path: root/plugins/org.eclipse.xtend.shared.ui/src/org/eclipse/xtend/shared/ui/core/action/SelectionDispatchAction.java

/*******************************************************************************
 * Copyright (c) 2005 - 2007 committers of openArchitectureWare and others. All
 * rights reserved. This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License v1.0 which
 * accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors: committers of openArchitectureWare - initial API and
 * implementation
 ******************************************************************************/
package org.eclipse.xtend.shared.ui.core.action;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jdt.ui.actions.ConvertingSelectionProvider;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.action.IAction;
import org.eclipse.jface.text.ITextSelection;
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 {@link IAction#run()} and the
 * {@link ISelectionChangedListener#selectionChanged} according to the type of
 * the selection.
 * 
 * <ul>
 * <li>if selection is of type {@link ITextSelection} then
 * {@link run(ITextSelection)} and <code>selectionChanged(ITextSelection)</code>
 * is called. </li>
 * <li>if selection is of type {@link IStructuredSelection} then
 * {@link run(IStructuredSelection)} and {@link 
 * selectionChanged(IStructuredSelection)} is called.</li>
 * <li>default is to call {@link run(ISelection)} and {@link
 * selectionChanged(ISelection)}.</li>
 * </ul>
 * 
 * Note: This class is not intended to be subclassed outside the Xtend UI plug-in.
 */
public abstract class SelectionDispatchAction extends Action implements ISelectionChangedListener {

	private final IWorkbenchSite site;

	private ISelectionProvider specialSelectionProvider;

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

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

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

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

	/**
	 * Returns the selection provider managed by the site owning this action or
	 * the selection provider explicitly set in
	 * {@link #setSpecialSelectionProvider(ISelectionProvider)}.
	 * 
	 * @return the site's selection provider
	 */
	public ISelectionProvider getSelectionProvider() {
		if (specialSelectionProvider != null) {
			return specialSelectionProvider;
		}
		return site.getSelectionProvider();
	}

	/**
	 * Sets a special selection provider which will be used instead of the
	 * site's selection provider. This method should be used directly after
	 * constructing the action and before the action is registered as a
	 * selection listener. The invocation will not a perform a selection change
	 * notification.
	 * 
	 * @param provider
	 *            a special selection provider which is used instead of the
	 *            site's selection provider or <code>null</code> to use the
	 *            site's selection provider. Clients can for example use a
	 *            {@link ConvertingSelectionProvider} to first convert a
	 *            selection before passing it to the action.
	 */
	public void setSpecialSelectionProvider(ISelectionProvider provider) {
		specialSelectionProvider = provider;
	}

	/**
	 * 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>.
	 * 
	 * @param selection
	 *            the selection
	 */
	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>.
	 * 
	 * @param selection
	 *            the selection
	 */
	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.
	 * 
	 * @param selection
	 *            the selection
	 */
	public void run(ISelection selection) {
	}

	@Override
	public void run() {
		dispatchRun(getSelection());
	}

	/**
	 * {@inheritDoc}
	 */
	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);
		}
	}
}