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bazarr/libs/bidict/_named.py

100 lines
3.8 KiB

# -*- coding: utf-8 -*-
# Copyright 2009-2021 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/.
"""Provide :func:`bidict.namedbidict`."""
import typing as _t
from sys import _getframe
from ._abc import BidirectionalMapping, KT, VT
from ._bidict import bidict
def namedbidict(
typename: str,
keyname: str,
valname: str,
*,
base_type: _t.Type[BidirectionalMapping[KT, VT]] = bidict,
) -> _t.Type[BidirectionalMapping[KT, VT]]:
r"""Create a new subclass of *base_type* with custom accessors.
Like :func:`collections.namedtuple` for bidicts.
The new class's ``__name__`` and ``__qualname__`` will be set to *typename*,
and its ``__module__`` will be set to the caller's module.
Instances of the new class will provide access to their
:attr:`inverse <BidirectionalMapping.inverse>` instances
via the custom *keyname*\_for property,
and access to themselves
via the custom *valname*\_for property.
*See also* the :ref:`namedbidict usage documentation
<other-bidict-types:\:func\:\`~bidict.namedbidict\`>`
:raises ValueError: if any of the *typename*, *keyname*, or *valname*
strings is not a valid Python identifier, or if *keyname == valname*.
:raises TypeError: if *base_type* is not a :class:`BidirectionalMapping` subclass
that provides ``_isinv`` and :meth:`~object.__getstate__` attributes.
(Any :class:`~bidict.BidictBase` subclass can be passed in, including all the
concrete bidict types pictured in the :ref:`other-bidict-types:Bidict Types Diagram`.
"""
if not issubclass(base_type, BidirectionalMapping) or not all(hasattr(base_type, i) for i in ('_isinv', '__getstate__')):
raise TypeError(base_type)
names = (typename, keyname, valname)
if not all(map(str.isidentifier, names)) or keyname == valname:
raise ValueError(names)
class _Named(base_type): # type: ignore [valid-type,misc]
__slots__ = ()
def _getfwd(self) -> '_Named':
return self.inverse if self._isinv else self # type: ignore [no-any-return]
def _getinv(self) -> '_Named':
return self if self._isinv else self.inverse # type: ignore [no-any-return]
@property
def _keyname(self) -> str:
return valname if self._isinv else keyname
@property
def _valname(self) -> str:
return keyname if self._isinv else valname
def __reduce__(self) -> '_t.Tuple[_t.Callable[[str, str, str, _t.Type[BidirectionalMapping]], BidirectionalMapping], _t.Tuple[str, str, str, _t.Type[BidirectionalMapping]], dict]':
return (_make_empty, (typename, keyname, valname, base_type), self.__getstate__())
bname = base_type.__name__
fname = valname + '_for'
iname = keyname + '_for'
fdoc = f'{typename} forward {bname}: {keyname}{valname}'
idoc = f'{typename} inverse {bname}: {valname}{keyname}'
setattr(_Named, fname, property(_Named._getfwd, doc=fdoc))
setattr(_Named, iname, property(_Named._getinv, doc=idoc))
_Named.__name__ = typename
_Named.__qualname__ = typename
_Named.__module__ = _getframe(1).f_globals.get('__name__') # type: ignore [assignment]
return _Named
def _make_empty(
typename: str,
keyname: str,
valname: str,
base_type: _t.Type[BidirectionalMapping] = bidict,
) -> BidirectionalMapping:
"""Create a named bidict with the indicated arguments and return an empty instance.
Used to make :func:`bidict.namedbidict` instances picklable.
"""
cls = namedbidict(typename, keyname, valname, base_type=base_type)
return cls()