/*
* 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.reasoner.transitiveReasoner;
import java.util.*;
import org.apache.jena.graph.* ;
import org.apache.jena.reasoner.* ;
import org.apache.jena.util.iterator.ExtendedIterator ;
import org.apache.jena.vocabulary.RDFS ;
/**
* Uses two transitive graph caches to store a subclass and a subproperty
* lattice and use them within a larger inference graph.
*/
public class TransitiveEngine {
/** The precomputed cache of the subClass graph */
protected TransitiveGraphCache subClassCache;
/** The precomputed cache of the subProperty graph */
protected TransitiveGraphCache subPropertyCache;
/** The base data set from which the caches can be rebuilt */
protected Finder data;
/** True if the internal data structures have been initialized */
protected boolean isPrepared = false;
/** The set of predicates which are aliases for subClassOf */
protected static HashSet<Node> subClassAliases;
/** The set of predicates which are aliases for subPropertyOf */
protected static HashSet<Node> subPropertyAliases;
/** Classification flag: not relevant to this engine */
private static final int NOT_RELEVANT = 1;
/** Classification flag: simple or indirect subClass */
private static final int SUBCLASS = 2;
/** Classification flag: simple subProperty */
private static final int SUBPROPERTY = 4;
/** Mask for the lattice update cases */
// private static final int UPDATE_MASK = SUBCLASS | SUBPROPERTY;
private static final int UPDATE_MASK = SUBCLASS | SUBPROPERTY | NOT_RELEVANT;
/** Classification flag: subProperty of subClass */
private static final int REBUILD_SUBCLASS = 8;
/** Classification flag: subProperty of subProperty */
private static final int REBUILD_SUBPROPERTY = 16;
/** The direct (minimal) version of the subPropertyOf property */
public static Node directSubPropertyOf;
/** The direct (minimal) version of the subClassOf property */
public static Node directSubClassOf;
/** The normal subPropertyOf property */
public static Node subPropertyOf;
/** The normal subClassOf property */
public static Node subClassOf;
// Static initializer
static {
directSubPropertyOf = TransitiveReasoner.directSubPropertyOf;
directSubClassOf = TransitiveReasoner.directSubClassOf;
subPropertyOf = RDFS.subPropertyOf.asNode();
subClassOf = RDFS.subClassOf.asNode();
}
/**
* Constructor.
* @param subClassCache pre-initialized subclass TGC
* @param subPropertyCache pre-initialized subproperty TGC
*/
public TransitiveEngine(TransitiveGraphCache subClassCache,
TransitiveGraphCache subPropertyCache) {
this.subClassCache = subClassCache;
this.subPropertyCache = subPropertyCache;
}
/**
* Constructor.
* @param tengine an instance of TransitiveEngine to be cloned
*/
public TransitiveEngine(TransitiveEngine tengine) {
this.subClassCache = tengine.getSubClassCache().deepCopy();
this.subPropertyCache = tengine.getSubPropertyCache().deepCopy();
}
/**
* Prepare the engine by inserting any new data not already included
* in the existing caches.
* @param baseData the base dataset on which the initial caches were based, could be null
* @param newData a dataset to be added to the engine, not known to be already
* included in the caches from construction time
* @return a concatenation of the inserted data and the original data
*/
public Finder insert(Finder baseData, FGraph newData) {
Graph newDataG = newData.getGraph();
if (baseData != null) {
data = FinderUtil.cascade(baseData, newData);
} else {
data = newData;
}
if ((TransitiveEngine.checkOccuranceUtility(subPropertyOf, newDataG, subPropertyCache) ||
TransitiveEngine.checkOccuranceUtility(subClassOf, newDataG, subPropertyCache))) {
subClassCache = new TransitiveGraphCache(directSubClassOf, subClassOf);
subPropertyCache = new TransitiveGraphCache(directSubPropertyOf, subPropertyOf);
TransitiveEngine.cacheSubPropUtility(data, subPropertyCache);
TransitiveEngine.cacheSubClassUtility(data, subPropertyCache, subClassCache);
}
return data;
}
/**
* Return the cache of the subclass lattice.
*/
public TransitiveGraphCache getSubClassCache() {
return subClassCache;
}
/**
* Return the cache of the subclass lattice.
