MWAttributeHandle.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.meta.MWClass;
import org.eclipse.persistence.tools.workbench.mappingsmodel.meta.MWClassAttribute;
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;

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

    /**
     * This is the actual attribute.
     * It is built from the declaring type and attribute names, below.
     */
    private volatile MWClassAttribute attribute;

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


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

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

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

    public MWAttributeHandle(MWModel parent, MWClassAttribute attribute, NodeReferenceScrubber scrubber) {
        super(parent, scrubber);
        this.attribute = attribute;
    }


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

    public MWClassAttribute getAttribute() {
        return this.attribute;
    }

    public void setAttribute(MWClassAttribute attribute) {
        this.attribute = attribute;
    }

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

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

    public void postProjectBuild() {
        super.postProjectBuild();
        if (this.attributeDeclaringTypeName != null && this.attributeName != null) {
            // the type will never be null - the repository will auto-generate one if necessary
            this.attribute = this.typeNamed(this.attributeDeclaringTypeName).attributeNamedFromCombinedAll(this.attributeName);
        }
        // Ensure attributeDeclaringTypeName and attributeName 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.attributeDeclaringTypeName = null;
        this.attributeName = null;
    }

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

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


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

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

        descriptor.setJavaClass(MWAttributeHandle.class);

        descriptor.addDirectMapping("attributeDeclaringTypeName", "getAttributeDeclaringTypeNameForTopLink", "setAttributeDeclaringTypeNameForTopLink", "attribute-declaring-type-name/text()");
        descriptor.addDirectMapping("attributeName", "getAttributeNameForTopLink", "setAttributeNameForTopLink", "attribute-name/text()");

        return descriptor;
    }

    private String getAttributeDeclaringTypeNameForTopLink(){
        return (this.attribute == null) ? null : this.attribute.getDeclaringType().getName();
    }

    private void setAttributeDeclaringTypeNameForTopLink(String attributeDeclaringTypeName){
        this.attributeDeclaringTypeName = attributeDeclaringTypeName;
    }

    private String getAttributeNameForTopLink() {
        return (this.attribute == null) ? null : attribute.getName();
    }

    private void setAttributeNameForTopLink(String attributeName) {
        this.attributeName = attributeName;
    }
}