/*
* 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
///////////////
package org.apache.jena.graph.compose;
// Imports
///////////////
import java.util.ArrayList ;
import java.util.Iterator ;
import java.util.List ;
import org.apache.jena.graph.Capabilities ;
import org.apache.jena.graph.Graph ;
import org.apache.jena.graph.TransactionHandler ;
import org.apache.jena.shared.JenaException ;
import org.apache.jena.shared.PrefixMapping ;
import org.apache.jena.util.iterator.ClosableIterator ;
/**
* <p>
* A base class for composition graphs that are composed from zero or more
* sub-graphs (thus providing a basis for polyadic composition operators).
* A distinguished graph is the designated graph for additions to the union.
* By default, this is the first sub-graph of the composition, however any
* of the graphs in the composition can be nominated to be the distinguished
* graph.
* </p>
*/
public abstract class Polyadic extends CompositionBase
{
// Constants
//////////////////////////////////
// Static variables
//////////////////////////////////
// Instance variables
//////////////////////////////////
/** A list of the sub-graphs that this composition contains */
protected List<Graph> m_subGraphs = new ArrayList<>();
/** The distinguished graph for adding to. If null, use the 0'th graph in the list. */
protected Graph m_baseGraph = null;
// Constructors
//////////////////////////////////
/**
* <p>
* Construct a composition of exactly no sub graphs.
* </p>
*/
public Polyadic() {
}
/**
* <p>
* Construct a composition of all of the given graphs
* </p>
*
* @param graphs An array of the sub-graphs of this composition
*/
public Polyadic( Graph[] graphs) {
for ( Graph graph : graphs )
{
m_subGraphs.add( graph );
}
}
@Override
protected PrefixMapping createPrefixMapping()
{
return new PolyadicPrefixMappingImpl( this );
}
/**
* <p>
* Construct a composition of all of the given graphs.
* </p>
*
* @param graphs An iterator of the sub-graphs of this composition. If graphs is
* a closable iterator, it will be automatically closed.
*/
public Polyadic( Iterator<Graph> graphs ) {
while (graphs.hasNext()) {
m_subGraphs.add( graphs.next() );
}
if (graphs instanceof ClosableIterator<?>) {
((ClosableIterator<Graph>) graphs).close();
}
}
// External signature methods
//////////////////////////////////
/**
* <p>
* Close the graph by closing all of the sub-graphs.
* </p>
*
* @see org.apache.jena.graph.Graph#close()
*/
@Override
public void close() {
for ( Graph m_subGraph : m_subGraphs )
{
m_subGraph.close();
}
super.close();
}
/**
* <p>
* Answer true if this graph contains the given graph as a sub-component.
* </p>
*
* @param graph A graph to test
* @return True if the graph is this graph, or is a sub-graph of this one.
* @see org.apache.jena.graph.Graph#dependsOn(Graph)
*/
@Override
public boolean dependsOn( Graph graph ) {
return (graph == this) || m_subGraphs.contains( graph );
}
/**
* <p>
* Add the given graph to this composition.
* </p>
*
* @param graph A sub-graph to add to this composition
*/
public void addGraph( Graph graph ) {
m_subGraphs.add( graph );
}
/**
* <p>
* Remove the given graph from this composition. If the removed graph is the
* designated updateable graph, the updatable graph goes back to the default
* for this composition.
* </p>
*
* @param graph A sub-graph to remove from this composition
*/
public void removeGraph( Graph graph ) {
m_subGraphs.remove( graph );
if (m_baseGraph == graph) {
m_baseGraph = null;
}
}
/**
* <p>
* Answer the distinguished graph for the composition, which will be the graph
* that receives triple adds and deletes. If no base graph is defined,
* return null.
* </p>
*
* @return The distinguished updateable graph, or null if there are no graphs
* in this composition
*/
public Graph getBaseGraph() {
if (m_baseGraph == null) {
// no designated graph, so default to the first graph on the list
return (m_subGraphs.size() == 0) ? null : m_subGraphs.get( 0 );
}
else {
return m_baseGraph;
}
}
/**
* <p>
* Answer the distinguished graph for the composition, which will be the graph
* that receives triple adds and deletes. If no base graph is defined, throw
* a {@link JenaException}.
* </p>
*
* @return The distinguished updateable graph, or null if there are no graphs
* in this composition
*/
public Graph getRequiredBaseGraph() {
Graph base = getBaseGraph();
if (base == null) {
throw new JenaException( "This polyadic graph should have a base graph, but none is defined" );
}
else {
return base;
}
}
/**
* <p>
* Set the designated updateable graph for this composition.
* </p>
*
* @param graph One of the graphs currently in this composition to be the
* designated graph to receive udpates
* @exception IllegalArgumentException if graph is not one of the members of
* the composition
*/
public void setBaseGraph( Graph graph ) {
if (m_subGraphs.contains( graph )) {
m_baseGraph = graph;
}
else {
throw new IllegalArgumentException( "The updateable graph must be one of the graphs from the composition" );
}
}
/**
* <p>
* Answer a list of the graphs other than the updateable (base) graph
* </p>
*
* @return A list of all of the sub-graphs, excluding the base graph.
*/
public List<Graph> getSubGraphs() {
List<Graph> sg = new ArrayList<>( m_subGraphs );
if (getBaseGraph() != null) {
sg.remove( getBaseGraph() );
}
return sg;
}
@Override
public TransactionHandler getTransactionHandler() {
return (getBaseGraph() == null) ? super.getTransactionHandler() : getBaseGraph().getTransactionHandler();
}
@Override
public Capabilities getCapabilities() {
return (getBaseGraph() == null) ? super.getCapabilities() : getBaseGraph().getCapabilities();
}
}