*/
public TransitiveGraphCache getSubPropertyCache() {
return subPropertyCache;
}
/**
* Set the closure caching flags.
* @param cacheSP true if caching of subPropertyOf closure is wanted
* @param cacheSC true if caching of subClassOf closure is wanted
*/
public void setCaching(boolean cacheSP, boolean cacheSC) {
subPropertyCache.setCaching(cacheSP);
subClassCache.setCaching(cacheSC);
}
/**
* Build alias tables for subclass and subproperty.
*/
private void prepare() {
if (isPrepared) return;
subClassAliases = new HashSet<>();
subClassAliases.add(subClassOf);
subClassAliases.add(directSubClassOf);
subPropertyAliases = new HashSet<>();
subPropertyAliases.add(subPropertyOf);
subPropertyAliases.add(directSubPropertyOf);
Iterator<Triple> subProps = subPropertyCache.find(new TriplePattern(null, subPropertyOf, subPropertyOf));
while (subProps.hasNext()) {
Triple spT = subProps.next();
Node spAlias = spT.getSubject();
subPropertyAliases.add(spAlias);
Iterator<Triple> subClasses = subPropertyCache.find(new TriplePattern(null, spAlias, subClassOf));
while (subClasses.hasNext()) {
subClassAliases.add(subClasses.next().getObject());
}
}
isPrepared = true;
}
/**
* Classify an incoming triple to detect whether it is relevant to this engine.
* @param t the triple being added
* @return a classification flag, as specified in the above private properties
*/
private int triage(Triple t) {
if (!isPrepared) prepare();
Node predicate = t.getPredicate();
if (subClassAliases.contains(predicate)) {
return SUBCLASS;
} else if (subPropertyAliases.contains(predicate)) {
Node target = t.getObject();
if (subClassAliases.contains(target)) {
return REBUILD_SUBCLASS | SUBPROPERTY;
} else if (subPropertyAliases.contains(target)) {
return REBUILD_SUBCLASS | REBUILD_SUBPROPERTY;
} else {
return SUBPROPERTY;
}
} else {
return NOT_RELEVANT;
}
}
/**
* Return a Finder instance appropriate for the given query.
*/
public Finder getFinder(TriplePattern pattern, Finder continuation) {
if (!isPrepared) prepare();
Node predicate = pattern.getPredicate();
if (predicate.isVariable()) {
// Want everything in the cache, the tbox and the continuation
return FinderUtil.cascade(subPropertyCache, subClassCache, continuation);
} else if (subPropertyAliases.contains(predicate)) {
return subPropertyCache;
} else if (subClassAliases.contains(predicate)) {
return subClassCache;
} else {
return continuation;
}
}
/**
* Add one triple to caches if it is relevant.
* @return true if the triple affected the caches
*/
public synchronized boolean add(Triple t) {
int triageClass = triage(t);
switch (triageClass & UPDATE_MASK) {
case SUBCLASS:
subClassCache.addRelation(t);
break;
case SUBPROPERTY:
subPropertyCache.addRelation(t);
break;
case NOT_RELEVANT:
return false;
}
// If we get here we might need to some cache rebuilding
if ((triageClass & REBUILD_SUBPROPERTY) != 0) {
TransitiveEngine.cacheSubPropUtility(data, subPropertyCache);
isPrepared = false;
}
if ((triageClass & REBUILD_SUBCLASS) != 0) {
TransitiveEngine.cacheSubClassUtility(data, subPropertyCache, subClassCache);
isPrepared = false;
}
return true;
}
/**
* Removes the triple t (if relevant) from the caches.
* @return true if the triple affected the caches
*/
public synchronized boolean delete(Triple t) {
int triageClass = triage(t);
switch (triageClass & UPDATE_MASK) {
case SUBCLASS:
subClassCache.removeRelation(t);
break;
case SUBPROPERTY:
subPropertyCache.removeRelation(t);
break;
case NOT_RELEVANT:
return false;
}
// If we get here we might need to some cache rebuilding
if ((triageClass & REBUILD_SUBPROPERTY) != 0) {
subPropertyCache.clear();
TransitiveEngine.cacheSubPropUtility(data, subPropertyCache);
isPrepared = false;
}
if ((triageClass & REBUILD_SUBCLASS) != 0) {
subClassCache.clear();
TransitiveEngine.cacheSubClassUtility(data, subPropertyCache, subClassCache);
isPrepared = false;
}
return true;
}
/**
* Test if there are any usages of prop within the given graph.
