package it.unimi.dsi.mg4j.document;
/*
* MG4J: Managing Gigabytes for Java
*
* Copyright (C) 2006-2010 Sebastiano Vigna
*
* 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 3 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 program; if not, see <http://www.gnu.org/licenses/>.
*
*/
import static it.unimi.dsi.mg4j.document.TRECDocumentCollection.DOCHDR_CLOSE;
import static it.unimi.dsi.mg4j.document.TRECDocumentCollection.DOCHDR_OPEN;
import static it.unimi.dsi.mg4j.document.TRECDocumentCollection.DOCNO_CLOSE;
import static it.unimi.dsi.mg4j.document.TRECDocumentCollection.DOCNO_OPEN;
import static it.unimi.dsi.mg4j.document.TRECDocumentCollection.DOC_OPEN;
import it.unimi.dsi.fastutil.io.FastBufferedInputStream;
import it.unimi.dsi.fastutil.objects.Reference2ObjectMap;
import it.unimi.dsi.io.WordReader;
import it.unimi.dsi.mg4j.document.PropertyBasedDocumentFactory.MetadataKeys;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
/** A factory without fields that is used to interpret the header of a
* TREC GOV2 document. It is usually the first factory to interpret
* a document of a {@link it.unimi.dsi.mg4j.document.TRECDocumentCollection}.
* <p>Presently, its only rôumflex;le is that of parsing the document
* URI and setting a metadata item with key {@link it.unimi.dsi.mg4j.document.PropertyBasedDocumentFactory.MetadataKeys#URI}.
*
* @author Alessio Orlandi
* @author Luca Natali
*/
public class TRECHeaderDocumentFactory extends AbstractDocumentFactory {
private static final long serialVersionUID = -8671564750345493607L;
private class TRECHeaderDocument extends AbstractDocument {
final Reference2ObjectMap<Enum<?>,Object> metadata;
public CharSequence title() {
CharSequence t = (CharSequence)metadata.get( MetadataKeys.TITLE );
return ( t == null ? "Title for " + uri() : t );
}
public CharSequence uri() {
return (CharSequence)metadata.get( MetadataKeys.URI );
}
public Object content( int fieldIndex ) throws IOException {
throw new IllegalArgumentException();
}
public WordReader wordReader( int fieldIndex ) {
throw new IllegalArgumentException();
}
public TRECHeaderDocument( Reference2ObjectMap<Enum<?>, Object> metadata ) {
this.metadata = metadata;
}
}
public int numberOfFields() {
return 0;
}
public String fieldName( int fieldIndex ) {
throw new IllegalArgumentException();
}
public int fieldIndex( String fieldName ) {
return -1;
}
public FieldType fieldType( int fieldIndex ) {
throw new IllegalArgumentException();
}
private byte buffer[] = new byte[ 8 * 1024 ];
protected static boolean startsWith( byte[] a, int l, byte[] b ) {
int len = b.length;
if ( len > l ) return false;
while( len-- != 0 ) if ( a[ len ] != b[ len ] ) return false;
return true;
}
protected static boolean startsWithIgnoreCase( byte[] a, int l, char[] b ) {
int len = b.length;
if ( len > l ) return false;
while( len-- != 0 ) if ( Character.toLowerCase( (char)a[ len ] ) != Character.toLowerCase( b[ len ] ) ) return false;
return true;
}
public Document getDocument( InputStream rawContent, Reference2ObjectMap<Enum<?>,Object> metadata ) throws IOException {
final FastBufferedInputStream fbis = new FastBufferedInputStream( rawContent );
int startedHeader = 0; // 0 == false, 1 == true, 2 === header started and uri collected
boolean foundDocNo = false;
int l = fbis.readLine( buffer );
if ( l < 0 ) throw new EOFException();
if ( ! TRECDocumentCollection.equals( buffer, l, DOC_OPEN ) ) throw new IllegalStateException ( "Document does not start with <DOC>: " + new String( buffer, 0, l ) );
while ( ( l = fbis.readLine( buffer ) ) != -1 ) {
if ( !foundDocNo && startsWith( buffer, l, DOCNO_OPEN ) ) {
foundDocNo = true;
metadata.put( MetadataKeys.TITLE, new String( buffer, DOCNO_OPEN.length, l - ( DOCNO_OPEN.length + DOCNO_CLOSE.length ) ) );
}
switch ( startedHeader ) {
case 0:
if ( TRECDocumentCollection.equals( buffer, l, DOCHDR_OPEN ) ) startedHeader = 1;
break;
case 1:
startedHeader = 2;
metadata.put( MetadataKeys.URI, new String( buffer, 0, l ) );
break;
case 2:
}
if ( TRECDocumentCollection.equals( buffer, l, DOCHDR_CLOSE ) ) break;
}
return new TRECHeaderDocument( metadata );
}
public DocumentFactory copy() {
return this;
}
}