/*
* $Header: /home/cvs/jakarta-slide/src/share/org/apache/slide/search/basic/expression/EmptyExpression.java,v 1.2.2.1 2004/02/05 16:05:11 mholz Exp $
* $Revision: 1.2.2.1 $
* $Date: 2004/02/05 16:05:11 $
*
* ====================================================================
*
* Copyright 1999-2002 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.apache.slide.search.basic.expression;
import org.apache.slide.search.SearchException;
import org.apache.slide.search.basic.BasicResultSetImpl;
import org.apache.slide.search.basic.ComparableResourcesPool;
import org.apache.slide.search.basic.IBasicExpression;
import org.apache.slide.search.basic.IBasicResultSet;
/**
* Represents an AND expression.
*
* @author <a href="mailto:martin.wallmer@softwareag.com">Martin Wallmer</a>
* @version $Revision: 1.2.2.1 $
*/
public class EmptyExpression implements IBasicExpression {
/**
* The pool of resources to apply the expression to.
*/
protected ComparableResourcesPool requestedResourcesPool = null;
/**
* Creates an empty expression. This occurs when no <where> clause
* was supplied
*
* @param requestedResourcesPool the pool of resources to apply the expression to.
*/
public EmptyExpression (ComparableResourcesPool requestedResourcesPool) {
this.requestedResourcesPool = requestedResourcesPool;
}
/**
* Executes the expression.
*
* @return a Set of RequestedResource objects
*
* @throws SearchException
*/
public IBasicResultSet execute () throws SearchException {
return new BasicResultSetImpl(requestedResourcesPool.getPool(),
requestedResourcesPool.partialResult());
}
/**
* String representation for debugging purposes.
*
* @return this expression as String
*/
public String toString () {
return "";
}
}