/*******************************************************************************
 * Copyright (c) 2005, 2007-2008 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
 *******************************************************************************/
module org.eclipse.core.internal.databinding.observable.ConstantObservableValue;

import java.lang.all;

import org.eclipse.core.databinding.observable.IChangeListener;
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}.
 * 
 * @see WritableValue
 */
public class ConstantObservableValue : IObservableValue {
    final Realm realm;
    final Object value;
    final Object type;

    /**
     * Construct a constant value of the given type, in the default realm.
     * 
     * @param value
     *            immutable value
     * @param type
     *            type
     */
    public this(Object 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 this(Realm realm, Object value, Object type) {
        Assert.isNotNull(realm, "Realm cannot be null"); //$NON-NLS-1$
        this.realm = realm;
        this.value = value;
        this.type = type;
    }

    public Object getValueType() {
        return type;
    }

    public Object getValue() {
        ObservableTracker.getterCalled(this);
        return value;
    }

    public void setValue(Object value) {
        throw new UnsupportedOperationException();
    }

    public void addValueChangeListener(IValueChangeListener listener) {
        // ignore
    }

    public void removeValueChangeListener(IValueChangeListener listener) {
        // ignore
    }

    public void addChangeListener(IChangeListener listener) {
        // ignore
    }

    public void addStaleListener(IStaleListener listener) {
        // ignore
    }

    public void dispose() {
        // nothing to dispose
    }

    public Realm getRealm() {
        return realm;
    }

    public bool isStale() {
        return false;
    }

    public void removeChangeListener(IChangeListener listener) {
        // ignore
    }

    public void removeStaleListener(IStaleListener listener) {
        // ignore
    }
}