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/*
* Copyright (c) 1998, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0,
* or the Eclipse Distribution License v. 1.0 which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
*/
// Contributors:
// Oracle - initial API and implementation from Oracle TopLink
package org.eclipse.persistence.indirection;
import java.io.Serializable;
/**
*
* Purpose: Act as a place holder for a variable that required a value holder interface.
* This class should be used to initialze an objects attributes that are using indirection is their mappings.
*/
public class ValueHolder implements WeavedAttributeValueHolderInterface, Cloneable, Serializable {
/**
* Stores the wrapped object.
*/
protected Object value;
/**
* The two variable below are used as part of the implementation of WeavedAttributeValueHolderInterface
* They are used to track whether a valueholder that has been weaved into a class is coordinated
* with the underlying property
*/
// Set internally in TopLink when the state of coordination between a weaved valueholder and the underlying property is known
private boolean isCoordinatedWithProperty = false;
// Used to determine if this ValueHolder was added instantiated as part of the constructor of a weaved class
private boolean isNewlyWeavedValueHolder = false;
/**
* PUBLIC:
* Initialize the holder.
*/
public ValueHolder() {
super();
}
/**
* PUBLIC:
* Initialize the holder with an object.
*/
public ValueHolder(Object value) {
this.value = value;
}
/**
* INTERNAL:
*/
public Object clone() {
try {
return super.clone();
} catch (CloneNotSupportedException exception) {
;
}
return null;
}
/**
* PUBLIC:
* Return the wrapped object.
*/
public Object getValue() {
return value;
}
/**
* Used as part of the implementation of WeavedAttributeValueHolderInterface
* Used to track whether a valueholder that has been weaved into a class is coordinated
* with the underlying property
*/
public boolean isCoordinatedWithProperty(){
return isCoordinatedWithProperty;
}
/**
* Used as part of the implementation of WeavedAttributeValueHolderInterface
* Used to determine if this ValueHolder was added instantiated as part of
* the constructor of a weaved class
*/
public boolean isNewlyWeavedValueHolder(){
return isNewlyWeavedValueHolder;
}
/**
* PUBLIC:
* Return a boolean indicating whether the
* wrapped object has been set or not.
*/
public boolean isInstantiated() {
// Always return true since we consider
// null to be a valid wrapped object.
return true;
}
/**
* Used as part of the implementation of WeavedAttributeValueHolderInterface
* Used to track whether a valueholder that has been weaved into a class is coordinated
* with the underlying property
*
* This method will be called internall when the state of Coordination between the
* weaved valueholder and the underlying value is known
*/
public void setIsCoordinatedWithProperty(boolean coordinated){
this.isCoordinatedWithProperty = coordinated;
// this is not a newly weaved valueholder any more since we have done some coordination work
isNewlyWeavedValueHolder = false;
}
/**
* Used as part of the implementation of WeavedAttributeValueHolderInterface
* Used to determine if this ValueHolder was added instantiated as part of
* the constructor of a weaved class
*
* This method will be called when a ValueHolder is instantiated in a weaved class
*/
public void setIsNewlyWeavedValueHolder(boolean isNew){
this.isNewlyWeavedValueHolder = isNew;
}
/**
* PUBLIC:
* Set the wrapped object.
*/
public void setValue(Object value) {
this.value = value;
}
/**
* INTERNAL:
* Return if add/remove should trigger instantiation or avoid.
* Current instantiation is avoided is using change tracking.
*/
public boolean shouldAllowInstantiationDeferral() {
return false;
}
/**
* INTERNAL:
*/
public String toString() {
if (getValue() == null) {
return "{" + null + "}";
}
return "{" + getValue().toString() + "}";
}
}