/*******************************************************************************
* Copyright (c) 2000, 2007 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.help.internal.context;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtensionRegistry;
import org.eclipse.core.runtime.Platform;
import org.eclipse.help.AbstractContextProvider;
import org.eclipse.help.IContext;
import org.eclipse.help.internal.HelpPlugin;
/*
* Manages all context-sensitive help data for the help system.
*/
public class ContextManager {
private static final String EXTENSION_POINT_ID_CONTEXT = HelpPlugin.PLUGIN_ID + ".contexts"; //$NON-NLS-1$
private static final String ELEMENT_NAME_CONTEXT_PROVIDER = "contextProvider"; //$NON-NLS-1$
private static final String ATTRIBUTE_NAME_CLASS = "class"; //$NON-NLS-1$
private Map providersByPluginId;
private List globalProviders;
private Map contextsById = new HashMap();
private Map idsByContext = new HashMap();
private int idCounter = 0;
/*
* Adds the given dynamically generated IContext to the system, and
* generates a unique ID for it.
*/
public String addContext(IContext context) {
String plugin = HelpPlugin.PLUGIN_ID;
String id = (String)idsByContext.get(context);
if (id != null) {
// context already registered
} else {
// generate ID and register the context
id = "ID" + idCounter++; //$NON-NLS-1$
idsByContext.put(context, id);
contextsById.put(id, context);
}
return plugin + "." + id; //$NON-NLS-1$
}
/*
* Returns the Context for the given id and locale.
*/
public IContext getContext(String contextId, String locale) {
// first check for dynamic context definitions
Context dynamicContext = (Context)contextsById.get(contextId);
if (dynamicContext != null) {
return dynamicContext;
}
// ask the providers
int index = contextId.lastIndexOf('.');
if (index != -1) {
String pluginId = contextId.substring(0, index);
Iterator iter = getContextProviders(pluginId).iterator();
while (iter.hasNext()) {
AbstractContextProvider provider = (AbstractContextProvider)iter.next();
try {
IContext context = provider.getContext(contextId, locale);
if (context != null) {
return new Context(context, contextId);
}
}
catch (Throwable t) {
// log and skip
String msg = "Error querying context provider (" + provider.getClass().getName() + ") with context Id: " + contextId; //$NON-NLS-1$ //$NON-NLS-2$
HelpPlugin.logError(msg, t);
}
}
}
return null;
}
/*
* Returns all registered context providers (potentially cached) for the
* given plug-in id.
*/
private List getContextProviders(String pluginId) {
if (providersByPluginId == null) {
loadContextProviders();
}
List list = new ArrayList();
List forPlugin = (List)providersByPluginId.get(pluginId);
if (forPlugin != null) {
list.addAll(forPlugin);
}
list.addAll(globalProviders);
return list;
}
/*
* Finds and instantiates all registered context-sensitive help providers.
*/
private void loadContextProviders() {
providersByPluginId = new HashMap();
globalProviders = new ArrayList();
IExtensionRegistry registry = Platform.getExtensionRegistry();
IConfigurationElement[] elements = registry.getConfigurationElementsFor(EXTENSION_POINT_ID_CONTEXT);
for (int i=0;i<elements.length;++i) {
IConfigurationElement elem = elements[i];
if (elem.getName().equals(ELEMENT_NAME_CONTEXT_PROVIDER)) {
try {
AbstractContextProvider provider = (AbstractContextProvider)elem.createExecutableExtension(ATTRIBUTE_NAME_CLASS);
String[] plugins = provider.getPlugins();
if (plugins != null) {
for (int j=0;j<plugins.length;++j) {
List list = (List)providersByPluginId.get(plugins[j]);
if (list == null) {
list = new ArrayList();
providersByPluginId.put(plugins[j], list);
}
list.add(provider);
}
}
else {
globalProviders.add(provider);
}
}
catch (CoreException e) {
// log and skip
String msg = "Error instantiating context-sensitive help provider class \"" + elem.getAttribute(ATTRIBUTE_NAME_CLASS) + '"'; //$NON-NLS-1$
HelpPlugin.logError(msg, e);
}
}
}
}
}