org.eclipse.persistence.internal.jpa.parsing.SelectGenerationContext 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, 2018 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.Set;

import org.eclipse.persistence.expressions.Expression;
import org.eclipse.persistence.internal.sessions.AbstractSession;

/**
 * INTERNAL:
 * An extension of GenerationContext the provides SELECT specific behavior.
 * Used when building the query features that are not usable in other types of queries
 */
public class SelectGenerationContext extends GenerationContext {
    //if a 1:1 is SELECTed in the EJBQL, then we need to use parallel expressions
    //with each ExpressionBuilder created using "new ExpressionBuilder(MyClass.class)"
    private boolean useParallelExpressions = false;

    //BUG 3105651: If a variable is SELECTed, and it's in an ORDER BY, then
    //we want the ExpressionBuilder to be instantiated using an empty constructor
    private boolean shouldCheckSelectNodeBeforeResolving = false;

    //If a NOT MEMBER OF is encountered, we need to store the MEMBER OF
    //so that the right side of the member of can use the stored expression
    //from the left
    private MemberOfNode memberOfNode = null;

    //Do we want to use outer joins? get("address") vs getAllowingNull("address")
    private boolean shouldUseOuterJoins = false;

    //Outer SelectGenerationContext
    private GenerationContext outer = null;

    public SelectGenerationContext() {
        super();
    }

    /**
     * Constructor used to create the context for a subquery.
     */
    public SelectGenerationContext(GenerationContext outer, ParseTree newParseTree) {
        this(outer.getParseTreeContext(), outer.getSession(), newParseTree);
        this.outer = outer;
    }

    public SelectGenerationContext(ParseTreeContext newContext, AbstractSession newSession, ParseTree newParseTree) {
        super(newContext, newSession, newParseTree);

        //indicate if we want parallel expressions or not
        useParallelExpressions = this.computeUseParallelExpressions();
    }

    //Set and get the contained MemberOfNode. This is for handling NOT MEMBER OF.
    public void setMemberOfNode(MemberOfNode newMemberOfNode) {
        memberOfNode = newMemberOfNode;
    }

    public MemberOfNode getMemberOfNode() {
        return memberOfNode;
    }

    private boolean computeUseParallelExpressions() {
        boolean computedUseParallelExpressions;

        //use parallel expressions if I have a 1:1 selected, and the same class isn't
        //declared in the FROM
        computedUseParallelExpressions = ((SelectNode)this.parseTree.getQueryNode()).hasOneToOneSelected(this);
        //check if they've SELECTed a variable declared in the IN clause in the FROM,
        //or they've mapped more than one variable to the same type in the FROM
        computedUseParallelExpressions = computedUseParallelExpressions || ((SelectNode)this.parseTree.getQueryNode()).isVariableInINClauseSelected(this) || this.parseTree.getContext().hasMoreThanOneVariablePerType() || this.parseTree.getContext().hasMoreThanOneAliasInFrom();
        return computedUseParallelExpressions;
    }

    //Answer true if we need to use parallel expressions
    //This will be the case if a 1:1 is SELECTed in the EJBQL.
    public boolean useParallelExpressions() {
        return useParallelExpressions;
    }

    //Indicate that we want VariableNodes to check if they're
    //SELECTed first, to determine how to instantiate the ExpressionBuilder
    public void checkSelectNodeBeforeResolving(boolean shouldCheck) {
        shouldCheckSelectNodeBeforeResolving = shouldCheck;
    }

    //Answer true if we want VariableNodes to check if they're
    //SELECTed first, to determine how to instantiate the ExpressionBuilder
    public boolean shouldCheckSelectNodeBeforeResolving() {
        return shouldCheckSelectNodeBeforeResolving;
    }

    //Answer true if we should use outer joins in our get() (vs getAllowingNull())
    public boolean shouldUseOuterJoins() {
        return shouldUseOuterJoins;
    }

    public void useOuterJoins() {
        shouldUseOuterJoins = true;
    }

    public void dontUseOuterJoins() {
        shouldUseOuterJoins = false;
    }

    //Answer true if we have a MemberOfNode contained. This is for handling NOT MEMBER OF
    public boolean hasMemberOfNode() {
        return memberOfNode != null;
    }

    public boolean isSelectGenerationContext() {
        return true;
    }

    /** */
    public GenerationContext getOuterContext() {
        return outer;
    }

    /**
     * Iterate the set of variables declared in an outer scope and
     * connect the inner variable expression with the outer one.
     */
    public Expression joinVariables(Set variables) {
        if ((outer == null) || (variables == null) || variables.isEmpty()) {
            // not an inner query or no variables to join
            return null;
        }
        Expression expr = null;
        for (Iterator i = variables.iterator(); i.hasNext(); ) {
            String name = (String)i.next();
            VariableNode var = new VariableNode(name);
            Expression innerExpr = var.generateExpression(this);
            Expression outerExpr = var.generateExpression(outer);

            // Join them only if they are not the same.
            if (innerExpr != outerExpr) {
                Expression join = innerExpr.equal(outerExpr);
                expr = var.appendExpression(expr, join);
            }
        }
        return expr;

    }
}