/*******************************************************************************
* Copyright (c) 1998, 2009 Oracle. 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 from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.mappings.querykeys;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.exceptions.QueryException;
import org.eclipse.persistence.expressions.Expression;
import org.eclipse.persistence.internal.expressions.DataExpression;
import org.eclipse.persistence.internal.expressions.ExpressionIterator;
import org.eclipse.persistence.internal.expressions.ParameterExpression;
import org.eclipse.persistence.internal.expressions.TableExpression;
import org.eclipse.persistence.internal.helper.DatabaseField;
import org.eclipse.persistence.internal.helper.DatabaseTable;
/** <p>
* <b>Purpose</b>:Represents a m-m join query.
*/
public class ManyToManyQueryKey extends ForeignReferenceQueryKey {
/**
* INTERNAL:
* override the isCollectionQueryKey() method in the superclass to return true.
* @return boolean
*/
public boolean isCollectionQueryKey() {
return true;
}
/**
* INTERNAL:
* override the isManyToManyQueryKey() method in the superclass to return true.
* @return boolean
*/
public boolean isManyToManyQueryKey() {
return true;
}
/**
* PUBLIC:
* Returns the reference table.
*/
public DatabaseTable getRelationTable(ClassDescriptor referenceDescriptor) {
ExpressionIterator expIterator = new ExpressionIterator() {
public void iterate(Expression each) {
if(each.isTableExpression()) {
((Collection)this.getResult()).add(((TableExpression)each).getTable());
}
else if(each.isDataExpression()) {
DatabaseField field = ((DataExpression)each).getField();
if(field != null && field.hasTableName()) {
((Collection)this.getResult()).add(field.getTable());
}
} else if(each.isParameterExpression()) {
DatabaseField field = ((ParameterExpression)each).getField();
if(field != null && field.hasTableName()) {
((Collection)this.getResult()).add(field.getTable());
}
}
}
};
expIterator.setResult(new HashSet());
expIterator.iterateOn(this.joinCriteria);
HashSet<DatabaseTable> tables = (HashSet)expIterator.getResult();
DatabaseTable relationTable = null;
Iterator<DatabaseTable> it = tables.iterator();
while(it.hasNext()) {
DatabaseTable table = it.next();
// neither source nor reference descriptor contains table - must be relationTable
if(!descriptor.getTables().contains(table) && !referenceDescriptor.getTables().contains(table)) {
relationTable = table;
break;
}
}
if(relationTable != null) {
return relationTable;
} else {
throw QueryException.noRelationTableInManyToManyQueryKey(this, this.joinCriteria);
}
}
}