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A library of composable components enabling simpler Computational Intelligence
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/**           __  __
 *    _____ _/ /_/ /_    Computational Intelligence Library (CIlib)
 *   / ___/ / / / __ \   (c) CIRG @ UP
 *  / /__/ / / / /_/ /   http://cilib.net
 *  \___/_/_/_/_.___/
 */
package net.sourceforge.cilib.moo.archive.constrained;

import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.ForwardingCollection;
import java.util.Collection;
import net.sourceforge.cilib.moo.archive.Archive;
import net.sourceforge.cilib.problem.solution.OptimisationSolution;

/**
 * 
 * An {@link Archive} constrained by the number of solutions that it can store.
 * 
 *
 */
public abstract class ConstrainedArchive extends ForwardingCollection implements Archive {

    private Predicate predicate;
    private int capacity;

    public ConstrainedArchive() {
        this.predicate = Predicates.alwaysTrue();
        this.capacity = 100000;
    }

    public ConstrainedArchive(ConstrainedArchive copy) {
        this.predicate = copy.predicate;
        this.capacity = copy.capacity;
    }

    public void setPredicate(Predicate predicate) {
        this.predicate = predicate;
    }

    public Predicate getPredicate() {
        return this.predicate;
    }

    public void setCapacity(int capacity) {
        this.capacity = capacity;
    }

    public int getCapacity() {
        return this.capacity;
    }

    /**
     * Iterates through the collection of {@code candidateSolutions} and adds the
     * non-dominated solutions to the archive. If the archive becomes too large
     * a pruning strategy is invoked afterwards.
     * @param candidateSolutions The solutions to add to the archive.
     * @return True if the archive changed as a result of the method call.
     */
    @Override
    public final boolean addAll(Collection candidateSolutions) {
        // For each candidate solution, try to add it to the archive.
        boolean changed = false;
        for (OptimisationSolution candidateSolution : candidateSolutions) {
            changed |= addNonDominatedSolution(candidateSolution);
        }

        // If the archive changed and the size of the archive is too large then invoke pruning method.
        if (changed && size() > getCapacity()) {
            prune();
        }

        return changed;
    }

    /**
     * Adds the {@code candidateSolution} if no solution within the archive dominates it.
     * If the archive becomes too large a pruning strategy is invoked afterwards.
     * @param candidateSolution The solution to add to the archive.
     * @return True if the archive changed as a result if the method call.
     */
    @Override
    public final boolean add(OptimisationSolution candidateSolution) {
        boolean changed = addNonDominatedSolution(candidateSolution);

        // If the archive changed and the size of the archive is too large then invoke pruning method.
        if (changed && size() > getCapacity()) {
            prune();
        }

        return changed;
    }

    protected final boolean addNonDominatedSolution(OptimisationSolution candidateSolution) {
        // If no solution in the archive dominates the candidate solution then proceed...
        if (this.predicate.apply(candidateSolution) && !this.dominates(candidateSolution)) {

            // Remove all the solutions in the archive that is dominated by the candidate solution.
            removeAll(getDominated(candidateSolution));

            // Add the candidate solution to the archive.
            return addToStructure(candidateSolution);
        }

        return false;
    }

    /**
     * Adds a non-dominated {@code candidateSolution} into the archive.
     * @param candidateSolution The non-dominated solution to add to the archive.
     */
    protected abstract boolean addToStructure(OptimisationSolution candidateSolution);

    /**
     * This method needs to be implemented by all subclasses to provide a way
     * in which certain solutions will be removed if the archive grows too big.
     */
    protected abstract void prune();
}