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/*
 * Copyright (c) 2006, 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
//
package org.eclipse.persistence.jpa.jpql.parser;

/**
 * The OR logical operator chains multiple criteria together. A valid operand of an OR
 * operator must be one of: TRUE, FALSE, and NULL. The OR operator has
 * a lower precedence than the AND operator.
 * 
 * NULL represents unknown. Therefore, if one operand is NULL and the other operand is
 * TRUE the result is TRUE, because one TRUE operand is sufficient for a
 * TRUE result. If one operand is NULL and the other operand is either FALSE or
 * NULL, the result is NULL (unknown).
 * 

 * The following table shows how the OR operator is evaluated based on its two operands:
 *
 * 
 * 
 * 
 * 
 * 
 * TRUE FALSE NULL
TRUE TRUE TRUE TRUE
FALSE TRUE FALSE NULL
NULL TRUE NULL NULL
 *
 * BNF: conditional_expression ::= conditional_expression OR conditional_term
 *
 * @version 2.5
 * @since 2.3
 * @author Pascal Filion
 */
public final class OrExpression extends LogicalExpression {

    /**
     * Creates a new OrExpression.
     *
     * @param parent The parent of this expression
     */
    public OrExpression(AbstractExpression parent) {
        super(parent, OR);
    }

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

    /**
     * {@inheritDoc}
     */
    @Override
    public String getLeftExpressionQueryBNFId() {
        return ConditionalExpressionBNF.ID;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getRightExpressionQueryBNFId() {
        return ConditionalTermBNF.ID;
    }
}

	TRUE	FALSE	NULL
TRUE	TRUE	TRUE	TRUE
FALSE	TRUE	FALSE	NULL
NULL	TRUE	NULL	NULL