/*
* 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.engine.iterator;
import org.apache.jena.atlas.io.IndentedWriter ;
import com.hp.hpl.jena.graph.Node ;
import com.hp.hpl.jena.query.QueryExecException ;
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.serializer.SerializationContext ;
import com.hp.hpl.jena.sparql.util.FmtUtils ;
import com.hp.hpl.jena.sparql.util.Utils ;
/** Extend each solution by a (var, node)
* When used with mustBeNewVar=false, this is a join.
* If the input already has the variable assigned, then
* it must be the same (.equals) node and if it is not,
* the input row is rejected.
* @see QueryIterAssign
*/
public class QueryIterAssignVarValue extends QueryIterProcessBinding
{
private final Var var ;
private final Node node ;
private final boolean mustBeNewVar ;
public QueryIterAssignVarValue(QueryIterator input, Var var, Node node, ExecutionContext qCxt)
{
this(input, var, node, qCxt, false) ;
}
public QueryIterAssignVarValue(QueryIterator input, Var var, Node node, ExecutionContext qCxt, boolean mustBeNewVar)
{
super(input, qCxt) ;
this.var = var ;
this.node = node ;
this.mustBeNewVar = mustBeNewVar ;
}
@Override
public Binding accept(Binding binding)
{
if ( binding.contains(var) )
{
if ( mustBeNewVar )
throw new QueryExecException("Already set: "+var) ;
Node n2 = binding.get(var) ;
if ( ! n2.equals(node) )
// And filter out.
return null ;
}
return BindingFactory.binding(binding, var, node) ;
}
@Override
protected void details(IndentedWriter out, SerializationContext cxt)
{
out.print(Utils.className(this)) ;
out.print(" ?"+var.toString()+" = "+FmtUtils.stringForNode(node, cxt)) ;
}
}