MWColumnPairHandle.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.MWColumnPair;
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.oxm.XMLDescriptor;

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

    /**
     * This is the actual column pair.
     * It is built from the table, reference, and column pair names, below.
     */
    private volatile MWColumnPair columnPair;

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


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

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

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

    public MWColumnPairHandle(MWModel parent, MWColumnPair columnPair, NodeReferenceScrubber scrubber) {
        super(parent, scrubber);
        this.columnPair = columnPair;
    }


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

    public MWColumnPair getColumnPair() {
        return this.columnPair;
    }

    public void setColumnPair(MWColumnPair columnPair) {
        this.columnPair = columnPair;
    }

    protected Node node() {
        return this.getColumnPair();
    }

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

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

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

    public void postProjectBuild() {
        super.postProjectBuild();

        if (this.tableName != null && this.referenceName != null && this.columnPairName != null) {
            MWTable table = this.getDatabase().tableNamed(this.tableName);
            if (table != null) {
                MWReference reference = table.referenceNamed(this.referenceName);
                if (reference != null) {
                    this.columnPair = reference.columnPairNamed(this.columnPairName);
                }
            }
        }

        // Ensure tableName, referenceName, and columnPairName 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.tableName = null;
        this.referenceName = null;
        this.columnPairName = null;
    }


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

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

        descriptor.setJavaClass(MWColumnPairHandle.class);

        descriptor.addDirectMapping("tableName", "getTableNameForTopLink", "setTableNameForTopLink", "table-name/text()");
        descriptor.addDirectMapping("referenceName", "getReferenceNameForTopLink", "setReferenceNameForTopLink", "reference-name/text()");
        descriptor.addDirectMapping("columnPairName", "getColumnPairNameForTopLink", "setColumnPairNameForTopLink", "column-pair-name/text()");

        return descriptor;
    }

    private String getTableNameForTopLink() {
        return (this.columnPair == null) ? null : this.columnPair.sourceTable().getName();
    }
    private void setTableNameForTopLink(String tableName) {
        this.tableName = tableName;
    }

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

    private String getColumnPairNameForTopLink() {
        return (this.columnPair == null) ? null : this.columnPair.getName();
    }
    private void setColumnPairNameForTopLink(String columnPairName) {
        this.columnPairName = columnPairName;
    }
}