* This includes indirect usages incurred by subProperties of prop.
*
* @param prop the property to be checked for
* @param graph the graph to be check
* @return true if there is a triple using prop or one of its sub properties
*/
public boolean checkOccurance(Node prop, Graph graph) {
return checkOccuranceUtility(prop, graph, subPropertyCache);
}
/**
* Caches all subClass declarations, including those that
* are defined via subProperties of subClassOf. Public to allow other reasoners
* to use it but not of interest to end users.
*
* @param graph a graph whose declarations are to be cached
* @param spCache the existing state of the subPropertyOf cache
* @param scCache the existing state of the subClassOf cache, will be updated
* @return true if there were new metalevel declarations discovered.
*/
public static boolean cacheSubClassUtility(Finder graph, TransitiveGraphCache spCache, TransitiveGraphCache scCache) {
if (graph == null) return false;
scCache.cacheAll(graph, TransitiveReasoner.subClassOf);
// Check for any properties which are subProperties of subClassOf
boolean foundAny = false;
ExtendedIterator<Triple> subClasses
= spCache.find(new TriplePattern(null, TransitiveReasoner.subPropertyOf, TransitiveReasoner.subClassOf));
while (subClasses.hasNext()) {
foundAny = true;
Triple t = subClasses.next();
Node subClass = t.getSubject();
if (!subClass.equals(TransitiveReasoner.subClassOf)) {
scCache.cacheAll(graph, subClass);
}
}
return foundAny;
}
/**
* Test if there are any usages of prop within the given graph.
* This includes indirect usages incurred by subProperties of prop.
* Public to allow other reasoners
* to use it but not of interest to end users.
*
* @param prop the property to be checked for
* @param graph the graph to be check
* @param spCache the subPropertyOf cache to use
* @return true if there is a triple using prop or one of its sub properties
*/
private static boolean checkOccuranceUtility(Node prop, Graph graph, TransitiveGraphCache spCache) {
boolean foundOne = false;
ExtendedIterator<Triple> uses = graph.find( null, prop, null );
foundOne = uses.hasNext();
uses.close();
if (foundOne) return foundOne;
ExtendedIterator<Triple> propVariants
= spCache.find(new TriplePattern(null, TransitiveReasoner.subPropertyOf, prop));
while (propVariants.hasNext() && !foundOne) {
Triple t = propVariants.next();
Node propVariant = t.getSubject();
uses = graph.find( null, propVariant, null );
foundOne = uses.hasNext();
uses.close();
}
propVariants.close();
return foundOne;
}
/**
* Caches all subPropertyOf declarations, including any meta level
* ones (subPropertyOf subPropertyOf). Public to allow other reasoners
* to use it but not of interest to end users.
*
* @param graph a graph whose declarations are to be cached
* @param spCache the existing state of the subPropertyOf cache, will be updated
* @return true if there were new metalevel declarations discovered.
*/
public static boolean cacheSubPropUtility(Finder graph, TransitiveGraphCache spCache) {
if (graph == null) return false;
spCache.cacheAll(graph, TransitiveReasoner.subPropertyOf);
// Check for any properties which are subProperties of subProperty
// and so introduce additional subProperty relations.
// Each one discovered might reveal indirect subPropertyOf subPropertyOf
// declarations - hence the double iteration
boolean foundAny = false;
boolean foundMore = false;
HashSet<Node> cached = new HashSet<>();
do {
ExtendedIterator<Triple> subProps
= spCache.find(new TriplePattern(null, TransitiveReasoner.subPropertyOf, TransitiveReasoner.subPropertyOf));
while (subProps.hasNext()) {
foundMore = false;
Triple t = subProps.next();
Node subProp = t.getSubject();
if (!subProp.equals(TransitiveReasoner.subPropertyOf) && !cached.contains(subProp)) {
foundAny = true;
cached.add(subProp);
spCache.cacheAll(graph, subProp);
foundMore = true;
}
}
} while (foundMore);
return foundAny;
}
}