# -*- coding: utf-8 -*-
# Copyright 2009-2020 Joshua Bronson. All Rights Reserved.
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#==============================================================================
# * Welcome to the bidict source code *
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#==============================================================================
# ← Prev: _frozenordered.py Current: _orderedbidict.py <FIN>
#==============================================================================
"""Provides :class:`OrderedBidict`."""
from ._mut import MutableBidict
from ._orderedbase import OrderedBidictBase
class OrderedBidict(OrderedBidictBase, MutableBidict):
"""Mutable bidict type that maintains items in insertion order."""
__slots__ = ()
def clear(self):
"""Remove all items."""
self._fwdm.clear()
self._invm.clear()
self._sntl.nxt = self._sntl.prv = self._sntl
def popitem(self, last=True): # pylint: disable=arguments-differ
"""*x.popitem() → (k, v)*
Remove and return the most recently added item as a (key, value) pair
if *last* is True, else the least recently added item.
:raises KeyError: if *x* is empty.
"""
if not self:
raise KeyError('mapping is empty')
key = next((reversed if last else iter)(self))
val = self._pop(key)
return key, val
def move_to_end(self, key, last=True):
"""Move an existing key to the beginning or end of this ordered bidict.
The item is moved to the end if *last* is True, else to the beginning.
:raises KeyError: if the key does not exist
"""
node = self._fwdm[key]
node.prv.nxt = node.nxt
node.nxt.prv = node.prv
sntl = self._sntl
if last:
last = sntl.prv
node.prv = last
node.nxt = sntl
sntl.prv = last.nxt = node
else:
first = sntl.nxt
node.prv = sntl
node.nxt = first
sntl.nxt = first.prv = node
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# ← Prev: _frozenordered.py Current: _orderedbidict.py <FIN>
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