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/*******************************************************************************
* Copyright (c) 2012, 2016 Obeo 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:
* Obeo - initial API and implementation
* Martin Fleck - bug 483798
*******************************************************************************/
package org.eclipse.emf.compare.rcp.extension;
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.ILog;
import org.eclipse.core.runtime.IRegistryEventListener;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.emf.compare.rcp.internal.EMFCompareRCPMessages;
/**
* Abstract utility class to listen to the {@link IExtensionRegistry}. It provides base implementation to
* {@link #added(IExtension[])} and {@link #removed(IExtension[])}. Users must implement
* {@link #readElement(IConfigurationElement, Action)} according to their extension schema.
* <p>
* The helper method {@link #readRegistry()} is browsing already registered extension to the extension
* registry making it easy to read the registry after having added the listener to it.
* <p>
* {@link #readRegistry()} is delegating to {@link #readElement(IConfigurationElement, Action)}.
*
* @author <a href="mailto:mikael.barbero@obeo.fr">Mikael Barbero</a>
*/
public abstract class AbstractRegistryEventListener implements IRegistryEventListener {
/**
* Enumeration that says if the {@link IConfigurationElement} is to be added or removed from the
* {@link IExtensionRegistry}.
*
* @author <a href="mailto:mikael.barbero@obeo.fr">Mikael Barbero</a>
*/
protected enum Action {
/**
* The {@link IConfigurationElement} is to be added.
*/
ADD,
/**
* The {@link IConfigurationElement} is to be removed.
*/
REMOVE
}
/**
* The namespace of the extension point to be monitored.
*/
private final String namespace;
/**
* The extension point ID to be monitored.
*/
private final String extensionPointID;
/** The log in which to report failures from this listener. */
private final ILog log;
/**
* Creates a new registry event listener.
*
* @param namespace
* The namespace of the extension point to be monitored.
* @param extensionPointID
* The extension point ID to be monitored
* @param log
* The log object to be used to log error and/or warning.
*/
public AbstractRegistryEventListener(String namespace, String extensionPointID, ILog log) {
this.namespace = namespace;
this.extensionPointID = extensionPointID;
this.log = log;
}
/**
* Reads the given registry and call {@link #readElement(IConfigurationElement, Action)} as the read
* {@link IConfigurationElement} were just added to it.
*
* @param extensionRegistry
* the registry to read.
*/
public void readRegistry(IExtensionRegistry extensionRegistry) {
IExtensionPoint point = extensionRegistry.getExtensionPoint(namespace, extensionPointID);
if (point != null) {
IConfigurationElement[] elements = point.getConfigurationElements();
for (int i = 0; i < elements.length; i++) {
internalReadElement(elements[i], Action.ADD);
}
}
}
/**
* Reads the given {@code element}. This method can be call when the element is added or remove. The
* {@code action} reflect it. It returns true if the element is recognized as valid regarding the
* monitored extension point. It will be call on sub elements recursively for all recognized ones.
*
* @param element
* the element to be read.
* @param action
* is the element added or removed.
* @return true if the element is recognized as valid regarding the monitored extension point.
*/
protected boolean readElement(IConfigurationElement element, Action action) {
final boolean ret;
if (validateExtensionElement(element)) {
switch (action) {
case ADD:
ret = addedValid(element);
break;
case REMOVE:
ret = removedValid(element);
break;
default:
ret = false;
break;
}
} else {
ret = false;
}
return ret;
}
/**
* Validates if the given element is an element for the given extension and is well constructed. Returns
* true if the element should be further parsed for addition or removal.
*
* @param element
* the element to validate.
* @return true if the element should be further parsed for addition or removal, else otherwise.
*/
protected abstract boolean validateExtensionElement(IConfigurationElement element);
/**
* Process the given element as the addition of a valid element extension.
*
* @param element
* the element to be added.
* @return true if the given element has been added and if its children should be processed, false
* otherwise.
*/
protected abstract boolean addedValid(IConfigurationElement element);
/**
* Process the given element as the removal of a valid element extension.
