org.eclipse.core.runtime.preferences.PreferenceModifyListener Maven / Gradle / Ivy

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AspectJ tools most notably contains the AspectJ compiler (AJC). AJC applies aspects to Java classes during compilation, fully replacing Javac for plain Java classes and also compiling native AspectJ or annotation-based @AspectJ syntax. Furthermore, AJC can weave aspects into existing class files in a post-compile binary weaving step. This library is a superset of AspectJ weaver and hence also of AspectJ runtime.

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/*******************************************************************************
 * Copyright (c) 2005, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.core.runtime.preferences;

/**
 * This class provides a hook into the preference service before particular operations
 * on the global preference tree. Preference modify listeners are registered with
 * the preference service via XML and the org.eclipse.equinox.preferences.preferences
 * or the org.eclipse.core.runtime.preferences extension point.
 * 
 * Clients may subclass this type.
 * 
 *
 * @since 3.1
 */
public abstract class PreferenceModifyListener {

	/**
	 * Clients are given the opportunity to modify the given tree before it is applied
	 * to the global preference tree. Clients should return the tree which should be
	 * applied globally. The tree passed in will not be null and clients
	 * must not return a null tree.
	 * 
	 * This method is called by the preference service from within calls to
	 * {@link IPreferencesService#applyPreferences(IExportedPreferences)} or
	 * {@link IPreferencesService#applyPreferences(IEclipsePreferences, IPreferenceFilter[])}.
	 * 
	 * 
	 * A typical action for clients to perform would be to intercept the incoming preference tree,
	 * migrate old preference values to new ones, and then return the new tree.
	 * 
	 *
	 * @param node the tree to modify
	 * @return the tree to apply to the global preferences
	 */
	public IEclipsePreferences preApply(IEclipsePreferences node) {
		// default implementation makes no modifications
		return node;
	}

}