MWReferenceHandle.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.mappingsmodel.handles;

import org.eclipse.persistence.tools.workbench.mappingsmodel.MWModel;
import org.eclipse.persistence.tools.workbench.mappingsmodel.db.MWReference;
import org.eclipse.persistence.tools.workbench.mappingsmodel.db.MWTable;
import org.eclipse.persistence.tools.workbench.utility.node.Node;

import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.mappings.OneToOneMapping;
import org.eclipse.persistence.oxm.XMLDescriptor;

/**
 * MWReferenceHandle is used to isolate the painful bits of code
 * necessary to correctly handle references to MWReferences.
 * Since a MWReference is nested within the XML file
 * for a MWTable, we need to store a reference to a particular
 * reference as a pair of instance variables:
 *   - the name of the containing table
 *   - the name of the reference
 *
 * This causes no end of pain when dealing with TopLink, property
 * change listeners, backward-compatibility, etc.
 */
public final class MWReferenceHandle extends MWHandle {

    /**
     * This is the actual reference.
     * It is built from the table and reference names, below.
     */
    private volatile MWReference reference;

    /**
     * The table and reference names are transient. They
     * are used only to hold their values until postProjectBuild()
     * is called and we can resolve the actual reference.
     * We do not keep these in synch with the reference itself because
     * we cannot know when the reference has been renamed etc.
     */
    private volatile String referenceTableName;
    private volatile String referenceName;


    // ********** constructors **********

    /**
     * default constructor - for TopLink use only
     */
    private MWReferenceHandle() {
        super();
    }

    public MWReferenceHandle(MWModel parent, NodeReferenceScrubber scrubber) {
        super(parent, scrubber);
    }

    public MWReferenceHandle(MWModel parent, MWReference reference, NodeReferenceScrubber scrubber) {
        super(parent, scrubber);
        this.reference = reference;
    }


    // ********** instance methods **********

    public MWReference getReference() {
        return this.reference;
    }

    public void setReference(MWReference reference) {
        this.reference = reference;
    }

    protected Node node() {
        return getReference();
    }

    public MWReferenceHandle setScrubber(NodeReferenceScrubber scrubber) {
        this.setScrubberInternal(scrubber);
        return this;
    }

    public void resolveReferenceHandles() {
        super.resolveReferenceHandles();
        if ((this.referenceTableName != null) && (this.referenceName != null)) {
            MWTable table = this.getDatabase().tableNamed(this.referenceTableName);
            if (table != null) {
                this.reference = table.referenceNamed(this.referenceName);
            }
        }
        // Ensure referenceTableName and referenceName are not used by setting them to null....
        // If the XML is corrupt and only one of these attributes is populated,
        // this will cause the populated attribute to be cleared out if the
        // objects are rewritten.
        this.referenceTableName = null;
        this.referenceName = null;
    }

    /**
     * Override to delegate comparison to the reference itself.
     * If the handles being compared are in a collection that is being sorted,
     * NEITHER reference should be null.
     */
    public int compareTo(Object o) {
        return this.reference.compareTo(((MWReferenceHandle) o).reference);
    }

    public void toString(StringBuffer sb) {
        if (this.reference == null) {
            sb.append("null");
        } else {
            this.reference.toString(sb);
        }
    }


    // ********** TopLink methods **********

    public static XMLDescriptor buildDescriptor() {
        XMLDescriptor descriptor = new XMLDescriptor();

        descriptor.setJavaClass(MWReferenceHandle.class);

        descriptor.addDirectMapping("referenceTableName", "getReferenceTableNameForTopLink", "setReferenceTableNameForTopLink", "reference-table-name/text()");
        descriptor.addDirectMapping("referenceName", "getReferenceNameForTopLink", "setReferenceNameForTopLink", "reference-name/text()");

        return descriptor;
    }

    private String getReferenceTableNameForTopLink() {
        return (this.reference == null) ? null : this.reference.getSourceTable().getName();
    }
    private void setReferenceTableNameForTopLink(String referenceTableName) {
        this.referenceTableName = referenceTableName;
    }

    private String getReferenceNameForTopLink() {
        return (this.reference == null) ? null : this.reference.getName();
    }
    private void setReferenceNameForTopLink(String referenceName) {
        this.referenceName = referenceName;
    }

}