/*******************************************************************************
* Copyright (c) 2005, 2015 Matt Carter 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:
* Matt Carter - initial API and implementation (bug 212518)
* Matthew Hall - bug 212518, 146397, 249526
* Stefan Xenos <sxenos@gmail.com> - Bug 335792
*******************************************************************************/
package org.eclipse.core.internal.databinding.observable;
import org.eclipse.core.databinding.observable.IChangeListener;
import org.eclipse.core.databinding.observable.IDisposeListener;
import org.eclipse.core.databinding.observable.IStaleListener;
import org.eclipse.core.databinding.observable.ObservableTracker;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.databinding.observable.value.IObservableValue;
import org.eclipse.core.databinding.observable.value.IValueChangeListener;
import org.eclipse.core.databinding.observable.value.WritableValue;
import org.eclipse.core.runtime.Assert;
/**
* An immutable {@link IObservableValue}.
*
* @param <T>
* the type of the value being observed
*
* @see WritableValue
*/
public class ConstantObservableValue<T> implements IObservableValue<T> {
final Realm realm;
final T value;
final Object type;
/**
* Construct a constant value of the given type, in the default realm.
*
* @param value
* immutable value
* @param type
* type
*/
public ConstantObservableValue(T value, Object type) {
this(Realm.getDefault(), value, type);
}
/**
* Construct a constant value of the given type, in the given realm.
*
* @param realm
* Realm
* @param value
* immutable value
* @param type
* type
*/
public ConstantObservableValue(Realm realm, T value, Object type) {
Assert.isNotNull(realm, "Realm cannot be null"); //$NON-NLS-1$
this.realm = realm;
this.value = value;
this.type = type;
ObservableTracker.observableCreated(this);
}
@Override
public Object getValueType() {
return type;
}
@Override
public T getValue() {
ObservableTracker.getterCalled(this);
return value;
}
@Override
public void setValue(T value) {
throw new UnsupportedOperationException();
}
@Override
public void addValueChangeListener(IValueChangeListener<? super T> listener) {
// ignore
}
@Override
public void removeValueChangeListener(IValueChangeListener<? super T> listener) {
// ignore
}
@Override
public void addChangeListener(IChangeListener listener) {
// ignore
}
@Override
public void addDisposeListener(IDisposeListener listener) {
// ignore
}
@Override
public void addStaleListener(IStaleListener listener) {
// ignore
}
@Override
public boolean isDisposed() {
return false;
}
@Override
public void dispose() {
// nothing to dispose
}
@Override
public Realm getRealm() {
return realm;
}
@Override
public boolean isStale() {
return false;
}
@Override
public void removeChangeListener(IChangeListener listener) {
// ignore
}
@Override
public void removeDisposeListener(IDisposeListener listener) {
// ignore
}
@Override
public void removeStaleListener(IStaleListener listener) {
// ignore
}
}