org.eclipse.gmf.runtime.emf.type.core/src/org/eclipse/gmf/runtime/emf/type/core/ClientContextManager.java - gmf-runtime/org.eclipse.gmf-runtime - Git at Google

 /******************************************************************************
  * Copyright (c) 2006, 2015 IBM Corporation, Christian W. Damus, 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
  *    Christian W. Damus - bug 457888
  ****************************************************************************/

 package org.eclipse.gmf.runtime.emf.type.core;

 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;

 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IExtension;
 import org.eclipse.core.runtime.IExtensionPoint;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.core.runtime.dynamichelpers.ExtensionTracker;
 import org.eclipse.core.runtime.dynamichelpers.IExtensionChangeHandler;
 import org.eclipse.core.runtime.dynamichelpers.IExtensionTracker;
 import org.eclipse.emf.ecore.EObject;
 import org.eclipse.gmf.runtime.common.core.util.Log;
 import org.eclipse.gmf.runtime.common.core.util.Trace;
 import org.eclipse.gmf.runtime.emf.type.core.internal.EMFTypeDebugOptions;
 import org.eclipse.gmf.runtime.emf.type.core.internal.EMFTypePlugin;
 import org.eclipse.gmf.runtime.emf.type.core.internal.EMFTypePluginStatusCodes;
 import org.eclipse.gmf.runtime.emf.type.core.internal.descriptors.IEditHelperAdviceDescriptor;
 import org.eclipse.gmf.runtime.emf.type.core.internal.impl.DefaultClientContext;
 import org.eclipse.gmf.runtime.emf.type.core.internal.impl.XMLClientContext;
 import org.eclipse.gmf.runtime.emf.type.core.internal.l10n.EMFTypeCoreMessages;

 /**
  * The context manager loads contexts from the <code>elementTypeBindings</code>
  * extension point and makes them available to the element type registry.
  * <P>
  * There is also a default client context, {@link #getDefaultClientContext()},
  * that is implicitly bound to all types and advice that otherwise have no
  * explicit binding.
  *
  * @author ldamus
  */
 public final class ClientContextManager {

 	/**
 	 * Extension point name for the element type bindings extension point.
 	 */
 	public static final String ELEMENT_TYPE_BINDINGS_EXT_P_NAME = "elementTypeBindings"; //$NON-NLS-1$

 	private static final String E_CLIENT_CONTEXT = "clientContext"; //$NON-NLS-1$

 	private static final String E_BINDING = "binding"; //$NON-NLS-1$

 	private static final String A_CONTEXT = "context"; //$NON-NLS-1$

 	private static final String E_ELEMENT_TYPE = "elementType"; //$NON-NLS-1$

 	private static final String E_ADVICE = "advice"; //$NON-NLS-1$

 	private static final String A_REF = "ref"; //$NON-NLS-1$

 	private static final String A_PATTERN = "pattern"; //$NON-NLS-1$

 	private static final ClientContextManager INSTANCE = new ClientContextManager();

 	private final Set clientContexts = new java.util.HashSet();

 	private final Map clientContextMap = new java.util.HashMap();

 	private final CopyOnWriteArrayList<IClientContextManagerListener> listeners = new CopyOnWriteArrayList<IClientContextManagerListener>();

 	private ExtensionTracker extensionTracker;

 	private IExtensionChangeHandler extensionListener;

 	/**
 	 * Not instantiable by clients.
 	 */
 	private ClientContextManager() {
 		super();

 		IConfigurationElement[] configs = Platform.getExtensionRegistry()
 				.getConfigurationElementsFor(EMFTypePlugin.getPluginId(),
 						ELEMENT_TYPE_BINDINGS_EXT_P_NAME);

 		if (EMFTypePlugin.isDynamicAware()) {
 			startExtensionTracking();
 		}

 		configureElementTypeBindings(configs);
 	}

 	private void startExtensionTracking() {
 		extensionListener = new IExtensionChangeHandler() {

 			public void addExtension(IExtensionTracker tracker,
 					IExtension extension) {
 				configureElementTypeBindings(extension.getConfigurationElements());
 			}

 			public void removeExtension(IExtension extension, Object[] objects) {
 				// Extension removal not supported
 			}
 		};

 		IExtensionPoint point = Platform.getExtensionRegistry()
 				.getExtensionPoint(EMFTypePlugin.getPluginId(),
 						ELEMENT_TYPE_BINDINGS_EXT_P_NAME);

 		extensionTracker = new ExtensionTracker();
 		extensionTracker.registerHandler(extensionListener, ExtensionTracker
 				.createExtensionPointFilter(point));
 	}

 	/**
 	 * Obtains the singleton instance of this class.
 	 *
 	 * @return the singleton context manager
 	 */
 	public static final ClientContextManager getInstance() {
 		return INSTANCE;
 	}

 	/**
 	 * Gets the default client context.
 	 *
 	 * @return the default context
 	 */
 	public static final IClientContext getDefaultClientContext() {
 		return getInstance().getClientContext(DefaultClientContext.ID);
 	}

 	/**
 	 * Obtains a client context by its unique identifier.
 	 *
 	 * @param contextId
 	 *            the client context ID to look for
 	 * @return the matching context, or <code>null</code> if none is
 	 *         registered under this ID
 	 */
 	public IClientContext getClientContext(String contextId) {

 		if (DefaultClientContext.ID.equals(contextId)) {
 			return DefaultClientContext.getInstance();
 		}

 		return (IClientContext) clientContextMap.get(contextId);
 	}

 	/**
 	 * Obtains all of the client contexts registered in the system.
 	 *
 	 * @return the available {@link IClientContext}s
 	 */
 	public Set getClientContexts() {
 		return clientContexts;
 	}

