/*******************************************************************************
 * Copyright (c) 2011, 2014 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 v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation
 *
 ******************************************************************************/
package org.eclipse.persistence.jpa.jpql.tools.model.query;

import org.eclipse.persistence.jpa.jpql.parser.InternalEntityTypeExpressionBNF;
import org.eclipse.persistence.jpa.jpql.parser.TypeExpression;
import static org.eclipse.persistence.jpa.jpql.parser.Expression.*;

/**
 * An entity type expression can be used to restrict query polymorphism. The <code><b>TYPE</b></code>
 * operator returns the exact type of the argument.
 * <p>
 * Part of JPA 2.0.
 *
 * <div><b>BNF:</b> <code>type_discriminator ::= TYPE(identification_variable |
 *                                                           single_valued_object_path_expression |
 *                                                           input_parameter)</code><p></div>
 *
 * @see TypeExpression
 *
 * @version 2.4
 * @since 2.4
 * @author Pascal Filion
 */
public class TypeExpressionStateObject extends AbstractSingleEncapsulatedExpressionStateObject {

	/**
	 * Creates a new <code>TypeExpressionStateObject</code>.
	 *
	 * @param parent The parent of this state object, which cannot be <code>null</code>
	 * @exception NullPointerException The given parent cannot be <code>null</code>
	 */
	public TypeExpressionStateObject(StateObject parent) {
		super(parent);
	}

	/**
	 * Creates a new <code>TypeExpressionStateObject</code>.
	 *
	 * @param parent The parent of this state object, which cannot be <code>null</code>
	 * @param stateObject The {@link StateObject} representing the encapsulated expression
	 * @exception NullPointerException The given parent cannot be <code>null</code>
	 */
	public TypeExpressionStateObject(StateObject parent, StateObject stateObject) {
		super(parent, stateObject);
	}

	/**
	 * Creates a new <code>TypeExpressionStateObject</code>.
	 *
	 * @param parent The parent of this state object, which cannot be <code>null</code>
	 * @param path Either the identification variable, the singled-valued object path expression or
	 * the input parameter
	 * @exception NullPointerException The given parent cannot be <code>null</code>
	 */
	public TypeExpressionStateObject(StateObject parent, String path) {
		super(parent, path);
	}

	/**
	 * {@inheritDoc}
	 */
	public void accept(StateObjectVisitor visitor) {
		visitor.visit(this);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public TypeExpression getExpression() {
		return (TypeExpression) super.getExpression();
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public String getIdentifier() {
		return TYPE;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected String getQueryBNFId() {
		return InternalEntityTypeExpressionBNF.ID;
	}

	/**
	 * Keeps a reference of the {@link TypeExpression parsed object} object, which should only be
	 * done when this object is instantiated during the conversion of a parsed JPQL query into
	 * {@link StateObject StateObjects}.
	 *
	 * @param expression The {@link TypeExpression parsed object} representing a <code><b>TYPE</b></code>
	 * expression
	 */
	public void setExpression(TypeExpression expression) {
		super.setExpression(expression);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void setStateObject(StateObject stateObject) {
		super.setStateObject(stateObject);
	}
}