| /******************************************************************************* |
| * Copyright (c) 2007, 2012 Oracle. 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: |
| * Oracle - initial API and implementation |
| ******************************************************************************/ |
| package org.eclipse.jpt.common.ui.jface; |
| |
| import java.io.Serializable; |
| import org.eclipse.jpt.common.utility.internal.StringTools; |
| |
| /** |
| * Implementations of this interface can be used to maintain the content of a |
| * specific tree element. The implementation will monitor the element for any |
| * changes that affect the element's children and forward them |
| * appropriately to the {@link Manager}. |
| * <p> |
| * Provisional API: This interface is part of an interim API that is still |
| * under development and expected to change significantly before reaching |
| * stability. It is available at this early stage to solicit feedback from |
| * pioneering adopters on the understanding that any code that uses this API |
| * will almost certainly be broken (repeatedly) as the API evolves. |
| * |
| * @see org.eclipse.jface.viewers.IContentProvider |
| * @see org.eclipse.jface.viewers.IStructuredContentProvider |
| * @see org.eclipse.jface.viewers.ITreeContentProvider |
| */ |
| public interface ItemTreeContentProvider |
| extends ItemStructuredContentProvider |
| { |
| /** |
| * Return the item's parent. |
| * |
| * @see org.eclipse.jface.viewers.ITreeContentProvider#getParent(Object) |
| */ |
| Object getParent(); |
| |
| /** |
| * Return whether the item has children. |
| * |
| * @see org.eclipse.jface.viewers.ITreeContentProvider#hasChildren(Object) |
| */ |
| boolean hasChildren(); |
| |
| /** |
| * Return the item's children. |
| * |
| * @see org.eclipse.jface.viewers.ITreeContentProvider#getChildren(Object) |
| */ |
| Object[] getChildren(); |
| |
| |
| /** |
| * An item tree content provider's manager is notified whenever the |
| * item's children have changed. |
| */ |
| interface Manager |
| extends ItemStructuredContentProvider.Manager |
| { |
| /** |
| * The children for the specified element have changed. |
| * Update appropriately. |
| */ |
| void updateChildren(Object element); |
| } |
| |
| |
| /** |
| * A "null" item tree content provider that has no elements, parent, |
| * or parent. |
| */ |
| final class Null |
| implements ItemTreeContentProvider, Serializable |
| { |
| public static final ItemStructuredContentProvider INSTANCE = new Null(); |
| public static ItemStructuredContentProvider instance() { |
| return INSTANCE; |
| } |
| // ensure single instance |
| private Null() { |
| super(); |
| } |
| public Object[] getElements() { |
| return EMPTY_ARRAY; |
| } |
| public Object getParent() { |
| return null; |
| } |
| public Object[] getChildren() { |
| return EMPTY_ARRAY; |
| } |
| public boolean hasChildren() { |
| return false; |
| } |
| public void dispose() { |
| // NOP |
| } |
| @Override |
| public String toString() { |
| return StringTools.buildSingletonToString(this); |
| } |
| private static final long serialVersionUID = 1L; |
| private Object readResolve() { |
| // replace this object with the singleton |
| return INSTANCE; |
| } |
| } |
| } |