bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/IDEWorkbenchActivityHelper.java

/*******************************************************************************
 * Copyright (c) 2003, 2005 IBM Corporation 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal.ide;

import java.util.HashMap;
import java.util.Map;

import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceChangeEvent;
import org.eclipse.core.resources.IResourceChangeListener;
import org.eclipse.core.resources.IResourceDelta;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IExtension;
import org.eclipse.core.runtime.IExtensionPoint;
import org.eclipse.core.runtime.IRegistryChangeEvent;
import org.eclipse.core.runtime.IRegistryChangeListener;
import org.eclipse.core.runtime.Platform;
import org.eclipse.ui.IPluginContribution;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.activities.ITriggerPoint;
import org.eclipse.ui.activities.IWorkbenchActivitySupport;
import org.eclipse.ui.activities.WorkbenchActivityHelper;

/**
 * Utility class that manages promotion of activites in response to workspace changes.
 * 
 * @since 3.0
 */
public class IDEWorkbenchActivityHelper {

    private static final String NATURE_POINT = "org.eclipse.ui.ide.natures"; //$NON-NLS-1$
    
    /**
     * Resource listener that reacts to new projects (and associated natures) 
     * coming into the workspace.
     */
    private IResourceChangeListener listener;

    /**
     * Mapping from composite nature ID to IPluginContribution.  Used for proper
     * activity mapping of natures.
     */
    private Map natureMap;

    /**
     * Singleton instance.
     */
    private static IDEWorkbenchActivityHelper singleton;

    /**
     * Get the singleton instance of this class.
     * @return the singleton instance of this class.
     * @since 3.0
     */
    public static IDEWorkbenchActivityHelper getInstance() {
        if (singleton == null) {
            singleton = new IDEWorkbenchActivityHelper();
        }
        return singleton;
    }

    /**
     * Create a new <code>IDEWorkbenchActivityHelper</code> which will listen 
     * for workspace changes and promote activities accordingly.
     */
    private IDEWorkbenchActivityHelper() {
        natureMap = new HashMap();
        // for dynamic UI
        Platform.getExtensionRegistry().addRegistryChangeListener(
                new IRegistryChangeListener() {
                    public void registryChanged(IRegistryChangeEvent event) {
                        if (event.getExtensionDeltas(
                                "org.eclipse.core.resources", "natures").length > 0) //$NON-NLS-1$ //$NON-NLS-2$
                            loadNatures();
                    }
                }, "org.eclipse.core.resources"); //$NON-NLS-1$
        loadNatures();
        listener = getChangeListener();
        ResourcesPlugin.getWorkspace().addResourceChangeListener(listener);
        // crawl the initial projects to set up nature bindings
        IProject[] projects = ResourcesPlugin.getWorkspace().getRoot()
                .getProjects();
        IWorkbenchActivitySupport workbenchActivitySupport = PlatformUI
                .getWorkbench().getActivitySupport();
        for (int i = 0; i < projects.length; i++) {
            try {
                processProject(projects[i], workbenchActivitySupport);
            } catch (CoreException e) {
                // do nothing
            }
        }
    }

    /**
     * For dynamic UI.  Clears the cache of known natures and recreates it.
     */
    public void loadNatures() {
        natureMap.clear();
        IExtensionPoint point = Platform.getExtensionRegistry()
                .getExtensionPoint("org.eclipse.core.resources.natures"); //$NON-NLS-1$
        IExtension[] extensions = point.getExtensions();
        for (int i = 0; i < extensions.length; i++) {
            IExtension extension = extensions[i];
            final String localId = extension.getSimpleIdentifier();
            final String pluginId = extension.getNamespace();
            String natureId = extension.getUniqueIdentifier();
            natureMap.put(natureId, new IPluginContribution() {
                public String getLocalId() {
                    return localId;
                }

                public String getPluginId() {
                    return pluginId;
                }
            });
        }
    }

    /**
     * Get a change listener for listening to resource changes.
     * 
     * @return the resource change listeners
     */
    private IResourceChangeListener getChangeListener() {
        return new IResourceChangeListener() {
            /*
             * (non-Javadoc) @see
             * org.eclipse.core.resources.IResourceChangeListener#resourceChanged(org.eclipse.core.resources.IResourceChangeEvent)
             */
            public void resourceChanged(IResourceChangeEvent event) {
                if (!WorkbenchActivityHelper.isFiltering())
                    return;
                IResourceDelta mainDelta = event.getDelta();

                if (mainDelta == null)
                    return;
                //Has the root changed?
                if (mainDelta.getKind() == IResourceDelta.CHANGED
                        && mainDelta.getResource().getType() == IResource.ROOT) {

                    try {
                        IResourceDelta[] children = mainDelta
                                .getAffectedChildren();
                        IWorkbenchActivitySupport workbenchActivitySupport = PlatformUI
                                .getWorkbench().getActivitySupport();
                        for (int i = 0; i < children.length; i++) {
                            IResourceDelta delta = children[i];
                            if (delta.getResource().getType() == IResource.PROJECT) {
                                IProject project = (IProject) delta
                                        .getResource();
                                processProject(project,
                                        workbenchActivitySupport);
                            }
                        }
                    } catch (CoreException exception) {
                        //Do nothing if there is a CoreException
                    }
                }
            }
        };
    }

    /**
     * Handle natures for the given project.
     * 
     * @param project the project
     * @param workbenchActivitySupport the activity support
     */
    protected void processProject(IProject project,
            IWorkbenchActivitySupport workbenchActivitySupport)
            throws CoreException {
        if (!project.isOpen())
            return;
        String[] ids = project.getDescription().getNatureIds();
        if (ids.length == 0)
            return;
        
        for (int j = 0; j < ids.length; j++) {
            IPluginContribution contribution = (IPluginContribution) natureMap
                    .get(ids[j]);
            if (contribution == null)
                continue; //bad nature ID.
            ITriggerPoint triggerPoint = workbenchActivitySupport
                    .getTriggerPointManager().getTriggerPoint(NATURE_POINT); 
            //consult the advisor - if the activities need enabling, they will be
            WorkbenchActivityHelper.allowUseOf(triggerPoint, contribution);
        }
    }

    /**
     * Unhooks the <code>IResourceChangeListener</code>.
     */
    public void shutdown() {
        if (listener != null) {
            ResourcesPlugin.getWorkspace().removeResourceChangeListener(
                    listener);
        }
    }

}