| /******************************************************************************* |
| * Copyright (c) 2008, 2009 Matthew Hall 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: |
| * Matthew Hall - initial API and implementation (bug 249992) |
| ******************************************************************************/ |
| |
| package org.eclipse.core.databinding.observable.value; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| import org.eclipse.core.databinding.observable.Diffs; |
| import org.eclipse.core.databinding.observable.Realm; |
| import org.eclipse.core.internal.databinding.observable.Util; |
| |
| /** |
| * An observable value which behaves similarly to the <select> and |
| * <option> HTML tags. A SelectObservableValue has a number of options |
| * added to it via the {@link #addOption(Object, IObservableValue)} method. The |
| * value of the SelectObservableValue is the value of whichever option's |
| * observable has a value of Boolean.TRUE, or null if none of the observable's |
| * values are Boolean.TRUE. |
| * |
| * @param <T> |
| * |
| * @noextend This class is not intended to be subclassed by clients. |
| * |
| * @since 1.2 |
| */ |
| public class SelectObservableValue<T> extends AbstractObservableValue<T> { |
| private class Option { |
| private final T value; |
| private final IObservableValue<Boolean> observable; |
| |
| public Option(T value, IObservableValue<Boolean> observable) { |
| this.value = value; |
| this.observable = observable; |
| } |
| } |
| |
| private final Object valueType; |
| |
| private List<Option> options; |
| private int selectionIndex = -1; // n/a while not hasListeners() |
| |
| private boolean updating = false; |
| |
| private IValueChangeListener<Boolean> listener = new IValueChangeListener<Boolean>() { |
| public void handleValueChange(ValueChangeEvent<Boolean> event) { |
| if (!updating) { |
| IObservableValue<? extends Boolean> observable = event |
| .getObservableValue(); |
| if (Boolean.TRUE.equals(observable.getValue())) { |
| notifyIfChanged(indexOfObservable(observable)); |
| } |
| } |
| } |
| }; |
| |
| /** |
| * Constructs a SelectObservableValue on the default realm. |
| */ |
| public SelectObservableValue() { |
| this(Realm.getDefault(), null); |
| } |
| |
| /** |
| * Constructs a SelectObservableValue on the specified realm. |
| * |
| * @param realm |
| * the realm |
| */ |
| public SelectObservableValue(Realm realm) { |
| this(realm, null); |
| } |
| |
| /** |
| * Constructs a SelectObservableValue on the default realm, with the given |
| * value type. |
| * |
| * @param valueType |
| * the value type |
| */ |
| public SelectObservableValue(Object valueType) { |
| this(Realm.getDefault(), valueType); |
| } |
| |
| /** |
| * Constructs a SelectObservableValue on the given realm, with the given |
| * value type. |
| * |
| * @param realm |
| * the realm |
| * @param valueType |
| * the value type |
| */ |
| public SelectObservableValue(Realm realm, Object valueType) { |
| super(realm); |
| this.valueType = valueType; |
| this.options = new ArrayList<Option>(); |
| } |
| |
| protected void firstListenerAdded() { |
| super.firstListenerAdded(); |
| selectionIndex = indexOfValue(getLiveValue()); |
| for (Option option : options) { |
| option.observable.addValueChangeListener(listener); |
| } |
| } |
| |
| protected void lastListenerRemoved() { |
| for (Option option : options) { |
| option.observable.removeValueChangeListener(listener); |
| } |
| selectionIndex = -1; |
| super.lastListenerRemoved(); |
| } |
| |
| public Object getValueType() { |
| return valueType; |
| } |
| |
| private void notifyIfChanged(int index) { |
| if (hasListeners() && selectionIndex != index) { |
| T oldValue = valueAtIndex(selectionIndex); |
| T newValue = valueAtIndex(index); |
| selectionIndex = index; |
| fireValueChange(Diffs.createValueDiff(oldValue, newValue)); |
| } |
| } |
| |
| /** |
| * Adds an option to this SelectObservableValue. If the observable contains |
| * Boolean.TRUE then the selection changes immediately to the given value. |
| * |
| * @param value |
| * The value associated with the provided observable |
| * @param observable |
| * an observable of value type Boolean.class or Boolean.TYPE |
| */ |
| public void addOption(T value, IObservableValue<Boolean> observable) { |
| checkRealm(); |
| |
| Option option = new Option(value, observable); |
| options.add(option); |
| |
| if (hasListeners()) { |
| observable.addValueChangeListener(listener); |
| if (Boolean.TRUE.equals(observable.getValue())) { |
| notifyIfChanged(indexOfObservable(observable)); |
| } |
| } |
| } |
| |
| protected T doGetValue() { |
| return hasListeners() ? valueAtIndex(selectionIndex) : getLiveValue(); |
| } |
| |
| private T getLiveValue() { |
| for (Option option : options) { |
| if (Boolean.TRUE.equals(option.observable.getValue())) |
| return option.value; |
| } |
| return null; |
| } |
| |
| protected void doSetValue(Object value) { |
| int index = indexOfValue(value); |
| |
| try { |
| updating = true; |
| for (int i = 0; i < options.size(); i++) { |
| options.get(i).observable.setValue(i == index ? Boolean.TRUE |
| : Boolean.FALSE); |
| } |
| } finally { |
| updating = false; |
| } |
| |
| notifyIfChanged(index); |
| } |
| |
| private T valueAtIndex(int index) { |
| if (index == -1) |
| return null; |
| return options.get(index).value; |
| } |
| |
| private int indexOfValue(Object value) { |
| for (int i = 0; i < options.size(); i++) |
| if (Util.equals(options.get(i).value, value)) |
| return i; |
| return -1; |
| } |
| |
| private int indexOfObservable(IObservableValue<? extends Boolean> observable) { |
| for (int i = 0; i < options.size(); i++) |
| if (options.get(i).observable == observable) |
| return i; |
| return -1; |
| } |
| } |