org.elasticsearch.index.analysis.EdgeNGramTokenFilterFactory Maven / Gradle / Ivy
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*
* http://www.apache.org/licenses/LICENSE-2.0
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package org.elasticsearch.index.analysis;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.ngram.EdgeNGramTokenFilter;
import org.apache.lucene.analysis.ngram.EdgeNGramTokenFilter.Side;
import org.apache.lucene.analysis.ngram.Lucene43EdgeNGramTokenizer;
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;
private final EdgeNGramTokenFilter.Side 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 = EdgeNGramTokenFilter.Side.getSide(settings.get("side", Lucene43EdgeNGramTokenizer.DEFAULT_SIDE.getLabel()));
this.esVersion = indexSettings.getAsVersion(IndexMetaData.SETTING_VERSION_CREATED, org.elasticsearch.Version.CURRENT);
}
@Override
public TokenStream create(TokenStream tokenStream) {
if (version.onOrAfter(Version.LUCENE_43) && 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.
*/
final Version version = this.version == Version.LUCENE_43 ? Version.LUCENE_44 : this.version; // always use 4.4 or higher
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(version, result);
}
result = new EdgeNGramTokenFilter(version, result, minGram, maxGram);
if (side == Side.BACK) {
result = new ReverseStringFilter(version, result);
}
return result;
}
return new EdgeNGramTokenFilter(version, tokenStream, side, minGram, maxGram);
}
}