 	/**
 	 * Obtains the client contexts to which the specified object belongs.
 	 *
 	 * @param eObject
 	 *            a model element
 	 * @return the client context to which the <code>eObject</code> belongs.
 	 *         This may be <code>null</code> if no context matches this
 	 *         element. It will be a <code>MultiClientContest</code> if more
 	 *         than one context matches the element.
 	 */
 	public IClientContext getClientContextFor(EObject eObject) {

 		Collection contexts = new java.util.ArrayList();

 		for (Iterator iter = getClientContexts().iterator(); iter.hasNext();) {
 			IClientContext next = (IClientContext) iter.next();
 			IElementMatcher matcher = next.getMatcher();

 			try {
 				if (matcher.matches(eObject)) {
 					contexts.add(next);
 				}
 			} catch (RuntimeException e) {
 				// client context matchers must not throw exceptions. This one
 				// will not be trusted in future validation operations. This
 				// is effected by removing it from the context manager
 				iter.remove();
 				clientContextMap.remove(next.getId());
 				// context

 				Trace.catching(EMFTypePlugin.getPlugin(),
 						EMFTypeDebugOptions.EXCEPTIONS_CATCHING, getClass(),
 						"getClientContextsFor", e); //$NON-NLS-1$

 				Log
 						.error(
 								EMFTypePlugin.getPlugin(),
 								EMFTypePluginStatusCodes.CLIENT_MATCHER_FAILURE,
 								EMFTypeCoreMessages
 										.bind(
 												EMFTypeCoreMessages.client_matcherFailure_ERROR_,
 												next.getId()), e);
 			}
 		}

 		return getClientContext(contexts);
 	}

 	/**
 	 * Constructs and returns an <code>IClientContext</code> that represents
 	 * all of the <code>contexts</code>.
 	 *
 	 * @param contexts
 	 *            the contexts
 	 * @return a multi-context that represents all of the <code>contexts</code>,
 	 *         or the single context if there is only one in
 	 *         <code>contexts</code>. If <code>contexts</code> is empty,
 	 *         returns the {@link DefaultClientContext#getInstance()}.
 	 */
 	private IClientContext getClientContext(Collection contexts) {

 		IClientContext result = DefaultClientContext.getInstance();

 		if (contexts.size() > 1) {
 			result = new MultiClientContext(contexts);

 		} else if (!contexts.isEmpty()) {
 			result = (IClientContext) contexts.iterator().next();
 		}

 		return result;
 	}

 	/**
 	 * Finds the {@link IClientContext} that is bound to the
 	 * <code>elementTypeDescriptor</code>. If more than one context is bound
 	 * to the <code>elementTypeDescriptor</code>, the context that is
 	 * returned will be a <code>MultiClientContext</code> representing them
 	 * all.
 	 *
 	 * @param elementTypeDescriptor
 	 *            the element type descriptor
 	 * @return the {@link IClientContext} that is bound to the
 	 *         <code>elementTypeDescriptor</code>. May be a multi-context.
 	 */
 	public IClientContext getBinding(
 			IElementTypeDescriptor elementTypeDescriptor) {
 		Collection result = new ArrayList();

 		for (Iterator i = getClientContexts().iterator(); i.hasNext();) {
 			IClientContext next = (IClientContext) i.next();

 			if (next.includes(elementTypeDescriptor)) {
 				result.add(next);
 			}
 		}
 		return getClientContext(result);
 	}

 	/**
 	 * Finds the {@link IClientContext}s that are bound to the
 	 * <code>elementType</code>. If there are more than one contexts bound,
 	 * returns a <code>MultiClientContext</code> representing them all.
 	 *
 	 * @param elementType
 	 *            the element type
 	 * @return the {@link IClientContext} that is bound to the
 	 *         <code>elementType</code>. May be a multi-context.
 	 */
 	public IClientContext getBinding(IElementType elementType) {
 		Collection result = new ArrayList();

 		for (Iterator i = getClientContexts().iterator(); i.hasNext();) {
 			IClientContext next = (IClientContext) i.next();

 			if (next.includes(elementType)) {
 				result.add(next);
 			}
 		}
 		return getClientContext(result);
 	}

 	/**
 	 * Finds the {@link IClientContext} that is bound to the <code>advice</code>.
 	 * If more than one context is bound to the <code>advice</code>, the
 	 * context that is returned will be a <code>MultiClientContext</code>
 	 * representing them all.
 	 *
 	 * @param elementType
 	 *            the element type
 	 * @return the {@link IClientContext} that is bound to the
 	 *         <code>advice</code>. May be a multi-context.
 	 */
 	public IClientContext getBinding(IEditHelperAdviceDescriptor advice) {
 		Collection result = new ArrayList();

 		for (Iterator i = getClientContexts().iterator(); i.hasNext();) {
 			IClientContext next = (IClientContext) i.next();

 			if (next.includes(advice)) {
 				result.add(next);
 			}
 		}
 		return getClientContext(result);
 	}

