/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.index.analysis;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.ngram.EdgeNGramTokenFilter;
import org.apache.lucene.analysis.ngram.Lucene43EdgeNGramTokenFilter;
import org.apache.lucene.analysis.ngram.NGramTokenFilter;
import org.apache.lucene.analysis.reverse.ReverseStringFilter;
import org.apache.lucene.util.Version;
import org.elasticsearch.cluster.metadata.IndexMetaData;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.inject.assistedinject.Assisted;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.index.Index;
import org.elasticsearch.index.settings.IndexSettings;
/**
*
*/
public class EdgeNGramTokenFilterFactory extends AbstractTokenFilterFactory {
private final int minGram;
private final int maxGram;
public static final int SIDE_FRONT = 1;
public static final int SIDE_BACK = 2;
private final int side;
private org.elasticsearch.Version esVersion;
@Inject
public EdgeNGramTokenFilterFactory(Index index, @IndexSettings Settings indexSettings, @Assisted String name, @Assisted Settings settings) {
super(index, indexSettings, name, settings);
this.minGram = settings.getAsInt("min_gram", NGramTokenFilter.DEFAULT_MIN_NGRAM_SIZE);
this.maxGram = settings.getAsInt("max_gram", NGramTokenFilter.DEFAULT_MAX_NGRAM_SIZE);
this.side = parseSide(settings.get("side", "front"));
this.esVersion = org.elasticsearch.Version.indexCreated(indexSettings);
}
static int parseSide(String side) {
switch(side) {
case "front": return SIDE_FRONT;
case "back": return SIDE_BACK;
default: throw new IllegalArgumentException("invalid side: " + side);
}
}
@Override
public TokenStream create(TokenStream tokenStream) {
TokenStream result = tokenStream;
// side=BACK is not supported anymore but applying ReverseStringFilter up-front and after the token filter has the same effect
if (side == SIDE_BACK) {
result = new ReverseStringFilter(result);
}
if (version.onOrAfter(Version.LUCENE_4_3) && esVersion.onOrAfter(org.elasticsearch.Version.V_0_90_2)) {
/*
* We added this in 0.90.2 but 0.90.1 used LUCENE_43 already so we can not rely on the lucene version.
* Yet if somebody uses 0.90.2 or higher with a prev. lucene version we should also use the deprecated version.
*/
result = new EdgeNGramTokenFilter(result, minGram, maxGram);
} else {
result = new Lucene43EdgeNGramTokenFilter(result, minGram, maxGram);
}
// side=BACK is not supported anymore but applying ReverseStringFilter up-front and after the token filter has the same effect
if (side == SIDE_BACK) {
result = new ReverseStringFilter(result);
}
return result;
}
}