44 lines
1.2 KiB
44 lines
1.2 KiB
4 years ago
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from typing import Iterable, Tuple, TypeVar
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T = TypeVar("T")
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def loop_first(values: Iterable[T]) -> Iterable[Tuple[bool, T]]:
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"""Iterate and generate a tuple with a flag for first value."""
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iter_values = iter(values)
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try:
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value = next(iter_values)
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except StopIteration:
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return
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yield True, value
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for value in iter_values:
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yield False, value
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def loop_last(values: Iterable[T]) -> Iterable[Tuple[bool, T]]:
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"""Iterate and generate a tuple with a flag for last value."""
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iter_values = iter(values)
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try:
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previous_value = next(iter_values)
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except StopIteration:
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return
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for value in iter_values:
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yield False, previous_value
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previous_value = value
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yield True, previous_value
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def loop_first_last(values: Iterable[T]) -> Iterable[Tuple[bool, bool, T]]:
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"""Iterate and generate a tuple with a flag for first and last value."""
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iter_values = iter(values)
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try:
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previous_value = next(iter_values)
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except StopIteration:
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return
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first = True
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for value in iter_values:
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yield first, False, previous_value
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first = False
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previous_value = value
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yield first, True, previous_value
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