 	/**
 	 * <p>
 	 * Configures my providers from the Eclipse configuration
 	 * <code>elements</code> representing implementations of my extension
 	 * point.
 	 * </p>
 	 * <p>
 	 * <b>NOTE</b> that this method should only be called by the EMF Model
 	 * Validation Plug-in, not by any client code!
 	 * </p>
 	 *
 	 * @param elements
 	 *            the configuration elements representing constraint binding
 	 *            extensions
 	 */
 	private synchronized void configureElementTypeBindings(IConfigurationElement[] elements) {
 		// must create all of the contexts before we process the bindings.
 		// Hence, this will loop over the elements twice
 		configureClientContexts(elements);
 		configureBindings(elements);
 	}

 	/**
 	 * Registers the <code>clientContext</code>. Does nothing if the context
 	 * has already been registered.
 	 *
 	 * @param clientContext
 	 *            the client context
 	 */
 	public void registerClientContext(IClientContext clientContext) {

 		// prevent duplicates
 		if (clientContexts.add(clientContext)) {
 			clientContextMap.put(clientContext.getId(), clientContext);

 			fireClientContextAdded(clientContext);
 		}
 	}

 	/**
 	 * Queries whether a {@code clientContext} was dynamically registered (that
 	 * is, not statically registered on the extension point).
 	 *
 	 * @param clientContext
 	 *            a clientContext
 	 * @return whether it was dynamically registered
 	 *
 	 * @since 1.9
 	 */
 	public boolean isDynamic(IClientContext clientContext) {
 		boolean result = true;

 		// If it's some other kind of client-context, then it cannot be one that
 		// we registered from the extension point, because all of those are of
 		// some subtype of ClientContext
 		if (clientContext instanceof ClientContext) {
 			result = ((ClientContext) clientContext).isDynamic();
 		}

 		return result;
 	}

 	/**
 	 * Removes a {@linkplain #isDynamic(IClientContext) dynamically-added} {@code clientContext} from the system.
 	 *
 	 * @param clientContext
 	 *            a client-context to remove
 	 * @return {@code true} if it was successfully removed, {@code false}
 	 *         otherwise, for example if it was not currently registered or a
 	 *         different context instance is registered under the same ID, or
 	 *         it was not {@linkplain #isDynamic(IClientContext) dynamically added}
 	 *
 	 * @since 1.9
 	 *
 	 * @see #isDynamic(IClientContext)
 	 */
 	public boolean deregisterClientContext(IClientContext clientContext) {
 		boolean result = false;

 		IClientContext existing = (IClientContext) clientContextMap.get(clientContext.getId());
 		if (existing != null) {
 			if (existing != clientContext) {
 				// An impostor
 				Log.warning(
 						EMFTypePlugin.getPlugin(),
 						EMFTypePluginStatusCodes.WRONG_CLIENT_CONTEXT,
 						EMFTypeCoreMessages.bind(
 								EMFTypeCoreMessages.wrong_type_WARN_,
 								new Object[] { clientContext.getId(),
 										EMFTypeCoreMessages.invalid_action_remove_context_WARN_,
 										clientContext.toString(), existing.toString() }));
 			} else if (!isDynamic(clientContext)) {
 				Log.warning(
 						EMFTypePlugin.getPlugin(),
 						EMFTypePluginStatusCodes.DEPENDENCY_CONSTRAINT,
 						EMFTypeCoreMessages.bind(EMFTypeCoreMessages.dependency_constraint_WARN_, new Object[] {
 								clientContext.getId(), EMFTypeCoreMessages.invalid_action_remove_context_WARN_,
 								EMFTypeCoreMessages.dependency_reason_static_WARN_ }));
 			} else {
 				clientContextMap.remove(clientContext.getId());
 				clientContexts.remove(clientContext);

 				result = true;
 			}
 		}

 		if (result) {
 			fireClientContextRemoved(clientContext);
 		}

 		return result;
 	}

 	/**
 	 * Helper method to configure the <code>&lt;clientContext&gt;</code>
 	 * occurrences amongst the <code>elements</code>.
 	 *
 	 * @param elements
 	 *            the top-level configuration elements on the
 	 *            <code>elementTypeBindings</code> extension point
 	 */
 	private void configureClientContexts(IConfigurationElement[] elements) {
 		for (int i = 0; i < elements.length; i++) {
 			IConfigurationElement config = elements[i];

 			if (E_CLIENT_CONTEXT.equals(config.getName())) {
 				try {
 					ClientContext context = new XMLClientContext(config);

 					// prevent duplicates
 					if (clientContexts.add(context)) {
 						clientContextMap.put(context.getId(), context);
 					}

 				} catch (CoreException ce) {
 					// this client context will not participate in extensible
 					// type registry
 					String sourcePluginId = config.getDeclaringExtension()
 							.getContributor().getName();
 					Log
 							.error(
 									EMFTypePlugin.getPlugin(),
 									ce.getStatus().getCode(),
 									EMFTypeCoreMessages
 											.bind(
 													EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
 													sourcePluginId, ce
 															.getStatus()
 															.getMessage()),
 									ce);

 				} catch (Exception e) {
 					// this client context will not participate in extensible
 					// type registry
 					String sourcePluginId = config.getDeclaringExtension()
 							.getContributor().getName();

 					Log
 							.error(
 									EMFTypePlugin.getPlugin(),
 									EMFTypePluginStatusCodes.ERROR_PARSING_XML,
 									EMFTypeCoreMessages
 											.bind(
 													EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
 													sourcePluginId, e
 															.getMessage()), e);
 				}
 			}
 		}
 	}

