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/*******************************************************************************
* Copyright (c) 2009, 2015 Oracle. 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:
* Oracle - initial API and implementation
******************************************************************************/
package org.eclipse.jpt.common.utility.internal.reference;
import java.io.Serializable;
import org.eclipse.jpt.common.utility.internal.ObjectTools;
import org.eclipse.jpt.common.utility.predicate.Predicate;
import org.eclipse.jpt.common.utility.reference.ModifiableObjectReference;
/**
* Provide a container for passing an object that can be changed by the recipient.
*
* @param <V> the type of the reference's value
* @see SynchronizedObject
*/
public class SimpleObjectReference<V>
implements ModifiableObjectReference<V>, Cloneable, Serializable
{
/** Backing value. */
private volatile V value;
private static final long serialVersionUID = 1L;
// ********** constructors **********
/**
* Create an object reference with the specified initial value.
*/
public SimpleObjectReference(V value) {
super();
this.value = value;
}
/**
* Create an object reference with an initial value of
* <code>null</code>.
*/
public SimpleObjectReference() {
this(null);
}
// ********** ObjectReference **********
public V getValue() {
return this.value;
}
public boolean valueEquals(Object object) {
return ObjectTools.equals(this.value, object);
}
public boolean valueNotEqual(Object object) {
return ObjectTools.notEquals(this.value, object);
}
public boolean is(Object object) {
return this.value == object;
}
public boolean isNot(Object object) {
return this.value != object;
}
public boolean isNull() {
return this.value == null;
}
public boolean isNotNull() {
return this.value != null;
}
public boolean isMemberOf(Predicate<? super V> predicate) {
return predicate.evaluate(this.value);
}
public boolean isNotMemberOf(Predicate<? super V> predicate) {
return ! predicate.evaluate(this.value);
}
// ********** ModifiableObjectReference **********
public V setValue(V value) {
V old = this.value;
this.value = value;
return old;
}
public V setNull() {
return this.setValue(null);
}
public boolean commit(V newValue, V expectedValue) {
if (ObjectTools.equals(this.value, expectedValue)) {
this.setValue(newValue);
return true;
}
return false;
}
public V swap(ModifiableObjectReference<V> other) {
if (other == this) {
return this.value;
}
V otherValue = other.getValue();
if (ObjectTools.equals(this.value, otherValue)) {
return this.value;
}
other.setValue(this.value);
this.setValue(otherValue);
return otherValue;
}
// ********** standard methods **********
@Override
public SimpleObjectReference<V> clone() {
try {
@SuppressWarnings("unchecked")
SimpleObjectReference<V> clone = (SimpleObjectReference<V>) super.clone();
return clone;
} catch (CloneNotSupportedException ex) {
throw new InternalError();
}
}
/**
* Object identity is critical to object references.
* There is no reason for two different object references to be
* <em>equal</em>.
*
* @see #valueEquals(Object)
*/
@Override
public boolean equals(Object obj) {
return super.equals(obj);
}
/**
* @see #equals(Object)
*/
@Override
public int hashCode() {
return super.hashCode();
}
@Override
public String toString() {
return '[' + String.valueOf(this.value) + ']';
}
}
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