org.eclipse.persistence.jpa.jpql.parser.SubstringExpression Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of eclipselink Show documentation

EclipseLink build based upon Git transaction 346465e

There is a newer version: 5.0.0-B07

/*******************************************************************************
 * Copyright (c) 2006, 2013 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;

/**
 * The second and third arguments of the SUBSTRING function denote the starting position and
 * length of the substring to be returned. These arguments are integers. The first position of a
 * string is denoted by 1. The SUBSTRING function returns a string.
 * 
 * JPA 1.0:
 * BNF ::= SUBSTRING(string_primary, simple_arithmetic_expression, simple_arithmetic_expression)
 * 
 * JPA 2.0:
 * BNF ::= SUBSTRING(string_primary, simple_arithmetic_expression [, simple_arithmetic_expression])
 * 
 * JPA 2.1:
 * BNF ::= SUBSTRING(string_expression, arithmetic_expression [, arithmetic_expression])
 * 
 * Example: UPDATE Employee e SET e.firstName = SUBSTRING('TopLink Workbench', 1, 8)
 *
 * @version 2.5
 * @since 2.3
 * @author Pascal Filion
 */
public final class SubstringExpression extends AbstractTripleEncapsulatedExpression {

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

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

	/**
	 * {@inheritDoc}
	 */
	@Override
	public String getParameterQueryBNFId(int index) {
		switch (index) {
			case 0:  return InternalSubstringStringExpressionBNF.ID;
			default: return InternalSubstringPositionExpressionBNF.ID;
		}
	}

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

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected boolean isThirdExpressionOptional() {
		return true;
	}
}