ITreeContentProvider


1   /*******************************************************************************
2    * Copyright (c) 2000, 2006 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.jface.viewers;
12  
13  /**
14   * An interface to content providers for tree-structure-oriented
15   * viewers.
16   *
17   * @see AbstractTreeViewer
18   */
19  public interface ITreeContentProvider extends IStructuredContentProvider {
20      /**
21       * Returns the child elements of the given parent element.
22       * <p>
23       * The difference between this method and <code>IStructuredContentProvider.getElements</code> 
24       * is that <code>getElements</code> is called to obtain the 
25       * tree viewer's root elements, whereas <code>getChildren</code> is used
26       * to obtain the children of a given parent element in the tree (including a root).
27       * </p>
28       * The result is not modified by the viewer.
29       *
30       * @param parentElement the parent element
31       * @return an array of child elements
32       */
33      public Object  [] getChildren(Object   parentElement);
34  
35      /**
36       * Returns the parent for the given element, or <code>null</code> 
37       * indicating that the parent can't be computed. 
38       * In this case the tree-structured viewer can't expand
39       * a given node correctly if requested.
40       *
41       * @param element the element
42       * @return the parent element, or <code>null</code> if it
43       *   has none or if the parent cannot be computed
44       */
45      public Object   getParent(Object   element);
46  
47      /**
48       * Returns whether the given element has children.
49       * <p>
50       * Intended as an optimization for when the viewer does not
51       * need the actual children.  Clients may be able to implement
52       * this more efficiently than <code>getChildren</code>.
53       * </p>
54       *
55       * @param element the element
56       * @return <code>true</code> if the given element has children,
57       *  and <code>false</code> if it has no children
58       */
59      public boolean hasChildren(Object   element);
60  }
61
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