/*******************************************************************************
 * Copyright (c) 2012, 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.parser;

import org.eclipse.persistence.jpa.jpql.WordParser;

/**
 * Returns an expression that allows a join <b>ON</b> clause to be defined.
 * <p>
 * New to EclipseLink 2.4 and JPA 2.1.
 *
 * <div><b>BNF:</b> <code>join_condition ::= ON conditional_expression</code></div>
 * <p>
 * Example: <code>SELECT e FROM Employee e LEFT JOIN e.projects p ON p.budget {@literal >} 10000</code>
 *
 * @version 2.4
 * @since 2.4
 * @author James Sutherland
 */
public final class OnClause extends AbstractConditionalClause {

	/**
	 * Creates a new <code>OnClause</code>.
	 *
	 * @param parent The parent of this expression
	 */
	public OnClause(AbstractExpression parent) {
		super(parent, ON);
	}

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

	/**
	 * {@inheritDoc}
	 */
	public JPQLQueryBNF getQueryBNF() {
		return getQueryBNF(OnClauseBNF.ID);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected boolean isParsingComplete(WordParser wordParser, String word, Expression expression) {
		return word.equalsIgnoreCase(LEFT)  ||
		       word.equalsIgnoreCase(OUTER) ||
		       word.equalsIgnoreCase(FETCH) ||
		       word.equalsIgnoreCase(INNER) ||
		       word.equalsIgnoreCase(JOIN)  ||
		       super.isParsingComplete(wordParser, word, expression);
	}
}