plugins/sqltools/org.eclipse.datatools.sqltools.sqleditor/src/org/eclipse/datatools/sqltools/sqleditor/internal/actions/SelectionDispatchAction.java

/*******************************************************************************
 * Copyright (c) 2004, 2005 Sybase, Inc. and others.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * Contributors:
 *     Sybase, Inc. - initial API and implementation
 *******************************************************************************/
package org.eclipse.datatools.sqltools.sqleditor.internal.actions;

import org.eclipse.jface.action.Action;
import org.eclipse.jface.text.ITextSelection;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ISelectionChangedListener;
import org.eclipse.jface.viewers.ISelectionProvider;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.SelectionChangedEvent;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.ui.IWorkbenchSite;

/**
 * Action that dispatches the <code>IAction#run()</code> and the
 * <code>ISelectionChangedListener#selectionChanged</code> according to the type of the selection.
 * 
 * <ul>
 * <li>if selection is of type <code>ITextSelection</code> then <code>run(ITextSelection)</code> and
 * <code>selectionChanged(ITextSelection)</code> is called.</li>
 * <li>if selection is of type <code>IStructuredSelection</code> then <code>run(IStructuredSelection)</code> and
 * <code>
 * 	selectionChanged(IStructuredSelection)</code> is called.</li>
 * <li>default is to call <code>run(ISelection)</code> and <code>
 * 	selectionChanged(ISelection)</code>.</li>
 * </ul>
 * 
 * @author Hui Cao
 *  
 */
public abstract class SelectionDispatchAction extends Action implements ISelectionChangedListener
{

    private IWorkbenchSite _fSite;

    /**
     * Creates a new action with no text and no image.
     * <p>
     * Configure the action later using the set methods.
     * </p>
     * 
     * @param site the site this action is working on
     */
    protected SelectionDispatchAction(IWorkbenchSite site)
    {
        Assert.isNotNull(site);
        _fSite = site;
    }

    /**
     * Returns the site owning this action.
     * 
     * @return the site owning this action
     */
    public IWorkbenchSite getSite()
    {
        return _fSite;
    }

    /**
     * Returns the selection provided by the site owning this action.
     * 
     * @return the site's selection
     */
    public ISelection getSelection()
    {
        if (getSelectionProvider() != null)
        return getSelectionProvider().getSelection();
        else
        return null;
    }

    /**
     * Returns the shell provided by the site owning this action.
     * 
     * @return the site's shell
     */
    public Shell getShell()
    {
        return _fSite.getShell();
    }

    /**
     * Returns the selection provider managed by the site owning this action.
     * 
     * @return the site's selection provider
     */
    public ISelectionProvider getSelectionProvider()
    {
        return _fSite.getSelectionProvider();
    }

    /**
     * Updates the action's enablement state according to the given selection. This default implementation calls one of
     * the <code>selectionChanged</code> methods depending on the type of the passed selection.
     * 
     * @param selection the selection this action is working on
     */
    public void update(ISelection selection)
    {
        dispatchSelectionChanged(selection);
    }

    /**
     * Notifies this action that the given structured selection has changed. This default implementation calls
     * <code>selectionChanged(ISelection selection)</code>.
     * 
     * @param selection the new selection
     */
    public void selectionChanged(IStructuredSelection selection)
    {
        selectionChanged((ISelection) selection);
    }

    /**
     * Executes this actions with the given structured selection. This default implementation calls
     * <code>run(ISelection selection)</code>.
     */
    public void run(IStructuredSelection selection)
    {
        run((ISelection) selection);
    }

    /**
     * Notifies this action that the given text selection has changed. This default implementation calls
     * <code>selectionChanged(ISelection selection)</code>.
     * 
     * @param selection the new selection
     */
    public void selectionChanged(ITextSelection selection)
    {
        selectionChanged((ISelection) selection);
    }

    /**
     * Executes this actions with the given text selection. This default implementation calls
     * <code>run(ISelection selection)</code>.
     */
    public void run(ITextSelection selection)
    {
        run((ISelection) selection);
    }

    /**
     * Notifies this action that the given selection has changed. This default implementation sets the action's
     * enablement state to <code>false</code>.
     * 
     * @param selection the new selection
     */
    public void selectionChanged(ISelection selection)
    {
        setEnabled(false);
    }

    /**
     * Executes this actions with the given selection. This default implementation does nothing.
     */
    public void run(ISelection selection)
    {
    }

    /*
     * (non-Javadoc) Method declared on IAction.
     */
    public void run()
    {
        dispatchRun(getSelection());
    }

    /*
     * (non-Javadoc) Method declared on ISelectionChangedListener.
     */
    public void selectionChanged(SelectionChangedEvent event)
    {
        dispatchSelectionChanged(event.getSelection());
    }

    private void dispatchSelectionChanged(ISelection selection)
    {
        if (selection instanceof IStructuredSelection)
        {
            selectionChanged((IStructuredSelection) selection);
        }
        else if (selection instanceof ITextSelection)
        {
            selectionChanged((ITextSelection) selection);
        }
        else
        {
            selectionChanged(selection);
        }
    }

    private void dispatchRun(ISelection selection)
    {
        if (selection instanceof IStructuredSelection)
        {
            run((IStructuredSelection) selection);
        }
        else if (selection instanceof ITextSelection)
        {
            run((ITextSelection) selection);
        }
        else
        {
            run(selection);
        }
    }
}