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allendowney
GitHub Repository: allendowney/cpython
 Path: blob/main/Tools/c-analyzer/c_common/iterutil.py
12 views
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def peek_and_iter(items):

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    if not items:

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        return None, None

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    items = iter(items)

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    try:

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        peeked = next(items)

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    except StopIteration:

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        return None, None

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    def chain():

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        yield peeked

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        yield from items

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    return chain(), peeked

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def iter_many(items, onempty=None):

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    if not items:

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        if onempty is None:

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            return

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        if not callable(onempty):

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            raise onEmpty

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        items = onempty(items)

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        yield from iter_many(items, onempty=None)

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        return

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    items = iter(items)

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    try:

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        first = next(items)

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    except StopIteration:

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        if onempty is None:

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            return

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        if not callable(onempty):

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            raise onEmpty

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        items = onempty(items)

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        yield from iter_many(items, onempty=None)

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    else:

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        try:

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            second = next(items)

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        except StopIteration:

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            yield first, False

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            return

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        else:

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            yield first, True

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            yield second, True

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        for item in items:

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            yield item, True

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