*
* @param element
* the element to be removed.
* @return true if the given element has been removed and if its children should be processed, false
* otherwise.
*/
protected abstract boolean removedValid(IConfigurationElement element);
/**
* Reads the given element and, if recognized, browse recursively the children and try to read it.
*
* @param element
* the element to be read.
* @param action
* is the element added or removed.
*/
private void internalReadElement(IConfigurationElement element, Action action) {
boolean recognized = readElement(element, action);
if (recognized) {
IConfigurationElement[] children = element.getChildren();
for (int i = 0; i < children.length; ++i) {
internalReadElement(children[i], action);
}
}
}
/**
* Delegates the logging of a missing attribute to {@link #log(IConfigurationElement, String)} with a
* proper message.
*
* @param element
* the element to which an attribute is missing.
* @param attributeName
* the name of the missing attribute.
*/
protected void logMissingAttribute(IConfigurationElement element, String attributeName) {
log(IStatus.ERROR, element, EMFCompareRCPMessages.getString("missing.extension.attribute", //$NON-NLS-1$
attributeName));
}
/**
* Log the error to the current plugin logger.
*
* @param severity
* Severity of this message. One of <code>IStatus.OK</code>, <code>IStatus.ERROR</code>,
* <code>IStatus.INFO</code>, <code>IStatus.WARNING</code>, or <code>IStatus.CANCEL</code>
* @param element
* the element from which comes to the error.
* @param message
* the message to be logged.
*/
protected void log(int severity, IConfigurationElement element, String message) {
log.log(new Status(severity, element.getDeclaringExtension().getContributor().getName(), message));
}
/**
* Log the error to the current plugin logger.
*
* @param element
* the element from which comes to the error.
* @param t
* the exception to be logged.
*/
protected void log(IConfigurationElement element, Throwable t) {
log.log(new Status(IStatus.ERROR, element.getDeclaringExtension().getContributor().getName(),
t.getMessage(), t));
}
/**
* Logs the given error with a human-readable error message.
*
* @param element
* The element from which originates the error.
* @param errorMessage
* Human-readable cause of this exception.
* @param cause
* Actual exception that is to be logged.
* @since 2.2
*/
protected void log(IConfigurationElement element, String errorMessage, Throwable cause) {
log.log(new Status(IStatus.ERROR, element.getDeclaringExtension().getContributor().getName(),
errorMessage, cause));
}
/**
* {@inheritDoc}
*
* @see org.eclipse.core.runtime.IRegistryEventListener#added(org.eclipse.core.runtime.IExtension[])
*/
public void added(IExtension[] extensions) {
for (IExtension extension : extensions) {
if (extension.getExtensionPointUniqueIdentifier().equals(extensionPointID)) {
IConfigurationElement[] configurationElement = extension.getConfigurationElements();
for (int j = 0; j < configurationElement.length; ++j) {
internalReadElement(configurationElement[j], Action.ADD);
}
}
}
}
/**
* {@inheritDoc}
*
* @see org.eclipse.core.runtime.IRegistryEventListener#removed(org.eclipse.core.runtime.IExtension[])
*/
public void removed(IExtension[] extensions) {
for (IExtension extension : extensions) {
if (extension.getExtensionPointUniqueIdentifier().equals(extensionPointID)) {
IConfigurationElement[] configurationElement = extension.getConfigurationElements();
for (int j = 0; j < configurationElement.length; ++j) {
internalReadElement(configurationElement[j], Action.REMOVE);
}
}
}
}
/**
* {@inheritDoc}
*
* @see org.eclipse.core.runtime.IRegistryEventListener#added(org.eclipse.core.runtime.IExtensionPoint[])
*/
public void added(IExtensionPoint[] extensionPoints) {
// no need to listen to this.
}
/**
* {@inheritDoc}
*
* @see org.eclipse.core.runtime.IRegistryEventListener#removed(org.eclipse.core.runtime.IExtensionPoint[])
*/
public void removed(IExtensionPoint[] extensionPoints) {
// no need to listen to this.
}
}
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