 	/**
 	 * Helper method to configure the <code>&lt;binding&gt;</code> occurrences
 	 * amongst the <code>elements</code>.
 	 *
 	 * @param elements
 	 *            the top-level configuration elements on the
 	 *            <code>elementTypeBindings</code> extension point
 	 */
 	private void configureBindings(IConfigurationElement[] elements) {
 		for (int i = 0; i < elements.length; i++) {
 			IConfigurationElement config = elements[i];

 			if (E_BINDING.equals(config.getName())) {
 				String contextId = config.getAttribute(A_CONTEXT);

 				if (contextId == null) {
 					Log
 							.error(
 									EMFTypePlugin.getPlugin(),
 									EMFTypePluginStatusCodes.BINDING_NO_CONTEXT,
 									EMFTypeCoreMessages
 											.bind(
 													EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
 													config
 															.getDeclaringExtension()
 															.getContributor()
 															.getName(),
 													EMFTypeCoreMessages.binding_noContextId_ERROR_));

 				} else {
 					ClientContext context = (ClientContext) getClientContext(contextId);

 					if (context == null) {
 						Log
 								.error(
 										EMFTypePlugin.getPlugin(),
 										EMFTypePluginStatusCodes.BINDING_NO_SUCH_CONTEXT,
 										EMFTypeCoreMessages
 												.bind(
 														EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
 														config
 																.getDeclaringExtension()
 																.getContributor()
 																.getName(),
 														EMFTypeCoreMessages.binding_noSuchContext_ERROR_));

 					} else {
 						configureBindings(context, config);
 					}
 				}
 			}
 		}
 	}

 	/**
 	 * Helper method to process a particular binding element for its client
 	 * <code>context</code>.
 	 *
 	 * @param context
 	 *            a client context referenced by a binding
 	 * @param config
 	 *            a particular <code>&lt;binding&gt;</config> element
 	 */
 	private void configureBindings(ClientContext context,
 			IConfigurationElement config) {

 		configureBindings(context, config, E_ELEMENT_TYPE);
 		configureBindings(context, config, E_ADVICE);
 	}

 	/**
 	 * Helper method to process a particular binding element for its client
 	 * <code>context</code>.
 	 *
 	 * @param context
 	 *            a client context referenced by a binding
 	 * @param config
 	 *            a particular <code>&lt;binding&gt;</config> element
 	 * @param elementName the name of the elements to process in the <code>&lt;binding&gt;</config> element
 	 */
 	private void configureBindings(ClientContext context,
 			IConfigurationElement config, String elementName) {

 		IConfigurationElement[] children = config.getChildren(elementName);

 		for (int i = 0; i < children.length; i++) {
 			String ref = children[i].getAttribute(A_REF);
 			String patternString = children[i].getAttribute(A_PATTERN);

 			if (ref == null && patternString == null) {
 				// must be one of ref or pattern
 				Log
 						.error(
 								EMFTypePlugin.getPlugin(),
 								EMFTypePluginStatusCodes.BINDING_NO_REF_OR_PATTERN,
 								EMFTypeCoreMessages
 										.bind(
 												EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
 												config.getDeclaringExtension()
 														.getContributor()
 														.getName(),
 												EMFTypeCoreMessages
 														.bind(
 																EMFTypeCoreMessages.binding_no_ref_or_pattern_ERROR_,
 																context.getId())));
 				return;
 			}

 			if (ref != null && patternString != null) {
 				// can't specify both ref and pattern
 				Log
 						.error(
 								EMFTypePlugin.getPlugin(),
 								EMFTypePluginStatusCodes.BINDING_BOTH_REF_AND_PATTERN,
 								EMFTypeCoreMessages
 										.bind(
 												EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
 												config.getDeclaringExtension()
 														.getContributor()
 														.getName(),
 												EMFTypeCoreMessages
 														.bind(
 																EMFTypeCoreMessages.binding_both_ref_and_pattern_ERROR_,
 																context.getId())));
 				return;
 			}

 			if (ref != null) {
 				context.bindId(ref);

 			} else {
 				try {
 					Pattern pattern = Pattern.compile(patternString);
 					context.bindPattern(pattern);

 				} catch (PatternSyntaxException pse) {
 					Log
 							.error(
 									EMFTypePlugin.getPlugin(),
 									EMFTypePluginStatusCodes.PATTERN_INVALID_SYNTAX,
 									EMFTypeCoreMessages
 											.bind(
 													EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
 													config
 															.getDeclaringExtension()
 															.getContributor()
 															.getName(),
 													EMFTypeCoreMessages
 															.bind(
 																	EMFTypeCoreMessages.pattern_invalid_syntax_ERROR_,
 																	patternString)), pse);
 				}
 			}
 		}
 	}

 	/**
 	 * Adds a {@code listener} for additions and removals of client contexts.
 	 * Has no effect if the {@code listener} is already attached.
 	 *
 	 * @param listener
 	 *            the listener to add
 	 *
 	 * @see #removeClientContextManagerListener(IClientContextManagerListener)
 	 *
 	 * @since 1.9
 	 */
 	public void addClientContextManagerListener(IClientContextManagerListener listener) {
 		listeners.addIfAbsent(listener);
 	}

