| /******************************************************************************* |
| * Copyright (c) 2005, 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.jface.internal.databinding.provisional.observable.value; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.HashSet; |
| |
| import org.eclipse.jface.internal.databinding.provisional.observable.Diffs; |
| |
| /** |
| * @since 1.0 |
| * |
| */ |
| public abstract class AbstractVetoableValue extends AbstractObservableValue |
| implements IVetoableValue { |
| |
| public void setValue(Object value) { |
| Object currentValue = doGetValue(); |
| ValueDiff diff = Diffs.createValueDiff(currentValue, value); |
| boolean okToProceed = fireValueChanging(diff); |
| if (!okToProceed) { |
| throw new ChangeVetoException("Change not permitted"); //$NON-NLS-1$ |
| } |
| doSetValue(value); |
| fireValueChange(diff); |
| } |
| |
| private Collection valueChangingListeners = null; |
| |
| public void addValueChangingListener(IValueChangingListener listener) { |
| if (valueChangingListeners == null) { |
| boolean hadListeners = hasListeners(); |
| valueChangingListeners = new ArrayList(); |
| valueChangingListeners.add(listener); |
| if (!hadListeners) { |
| firstListenerAdded(); |
| } |
| } else if (valueChangingListeners.size() > 16) { |
| HashSet listenerList = new HashSet(); |
| listenerList.addAll(valueChangingListeners); |
| valueChangingListeners = listenerList; |
| valueChangingListeners.add(listener); |
| } |
| } |
| |
| public void removeValueChangingListener(IValueChangingListener listener) { |
| valueChangingListeners.remove(listener); |
| if (valueChangingListeners.size() == 0) { |
| valueChangingListeners = null; |
| } |
| if (!hasListeners()) { |
| lastListenerRemoved(); |
| } |
| } |
| |
| /** |
| * Notifies listeners about a pending change, and returns true if no |
| * listener vetoed the change. |
| * |
| * @param diff |
| * @return false if the change was vetoed, true otherwise |
| */ |
| protected boolean fireValueChanging(ValueDiff diff) { |
| if (valueChangingListeners != null) { |
| IValueChangingListener[] listeners = (IValueChangingListener[]) valueChangingListeners |
| .toArray(new IValueChangingListener[valueChangingListeners |
| .size()]); |
| for (int i = 0; i < listeners.length; i++) { |
| boolean okToProceed = listeners[i].handleValueChanging(this, |
| diff); |
| if (!okToProceed) { |
| return false; |
| } |
| } |
| } |
| return true; |
| } |
| |
| protected abstract void doSetValue(Object value); |
| |
| protected boolean hasListeners() { |
| return super.hasListeners(); |
| } |
| |
| public void dispose() { |
| super.dispose(); |
| } |
| |
| } |