content: /*******************************************************************************
   * Copyright (c) 2000, 2007 IBM Corporation and others.
   * This program and the accompanying materials are made available under the
   * terms of the Eclipse Public License v. 2.0 which is available at
   * http://www.eclipse.org/legal/epl-2.0.
   * 
   * SPDX-License-Identifier: EPL-2.0
   *
   
   *******************************************************************************/
  package org.eclipse.dltk.core;
  
  /**
   * A Java model region describes a hierarchical set of elements.
   * Regions are often used to describe a set of elements to be considered
   * when performing operations; for example, the set of elements to be
   * considered during a search. A region may include elements from different
   * projects.
   * <p>
   * When an element is included in a region, all of its children
   * are considered to be included. Children of an included element 
   * <b>cannot</b> be selectively excluded.
   * </p>
   * <p>
   * This interface is not intended to be implemented by clients.
   * Instances can be created via the <code>JavaCore.newRegion</code>.
   * </p>
   *
   * @see JavaCore#newRegion()
   */
  public interface IRegion {
  	/**
  	 * Adds the given element and all of its descendents to this region.
  	 * If the specified element is already included, or one of its
  	 * ancestors is already included, this has no effect. If the element
  	 * being added is an ancestor of an element already contained in this
  	 * region, the ancestor subsumes the descendent.
  	 * 
  	 * @param element the given element
  	 */
  	void add(IModelElement element);
  	/**
  	 * Returns whether the given element is contained in this region.
  	 * 
  	 * @param element the given element
  	 * @return true if the given element is contained in this region, false otherwise
  	 */
  	boolean contains(IModelElement element);
  	/**
  	 * Returns the top level elements in this region.
  	 * All descendents of these elements are also included in this region.
  	 * 
  	 * @return the top level elements in this region
  	 */
  	IModelElement[] getElements();
  	/**
  	 * Removes the specified element from the region and returns
  	 * <code>true</code> if successful, <code>false</code> if the remove
  	 * fails. If an ancestor of the given element is included, the
  	 * remove fails (in other words, it is not possible to selectively
  	 * exclude descendants of included ancestors).
  	 * 
  	 * @param element the given element
  	 * @return <code>true</code> if successful, <code>false</code> if the remove fails
  	 */
  	boolean remove(IModelElement element);
  }
  