package it.unimi.dsi.mg4j.document;
/*
* MG4J: Managing Gigabytes for Java
*
* Copyright (C) 2005-2010 Paolo Boldi and 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 it.unimi.dsi.fastutil.objects.Reference2ObjectMap;
import it.unimi.dsi.io.FastBufferedReader;
import it.unimi.dsi.io.LineWordReader;
import it.unimi.dsi.io.WordReader;
import it.unimi.dsi.lang.ObjectParser;
import it.unimi.dsi.mg4j.util.MG4JClassParser;
import it.unimi.dsi.util.Properties;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import org.apache.commons.configuration.ConfigurationException;
/** A factory that provides a single field containing just the raw input stream; the encoding
* is set using the property {@link it.unimi.dsi.mg4j.document.PropertyBasedDocumentFactory.MetadataKeys#ENCODING}.
* The field is named <samp>text</samp>, but you can change the name using the property
* <samp>fieldname</samp>.
*
* <p>By default, the {@link WordReader} provided by this factory
* is just a {@link FastBufferedReader}, but you can specify
* an alternative word reader using the property
* {@link it.unimi.dsi.mg4j.document.PropertyBasedDocumentFactory.MetadataKeys#WORDREADER}.
* For instance, if you need to index a list of identifiers to retrieve documents from
* the collection more easily, you can use a {@link LineWordReader}
* to index each line of a file as a whole.
*
*/
public class IdentityDocumentFactory extends PropertyBasedDocumentFactory {
private static final long serialVersionUID = 2L;
/** Case-insensitive keys for metadata.
*
* @see PropertyBasedDocumentFactory.MetadataKeys
*/
public static enum MetadataKeys {
/** The tag for the optional name of the only field provided by this factory. */
FIELDNAME
};
/** The name of the only field. */
private String fieldName;
/** The word reader used for all documents. */
private transient WordReader wordReader;
protected boolean parseProperty( final String key, final String[] values, final Reference2ObjectMap<Enum<?>,Object> metadata ) throws ConfigurationException {
if ( sameKey( PropertyBasedDocumentFactory.MetadataKeys.ENCODING, key ) ) {
metadata.put( PropertyBasedDocumentFactory.MetadataKeys.ENCODING, Charset.forName( ensureJustOne( key, values ) ).toString() );
return true;
}
if ( sameKey( PropertyBasedDocumentFactory.MetadataKeys.WORDREADER, key ) ) {
try {
final String spec = ( ensureJustOne( key, values ) ).toString();
metadata.put( PropertyBasedDocumentFactory.MetadataKeys.WORDREADER, spec );
// Just to check
ObjectParser.fromSpec( spec, WordReader.class, MG4JClassParser.PACKAGE );
}
catch ( ClassNotFoundException e ) {
throw new ConfigurationException( e );
}
// TODO: this must turn into a more appropriate exception
catch ( Exception e ) {
throw new ConfigurationException( e );
}
return true;
}
if ( sameKey( MetadataKeys.FIELDNAME, key ) ) {
ensureJustOne( key, values );
return true;
}
return super.parseProperty( key, values, metadata );
}
public IdentityDocumentFactory() {
init();
}
private void init() {
Object o = defaultMetadata.get( MetadataKeys.FIELDNAME );
fieldName = o == null ? "text" : o.toString();
try {
o = defaultMetadata.get( PropertyBasedDocumentFactory.MetadataKeys.WORDREADER );
wordReader = o == null ? new FastBufferedReader() : ObjectParser.fromSpec( o.toString(), WordReader.class, MG4JClassParser.PACKAGE );
}
catch ( Exception e ) {
throw new RuntimeException( e );
}
}
public IdentityDocumentFactory( final Reference2ObjectMap<Enum<?>,Object> defaultMetadata ) {
super( defaultMetadata );
init();
}
public IdentityDocumentFactory( final Properties properties ) throws ConfigurationException {
super( properties );
init();
}
public IdentityDocumentFactory( final String[] property ) throws ConfigurationException {
super( property );
init();
}
public IdentityDocumentFactory copy() {
return new IdentityDocumentFactory( defaultMetadata );
}
public int numberOfFields() {
return 1;
}
public String fieldName( final int field ) {
ensureFieldIndex( field );
return fieldName;
}
public int fieldIndex( final String fieldName ) {
return fieldName.equals( this.fieldName ) ? 0: -1;
}
public FieldType fieldType( final int field ) {
ensureFieldIndex( field );
return FieldType.TEXT;
}
public Document getDocument( final InputStream rawContent, final Reference2ObjectMap<Enum<?>,Object> metadata ) {
return new Document() {
public CharSequence title() {
return (CharSequence)resolve( PropertyBasedDocumentFactory.MetadataKeys.TITLE, metadata );
}
public String toString() {
return title().toString();
}
public CharSequence uri() {
return (CharSequence)resolve( PropertyBasedDocumentFactory.MetadataKeys.URI, metadata );
}
public Object content( final int field ) {
ensureFieldIndex( field );
try {
return new InputStreamReader( rawContent, (String)resolveNotNull( PropertyBasedDocumentFactory.MetadataKeys.ENCODING, metadata ) );
}
catch( UnsupportedEncodingException e ) {
throw new RuntimeException( e );
}
}
public WordReader wordReader( final int field ) {
ensureFieldIndex( field );
// TODO: should depend on locale (or something)
return wordReader;
}
public void close() {}
};
}
private void readObject( final ObjectInputStream s ) throws IOException, ClassNotFoundException {
s.defaultReadObject();
init();
}
}