EmptySelectionPseudoNode.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.framework.internal;

import java.awt.Component;

import org.eclipse.persistence.tools.workbench.framework.app.AbstractApplicationNode;
import org.eclipse.persistence.tools.workbench.framework.app.GroupContainerDescription;
import org.eclipse.persistence.tools.workbench.framework.context.ApplicationContext;
import org.eclipse.persistence.tools.workbench.framework.context.ShellWorkbenchContext;
import org.eclipse.persistence.tools.workbench.framework.context.WorkbenchContext;
import org.eclipse.persistence.tools.workbench.framework.ui.view.EmptyPropertiesPage;


/**
 * This is a pseudo-node that is "selected" whenever no nodes
 * on the tree are selected. It supplies a properties page that
 * displays nothing.
 *
 * There is one empty selection "pseudo-node" per workspace view.
 */
final class EmptySelectionPseudoNode
    extends AbstractApplicationNode
{
    /** cache the properties page so we don't have to rebuild it repeatedly */
    private Component emptyPropertiesPage;


    // ************ constructor ************

    /**
     * use the super-secret, framework-only constructor...
     */
    public EmptySelectionPseudoNode(ApplicationContext context) {
        super(context);
        this.emptyPropertiesPage = new EmptyPropertiesPage(new ShellWorkbenchContext(this.getApplicationContext()));
    }


    // ********** AbstractTreeNodeValueModel overrides **********

    public boolean equals(Object o) {
        return this == o;
    }

    public int hashCode() {
        return System.identityHashCode(this);
    }


    // ********** AbstractApplicationNode overrides **********

    /**
     * this node does not have a value; do not call this method
     * willy-nilly on a collection of heterogeneous nodes - narrow
     * down the collection to the relevant nodes  ~bjv
     */
    public Object getValue() {
        throw new UnsupportedOperationException();
    }

    /**
     * the problems view will want to listen to our list of problems,
     * but we don't have any
     */
    protected void engageValueBranchProblems() {
        // do nothing since we don't have a value
    }
    protected void disengageValueBranchProblems() {
        // do nothing since we don't have a value
    }

    public void toString(StringBuffer sb) {
        sb.append("[empty]");
    }


    // ********** ApplicationNode implementation **********

    public GroupContainerDescription buildMenuDescription(WorkbenchContext workbenchContext) {
        throw new UnsupportedOperationException();
    }

    public GroupContainerDescription buildToolBarDescription(WorkbenchContext workbenchContext) {
        throw new UnsupportedOperationException();
    }


    // ********** EditorNode implementation **********

    public Component propertiesPage(WorkbenchContext workbenchContext) {
        return this.emptyPropertiesPage;
    }

    public void releasePropertiesPage(Component propertiesPage) {
        // do nothing
    }

}