/*******************************************************************************
 * Copyright (c) 2000, 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.ui;

/**
 * An adapter which performs action filtering.
 * <p>
 * Within the workbench a plugin may extend the actions which appear in the
 * context menu for any object. The visibility of each action extension is
 * controlled by action filtering. By default, the workbench will filter each
 * action extension using the <code>objectClass</code> and optional
 * <code>nameFilter</code> attributes defined in xml. If the action extension
 * passes this test the action will be added to the context menu for the object.
 * </p>
 * <p>
 * In some situations the object class and name are not enough to describe the
 * intended target action. In those situations an action extension may define
 * one or more <code>filter</code> sub-elements. Each one of these elements
 * describes one attribute of the action target using a <code>name value</code>
 * pair. The attributes for an object are type specific and beyond the domain of
 * the workbench itself, so the workbench will delegate filtering at this level
 * to an <code>IActionFilter</code>. This is a filtering strategy which is
 * provided by the selection itself and may perform type specific filtering.
 * </p>
 * <p>
 * The workbench will retrieve the filter from the selected object by testing to
 * see if it implements <code>IActionFilter</code>. If that fails, the workbench
 * will ask for a filter through through the <code>IAdaptable</code> mechanism.
 * If a filter is found the workbench will pass each name value pair to the
 * filter to determine if it matches the state of the selected object. If so, or
 * there is no filter, the action will be added to the context menu for the
 * object.
 * </p>
 * <p>
 * Clients that implement this filter mechanism are strongly encouraged to
 * extend this interface to provide a list of attribute names and possible
 * values that are considered public for other clients to reference.
 * </p>
 *
 * @see org.eclipse.core.runtime.IAdaptable
 */
public interface IActionFilter {
	/**
	 * Returns whether the specific attribute matches the state of the target
	 * object.
	 *
	 * @param target the target object
	 * @param name   the attribute name
	 * @param value  the attribute value
	 * @return <code>true</code> if the attribute matches; <code>false</code>
	 *         otherwise
	 */
	boolean testAttribute(Object target, String name, String value);
}
