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/*
 * Copyright (c) 1998, 2020 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 from Oracle TopLink
package org.eclipse.persistence.internal.jpa.parsing;

import java.util.Iterator;
import java.util.List;
import org.eclipse.persistence.expressions.*;
import org.eclipse.persistence.internal.expressions.ConstantExpression;
import org.eclipse.persistence.internal.queries.ReportItem;
import org.eclipse.persistence.queries.ReportQuery;

/**
 * INTERNAL
 * 

Purpose: Represent an EXISTS subquery. */ public class ExistsNode extends Node { /** True in case of a NOT EXISTS (...) query. */ private boolean notIndicated = false; /** * Return a new ExistsNode. */ public ExistsNode() { super(); } /** * INTERNAL * Validate node and calculate its type. * Change subquery SELECT clause. */ @Override public void validate(ParseTreeContext context) { if (left != null) { // change SELECT clause of subquery SubqueryNode subqueryNode = (SubqueryNode)getLeft(); // validate changed subquery subqueryNode.validate(context); TypeHelper typeHelper = context.getTypeHelper(); setType(typeHelper.getBooleanType()); } } /** * INTERNAL * Generate the EclipseLink expression for this node */ @Override public Expression generateExpression(GenerationContext context) { SubqueryNode subqueryNode = (SubqueryNode)getLeft(); ReportQuery reportQuery = subqueryNode.getReportQuery(context); // Replace the SELECT clause of the exists subquery by SELECT 1 to // avoid problems with databases not supporting multiple columns in the // subquery SELECT clause in SQL. // The original select clause expressions might include relationship // navigations which should result in FK joins in the generated SQL, // e.g. ... EXISTS (SELECT o.customer FROM Order o ...). Add the // select clause expressions as non fetch join attributes to the // ReportQuery representing the subquery. This make sure the FK joins // get generated. List items = reportQuery.getItems(); for (Iterator i = items.iterator(); i.hasNext();) { ReportItem item = (ReportItem)i.next(); Expression expr = item.getAttributeExpression(); reportQuery.addNonFetchJoinedAttribute(expr); } reportQuery.clearItems(); Expression one = new ConstantExpression(Integer.valueOf(1), new ExpressionBuilder()); reportQuery.addItem("one", one); reportQuery.dontUseDistinct(); Expression expr = context.getBaseExpression(); return notIndicated() ? expr.notExists(reportQuery) : expr.exists(reportQuery); } /** * INTERNAL * Indicate if a NOT was found in the WHERE clause. * Examples: WHERE ... NOT EXISTS(...) */ public void indicateNot() { notIndicated = true; } public boolean notIndicated() { return notIndicated; } }





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