MWQueryableHandle.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.descriptor.relational.MWRelationalClassDescriptor;
import org.eclipse.persistence.tools.workbench.mappingsmodel.query.MWQueryable;
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;


/**
 * MWQueryableHandle is used to isolate the painful bits of code
 * necessary to correctly handle references to MWQueryables.
 *
 * MWQueryables are some MWMappings and MWUserDefinedQueryKeys.
 *
 * Since MWQueryables are nested within the XML files
 * for MWClassDescriptor, we need to store a reference to a particular
 * queryable as a pair of instance variables:
 *   - the name of the containing mapping descriptor
 *   - the name of the queryable
 *
 * This causes no end of pain when dealing with TopLink, property
 * change listeners, backward-compatibility, etc.
 */

public final class MWQueryableHandle extends MWHandle {

    /**
     * This is the actual queryable.
     * It is built from the mapping descriptor and queryable names, below.
     */
    private volatile MWQueryable queryable;

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

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

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

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

    public MWQueryableHandle(MWModel parent, MWQueryable queryable, NodeReferenceScrubber scrubber) {
        super(parent, scrubber);
        this.queryable = queryable;
    }


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

    public MWQueryable getQueryable() {
        return this.queryable;
    }

    public void setQueryable(MWQueryable queryable) {
        this.queryable = queryable;
    }

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

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

    public void postProjectBuild() {
        super.postProjectBuild();
        if (this.mappingDescriptorName != null && this.queryableName != null) {
            MWRelationalClassDescriptor mappingDescriptor = (MWRelationalClassDescriptor) this.getProject().descriptorNamed(this.mappingDescriptorName);
            if (mappingDescriptor != null) {
                this.queryable = mappingDescriptor.queryableNamed(this.queryableName);
            }
        }
        // Ensure mappingDescriptorName and queryable name 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.mappingDescriptorName = null;
        this.queryableName = null;
    }

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

    public void toString(StringBuffer sb) {
        sb.append((this.queryable == null) ? "null" : this.queryable.getName());
    }


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

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

        descriptor.setJavaClass(MWQueryableHandle.class);

        descriptor.addDirectMapping("mappingDescriptorName", "getMappingDescriptorNameForToplink", "setMappingDescriptorNameForToplink", "mapping-descriptor-name/text()");
        descriptor.addDirectMapping("queryableName", "getQueryableNameForToplink", "setQueryableNameForToplink", "queryable-name/text()");

        return descriptor;
    }

    private String getMappingDescriptorNameForToplink() {
        return (this.queryable == null) ? null : this.queryable.getParentDescriptor().getName();
    }

    private void setMappingDescriptorNameForToplink(String mappingDescriptorName) {
        this.mappingDescriptorName = mappingDescriptorName;
    }

    private String getQueryableNameForToplink() {
        return (this.queryable == null) ? null : this.queryable.getName();
    }

    private void setQueryableNameForToplink(String queryableName) {
        this.queryableName = queryableName;
    }

}