content: /**
   * Copyright (c) 2019 Siemens AG
   * All rights reserved.
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * 
   * 1) Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   * 
   * 2) Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  package at.ac.tuwien.kr.alpha.core.solver.heuristics;
  
  import at.ac.tuwien.kr.alpha.core.common.NoGood;
  import at.ac.tuwien.kr.alpha.core.programs.atoms.Literals;
  import at.ac.tuwien.kr.alpha.core.solver.ChoiceManager;
  import at.ac.tuwien.kr.alpha.core.solver.learning.GroundConflictNoGoodLearner.ConflictAnalysisResult;
  
  import java.util.Iterator;
  import java.util.List;
  
  /**
   * A heuristic that replays a fixed list of choices.
   */
  public class ReplayHeuristic implements BranchingHeuristic {
  
  	private final Iterator<Integer> choicesIterator;
  	private final ChoiceManager choiceManager;
  
  	/**
  	 * Initializes the heuristic
  	 * @param choices a list of signed atoms (positive if atom shall be made true, negative otherwise)
  	 * @param choiceManager
  	 */
  	public ReplayHeuristic(List<Integer> choices, ChoiceManager choiceManager) {
  		super();
  		this.choicesIterator = choices.iterator();
  		this.choiceManager = choiceManager;
  	}
  
  	@Override
  	public void violatedNoGood(NoGood violatedNoGood) {
  	}
  
  	@Override
  	public void analyzedConflict(ConflictAnalysisResult analysisResult) {
  	}
  
  	@Override
  	public void newNoGood(NoGood newNoGood) {
  	}
  
  	@Override
  	public int chooseLiteral() {
  		if (!choicesIterator.hasNext()) {
  			return DEFAULT_CHOICE_LITERAL;
  		}
  		int replayChoiceSignedAtom = choicesIterator.next();
  		if (replayChoiceSignedAtom == 0) {
  			// Use 0 to signal no more choices.
  			return DEFAULT_CHOICE_LITERAL;
  		}
  		int replayChoiceAtom = Math.abs(replayChoiceSignedAtom);
  		int replayChoiceLiteral = Literals.atomToLiteral(replayChoiceAtom, replayChoiceSignedAtom > 0);
  		if (!choiceManager.isActiveChoiceAtom(replayChoiceAtom)) {
  			throw new IllegalStateException("Replay choice is not an active choice point: " + replayChoiceAtom);
  		}
  		return replayChoiceLiteral;
  	}
  	
  	@Override
  	public String toString() {
  		return this.getClass().getSimpleName();
  	}
  
  }
  