/*
* Licensed to the Apache Software Foundation (ASF) under one
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* 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 org.apache.jena.graph.compose;
import java.util.Set ;
import org.apache.jena.graph.Graph ;
import org.apache.jena.graph.Triple ;
import org.apache.jena.util.CollectionFactory ;
import org.apache.jena.util.iterator.ExtendedIterator ;
/**
A class representing the dynamic union of two graphs. Addition only affects the left
operand, deletion affects both.
@see MultiUnion
*/
public class Union extends Dyadic implements Graph
{
public Union( Graph L, Graph R )
{ super( L, R ); }
/**
To add a triple to the union, add it to the left operand; this is asymmetric.
*/
@Override public void performAdd( Triple t )
{ L.add( t ); }
/**
To remove a triple, remove it from <i>both</i> operands.
*/
@Override public void performDelete( Triple t )
{
L.delete( t );
R.delete( t );
}
@Override public boolean graphBaseContains( Triple t )
{ return L.contains( t ) || R.contains( t ); }
/**
To find in the union, find in the components, concatenate the results, and omit
duplicates. That last is a performance penalty, but I see no way to remove it
unless we know the graphs do not overlap.
*/
@Override protected ExtendedIterator<Triple> _graphBaseFind( final Triple t )
{
Set<Triple> seen = CollectionFactory.createHashedSet();
return recording( L.find( t ), seen ).andThen( rejecting( R.find( t ), seen ) );
// return L.find( t ) .andThen( rejecting( R.find( t ), L ) );
}
}