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OptaPlanner solves planning problems. This lightweight, embeddable planning engine implements powerful and scalable algorithms to optimize business resource scheduling and planning. This module contains implementation of Constraint streams (Bavet).

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package org.optaplanner.constraint.streams.bavet;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.optaplanner.constraint.streams.bavet.common.AbstractNode;
import org.optaplanner.constraint.streams.bavet.common.BavetAbstractConstraintStream;
import org.optaplanner.constraint.streams.bavet.common.NodeBuildHelper;
import org.optaplanner.constraint.streams.bavet.uni.ForEachUniNode;
import org.optaplanner.constraint.streams.common.inliner.AbstractScoreInliner;
import org.optaplanner.core.api.score.Score;
import org.optaplanner.core.api.score.stream.Constraint;
import org.optaplanner.core.impl.domain.solution.descriptor.SolutionDescriptor;
import org.optaplanner.core.impl.score.definition.ScoreDefinition;

public final class BavetConstraintSessionFactory> {

    private final SolutionDescriptor solutionDescriptor;
    private final List> constraintList;

    public BavetConstraintSessionFactory(SolutionDescriptor solutionDescriptor,
            List> constraintList) {
        this.solutionDescriptor = solutionDescriptor;
        this.constraintList = constraintList;
    }

    // ************************************************************************
    // Node creation
    // ************************************************************************

    public BavetConstraintSession buildSession(boolean constraintMatchEnabled,
            Solution_ workingSolution) {
        ScoreDefinition scoreDefinition = solutionDescriptor.getScoreDefinition();
        AbstractScoreInliner scoreInliner = AbstractScoreInliner.buildScoreInliner(scoreDefinition,
                constraintMatchEnabled);

        Score_ zeroScore = scoreDefinition.getZeroScore();
        Set> constraintStreamSet = new LinkedHashSet<>();
        Map constraintWeightMap = new HashMap<>(constraintList.size());
        for (BavetConstraint constraint : constraintList) {
            Score_ constraintWeight = constraint.extractConstraintWeight(workingSolution);
            // Filter out nodes that only lead to constraints with zero weight.
            // Note: Node sharing happens earlier, in BavetConstraintFactory#share(Stream_).
            if (!constraintWeight.equals(zeroScore)) {
                // Relies on BavetConstraintFactory#share(Stream_) occurring for all constraint stream instances
                // to ensure there are no 2 equal ConstraintStream instances (with different child stream lists).
                constraint.collectActiveConstraintStreams(constraintStreamSet);
                constraintWeightMap.put(constraint, constraintWeight);
            }
        }
        NodeBuildHelper buildHelper = new NodeBuildHelper<>(constraintStreamSet, constraintWeightMap, scoreInliner);
        // Build constraintStreamSet in reverse order to create downstream nodes first
        // so every node only has final variables (some of which have downstream node method references).
        List> reversedConstraintStreamList = new ArrayList<>(constraintStreamSet);
        Collections.reverse(reversedConstraintStreamList);
        for (BavetAbstractConstraintStream constraintStream : reversedConstraintStreamList) {
            constraintStream.buildNode(buildHelper);
        }
        List nodeList = buildHelper.destroyAndGetNodeList();
        Map, ForEachUniNode