 	/**
 	 * Removes a {@code listener} from me. Has no effect if the {@code listener}
 	 * is not currently attached.
 	 *
 	 * @param listener
 	 *            the listener to remove
 	 *
 	 * @see #addClientContextManagerListener(IClientContextManagerListener)
 	 *
 	 * @since 1.8
 	 */
 	public void removeClientContextManagerListener(IClientContextManagerListener listener) {
 		listeners.remove(listener);
 	}

 	private void fireClientContextAdded(IClientContext context) {
 		if (!listeners.isEmpty()) {
 			ClientContextAddedEvent event = new ClientContextAddedEvent(context);
 			for (IClientContextManagerListener next : listeners) {
 				try {
 					next.clientContextAdded(event);
 				} catch (Exception e) {
 					Log.warning(EMFTypePlugin.getPlugin(), EMFTypePluginStatusCodes.LISTENER_EXCEPTION,
 							EMFTypeCoreMessages.contextManager_listener_exception_WARN_, e);
 				}
 			}
 		}
 	}

 	private void fireClientContextRemoved(IClientContext context) {
 		if (!listeners.isEmpty()) {
 			ClientContextRemovedEvent event = new ClientContextRemovedEvent(context);
 			for (IClientContextManagerListener next : listeners) {
 				try {
 					next.clientContextRemoved(event);
 				} catch (Exception e) {
 					Log.warning(EMFTypePlugin.getPlugin(), EMFTypePluginStatusCodes.LISTENER_EXCEPTION,
 							EMFTypeCoreMessages.contextManager_listener_exception_WARN_, e);
 				}
 			}
 		}
 	}
 }
	/******************************************************************************
	* Copyright (c) 2006, 2015 IBM Corporation, Christian W. Damus, 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
	* Christian W. Damus - bug 457888
	****************************************************************************/

	package org.eclipse.gmf.runtime.emf.type.core;

	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.Iterator;
	import java.util.Map;
	import java.util.Set;
	import java.util.concurrent.CopyOnWriteArrayList;
	import java.util.regex.Pattern;
	import java.util.regex.PatternSyntaxException;

	import org.eclipse.core.runtime.CoreException;
	import org.eclipse.core.runtime.IConfigurationElement;
	import org.eclipse.core.runtime.IExtension;
	import org.eclipse.core.runtime.IExtensionPoint;
	import org.eclipse.core.runtime.Platform;
	import org.eclipse.core.runtime.dynamichelpers.ExtensionTracker;
	import org.eclipse.core.runtime.dynamichelpers.IExtensionChangeHandler;
	import org.eclipse.core.runtime.dynamichelpers.IExtensionTracker;
	import org.eclipse.emf.ecore.EObject;
	import org.eclipse.gmf.runtime.common.core.util.Log;
	import org.eclipse.gmf.runtime.common.core.util.Trace;
	import org.eclipse.gmf.runtime.emf.type.core.internal.EMFTypeDebugOptions;
	import org.eclipse.gmf.runtime.emf.type.core.internal.EMFTypePlugin;
	import org.eclipse.gmf.runtime.emf.type.core.internal.EMFTypePluginStatusCodes;
	import org.eclipse.gmf.runtime.emf.type.core.internal.descriptors.IEditHelperAdviceDescriptor;
	import org.eclipse.gmf.runtime.emf.type.core.internal.impl.DefaultClientContext;
	import org.eclipse.gmf.runtime.emf.type.core.internal.impl.XMLClientContext;
	import org.eclipse.gmf.runtime.emf.type.core.internal.l10n.EMFTypeCoreMessages;

	/**
	* The context manager loads contexts from the <code>elementTypeBindings</code>
	* extension point and makes them available to the element type registry.
	* <P>
	* There is also a default client context, {@link #getDefaultClientContext()},
	* that is implicitly bound to all types and advice that otherwise have no
	* explicit binding.
	*
	* @author ldamus
	*/
	public final class ClientContextManager {

	/**
	* Extension point name for the element type bindings extension point.
	*/
	public static final String ELEMENT_TYPE_BINDINGS_EXT_P_NAME = "elementTypeBindings"; //$NON-NLS-1$

	private static final String E_CLIENT_CONTEXT = "clientContext"; //$NON-NLS-1$

	private static final String E_BINDING = "binding"; //$NON-NLS-1$

	private static final String A_CONTEXT = "context"; //$NON-NLS-1$

	private static final String E_ELEMENT_TYPE = "elementType"; //$NON-NLS-1$

	private static final String E_ADVICE = "advice"; //$NON-NLS-1$

	private static final String A_REF = "ref"; //$NON-NLS-1$

	private static final String A_PATTERN = "pattern"; //$NON-NLS-1$

	private static final ClientContextManager INSTANCE = new ClientContextManager();

	private final Set clientContexts = new java.util.HashSet();

	private final Map clientContextMap = new java.util.HashMap();

	private final CopyOnWriteArrayList<IClientContextManagerListener> listeners = new CopyOnWriteArrayList<IClientContextManagerListener>();

	private ExtensionTracker extensionTracker;

	private IExtensionChangeHandler extensionListener;

	/**
	* Not instantiable by clients.
	*/
	private ClientContextManager() {
	super();

	IConfigurationElement[] configs = Platform.getExtensionRegistry()
	.getConfigurationElementsFor(EMFTypePlugin.getPluginId(),
	ELEMENT_TYPE_BINDINGS_EXT_P_NAME);

	if (EMFTypePlugin.isDynamicAware()) {
	startExtensionTracking();
	}

	configureElementTypeBindings(configs);
	}

	private void startExtensionTracking() {
	extensionListener = new IExtensionChangeHandler() {

	public void addExtension(IExtensionTracker tracker,
	IExtension extension) {
	configureElementTypeBindings(extension.getConfigurationElements());
	}

	public void removeExtension(IExtension extension, Object[] objects) {
	// Extension removal not supported
	}
	};

