org.eclipse.persistence.jpa.jpql.parser.ExistsExpression 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 f2b9fc5
There is a newer version: 5.0.0-B03
/*
 * Copyright (c) 2006, 2021 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;

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

/**
 * An EXISTS expression is a predicate that is true only if the result of the
 * subquery consists of one or more values and that is false otherwise.
 *
 * BNF: exists_expression ::= [NOT] EXISTS(subquery)
 *
 * @version 2.5
 * @since 2.3
 * @author Pascal Filion
 */
public final class ExistsExpression extends AbstractSingleEncapsulatedExpression {

    /**
     * The actual NOT identifier found in the string representation of the JPQL query.
     */
    private String notIdentifier;

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

    @Override
    public void accept(ExpressionVisitor visitor) {
        visitor.visit(this);
    }

    @Override
    public String getEncapsulatedExpressionQueryBNFId() {
        return SubqueryBNF.ID;
    }

    /**
     * Returns the actual NOT identifier found in the string representation of the JPQL query,
     * which has the actual case that was used.
     *
     * @return The NOT identifier that was actually parsed, or an empty string if it was not
     * parsed
     */
    public String getActualNotIdentifier() {
        return (notIdentifier != null) ? notIdentifier : ExpressionTools.EMPTY_STRING;
    }

    @Override
    public JPQLQueryBNF getQueryBNF() {
        return getQueryBNF(ExistsExpressionBNF.ID);
    }

    /**
     * Determines whether the identifier NOT was parsed.
     *
     * @return true if the identifier NOT was parsed; false otherwise
     */
    public boolean hasNot() {
        return (notIdentifier != null);
    }

    @Override
    protected void parse(WordParser wordParser, boolean tolerant) {

        // Parse 'NOT'
        if (wordParser.startsWithIgnoreCase('N')) {
            int position = wordParser.position();
            notIdentifier = wordParser.substring(position, position + 3);
            setText(NOT_EXISTS);
        }

        super.parse(wordParser, tolerant);
    }

    @Override
    protected AbstractExpression parse(WordParser wordParser, String queryBNFId, boolean tolerant) {

        if (tolerant) {
            return super.parse(wordParser, queryBNFId, tolerant);
        }

        SimpleSelectStatement expression = new SimpleSelectStatement(this);
        expression.parse(wordParser, tolerant);
        return expression;
    }
}