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/*******************************************************************************
 * Copyright (c) 2006, 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 java.util.ArrayList;
import java.util.List;

/**
 * The CONCAT function returns a string that is a concatenation of its arguments.
 * 
 * JPA 1.0:
 * 
BNF: expression ::= CONCAT(string_primary, string_primary)
 * 
 * JPA 2.0:
 * 
BNF: expression ::= CONCAT(string_primary, string_primary {, string_primary}*)
 * 
 * JPA 2.1:
 * 
BNF: expression ::= CONCAT(string_expression, string_expression {, string_expression}*)
 *
 * Example: SELECT c.firstName FROM Customer c HAVING c.firstName = CONCAT(:fname, :lname)
 *
 * @version 2.5
 * @since 2.3
 * @author Pascal Filion
 */
public final class ConcatExpression extends AbstractSingleEncapsulatedExpression {

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

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

	/**
	 * Creates a new {@link CollectionExpression} that will wrap the single constructor item.
	 *
	 * @return The single constructor item represented by a temporary collection
	 */
	public CollectionExpression buildCollectionExpression() {

		List children = new ArrayList(1);
		children.add((AbstractExpression) getExpression());

		List commas = new ArrayList(1);
		commas.add(Boolean.FALSE);

		List spaces = new ArrayList(1);
		spaces.add(Boolean.FALSE);

		return new CollectionExpression(this, children, commas, spaces, true);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public String getEncapsulatedExpressionQueryBNFId() {
		return InternalConcatExpressionBNF.ID;
	}

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