	IExtensionPoint point = Platform.getExtensionRegistry()
	.getExtensionPoint(EMFTypePlugin.getPluginId(),
	ELEMENT_TYPE_BINDINGS_EXT_P_NAME);

	extensionTracker = new ExtensionTracker();
	extensionTracker.registerHandler(extensionListener, ExtensionTracker
	.createExtensionPointFilter(point));
	}

	/**
	* Obtains the singleton instance of this class.
	*
	* @return the singleton context manager
	*/
	public static final ClientContextManager getInstance() {
	return INSTANCE;
	}

	/**
	* Gets the default client context.
	*
	* @return the default context
	*/
	public static final IClientContext getDefaultClientContext() {
	return getInstance().getClientContext(DefaultClientContext.ID);
	}

	/**
	* Obtains a client context by its unique identifier.
	*
	* @param contextId
	* the client context ID to look for
	* @return the matching context, or <code>null</code> if none is
	* registered under this ID
	*/
	public IClientContext getClientContext(String contextId) {

	if (DefaultClientContext.ID.equals(contextId)) {
	return DefaultClientContext.getInstance();
	}

	return (IClientContext) clientContextMap.get(contextId);
	}

	/**
	* Obtains all of the client contexts registered in the system.
	*
	* @return the available {@link IClientContext}s
	*/
	public Set getClientContexts() {
	return clientContexts;
	}

	/**
	* Obtains the client contexts to which the specified object belongs.
	*
	* @param eObject
	* a model element
	* @return the client context to which the <code>eObject</code> belongs.
	* This may be <code>null</code> if no context matches this
	* element. It will be a <code>MultiClientContest</code> if more
	* than one context matches the element.
	*/
	public IClientContext getClientContextFor(EObject eObject) {

	Collection contexts = new java.util.ArrayList();

	for (Iterator iter = getClientContexts().iterator(); iter.hasNext();) {
	IClientContext next = (IClientContext) iter.next();
	IElementMatcher matcher = next.getMatcher();

	try {
	if (matcher.matches(eObject)) {
	contexts.add(next);
	}
	} catch (RuntimeException e) {
	// client context matchers must not throw exceptions. This one
	// will not be trusted in future validation operations. This
	// is effected by removing it from the context manager
	iter.remove();
	clientContextMap.remove(next.getId());
	// context

	Trace.catching(EMFTypePlugin.getPlugin(),
	EMFTypeDebugOptions.EXCEPTIONS_CATCHING, getClass(),
	"getClientContextsFor", e); //$NON-NLS-1$

	Log
	.error(
	EMFTypePlugin.getPlugin(),
	EMFTypePluginStatusCodes.CLIENT_MATCHER_FAILURE,
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.client_matcherFailure_ERROR_,
	next.getId()), e);
	}
	}

	return getClientContext(contexts);
	}

	/**
	* Constructs and returns an <code>IClientContext</code> that represents
	* all of the <code>contexts</code>.
	*
	* @param contexts
	* the contexts
	* @return a multi-context that represents all of the <code>contexts</code>,
	* or the single context if there is only one in
	* <code>contexts</code>. If <code>contexts</code> is empty,
	* returns the {@link DefaultClientContext#getInstance()}.
	*/
	private IClientContext getClientContext(Collection contexts) {

	IClientContext result = DefaultClientContext.getInstance();

	if (contexts.size() > 1) {
	result = new MultiClientContext(contexts);

	} else if (!contexts.isEmpty()) {
	result = (IClientContext) contexts.iterator().next();
	}

	return result;
	}

	/**
	* Finds the {@link IClientContext} that is bound to the
	* <code>elementTypeDescriptor</code>. If more than one context is bound
	* to the <code>elementTypeDescriptor</code>, the context that is
	* returned will be a <code>MultiClientContext</code> representing them
	* all.
	*
	* @param elementTypeDescriptor
	* the element type descriptor
	* @return the {@link IClientContext} that is bound to the
	* <code>elementTypeDescriptor</code>. May be a multi-context.
	*/
	public IClientContext getBinding(
	IElementTypeDescriptor elementTypeDescriptor) {
	Collection result = new ArrayList();

	for (Iterator i = getClientContexts().iterator(); i.hasNext();) {
	IClientContext next = (IClientContext) i.next();

	if (next.includes(elementTypeDescriptor)) {
	result.add(next);
	}
	}
	return getClientContext(result);
	}

	/**
	* Finds the {@link IClientContext}s that are bound to the
	* <code>elementType</code>. If there are more than one contexts bound,
	* returns a <code>MultiClientContext</code> representing them all.
	*
	* @param elementType
	* the element type
	* @return the {@link IClientContext} that is bound to the
	* <code>elementType</code>. May be a multi-context.
	*/
	public IClientContext getBinding(IElementType elementType) {
	Collection result = new ArrayList();

	for (Iterator i = getClientContexts().iterator(); i.hasNext();) {
	IClientContext next = (IClientContext) i.next();

	if (next.includes(elementType)) {
	result.add(next);
	}
	}
	return getClientContext(result);
	}

	/**
	* Finds the {@link IClientContext} that is bound to the <code>advice</code>.
	* If more than one context is bound to the <code>advice</code>, the
	* context that is returned will be a <code>MultiClientContext</code>
	* representing them all.
	*
	* @param elementType
	* the element type
	* @return the {@link IClientContext} that is bound to the
	* <code>advice</code>. May be a multi-context.
	*/
	public IClientContext getBinding(IEditHelperAdviceDescriptor advice) {
	Collection result = new ArrayList();

	for (Iterator i = getClientContexts().iterator(); i.hasNext();) {
	IClientContext next = (IClientContext) i.next();

	if (next.includes(advice)) {
	result.add(next);
	}
	}
	return getClientContext(result);
	}

