47 lines
1.5 KiB
Python
47 lines
1.5 KiB
Python
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# Copyright 2009-2022 Joshua Bronson. All rights reserved.
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#
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# This Source Code Form is subject to the terms of the Mozilla Public
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# License, v. 2.0. If a copy of the MPL was not distributed with this
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# file, You can obtain one at http://mozilla.org/MPL/2.0/.
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"""Functions for iterating over items in a mapping."""
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from __future__ import annotations
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from operator import itemgetter
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import typing as t
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from ._typing import KT, VT, ItemsIter, MapOrItems
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def iteritems_mapping_or_iterable(arg: MapOrItems[KT, VT]) -> ItemsIter[KT, VT]:
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"""Yield the items in *arg* based on whether it's a mapping."""
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yield from arg.items() if isinstance(arg, t.Mapping) else arg
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def iteritems(__arg: MapOrItems[KT, VT], **kw: VT) -> ItemsIter[KT, VT]:
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"""Yield the items from *arg* and then any from *kw* in the order given."""
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yield from iteritems_mapping_or_iterable(__arg)
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yield from kw.items() # type: ignore [misc]
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swap = itemgetter(1, 0)
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def inverted(arg: MapOrItems[KT, VT]) -> ItemsIter[VT, KT]:
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"""Yield the inverse items of the provided object.
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If *arg* has a :func:`callable` ``__inverted__`` attribute,
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return the result of calling it.
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Otherwise, return an iterator over the items in `arg`,
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inverting each item on the fly.
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*See also* :attr:`bidict.BidirectionalMapping.__inverted__`
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"""
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invattr = getattr(arg, '__inverted__', None)
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if callable(invattr):
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inv: ItemsIter[VT, KT] = invattr()
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return inv
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return map(swap, iteritems_mapping_or_iterable(arg))
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