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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.score.definition;

import org.drools.planner.core.score.Score;
import org.drools.planner.core.score.holder.ScoreHolder;
import org.drools.planner.core.score.buildin.hardandsoft.HardAndSoftScoreDefinition;
import org.drools.planner.core.solver.DefaultSolverScope;
import org.drools.planner.core.termination.Termination;

/**
 * A ScoreDefinition knows how to compare scores and what the perfect maximum/minimum Score is.
 * @see AbstractScoreDefinition
 * @see HardAndSoftScoreDefinition
 */
public interface ScoreDefinition {

    /**
     * The perfect maximum score is the score of which there is no better in any problem instance.
     * This doesn't mean that the current problem instance, or any problem instance for that matter,
     * could ever attain that score.
     * 
     * For example, most cases have a perfect maximum score of zero, as most use cases only have negative scores.
     * @return null if not supported
     */
    S getPerfectMaximumScore();

    /**
     * The perfect minimum score is the score of which there is no worser in any problem instance.
     * This doesn't mean that the current problem instance, or any problem instance for that matter,
     * could ever attain such a bad score.
     * 
     * For example, most cases have a perfect minimum score of negative infinity.
     * @return null if not supported
     */
    S getPerfectMinimumScore();

    /**
     * Parses the String and returns a Score.
     * @param scoreString never null
     * @return never null
     */
    Score parseScore(String scoreString);

    /**
     * See explanation in {@link Termination#calculateSolverTimeGradient(DefaultSolverScope)}.
     * @param startScore never null
     * @param endScore never null
     * @param score never null
     * @return between 0.0 and 1.0
     */
    double calculateTimeGradient(S startScore, S endScore, S score);

    /**
     * @param score never null
     * @return null if should not be shown on the graph
     */
    Double translateScoreToGraphValue(S score);

    /**
     * TODO JBRULES-2238 remove when the rule that sums the final score can be written as a single rule and {@link ScoreHolder} is dead
     * @return never null
     */
    ScoreHolder buildScoreHolder();

}