/*
* 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.graph.Node ;
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.binding.BindingFactory ;
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 ;
import com.hp.hpl.jena.sparql.util.FmtUtils ;
/** A table of one row of one binding */
public class Table1 extends TableBase
{
private Var var ;
private Node value ;
public Table1(Var var, Node value)
{
this.var = var ;
this.value = value ;
}
@Override
public QueryIterator iterator(ExecutionContext execCxt)
{
// Root binding?
Binding binding = BindingFactory.binding(var, value) ;
QueryIterator qIter = QueryIterSingleton.create(binding, var, value, execCxt) ;
return qIter ;
}
@Override
public QueryIterator matchRightLeft(Binding bindingLeft, boolean includeOnNoMatch,
ExprList conditions,
ExecutionContext execContext)
{
boolean matches = true ;
Node other = bindingLeft.get(var) ;
if ( other == null )
{
// Not present - return the merge = the other binding + this (var/value)
Binding mergedBinding = BindingFactory.binding(bindingLeft, var, value) ;
return QueryIterSingleton.create(mergedBinding, execContext) ;
}
if ( ! other.equals(value) )
matches = false ;
else
{
if ( conditions != null )
matches = conditions.isSatisfied(bindingLeft, execContext) ;
}
if ( ! matches && ! includeOnNoMatch)
return new QueryIterNullIterator(execContext) ;
// Matches, or does not match and it's a left join - return the left binding.
return QueryIterSingleton.create(bindingLeft, execContext) ;
}
@Override
public void closeTable() {}
@Override
public List<Var> getVars()
{
List<Var> x = new ArrayList<Var>() ;
x.add(var) ;
return x ;
}
@Override
public List<String> getVarNames()
{
List<String> x = new ArrayList<String>() ;
x.add(var.getVarName()) ;
return x ;
}
@Override
public int size() { return 1 ; }
@Override
public boolean isEmpty() { return false ; }
@Override
public String toString() { return "Table1("+var+","+FmtUtils.stringForNode(value)+")" ; }
}