| /* |
| * 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 org.apache.jena.graph.compose; |
| |
| import org.apache.jena.graph.* ; |
| import org.apache.jena.util.iterator.* ; |
| |
| /** |
| Class representing the dynamic set difference L - R of two graphs. This is updatable; |
| the updates are written through to one or other of the base graphs. |
| */ |
| public class Difference extends Dyadic implements Graph |
| { |
| /** |
| Initialise a graph representing the difference L - R. |
| */ |
| public Difference( Graph L, Graph R ) |
| { super( L, R ); } |
| |
| /** |
| Add a triple to the difference: add it to the left operand, and remove it from the |
| right operand. |
| */ |
| @Override public void performAdd( Triple t ) |
| { |
| L.add( t ); |
| R.delete( t ); |
| } |
| |
| /** |
| Remove a triple from the difference: remove it from the left operand. [It could |
| be added to the right operand instead, but somehow that feels less satisfactory.] |
| */ |
| @Override public void performDelete( Triple t ) |
| { L.delete( t ); } |
| |
| @Override public ExtendedIterator<Triple> _graphBaseFind( Triple t ) |
| { return L.find( t ). filterDrop ( ifIn( R ) ); } |
| } |