org.jgap.gp.function.ExchangeMemory.java Source code

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Here is the source code for org.jgap.gp.function.ExchangeMemory.java

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/*
 * This file is part of JGAP.
 *
 * JGAP offers a dual license model containing the LGPL as well as the MPL.
 *
 * For licensing information please see the file license.txt included with JGAP
 * or have a look at the top of class org.jgap.Chromosome which representatively
 * includes the JGAP license policy applicable for any file delivered with JGAP.
 */
package org.jgap.gp.function;

import org.jgap.*;
import org.jgap.gp.*;
import org.apache.commons.lang.builder.*;
import org.jgap.gp.impl.*;
import org.jgap.util.*;

/**
 * Exchanges the values of two memory cells.
 *
 * @author Klaus Meffert
 * @since 3.2
 */
public class ExchangeMemory extends CommandGene implements ICloneable {
    /** String containing the CVS revision. Read out via reflection!*/
    private final static String CVS_REVISION = "$Revision: 1.4 $";

    /**
     * Symbolic name of the storage. Must correspond with a chosen name for
     * ReadTerminalCommand.
     */
    private String m_sourceStorageName;

    private String m_targetStorageName;

    public ExchangeMemory(final GPConfiguration a_conf, String a_firstStorageName, String a_secondStorageName)
            throws InvalidConfigurationException {
        super(a_conf, 0, CommandGene.VoidClass);
        if (a_firstStorageName == null || a_firstStorageName.length() < 1) {
            throw new IllegalArgumentException("First memory name must not be empty!");
        }
        if (a_secondStorageName == null || a_secondStorageName.length() < 1) {
            throw new IllegalArgumentException("Second memory name must not be empty!");
        }
        if (a_firstStorageName.equals(a_secondStorageName)) {
            throw new IllegalArgumentException("First and second memory name must be different!");
        }
        m_sourceStorageName = a_firstStorageName;
        m_targetStorageName = a_secondStorageName;
    }

    public String toString() {
        return "exchange(" + m_sourceStorageName + ", " + m_targetStorageName + ")";
    }

    /**
     * @return textual name of this command
     *
     * @author Klaus Meffert
     * @since 3.2
     */
    public String getName() {
        return "Exchange Memory";
    }

    public void execute_void(ProgramChromosome c, int n, Object[] args) {
        check(c);
        // Read from memory.
        // -----------------
        try {
            Object value1 = getGPConfiguration().readFromMemory(m_sourceStorageName);
            Object value2 = getGPConfiguration().readFromMemory(m_targetStorageName);
            // Store in memory.
            // ----------------
            getGPConfiguration().storeInMemory(m_sourceStorageName, value2);
            getGPConfiguration().storeInMemory(m_targetStorageName, value1);
        } catch (IllegalArgumentException iex) {
            throw new IllegalStateException("ExchangeMemory without preceeding StoreTerminal");
        }
    }

    public boolean isAffectGlobalState() {
        /**@todo subclass from new abstract class MemoryCommand?*/
        return true;
    }

    public boolean isValid(ProgramChromosome a_program) {
        return true;
    }

    public Class getChildType(IGPProgram a_ind, int a_chromNum) {
        return null;
    }

    /**
     * The compareTo-method.
     *
     * @param a_other the other object to compare
     * @return -1, 0, 1
     *
     * @author Klaus Meffert
     * @since 3.2
     */
    public int compareTo(Object a_other) {
        if (a_other == null) {
            return 1;
        } else {
            ExchangeMemory other = (ExchangeMemory) a_other;
            return new CompareToBuilder().append(m_sourceStorageName, other.m_sourceStorageName)
                    .append(m_targetStorageName, other.m_targetStorageName).toComparison();
        }
    }

    /**
     * The equals-method.
     *
     * @param a_other the other object to compare
     * @return true if the objects are seen as equal
     *
     * @author Klaus Meffert
     * @since 3.2
     */
    public boolean equals(Object a_other) {
        if (a_other == null) {
            return false;
        } else {
            try {
                ExchangeMemory other = (ExchangeMemory) a_other;
                return new EqualsBuilder().append(m_sourceStorageName, other.m_sourceStorageName)
                        .append(m_targetStorageName, other.m_targetStorageName).isEquals();
            } catch (ClassCastException cex) {
                return false;
            }
        }
    }

    /**
     * Clones the object. Simple and straight forward implementation here.
     *
     * @return cloned instance of this object
     *
     * @author Klaus Meffert
     * @since 3.4
     */
    public Object clone() {
        try {
            ExchangeMemory result = new ExchangeMemory(getGPConfiguration(), m_sourceStorageName,
                    m_targetStorageName);
            return result;
        } catch (Exception ex) {
            throw new CloneException(ex);
        }
    }
}