# -*- coding: utf-8 -*-
"""
Copyright Sylvain Bouveret, Yann Chevaleyre and François Durand
sylvain.bouveret@imag.fr, yann.chevaleyre@dauphine.fr, fradurand@gmail.com
This file is part of Whalrus.
Whalrus is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Whalrus is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Whalrus. If not, see <http://www.gnu.org/licenses/>.
"""
from whalrus.converters_ballot.converter_ballot import ConverterBallot
from whalrus.converters_ballot.converter_ballot_general import ConverterBallotGeneral
from whalrus.ballots.ballot import Ballot
from whalrus.ballots.ballot_plurality import BallotPlurality
from whalrus.ballots.ballot_veto import BallotVeto
from whalrus.ballots.ballot_one_name import BallotOneName
from whalrus.ballots.ballot_order import BallotOrder
from whalrus.priorities.priority import Priority
[docs]class ConverterBallotToVeto(ConverterBallot):
"""
Default converter to a :class:`BallotVeto`.
Parameters
----------
priority : Priority
Serves as a default value for the other parameters if they are not explicitly mentioned. Default:
:attr:`Priority.UNAMBIGUOUS`.
order_priority : Priority
Option passed to :meth:`BallotOrder.last`. Default: ``priority``.
plurality_priority : Priority
Option passed to :meth:`BallotPlurality.last`. Default: ``priority``.
veto_priority : Priority
Option passed to :meth:`BallotVeto.last`. Default: ``priority``.
one_name_priority : Priority
Option passed to :meth:`BallotOneName.last`. Default: ``priority``.
Examples
--------
Typical usages:
>>> converter = ConverterBallotToVeto()
>>> converter(BallotOneName('a', candidates={'a', 'b'}))
BallotVeto('a', candidates={'a', 'b'})
>>> converter(BallotPlurality('a', candidates={'a', 'b'}))
BallotVeto('b', candidates={'a', 'b'})
>>> converter({'a': 10, 'b': 7, 'c':0})
BallotVeto('c', candidates={'a', 'b', 'c'})
>>> converter('a ~ b > c')
BallotVeto('c', candidates={'a', 'b', 'c'})
>>> converter([{'a', 'b'}, 'c'])
BallotVeto('c', candidates={'a', 'b', 'c'})
Use options for the restrictions:
>>> converter = ConverterBallotToVeto(priority=Priority.ASCENDING)
>>> converter('a > b ~ c')
BallotVeto('c', candidates={'a', 'b', 'c'})
"""
def __init__(self,
priority: Priority = Priority.UNAMBIGUOUS,
order_priority: Priority = None,
plurality_priority: Priority = None,
veto_priority: Priority = None,
one_name_priority: Priority = None):
# Default parameters
if order_priority is None:
order_priority = priority
if plurality_priority is None:
plurality_priority = priority
if veto_priority is None:
veto_priority = priority
if one_name_priority is None:
one_name_priority = priority
# Parameters
self.order_priority = order_priority
self.plurality_priority = plurality_priority
self.veto_priority = veto_priority
self.one_name_priority = one_name_priority
def __call__(self, x: object, candidates: set = None) -> BallotVeto:
x = ConverterBallotGeneral()(x, candidates=None)
if isinstance(x, BallotPlurality):
last = x.last(candidates=candidates, priority=self.plurality_priority)
if candidates is None:
candidates = x.candidates
else:
candidates = x.candidates & candidates
return BallotVeto(last, candidates=candidates)
if isinstance(x, BallotVeto):
return x.restrict(candidates=candidates, priority=self.veto_priority)
if isinstance(x, BallotOneName):
x = BallotVeto(x.candidate, candidates=x.candidates)
return x.restrict(candidates=candidates, priority=self.one_name_priority)
if isinstance(x, BallotOrder):
x = x.restrict(candidates=candidates)
return BallotVeto(x.last(priority=self.order_priority), candidates=x.candidates)
if isinstance(x, Ballot):
x = ConverterBallotGeneral()(x, candidates=candidates)
return BallotVeto(x.last(), candidates=x.candidates)