59 lines
1.8 KiB
Python
59 lines
1.8 KiB
Python
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# -*- coding: utf-8 -*-
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# Copyright 2009-2020 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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"""Provide :class:`OnDup` and related functionality."""
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from collections import namedtuple
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from enum import Enum
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class OnDupAction(Enum):
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"""An action to take to prevent duplication from occurring."""
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#: Raise a :class:`~bidict.DuplicationError`.
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RAISE = 'RAISE'
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#: Overwrite existing items with new items.
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DROP_OLD = 'DROP_OLD'
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#: Keep existing items and drop new items.
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DROP_NEW = 'DROP_NEW'
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def __repr__(self) -> str:
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return f'<{self.name}>'
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RAISE = OnDupAction.RAISE
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DROP_OLD = OnDupAction.DROP_OLD
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DROP_NEW = OnDupAction.DROP_NEW
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class OnDup(namedtuple('_OnDup', 'key val kv')):
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r"""A 3-tuple of :class:`OnDupAction`\s specifying how to handle the 3 kinds of duplication.
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*See also* :ref:`basic-usage:Values Must Be Unique`
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If *kv* is not specified, *val* will be used for *kv*.
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"""
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__slots__ = ()
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def __new__(cls, key: OnDupAction = DROP_OLD, val: OnDupAction = RAISE, kv: OnDupAction = RAISE) -> 'OnDup':
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"""Override to provide user-friendly default values."""
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return super().__new__(cls, key, val, kv or val)
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#: Default :class:`OnDup` used for the
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#: :meth:`~bidict.bidict.__init__`,
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#: :meth:`~bidict.bidict.__setitem__`, and
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#: :meth:`~bidict.bidict.update` methods.
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ON_DUP_DEFAULT = OnDup()
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#: An :class:`OnDup` whose members are all :obj:`RAISE`.
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ON_DUP_RAISE = OnDup(key=RAISE, val=RAISE, kv=RAISE)
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#: An :class:`OnDup` whose members are all :obj:`DROP_OLD`.
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ON_DUP_DROP_OLD = OnDup(key=DROP_OLD, val=DROP_OLD, kv=DROP_OLD)
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