/*******************************************************************************
* Copyright (c) 2006, 2015 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
* Brad Reynolds - bug 158687
* Brad Reynolds - bug 164653, 147515
* Boris Bokowski - bug 256422
* Matthew Hall - bug 256422
* Stefan Xenos <sxenos@gmail.com> - Bug 335792
*******************************************************************************/
package org.eclipse.core.databinding.observable.value;
import org.eclipse.core.databinding.observable.Diffs;
import org.eclipse.core.databinding.observable.Realm;
/**
* Mutable (writable) implementation of {@link IObservableValue} that will
* maintain a value and fire change events when the value changes.
* <p>
* This class is thread safe. All state accessing methods must be invoked from
* the {@link Realm#isCurrent() current realm}. Methods for adding and removing
* listeners may be invoked from any thread.
* </p>
*
* @param <T>
* the type of value being observed
* @since 1.0
*/
public class WritableValue<T> extends AbstractObservableValue<T> {
private final Object valueType;
/**
* Constructs a new instance with the default realm, a <code>null</code>
* value type, and a <code>null</code> value.
*/
public WritableValue() {
this(null, null);
}
/**
* Constructs a new instance with the default realm.
*
* @param initialValue
* can be <code>null</code>
* @param valueType
* can be <code>null</code>
*/
public WritableValue(T initialValue, Object valueType) {
this(Realm.getDefault(), initialValue, valueType);
}
/**
* Constructs a new instance with the provided <code>realm</code>, a
* <code>null</code> value type, and a <code>null</code> initial value.
*
* @param realm
*/
public WritableValue(Realm realm) {
this(realm, null, null);
}
/**
* Constructs a new instance.
*
* @param realm
* @param initialValue
* can be <code>null</code>
* @param valueType
* can be <code>null</code>
*/
public WritableValue(Realm realm, T initialValue, Object valueType) {
super(realm);
this.valueType = valueType;
this.value = initialValue;
}
private T value = null;
@Override
public T doGetValue() {
return value;
}
/**
* @param value
* The value to set.
*/
@Override
public void doSetValue(T value) {
if (this.value != value) {
fireValueChange(Diffs.createValueDiff(this.value,
this.value = value));
}
}
@Override
public Object getValueType() {
return valueType;
}
/**
* @param <T2>
* @param elementType
* can be <code>null</code>
* @return new instance with the default realm and a value of
* <code>null</code>
*/
public static <T2> WritableValue<T2> withValueType(Object elementType) {
return new WritableValue<>(Realm.getDefault(), null, elementType);
}
}