/*******************************************************************************
* Copyright (c) 2011, 2015 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.internal.jpa.jpql;
import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.expressions.Expression;
import org.eclipse.persistence.expressions.ExpressionBuilder;
import org.eclipse.persistence.mappings.DatabaseMapping;
/**
* This <code>DerivedDeclaration</code> represents an identification variable declaration that was
* declared in the <code><b>FROM</b></code> clause of a <code><b>SELECT</b></code> subquery. The
* "root" object is not an entity name but a derived path expression.
*
* @see org.eclipse.persistence.jpa.jpql.parser.IdentificationVariableDeclaration IdentificationVariableDeclaration
*
* @version 2.5
* @since 2.4
* @author Pascal Filion
*/
final class DerivedDeclaration extends AbstractRangeDeclaration {
/**
* Creates a new <code>DerivedDeclaration</code>.
*
* @param queryContext The context used to query information about the application metadata and
* cached information
*/
DerivedDeclaration(JPQLQueryContext queryContext) {
super(queryContext);
}
/**
* {@inheritDoc}
*/
@Override
Expression buildQueryExpression() {
DatabaseMapping mapping = resolveMapping();
// If the derived expression is a class (non direct collection), then create a new expression
// builder for it, this builder will be compared as equal to the outer reference
if ((mapping != null) && (mapping.getReferenceDescriptor() != null)) {
Expression expression = new ExpressionBuilder(mapping.getReferenceDescriptor().getJavaClass());
queryContext.addUsedIdentificationVariable(rootPath);
queryContext.addQueryExpression(rootPath, expression);
// Check to see if the Expression exists in the parent's context,
// if not, then create/cache a new instance
JPQLQueryContext parentContext = queryContext.getParent();
if (parentContext.getQueryExpressionImp(rootPath) == null) {
parentContext.addQueryExpressionImp(rootPath, queryContext.buildExpression(baseExpression));
}
return expression;
}
else {
// Otherwise it will be derived by duplicating the join to the outer builder inside the
// sub select. The same could be done for direct collection, but difficult to create a
// builder on a table. Retrieve the superquery identification variable from the derived path
int index = rootPath.indexOf('.');
String superqueryVariableName = rootPath.substring(0, index).toUpperCase().intern();
// Create the local ExpressionBuilder for the super identification variable
Expression expression = queryContext.getParent().findQueryExpressionImp(superqueryVariableName);
expression = new ExpressionBuilder(expression.getBuilder().getQueryClass());
queryContext.addUsedIdentificationVariable(superqueryVariableName);
queryContext.addQueryExpression(superqueryVariableName, expression);
// Now create the base Expression for the actual derived path
return queryContext.buildExpression(baseExpression);
}
}
/**
* {@inheritDoc}
*/
@Override
public Type getType() {
return Type.DERIVED;
}
/**
* {@inheritDoc}
*/
@Override
ClassDescriptor resolveDescriptor() {
return queryContext.resolveDescriptor(getBaseExpression().getRootObject());
}
/**
* {@inheritDoc}
*/
@Override
DatabaseMapping resolveMapping() {
return queryContext.resolveMapping(getBaseExpression().getRootObject());
}
}