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package be.ugent.rml.store;
import be.ugent.rml.term.Term;
import org.eclipse.rdf4j.rio.RDFFormat;
import java.io.*;
import java.util.Collections;
import java.util.List;
/**
* Vendor-neutral interface for managing RDF collections.
* Implemented for RDF4J
* and custom SimpleQuadStore (for faster implementation without indexing of RDF libraries)
*/
public abstract class QuadStore {
// START ABSTRACT METHODS
// implement these when extending QuadStore
@Override
public abstract boolean equals(Object o);
/**
* Remove all Quads matching input from store.
* @param subject
* @param predicate
* @param object
* @param graph
*/
public abstract void removeQuads(Term subject, Term predicate, Term object, Term graph);
/**
* True if Quad matching input is present in store.
* @param subject
* @param predicate
* @param object
* @param graph
* @return
*/
public abstract boolean contains(Term subject, Term predicate, Term object, Term graph);
/**
* Test if given store and this store are isomorphic RDF graph representations
* @param store
* @return
*/
public abstract boolean isIsomorphic(QuadStore store);
/**
* Test if given store is subset of this store
* @param store
* @return
*/
public abstract boolean isSubset(QuadStore store);
/**
* Remove duplicate quads
*/
public abstract void removeDuplicates();
/**
* Add given Quad to store
* @param subject
* @param predicate
* @param object
* @param graph
*/
public abstract void addQuad(Term subject, Term predicate, Term object, Term graph);
/**
* Get all Quads in store matching arguments.
* Null can be used as a wildcard.
* @param subject
* @param predicate
* @param object
* @param graph
* @return
*/
public abstract List getQuads(Term subject, Term predicate, Term object, Term graph);
/**
* Copy namespaces between stores. Used in retaining the prefixes in the mapping file in the output.
* TODO define general Namespace class to use between QuadStore instances
*
* @param store QuadStore with namespaces to be copied to this store
*/
public abstract void copyNameSpaces(QuadStore store);
/**
* True if RDF quads present is 0
*
* @return boolean
*/
public abstract boolean isEmpty();
/**
* Number of RDF quads
*
* @return int
*/
public abstract int size();
/**
* Read RDF to QuadStore
* TODO use class or enum for input format
*
* @param is Stream of RDF in given format
* @param base Base URL
* @param format Given format for RDF
*/
public abstract void read(InputStream is, String base, RDFFormat format) throws Exception;
/**
* Write out the QuadStore in given format
* TODO use class or enum for output format
*
* @param out Writer output location
* @param format QuadStore format (.TTL)
* @throws Exception
*/
public abstract void write(Writer out, String format) throws Exception;
// END OF ABSTRACT METHODS
// following final methods use the abstract methods to provide additional functionality or helper functions
/**
* Helper function
*
* @param out
* @param format
* @throws Exception
*/
public final void write(ByteArrayOutputStream out, String format) throws Exception {
write(new BufferedWriter(new OutputStreamWriter(out)), format);
}
/**
* Helper function
*
* @param out
* @param format
* @throws Exception
*/
public final void write(PrintStream out, String format) throws Exception {
write(new PrintWriter(out), format);
}
/**
* Helper function
*
* @param subject
* @param predicate
* @param object
* @param graph
* @return
* @throws Exception
*/
public final Quad getQuad(Term subject, Term predicate, Term object, Term graph) throws Exception {
List list = getQuads(subject, predicate, object, graph);
if (list.size() != 1) {
throw new Exception(String.format("Single Quad expected, found %s", list.size()));
}
return list.get(0);
}
/**
* Helper function
*
* @param subject
* @param predicate
* @param object
* @return
* @throws Exception
*/
public final Quad getQuad(Term subject, Term predicate, Term object) throws Exception {
return getQuad(subject, predicate, object, null);
}
/**
* Helper function
*
* @param subject
* @param predicate
* @param object
* @return
*/
public final List getQuads(Term subject, Term predicate, Term object) {
return getQuads(subject, predicate, object, null);
}
public abstract List getSubjects();
/**
* Helper function
* @param subject
* @param predicate
* @param object
* @return
*/
public final boolean contains(Term subject, Term predicate, Term object) {
return contains(subject, predicate, object, null);
}
/**
* Helper function
*
* @param subject
* @param predicate
* @param object
*/
public final void addQuad(Term subject, Term predicate, Term object) {
addQuad(subject, predicate, object, null);
}
/**
* Helper function
* @param q
*/
public final void addQuad(Quad q) {
addQuad(q.getSubject(), q.getPredicate(), q.getObject(), q.getGraph());
}
/**
* Add all quads in given list
*
* @param quads to be added to QuadStore
*/
public final void addQuads(List quads) {
quads.forEach(quad -> addQuad(quad.getSubject(), quad.getPredicate(), quad.getObject(), quad.getGraph()));
}
/**
* Helper function
* @param subject
* @param predicate
* @param object
*/
public final void removeQuads(Term subject, Term predicate, Term object) {
removeQuads(subject, predicate, object, null);
}
public final void removeQuads(Quad quad) {
removeQuads(quad.getSubject(), quad.getPredicate(), quad.getObject(), quad.getGraph());
}
public final void removeQuads(List quads) {
for (Quad quad : quads) {
removeQuads(quad);
}
}
/**
* If fromPredicate is present on from, rename it to toPredicate and move it to to
* @param from
* @param fromPredicate
* @param to
* @param toPredicate
*/
public final void tryPropertyTranslation(Term from, Term fromPredicate, Term to, Term toPredicate) {
List quads = getQuads(from, fromPredicate, null);
for (Quad quad : quads) {
addQuad(to, toPredicate, quad.getObject());
}
removeQuads(quads);
}
/**
* Rename all predicates in graph
* @param fromPredicate predicate to be renamed
* @param toPredicate new predicate name
*/
public final void renameAllPredicates(Term fromPredicate, Term toPredicate) {
List quads = getQuads(null, fromPredicate, null);
for (Quad q : quads) {
addQuad(q.getSubject(), toPredicate, q.getObject());
}
removeQuads(quads);
}
public final void renameAllObjects(Term fromObject, Term toObject) {
List quads = getQuads(null, null, fromObject);
for (Quad q : quads) {
addQuad(q.getSubject(), q.getPredicate(), toObject);
}
removeQuads(quads);
}
/**
* Uses Quads in string representation
*
* @return String of QuadStore
*/
public final String toString() {
StringBuilder output = new StringBuilder();
List quads = getQuads(null, null, null);
for (Quad q : quads) {
output.append(q.getSubject()).append(" ").append(q.getPredicate()).append(" ").append(q.getObject()).append(" ").append(q.getGraph()).append("\n");
}
return output.toString();
}
/**
* Use sorted Quads in string representation
*
* @return sorted String of QuadStore
*/
public final String toSortedString() {
StringBuilder output = new StringBuilder();
List quads = getQuads(null, null, null);
Collections.sort(quads);
for (Quad q : quads) {
output.append(q.getSubject()).append(" ").append(q.getPredicate()).append(" ").append(q.getObject()).append(" ").append(q.getGraph()).append("\n");
}
return output.toString();
}
}