	/**
	* <p>
	* Configures my providers from the Eclipse configuration
	* <code>elements</code> representing implementations of my extension
	* point.
	* </p>
	* <p>
	* <b>NOTE</b> that this method should only be called by the EMF Model
	* Validation Plug-in, not by any client code!
	* </p>
	*
	* @param elements
	* the configuration elements representing constraint binding
	* extensions
	*/
	private synchronized void configureElementTypeBindings(IConfigurationElement[] elements) {
	// must create all of the contexts before we process the bindings.
	// Hence, this will loop over the elements twice
	configureClientContexts(elements);
	configureBindings(elements);
	}

	/**
	* Registers the <code>clientContext</code>. Does nothing if the context
	* has already been registered.
	*
	* @param clientContext
	* the client context
	*/
	public void registerClientContext(IClientContext clientContext) {

	// prevent duplicates
	if (clientContexts.add(clientContext)) {
	clientContextMap.put(clientContext.getId(), clientContext);

	fireClientContextAdded(clientContext);
	}
	}

	/**
	* Queries whether a {@code clientContext} was dynamically registered (that
	* is, not statically registered on the extension point).
	*
	* @param clientContext
	* a clientContext
	* @return whether it was dynamically registered
	*
	* @since 1.9
	*/
	public boolean isDynamic(IClientContext clientContext) {
	boolean result = true;

	// If it's some other kind of client-context, then it cannot be one that
	// we registered from the extension point, because all of those are of
	// some subtype of ClientContext
	if (clientContext instanceof ClientContext) {
	result = ((ClientContext) clientContext).isDynamic();
	}

	return result;
	}

	/**
	* Removes a {@linkplain #isDynamic(IClientContext) dynamically-added} {@code clientContext} from the system.
	*
	* @param clientContext
	* a client-context to remove
	* @return {@code true} if it was successfully removed, {@code false}
	* otherwise, for example if it was not currently registered or a
	* different context instance is registered under the same ID, or
	* it was not {@linkplain #isDynamic(IClientContext) dynamically added}
	*
	* @since 1.9
	*
	* @see #isDynamic(IClientContext)
	*/
	public boolean deregisterClientContext(IClientContext clientContext) {
	boolean result = false;

	IClientContext existing = (IClientContext) clientContextMap.get(clientContext.getId());
	if (existing != null) {
	if (existing != clientContext) {
	// An impostor
	Log.warning(
	EMFTypePlugin.getPlugin(),
	EMFTypePluginStatusCodes.WRONG_CLIENT_CONTEXT,
	EMFTypeCoreMessages.bind(
	EMFTypeCoreMessages.wrong_type_WARN_,
	new Object[] { clientContext.getId(),
	EMFTypeCoreMessages.invalid_action_remove_context_WARN_,
	clientContext.toString(), existing.toString() }));
	} else if (!isDynamic(clientContext)) {
	Log.warning(
	EMFTypePlugin.getPlugin(),
	EMFTypePluginStatusCodes.DEPENDENCY_CONSTRAINT,
	EMFTypeCoreMessages.bind(EMFTypeCoreMessages.dependency_constraint_WARN_, new Object[] {
	clientContext.getId(), EMFTypeCoreMessages.invalid_action_remove_context_WARN_,
	EMFTypeCoreMessages.dependency_reason_static_WARN_ }));
	} else {
	clientContextMap.remove(clientContext.getId());
	clientContexts.remove(clientContext);

	result = true;
	}
	}

	if (result) {
	fireClientContextRemoved(clientContext);
	}

	return result;
	}

	/**
	* Helper method to configure the <code><clientContext></code>
	* occurrences amongst the <code>elements</code>.
	*
	* @param elements
	* the top-level configuration elements on the
	* <code>elementTypeBindings</code> extension point
	*/
	private void configureClientContexts(IConfigurationElement[] elements) {
	for (int i = 0; i < elements.length; i++) {
	IConfigurationElement config = elements[i];

	if (E_CLIENT_CONTEXT.equals(config.getName())) {
	try {
	ClientContext context = new XMLClientContext(config);

	// prevent duplicates
	if (clientContexts.add(context)) {
	clientContextMap.put(context.getId(), context);
	}

	} catch (CoreException ce) {
	// this client context will not participate in extensible
	// type registry
	String sourcePluginId = config.getDeclaringExtension()
	.getContributor().getName();
	Log
	.error(
	EMFTypePlugin.getPlugin(),
	ce.getStatus().getCode(),
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
	sourcePluginId, ce
	.getStatus()
	.getMessage()),
	ce);

	} catch (Exception e) {
	// this client context will not participate in extensible
	// type registry
	String sourcePluginId = config.getDeclaringExtension()
	.getContributor().getName();

	Log
	.error(
	EMFTypePlugin.getPlugin(),
	EMFTypePluginStatusCodes.ERROR_PARSING_XML,
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
	sourcePluginId, e
	.getMessage()), e);
	}
	}
	}
	}

