/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 com.hp.hpl.jena.sparql.algebra.table;
import java.util.ArrayList ;
import java.util.List ;
import com.hp.hpl.jena.sparql.core.Var ;
import com.hp.hpl.jena.sparql.engine.ExecutionContext ;
import com.hp.hpl.jena.sparql.engine.QueryIterator ;
import com.hp.hpl.jena.sparql.engine.binding.Binding ;
import com.hp.hpl.jena.sparql.engine.iterator.QueryIterNullIterator ;
import com.hp.hpl.jena.sparql.engine.iterator.QueryIterSingleton ;
import com.hp.hpl.jena.sparql.expr.ExprList ;
public class TableEmpty extends TableBase
{
public TableEmpty()
{ }
@Override
public QueryIterator iterator(ExecutionContext execCxt)
{
return new QueryIterNullIterator(execCxt) ;
}
@Override
public QueryIterator matchRightLeft(Binding bindingLeft, boolean includeOnNoMatch,
ExprList conditions,
ExecutionContext execContext)
{
if ( includeOnNoMatch )
return QueryIterSingleton.create(bindingLeft, execContext) ;
else
// No rows - no match
return new QueryIterNullIterator(execContext) ;
}
@Override
public boolean contains(Binding binding) { return false ; }
@Override
public void closeTable() { }
@Override
public List<String> getVarNames() { return new ArrayList<String>() ; }
@Override
public List<Var> getVars() { return new ArrayList<Var>() ; }
@Override
public String toString() { return "TableEmpty" ; }
@Override
public int size() { return 0 ; }
@Override
public boolean isEmpty() { return true ; }
}