%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  This file is part of Logtalk <https://logtalk.org/>
%  Copyright 1998-2021 Paulo Moura <pmoura@logtalk.org>
%  SPDX-License-Identifier: Apache-2.0
%
%  Licensed under the Apache License, Version 2.0 (the "License");
%  you may not use this file except in compliance with the License.
%  You may obtain a copy of the License at
%
%      http://www.apache.org/licenses/LICENSE-2.0
%
%  Unless required by applicable law or agreed to in writing, software
%  distributed under the License is distributed on an "AS IS" BASIS,
%  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%  See the License for the specific language governing permissions and
%  limitations under the License.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


:- object(heuristic_search(_Threshold_),
	instantiates(class),
	specializes(search_strategy)).

	:- info([
		version is 1:1:0,
		author is 'Paulo Moura',
		date is 2021-02-07,
		comment is 'Heuristic state space search strategies.',
		parnames is ['Threshold']
	]).

	:- public(threshold/1).
	:- mode(threshold(?number), one).
	:- info(threshold/1, [
		comment is 'Search cost threshold.',
		argnames is ['Threshold']
	]).

	:- public(solve/4).
	:- mode(solve(+object, +nonvar, -list, -number), zero_or_more).
	:- info(solve/4, [
		comment is 'State space search solution.',
		argnames is ['Space', 'State', 'Path', 'Cost']
	]).

	:- protected(search/5).
	:- mode(search(+object, +nonvar, +number, -list, -number), zero_or_more).
	:- info(search/5, [
		comment is 'State space search solution.',
		argnames is ['Space', 'State', 'Threshold', 'Path', 'Cost']
	]).

	solve(Space, State, Path) :-
		::solve(Space, State, Path, _).

	solve(Space, State, Path, Cost) :-
		::threshold(Threshold),
		::search(Space, State, Threshold, Path, Cost).

	threshold(_Threshold_).

:- end_object.
