/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2013, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.loader.plan2.exec.internal;
import org.hibernate.loader.plan2.spi.EntityQuerySpace;
import org.hibernate.loader.plan2.spi.LoadPlan;
import org.hibernate.loader.plan2.spi.QuerySpace;
import org.hibernate.loader.plan2.spi.QuerySpaces;
import org.hibernate.loader.plan2.spi.Return;
/**
* @author Steve Ebersole
*/
public class Helper {
/**
* Singleton access
*/
public static final Helper INSTANCE = new Helper();
/**
* Disallow direct instantiation
*/
private Helper() {
}
/**
* Extract the root return of the LoadPlan, assuming there is just one.
*
* @param loadPlan The LoadPlan from which to extract the root return
* @param returnType The Return type expected, passed as an argument
* @param <T> The parameterized type of the specific Return type expected
*
* @return The root Return
*
* @throws IllegalStateException If there is no root, more than one root or the single root
* is not of the expected type.
*/
@SuppressWarnings("unchecked")
public <T extends Return> T extractRootReturn(LoadPlan loadPlan, Class<T> returnType) {
if ( loadPlan.getReturns().size() == 0 ) {
throw new IllegalStateException( "LoadPlan contained no root returns" );
}
else if ( loadPlan.getReturns().size() > 1 ) {
throw new IllegalStateException( "LoadPlan contained more than one root returns" );
}
final Return rootReturn = loadPlan.getReturns().get( 0 );
if ( !returnType.isInstance( rootReturn ) ) {
throw new IllegalStateException(
String.format(
"Unexpected LoadPlan root return; expecting %s, but found %s",
returnType.getName(),
rootReturn.getClass().getName()
)
);
}
return (T) rootReturn;
}
/**
* Extract the root QuerySpace of the LoadPlan, assuming there is just one.
*
*
* @param querySpaces The QuerySpaces from which to extract the root.
* @param returnType The QuerySpace type expected, passed as an argument
*
* @return The root QuerySpace
*
* @throws IllegalStateException If there is no root, more than one root or the single root
* is not of the expected type.
*/
@SuppressWarnings("unchecked")
public <T extends QuerySpace> T extractRootQuerySpace(QuerySpaces querySpaces, Class<EntityQuerySpace> returnType) {
if ( querySpaces.getRootQuerySpaces().size() == 0 ) {
throw new IllegalStateException( "LoadPlan contained no root query-spaces" );
}
else if ( querySpaces.getRootQuerySpaces().size() > 1 ) {
throw new IllegalStateException( "LoadPlan contained more than one root query-space" );
}
final QuerySpace querySpace = querySpaces.getRootQuerySpaces().get( 0 );
if ( !returnType.isInstance( querySpace ) ) {
throw new IllegalStateException(
String.format(
"Unexpected LoadPlan root query-space; expecting %s, but found %s",
returnType.getName(),
querySpace.getClass().getName()
)
);
}
return (T) querySpace;
}
}