161 lines
6.8 KiB
Python
161 lines
6.8 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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# * Code review nav *
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# (see comments in __init__.py)
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#==============================================================================
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# ← Prev: _frozenordered.py Current: _orderedbidict.py <FIN>
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#==============================================================================
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"""Provide :class:`OrderedBidict`."""
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from __future__ import annotations
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from collections.abc import Set
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import typing as t
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from ._base import BidictKeysView
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from ._bidict import MutableBidict
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from ._orderedbase import OrderedBidictBase
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from ._typing import KT, VT
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class OrderedBidict(OrderedBidictBase[KT, VT], MutableBidict[KT, VT]):
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"""Mutable bidict type that maintains items in insertion order."""
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if t.TYPE_CHECKING:
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@property
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def inverse(self) -> OrderedBidict[VT, KT]: ...
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def clear(self) -> None:
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"""Remove all items."""
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super().clear()
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self._node_by_korv.clear()
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self._sntl.nxt = self._sntl.prv = self._sntl
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def _pop(self, key: KT) -> VT:
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val = super()._pop(key)
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node = self._node_by_korv[key if self._bykey else val]
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self._dissoc_node(node)
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return val
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def popitem(self, last: bool = True) -> tuple[KT, VT]:
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"""*b.popitem() → (k, v)*
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If *last* is true,
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remove and return the most recently added item as a (key, value) pair.
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Otherwise, remove and return the least recently added item.
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:raises KeyError: if *b* is empty.
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"""
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if not self:
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raise KeyError('OrderedBidict is empty')
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node = getattr(self._sntl, 'prv' if last else 'nxt')
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korv = self._node_by_korv.inverse[node]
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if self._bykey:
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return korv, self._pop(korv)
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return self.inverse._pop(korv), korv
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def move_to_end(self, key: KT, last: bool = True) -> None:
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"""Move the item with the given key to the end if *last* is true, else to the beginning.
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:raises KeyError: if *key* is missing
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"""
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korv = key if self._bykey else self._fwdm[key]
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node = self._node_by_korv[korv]
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node.prv.nxt = node.nxt
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node.nxt.prv = node.prv
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sntl = self._sntl
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if last:
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lastnode = sntl.prv
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node.prv = lastnode
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node.nxt = sntl
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sntl.prv = lastnode.nxt = node
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else:
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firstnode = sntl.nxt
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node.prv = sntl
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node.nxt = firstnode
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sntl.nxt = firstnode.prv = node
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# Override the keys() and items() implementations inherited from BidictBase,
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# which may delegate to the backing _fwdm dict, since this is a mutable ordered bidict,
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# and therefore the ordering of items can get out of sync with the backing mappings
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# after mutation. (Need not override values() because it delegates to .inverse.keys().)
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def keys(self) -> t.KeysView[KT]:
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"""A set-like object providing a view on the contained keys."""
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return _OrderedBidictKeysView(self)
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def items(self) -> t.ItemsView[KT, VT]:
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"""A set-like object providing a view on the contained items."""
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return _OrderedBidictItemsView(self)
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# The following MappingView implementations use the __iter__ implementations
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# inherited from their superclass counterparts in collections.abc, so they
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# continue to yield items in the correct order even after an OrderedBidict
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# is mutated. They also provide a __reversed__ implementation, which is not
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# provided by the collections.abc superclasses.
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class _OrderedBidictKeysView(BidictKeysView[KT]):
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_mapping: OrderedBidict[KT, t.Any]
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def __reversed__(self) -> t.Iterator[KT]:
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return reversed(self._mapping)
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class _OrderedBidictItemsView(t.ItemsView[KT, VT]):
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_mapping: OrderedBidict[KT, VT]
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def __reversed__(self) -> t.Iterator[tuple[KT, VT]]:
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ob = self._mapping
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for key in reversed(ob):
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yield key, ob[key]
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# For better performance, make _OrderedBidictKeysView and _OrderedBidictItemsView delegate
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# to backing dicts for the methods they inherit from collections.abc.Set. (Cannot delegate
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# for __iter__ and __reversed__ since they are order-sensitive.) See also: https://bugs.python.org/issue46713
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def _override_set_methods_to_use_backing_dict(
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cls: t.Type[_OrderedBidictKeysView[KT]] | t.Type[_OrderedBidictItemsView[KT, t.Any]],
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viewname: str,
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_setmethodnames: t.Iterable[str] = (
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'__lt__', '__le__', '__gt__', '__ge__', '__eq__', '__ne__', '__sub__', '__rsub__',
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'__or__', '__ror__', '__xor__', '__rxor__', '__and__', '__rand__', 'isdisjoint',
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)
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) -> None:
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def make_proxy_method(methodname: str) -> t.Any:
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def method(self: _OrderedBidictKeysView[KT] | _OrderedBidictItemsView[KT, t.Any], *args: t.Any) -> t.Any:
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fwdm = self._mapping._fwdm
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if not isinstance(fwdm, dict): # dict view speedup not available, fall back to Set's implementation.
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return getattr(Set, methodname)(self, *args)
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fwdm_dict_view = getattr(fwdm, viewname)()
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fwdm_dict_view_method = getattr(fwdm_dict_view, methodname)
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if len(args) != 1 or not isinstance(args[0], self.__class__) or not isinstance(args[0]._mapping._fwdm, dict):
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return fwdm_dict_view_method(*args)
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# self and arg are both _OrderedBidictKeysViews or _OrderedBidictItemsViews whose bidicts are backed by a dict.
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# Use arg's backing dict's corresponding view instead of arg. Otherwise, e.g. `ob1.keys() < ob2.keys()` would give
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# "TypeError: '<' not supported between instances of '_OrderedBidictKeysView' and '_OrderedBidictKeysView'", because
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# both `dict_keys(ob1).__lt__(ob2.keys()) is NotImplemented` and `dict_keys(ob2).__gt__(ob1.keys()) is NotImplemented`.
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arg_dict = args[0]._mapping._fwdm
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arg_dict_view = getattr(arg_dict, viewname)()
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return fwdm_dict_view_method(arg_dict_view)
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method.__name__ = methodname
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method.__qualname__ = f'{cls.__qualname__}.{methodname}'
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return method
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for name in _setmethodnames:
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setattr(cls, name, make_proxy_method(name))
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_override_set_methods_to_use_backing_dict(_OrderedBidictKeysView, 'keys')
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_override_set_methods_to_use_backing_dict(_OrderedBidictItemsView, 'items')
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# * Code review nav *
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#==============================================================================
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# ← Prev: _frozenordered.py Current: _orderedbidict.py <FIN>
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#==============================================================================
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