org.eclipse.persistence.internal.jpa.parsing.CaseNode 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) 1998, 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:
//     tware - initial implementation as part of JPA 2.0 RI
package org.eclipse.persistence.internal.jpa.parsing;

import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.eclipse.persistence.expressions.Expression;
import org.eclipse.persistence.queries.ObjectLevelReadQuery;
import org.eclipse.persistence.queries.ReportQuery;

/**
 * INTERNAL
 * Purpose: Represent an CASE statement in EJBQL
 * 
Responsibilities:

 *  Generate the correct expression for an CASE in EJBQL
 * 
 *    @author tware
 *    @since EclipseLink 1.2
 */
public class CaseNode extends Node implements AliasableNode {

    private List whenClauses = null;


    public CaseNode(){
        super();
    }

    /**
     * INTERNAL
     * Apply this node to the passed query
     */
    @Override
    public void applyToQuery(ObjectLevelReadQuery theQuery, GenerationContext generationContext) {
        if (theQuery instanceof ReportQuery) {
            ReportQuery reportQuery = (ReportQuery)theQuery;
            Expression expression = generateExpression(generationContext);
            reportQuery.addAttribute("Case", expression, (Class)getType());
        }
    }

    /**
     * INTERNAL
     * Generate the a new EclipseLink TableEntryExpression for this node.
     */
    @Override
    public Expression generateExpression(GenerationContext context) {
        Map whenClauseMap = new LinkedHashMap<>(whenClauses.size());
        Iterator i = whenClauses.iterator();
        while (i.hasNext()){
            WhenThenNode clause = (WhenThenNode)i.next();
            whenClauseMap.put(clause.generateExpressionForWhen(context), clause.generateExpressionForThen(context));
        }

        Expression whereClause = null;
        if (getLeft() == null){
            whereClause = context.getBaseExpression().caseStatement(whenClauseMap, getRight().generateExpression(context));
        } else {
            whereClause = getLeft().generateExpression(context).caseStatement(whenClauseMap, getRight().generateExpression(context));
        }
        return whereClause;
    }

    @Override
    public void validate(ParseTreeContext context) {
        TypeHelper typeHelper = context.getTypeHelper();
        if (left != null){
            left.validate(context);
        }
        right.validate(context);
        Iterator i = whenClauses.iterator();
        Object type = null;
        while (i.hasNext()){
            Node node = i.next();
            node.validate(context);
            if (type == null){
                type = node.getType();
            } else if (!type.equals(node.getType())){
                type = Object.class;
            }
        }
        if (getRight().getType() != type){
            type = typeHelper.getObjectType();
        }
        setType(type);
    }


    public List getWhenClauses() {
        return whenClauses;
    }

    public void setWhenClauses(List whenClauses) {
        this.whenClauses = whenClauses;
    }

    @Override
    public boolean isAliasableNode(){
        return true;
    }
}