firestar5683
28 lines
558 B
Python
28 lines
558 B
Python
from typing import Callable, Optional, TypeVar
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from reactivex import Observable, compose
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from reactivex import operators as ops
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from reactivex.typing import Predicate
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_T = TypeVar("_T")
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def count_(
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predicate: Optional[Predicate[_T]] = None,
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) -> Callable[[Observable[_T]], Observable[int]]:
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if predicate:
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return compose(
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ops.filter(predicate),
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ops.count(),
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)
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def reducer(n: int, _: _T) -> int:
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return n + 1
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counter = ops.reduce(reducer, seed=0)
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return counter
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__all__ = ["count_"]
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