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firestar5683
70 lines
1.9 KiB
Python
70 lines
1.9 KiB
Python
from typing import Any, Callable, Optional, TypeVar
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from reactivex import Observable, abc
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from reactivex import operators as ops
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from reactivex import typing
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from reactivex.internal.exceptions import SequenceContainsNoElementsError
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_T = TypeVar("_T")
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def last_or_default_async(
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source: Observable[_T],
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has_default: bool = False,
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default_value: Optional[_T] = None,
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) -> Observable[Optional[_T]]:
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def subscribe(
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observer: abc.ObserverBase[Optional[_T]],
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scheduler: Optional[abc.SchedulerBase] = None,
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):
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value = [default_value]
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seen_value = [False]
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def on_next(x: _T) -> None:
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value[0] = x
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seen_value[0] = True
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def on_completed():
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if not seen_value[0] and not has_default:
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observer.on_error(SequenceContainsNoElementsError())
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else:
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observer.on_next(value[0])
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observer.on_completed()
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return source.subscribe(
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on_next, observer.on_error, on_completed, scheduler=scheduler
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)
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return Observable(subscribe)
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def last_or_default(
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default_value: Optional[_T] = None, predicate: Optional[typing.Predicate[_T]] = None
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) -> Callable[[Observable[_T]], Observable[Any]]:
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def last_or_default(source: Observable[Any]) -> Observable[Any]:
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"""Return last or default element.
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Examples:
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>>> res = _last_or_default(source)
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Args:
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source: Observable sequence to get the last item from.
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Returns:
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Observable sequence containing the last element in the
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observable sequence.
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"""
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if predicate:
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return source.pipe(
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ops.filter(predicate),
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ops.last_or_default(default_value),
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)
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return last_or_default_async(source, True, default_value)
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return last_or_default
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__all__ = ["last_or_default", "last_or_default_async"]
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