org.drools.planner.core.localsearch.decider.acceptor.tabu.SolutionTabuAcceptor Maven / Gradle / Ivy

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Drools Planner optimizes automated planning by combining metaheuristic search algorithms with rule engine powered score calculation. This is the drools-planner-core module which contains metaheuristic algorithms.

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/*
 * Copyright 2010 JBoss Inc
 *
 * 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.
 */

package org.drools.planner.core.localsearch.decider.acceptor.tabu;

import java.util.Collection;
import java.util.Collections;

import org.drools.planner.core.localsearch.LocalSearchSolverPhaseScope;
import org.drools.planner.core.localsearch.LocalSearchStepScope;
import org.drools.planner.core.localsearch.decider.MoveScope;

public class SolutionTabuAcceptor extends AbstractTabuAcceptor {

    public SolutionTabuAcceptor() {
        // Disable aspiration by default because it's useless on solution tabu
        aspirationEnabled = false;
    }

    // ************************************************************************
    // Worker methods
    // ************************************************************************

    @Override
    protected Collection findTabu(MoveScope moveScope) {
        return Collections.singletonList(moveScope.getWorkingSolution());
    }

    @Override
    protected Collection findNewTabu(LocalSearchStepScope localSearchStepScope) {
        // TODO this should be better done in stepTaken
        return Collections.singletonList(localSearchStepScope.createOrGetClonedSolution());
    }
    
    @Override
    public void phaseStarted(LocalSearchSolverPhaseScope localSearchSolverPhaseScope) {
        super.phaseStarted(localSearchSolverPhaseScope);
        // Add the starting solution to the tabu list
        Object tabu = localSearchSolverPhaseScope.getWorkingSolution().cloneSolution();
        tabuToStepIndexMap.put(tabu, 0); // TODO should -1 when AbstractTabuAcceptor can handle that
        tabuSequenceList.add(tabu);
    }

}