| /******************************************************************************* |
| * Copyright (c) 2006 IBM Corporation and others. |
| * 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: |
| * IBM Corporation - initial API and implementation |
| ******************************************************************************/ |
| |
| package org.eclipse.core.databinding.observable.set; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.Iterator; |
| import java.util.Set; |
| |
| import org.eclipse.core.databinding.observable.Diffs; |
| import org.eclipse.core.internal.databinding.observable.IStalenessConsumer; |
| import org.eclipse.core.internal.databinding.observable.StalenessTracker; |
| |
| /** |
| * Represents a set consisting of the union of elements from one or more other |
| * sets. This object does not need to be explicitly disposed. If nobody is |
| * listening to the UnionSet, the set will remove its listeners. |
| * |
| * @since 1.0 |
| */ |
| public final class UnionSet extends ObservableSet { |
| |
| /** |
| * child sets |
| */ |
| private IObservableSet[] childSets; |
| |
| private boolean stale = false; |
| |
| /** |
| * Map of elements onto Integer reference counts. This map is constructed |
| * when the first listener is added to the union set. Null if nobody is |
| * listening to the UnionSet. |
| */ |
| private HashMap refCounts = null; |
| |
| private StalenessTracker stalenessTracker; |
| |
| /** |
| * @param childSets |
| */ |
| public UnionSet(IObservableSet[] childSets) { |
| super(childSets[0].getRealm(), null, childSets[0].getElementType()); |
| this.childSets = childSets; |
| this.stalenessTracker = new StalenessTracker(childSets, |
| stalenessConsumer); |
| } |
| |
| private ISetChangeListener childSetChangeListener = new ISetChangeListener() { |
| public void handleSetChange(SetChangeEvent event) { |
| processAddsAndRemoves(event.diff.getAdditions(), event.diff.getRemovals()); |
| } |
| }; |
| |
| private IStalenessConsumer stalenessConsumer = new IStalenessConsumer() { |
| public void setStale(boolean stale) { |
| boolean oldStale = UnionSet.this.stale; |
| UnionSet.this.stale = stale; |
| if (stale && !oldStale) { |
| fireStale(); |
| } |
| } |
| }; |
| |
| public boolean isStale() { |
| if (refCounts != null) { |
| return stale; |
| } |
| |
| for (int i = 0; i < childSets.length; i++) { |
| IObservableSet childSet = childSets[i]; |
| |
| if (childSet.isStale()) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| private void processAddsAndRemoves(Set adds, Set removes) { |
| Set addsToFire = new HashSet(); |
| Set removesToFire = new HashSet(); |
| |
| for (Iterator iter = adds.iterator(); iter.hasNext();) { |
| Object added = iter.next(); |
| |
| Integer refCount = (Integer) refCounts.get(added); |
| if (refCount == null) { |
| refCounts.put(added, new Integer(1)); |
| addsToFire.add(added); |
| } else { |
| int refs = refCount.intValue(); |
| refCount = new Integer(refs + 1); |
| refCounts.put(added, refCount); |
| } |
| } |
| |
| for (Iterator iter = removes.iterator(); iter.hasNext();) { |
| Object removed = iter.next(); |
| |
| Integer refCount = (Integer) refCounts.get(removed); |
| if (refCount != null) { |
| int refs = refCount.intValue(); |
| if (refs <= 1) { |
| removesToFire.add(removed); |
| refCounts.remove(removed); |
| } else { |
| refCount = new Integer(refCount.intValue() - 1); |
| refCounts.put(removed, refCount); |
| } |
| } |
| } |
| |
| // just in case the removes overlapped with the adds |
| addsToFire.removeAll(removesToFire); |
| |
| if (addsToFire.size() > 0 || removesToFire.size() > 0) { |
| fireSetChange(Diffs.createSetDiff(addsToFire, removesToFire)); |
| } |
| } |
| |
| protected void firstListenerAdded() { |
| super.firstListenerAdded(); |
| |
| refCounts = new HashMap(); |
| for (int i = 0; i < childSets.length; i++) { |
| IObservableSet next = childSets[i]; |
| next.addSetChangeListener(childSetChangeListener); |
| incrementRefCounts(next); |
| } |
| stalenessTracker = new StalenessTracker(childSets, stalenessConsumer); |
| setWrappedSet(refCounts.keySet()); |
| } |
| |
| protected void lastListenerRemoved() { |
| super.lastListenerRemoved(); |
| |
| for (int i = 0; i < childSets.length; i++) { |
| IObservableSet next = childSets[i]; |
| |
| next.removeSetChangeListener(childSetChangeListener); |
| stalenessTracker.removeObservable(next); |
| } |
| refCounts = null; |
| stalenessTracker = null; |
| setWrappedSet(null); |
| } |
| |
| private ArrayList incrementRefCounts(Collection added) { |
| ArrayList adds = new ArrayList(); |
| |
| for (Iterator iter = added.iterator(); iter.hasNext();) { |
| Object next = iter.next(); |
| |
| Integer refCount = (Integer) refCounts.get(next); |
| if (refCount == null) { |
| adds.add(next); |
| refCount = new Integer(1); |
| refCounts.put(next, refCount); |
| } else { |
| refCount = new Integer(refCount.intValue() + 1); |
| refCounts.put(next, refCount); |
| } |
| } |
| return adds; |
| } |
| |
| protected void getterCalled() { |
| super.getterCalled(); |
| if (refCounts == null) { |
| // no listeners, recompute |
| setWrappedSet(computeElements()); |
| } |
| } |
| |
| private Set computeElements() { |
| // If there is no cached value, compute the union from scratch |
| if (refCounts == null) { |
| Set result = new HashSet(); |
| for (int i = 0; i < childSets.length; i++) { |
| result.addAll(childSets[i]); |
| } |
| return result; |
| } |
| |
| // Else there is a cached value. Return it. |
| return refCounts.keySet(); |
| } |
| |
| } |