	/**
	* Helper method to configure the <code><binding></code> occurrences
	* amongst the <code>elements</code>.
	*
	* @param elements
	* the top-level configuration elements on the
	* <code>elementTypeBindings</code> extension point
	*/
	private void configureBindings(IConfigurationElement[] elements) {
	for (int i = 0; i < elements.length; i++) {
	IConfigurationElement config = elements[i];

	if (E_BINDING.equals(config.getName())) {
	String contextId = config.getAttribute(A_CONTEXT);

	if (contextId == null) {
	Log
	.error(
	EMFTypePlugin.getPlugin(),
	EMFTypePluginStatusCodes.BINDING_NO_CONTEXT,
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
	config
	.getDeclaringExtension()
	.getContributor()
	.getName(),
	EMFTypeCoreMessages.binding_noContextId_ERROR_));

	} else {
	ClientContext context = (ClientContext) getClientContext(contextId);

	if (context == null) {
	Log
	.error(
	EMFTypePlugin.getPlugin(),
	EMFTypePluginStatusCodes.BINDING_NO_SUCH_CONTEXT,
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
	config
	.getDeclaringExtension()
	.getContributor()
	.getName(),
	EMFTypeCoreMessages.binding_noSuchContext_ERROR_));

	} else {
	configureBindings(context, config);
	}
	}
	}
	}
	}

	/**
	* Helper method to process a particular binding element for its client
	* <code>context</code>.
	*
	* @param context
	* a client context referenced by a binding
	* @param config
	* a particular <code><binding></config> element
	*/
	private void configureBindings(ClientContext context,
	IConfigurationElement config) {

	configureBindings(context, config, E_ELEMENT_TYPE);
	configureBindings(context, config, E_ADVICE);
	}

	/**
	* Helper method to process a particular binding element for its client
	* <code>context</code>.
	*
	* @param context
	* a client context referenced by a binding
	* @param config
	* a particular <code><binding></config> element
	* @param elementName the name of the elements to process in the <code><binding></config> element
	*/
	private void configureBindings(ClientContext context,
	IConfigurationElement config, String elementName) {

	IConfigurationElement[] children = config.getChildren(elementName);

	for (int i = 0; i < children.length; i++) {
	String ref = children[i].getAttribute(A_REF);
	String patternString = children[i].getAttribute(A_PATTERN);

	if (ref == null && patternString == null) {
	// must be one of ref or pattern
	Log
	.error(
	EMFTypePlugin.getPlugin(),
	EMFTypePluginStatusCodes.BINDING_NO_REF_OR_PATTERN,
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
	config.getDeclaringExtension()
	.getContributor()
	.getName(),
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.binding_no_ref_or_pattern_ERROR_,
	context.getId())));
	return;
	}

	if (ref != null && patternString != null) {
	// can't specify both ref and pattern
	Log
	.error(
	EMFTypePlugin.getPlugin(),
	EMFTypePluginStatusCodes.BINDING_BOTH_REF_AND_PATTERN,
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
	config.getDeclaringExtension()
	.getContributor()
	.getName(),
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.binding_both_ref_and_pattern_ERROR_,
	context.getId())));
	return;
	}

	if (ref != null) {
	context.bindId(ref);

	} else {
	try {
	Pattern pattern = Pattern.compile(patternString);
	context.bindPattern(pattern);

	} catch (PatternSyntaxException pse) {
	Log
	.error(
	EMFTypePlugin.getPlugin(),
	EMFTypePluginStatusCodes.PATTERN_INVALID_SYNTAX,
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.xml_parsing_elementTypeBindings_ERROR_,
	config
	.getDeclaringExtension()
	.getContributor()
	.getName(),
	EMFTypeCoreMessages
	.bind(
	EMFTypeCoreMessages.pattern_invalid_syntax_ERROR_,
	patternString)), pse);
	}
	}
	}
	}

	/**
	* Adds a {@code listener} for additions and removals of client contexts.
	* Has no effect if the {@code listener} is already attached.
	*
	* @param listener
	* the listener to add
	*
	* @see #removeClientContextManagerListener(IClientContextManagerListener)
	*
	* @since 1.9
	*/
	public void addClientContextManagerListener(IClientContextManagerListener listener) {
	listeners.addIfAbsent(listener);
	}

	/**
	* Removes a {@code listener} from me. Has no effect if the {@code listener}
	* is not currently attached.
	*
	* @param listener
	* the listener to remove
	*
	* @see #addClientContextManagerListener(IClientContextManagerListener)
	*
	* @since 1.8
	*/
	public void removeClientContextManagerListener(IClientContextManagerListener listener) {
	listeners.remove(listener);
	}

	private void fireClientContextAdded(IClientContext context) {
	if (!listeners.isEmpty()) {
	ClientContextAddedEvent event = new ClientContextAddedEvent(context);
	for (IClientContextManagerListener next : listeners) {
	try {
	next.clientContextAdded(event);
	} catch (Exception e) {
	Log.warning(EMFTypePlugin.getPlugin(), EMFTypePluginStatusCodes.LISTENER_EXCEPTION,
	EMFTypeCoreMessages.contextManager_listener_exception_WARN_, e);
	}
	}
	}
	}

	private void fireClientContextRemoved(IClientContext context) {
	if (!listeners.isEmpty()) {
	ClientContextRemovedEvent event = new ClientContextRemovedEvent(context);
	for (IClientContextManagerListener next : listeners) {
	try {
	next.clientContextRemoved(event);
	} catch (Exception e) {
	Log.warning(EMFTypePlugin.getPlugin(), EMFTypePluginStatusCodes.LISTENER_EXCEPTION,
	EMFTypeCoreMessages.contextManager_listener_exception_WARN_, e);
	}
	}
	}
	}
	}