1 /******************************************************************************* 2 * Copyright (c) 2006, 2017 IBM Corporation and others. 3 * 4 * This program and the accompanying materials 5 * are made available under the terms of the Eclipse Public License 2.0 6 * which accompanies this distribution, and is available at 7 * https://www.eclipse.org/legal/epl-2.0/ 8 * 9 * SPDX-License-Identifier: EPL-2.0 10 * 11 * Contributors: 12 * IBM Corporation - initial API and implementation 13 * Stefan Xenos <sxenos@gmail.com> - Bug 335792 14 *******************************************************************************/ 15 16 package org.eclipse.core.databinding.observable.set; 17 18 import java.util.HashSet; 19 import java.util.Set; 20 21 import org.eclipse.core.databinding.observable.Diffs; 22 import org.eclipse.core.databinding.observable.Realm; 23 import org.eclipse.core.databinding.observable.list.IListChangeListener; 24 import org.eclipse.core.databinding.observable.list.IObservableList; 25 import org.eclipse.core.databinding.observable.list.ListDiffEntry; 26 27 /** 28 * Observable set backed by an observable list. The wrapped list must not 29 * contain duplicate elements. 30 * 31 * <p> 32 * This class is thread safe. All state accessing methods must be invoked from 33 * the {@link Realm#isCurrent() current realm}. Methods for adding and removing 34 * listeners may be invoked from any thread. 35 * </p> 36 * 37 * @param <E> 38 * the type of elements in the collection 39 * @since 1.0 40 * 41 */ 42 public class ListToSetAdapter<E> extends ObservableSet<E> { 43 44 private final IObservableList<E> list; 45 46 private IListChangeListener<E> listener = event -> { 47 Set<E> added = new HashSet<>(); 48 Set<E> removed = new HashSet<>(); 49 ListDiffEntry<? extends E>[] differences = event.diff.getDifferences(); 50 for (ListDiffEntry<? extends E> entry : differences) { 51 E element = entry.getElement(); 52 if (entry.isAddition()) { 53 if (wrappedSet.add(element)) { 54 if (!removed.remove(element)) 55 added.add(element); 56 } 57 } else { 58 if (wrappedSet.remove(element)) { 59 removed.add(element); 60 added.remove(element); 61 } 62 } 63 } 64 fireSetChange(Diffs.createSetDiff(added, removed)); 65 }; 66 67 /** 68 * @param list the list to adapt 69 */ ListToSetAdapter(IObservableList<E> list)70 public ListToSetAdapter(IObservableList<E> list) { 71 super(list.getRealm(), new HashSet<E>(), list.getElementType()); 72 this.list = list; 73 wrappedSet.addAll(list); 74 this.list.addListChangeListener(listener); 75 } 76 77 @Override dispose()78 public synchronized void dispose() { 79 super.dispose(); 80 if (list != null && listener != null) { 81 list.removeListChangeListener(listener); 82 listener = null; 83 } 84 } 85 86 } 87