codekingpro/portable-devtools

1from typing import Iterable, Tuple, TypeVar2 3T = TypeVar("T")4 5 6def loop_first(values: Iterable[T]) -> Iterable[Tuple[bool, T]]:7    """Iterate and generate a tuple with a flag for first value."""8    iter_values = iter(values)9    try:10        value = next(iter_values)11    except StopIteration:12        return13    yield True, value14    for value in iter_values:15        yield False, value16 17 18def loop_last(values: Iterable[T]) -> Iterable[Tuple[bool, T]]:19    """Iterate and generate a tuple with a flag for last value."""20    iter_values = iter(values)21    try:22        previous_value = next(iter_values)23    except StopIteration:24        return25    for value in iter_values:26        yield False, previous_value27        previous_value = value28    yield True, previous_value29 30 31def loop_first_last(values: Iterable[T]) -> Iterable[Tuple[bool, bool, T]]:32    """Iterate and generate a tuple with a flag for first and last value."""33    iter_values = iter(values)34    try:35        previous_value = next(iter_values)36    except StopIteration:37        return38    first = True39    for value in iter_values:40        yield first, False, previous_value41        first = False42        previous_value = value43    yield first, True, previous_value44