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HDT Core Library Implementation in Java
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/*
* File: $HeadURL: https://hdt-java.googlecode.com/svn/trunk/hdt-java/src/org/rdfhdt/hdt/header/PlainHeader.java $
* Revision: $Rev: 191 $
* Last modified: $Date: 2013-03-03 11:41:43 +0000 (dom, 03 mar 2013) $
* Last modified by: $Author: mario.arias $
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Contacting the authors:
* Mario Arias: [email protected]
* Javier D. Fernandez: [email protected]
* Miguel A. Martinez-Prieto: [email protected]
* Alejandro Andres: [email protected]
*/
package org.rdfhdt.hdt.header;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.rdfhdt.hdt.enums.RDFNotation;
import org.rdfhdt.hdt.exceptions.IllegalFormatException;
import org.rdfhdt.hdt.exceptions.ParserException;
import org.rdfhdt.hdt.hdt.HDTVocabulary;
import org.rdfhdt.hdt.listener.ProgressListener;
import org.rdfhdt.hdt.options.ControlInfo;
import org.rdfhdt.hdt.options.HDTOptions;
import org.rdfhdt.hdt.options.HDTSpecification;
import org.rdfhdt.hdt.rdf.RDFParserCallback.RDFCallback;
import org.rdfhdt.hdt.rdf.parsers.RDFParserSimple;
import org.rdfhdt.hdt.triples.IteratorTripleString;
import org.rdfhdt.hdt.triples.TripleString;
import org.rdfhdt.hdt.util.io.IOUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* @author mario.arias
*
*/
public class PlainHeader implements HeaderPrivate, RDFCallback {
private static final Logger log = LoggerFactory.getLogger(PlainHeader.class);
protected final HDTOptions spec;
protected final List triples= new ArrayList<>();
public PlainHeader() {
spec = new HDTSpecification();
}
public PlainHeader(HDTOptions spec) {
this.spec = spec;
}
/* (non-Javadoc)
* @see hdt.rdf.RDFStorage#insert(java.lang.String, java.lang.String, java.lang.String)
*/
@Override
public void insert(CharSequence subject, CharSequence predicate, CharSequence object) {
String objStr = object.toString();
if(objStr.charAt(0)=='<'|| objStr.charAt(0)=='"' || objStr.startsWith("http://")||objStr.startsWith("file://")) {
triples.add(new TripleString(HeaderUtil.cleanURI(subject), HeaderUtil.cleanURI(predicate), object));
} else {
triples.add(new TripleString(HeaderUtil.cleanURI(subject), HeaderUtil.cleanURI(predicate), '"'+objStr+'"'));
}
}
/* (non-Javadoc)
* @see hdt.rdf.RDFStorage#insert(java.lang.String, java.lang.String, long)
*/
@Override
public void insert(CharSequence subject, CharSequence predicate, long object) {
triples.add(new TripleString(HeaderUtil.cleanURI(subject), HeaderUtil.cleanURI(predicate), '"'+Long.toString(object)+'"'));
}
/* (non-Javadoc)
* @see hdt.header.Header#save(java.io.OutputStream, hdt.ControlInfo, hdt.ProgressListener)
*/
@Override
public void save(OutputStream output, ControlInfo ci, ProgressListener listener) throws IOException {
// Dump header into an array to calculate size and have it prepared.
ByteArrayOutputStream headerData = new ByteArrayOutputStream();
IteratorTripleString iterator = this.search("", "", "");
while(iterator.hasNext()) {
TripleString next = iterator.next();
IOUtil.writeString(headerData, next.asNtriple().toString());
}
// Create ControlInfo
ci.clear();
ci.setType(ControlInfo.Type.HEADER);
ci.setFormat(HDTVocabulary.HEADER_NTRIPLES);
ci.setInt("length",headerData.size());
ci.save(output);
// Save Data
output.write(headerData.toByteArray());
}
/* (non-Javadoc)
* @see hdt.header.Header#load(java.io.InputStream, hdt.ControlInfo, hdt.ProgressListener)
*/
@Override
public void load(InputStream input, ControlInfo ci, ProgressListener listener) throws IOException {
String format = ci.getFormat();
if(!format.equals(HDTVocabulary.HEADER_NTRIPLES)) {
// FIXME: Add support for other formats
throw new IllegalArgumentException("Cannot parse this Header Format");
}
long headerSize = ci.getInt("length");
byte [] headerData = IOUtil.readBuffer(input, (int)headerSize, listener);
try {
RDFParserSimple parser = new RDFParserSimple();
parser.doParse(new ByteArrayInputStream(headerData), "http://www.rdfhdt.org", RDFNotation.NTRIPLES, this);
} catch (ParserException e) {
log.error("Unexpected exception.", e);
throw new IllegalFormatException("Error parsing header");
}
}
/* (non-Javadoc)
* @see hdt.header.Header#getNumberOfElements()
*/
@Override
public int getNumberOfElements() {
return triples.size();
}
/* (non-Javadoc)
* @see hdt.header.Header#search(java.lang.String, java.lang.String, java.lang.String)
*/
@Override
public IteratorTripleString search(CharSequence subject, CharSequence predicate, CharSequence object) {
TripleString pattern = new TripleString(subject.toString(), predicate.toString(), object.toString());
return new PlainHeaderIterator(this, pattern);
}
@Override
public void processTriple(TripleString triple, long pos) {
triples.add(new TripleString(triple));
}
@Override
public void remove(CharSequence subject, CharSequence predicate, CharSequence object) {
TripleString pattern = new TripleString(subject.toString(), predicate.toString(), object.toString());
Iterator iter = triples.iterator();
while(iter.hasNext()) {
TripleString next = iter.next();
if(next.match(pattern)) {
iter.remove();
}
}
}
@Override
public CharSequence getBaseURI() {
IteratorTripleString it = search("", HeaderUtil.cleanURI(HDTVocabulary.RDF_TYPE), HeaderUtil.cleanURI(HDTVocabulary.HDT_DATASET));
if(it.hasNext()) {
TripleString ts = it.next();
return ts.getSubject();
}
return "";
}
}