| /******************************************************************************* |
| * Copyright (c) 2000, 2006 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.navigator.extensions; |
| |
| import java.util.Arrays; |
| import java.util.Collections; |
| import java.util.Comparator; |
| |
| import org.eclipse.core.runtime.IConfigurationElement; |
| import org.eclipse.core.runtime.IExtension; |
| import org.eclipse.core.runtime.IExtensionPoint; |
| import org.eclipse.core.runtime.IExtensionRegistry; |
| import org.eclipse.core.runtime.Platform; |
| import org.eclipse.ui.internal.navigator.NavigatorPlugin; |
| |
| /** |
| * Template implementation of a registry reader that creates objects representing registry contents. |
| * Typically, an extension contains one element, but this reader handles multiple elements per |
| * extension. |
| * |
| * To start reading the extensions from the registry for an extension point, call the method |
| * <code>readRegistry</code>. |
| * |
| * To read children of an IConfigurationElement, call the method <code>readElementChildren</code> |
| * from your implementation of the method <code>readElement</code>, as it will not be done by |
| * default. |
| * <p> |
| * <strong>EXPERIMENTAL</strong>. This class or interface has been added as part of a work in |
| * progress. There is a guarantee neither that this API will work nor that it will remain the same. |
| * Please do not use this API without consulting with the Platform/UI team. |
| * </p> |
| * |
| * @since 3.2 |
| */ |
| public abstract class RegistryReader { |
| |
| protected static final String TAG_DESCRIPTION = "description"; //$NON-NLS-1$ |
| |
| private boolean isInitialized; |
| private final String extensionPointId; |
| private final String pluginId; |
| private final IExtensionRegistry registry; |
| |
| /** |
| * The constructor. |
| */ |
| protected RegistryReader(String aPluginId, String anExtensionPoint) { |
| this.registry = Platform.getExtensionRegistry(); |
| this.pluginId = aPluginId; |
| this.extensionPointId = anExtensionPoint; |
| } |
| |
| /** |
| * This method extracts description as a subelement of the given element. |
| * |
| * @return description string if defined, or empty string if not. |
| */ |
| protected String getDescription(IConfigurationElement config) { |
| IConfigurationElement[] children = config.getChildren(TAG_DESCRIPTION); |
| if (children.length >= 1) { |
| return children[0].getValue(); |
| } |
| return "";//$NON-NLS-1$ |
| } |
| |
| /** |
| * Logs the error in the workbench log using the provided text and the information in the |
| * configuration element. |
| */ |
| protected static void logError(IConfigurationElement element, String text) { |
| IExtension extension = element.getDeclaringExtension(); |
| StringBuffer buf = new StringBuffer(); |
| buf.append("Plugin " + extension.getNamespaceIdentifier() + ", extension " + extension.getExtensionPointUniqueIdentifier());//$NON-NLS-2$//$NON-NLS-1$ |
| buf.append("\n" + text);//$NON-NLS-1$ |
| NavigatorPlugin.logError(0, buf.toString(), null); |
| } |
| |
| /** |
| * Logs a very common registry error when a required attribute is missing. |
| */ |
| protected static void logMissingAttribute(IConfigurationElement element, String attributeName) { |
| logError(element, "Required attribute '" + attributeName + "' not defined");//$NON-NLS-2$//$NON-NLS-1$ |
| } |
| |
| /** |
| * Logs a very common registry error when a required child is missing. |
| */ |
| protected static void logMissingElement(IConfigurationElement element, String elementName) { |
| logError(element, "Required sub element '" + elementName + "' not defined");//$NON-NLS-2$//$NON-NLS-1$ |
| } |
| |
| /** |
| * Logs a registry error when the configuration element is unknown. |
| */ |
| protected static void logUnknownElement(IConfigurationElement element) { |
| logError(element, "Unknown extension tag found: " + element.getName());//$NON-NLS-1$ |
| } |
| |
| /** |
| * Apply a reproducable order to the list of extensions provided, such that the order will not |
| * change as extensions are added or removed. |
| */ |
| protected IExtension[] orderExtensions(IExtension[] extensions) { |
| // By default, the order is based on plugin id sorted |
| // in ascending order. The order for a plugin providing |
| // more than one extension for an extension point is |
| // dependent in the order listed in the XML file. |
| IExtension[] sortedExtension = new IExtension[extensions.length]; |
| System.arraycopy(extensions, 0, sortedExtension, 0, extensions.length); |
| Comparator comparer = new Comparator() { |
| public int compare(Object arg0, Object arg1) { |
| String s1 = ((IExtension) arg0).getNamespaceIdentifier(); |
| String s2 = ((IExtension) arg1).getNamespaceIdentifier(); |
| return s1.compareToIgnoreCase(s2); |
| } |
| }; |
| Collections.sort(Arrays.asList(sortedExtension), comparer); |
| return sortedExtension; |
| } |
| |
| /** |
| * Implement this method to read element's attributes. If children should also be read, then |
| * implementor is responsible for calling <code>readElementChildren</code>. Implementor is |
| * also responsible for logging missing attributes. |
| * |
| * @return true if element was recognized, false if not. |
| */ |
| protected abstract boolean readElement(IConfigurationElement element); |
| |
| /** |
| * Read the element's children. This is called by the subclass' readElement method when it wants |
| * to read the children of the element. |
| */ |
| protected void readElementChildren(IConfigurationElement element) { |
| readElements(element.getChildren()); |
| } |
| |
| /** |
| * Read each element one at a time by calling the subclass implementation of |
| * <code>readElement</code>. |
| * |
| * Logs an error if the element was not recognized. |
| */ |
| protected void readElements(IConfigurationElement[] elements) { |
| for (int i = 0; i < elements.length; i++) { |
| if (!readElement(elements[i])) { |
| logUnknownElement(elements[i]); |
| } |
| } |
| } |
| |
| /** |
| * Read one extension by looping through its configuration elements. |
| */ |
| protected void readExtension(IExtension extension) { |
| readElements(extension.getConfigurationElements()); |
| } |
| |
| /** |
| * Start the registry reading process using the supplied plugin ID and extension point. |
| */ |
| public void readRegistry() { |
| if (isInitialized) { |
| return; |
| } |
| synchronized (this) { |
| if (!isInitialized) { |
| IExtensionPoint point = registry.getExtensionPoint(pluginId, extensionPointId); |
| if (point == null) { |
| return; |
| } |
| IExtension[] extensions = point.getExtensions(); |
| extensions = orderExtensions(extensions); |
| for (int i = 0; i < extensions.length; i++) { |
| readExtension(extensions[i]); |
| } |
| isInitialized = true; |
| } |
| |
| } |
| } |
| } |