
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if not running:
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return
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try:
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running = predicate(value, i)
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except Exception as exn:
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observer.on_error(exn)
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return
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else:
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i += 1
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if running:
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observer.on_next(value)
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else:
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if inclusive:
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observer.on_next(value)
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observer.on_completed()
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return source.subscribe(
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on_next, observer.on_error, observer.on_completed, scheduler=scheduler
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)
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return Observable(subscribe)
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return take_while_indexed
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__all__ = ["take_while_", "take_while_indexed_"]
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