org.elasticsearch.index.analysis.NGramTokenizerFactory Maven / Gradle / Ivy
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* Licensed to ElasticSearch and Shay Banon under one
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* 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
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* Unless required by applicable law or agreed to in writing,
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*/
package org.elasticsearch.index.analysis;
import com.google.common.collect.ImmutableMap;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.ngram.NGramTokenizer;
import org.apache.lucene.analysis.ngram.XNGramTokenizer;
import org.apache.lucene.util.Version;
import org.elasticsearch.ElasticSearchIllegalArgumentException;
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;
import java.io.Reader;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Locale;
import java.util.Map;
/**
*
*/
public class NGramTokenizerFactory extends AbstractTokenizerFactory {
private final int minGram;
private final int maxGram;
private final CharMatcher matcher;
static final Map MATCHERS;
static {
ImmutableMap.Builder builder = ImmutableMap.builder();
builder.put("letter", CharMatcher.Basic.LETTER);
builder.put("digit", CharMatcher.Basic.DIGIT);
builder.put("whitespace", CharMatcher.Basic.WHITESPACE);
builder.put("punctuation", CharMatcher.Basic.PUNCTUATION);
builder.put("symbol", CharMatcher.Basic.SYMBOL);
// Populate with unicode categories from java.lang.Character
for (Field field : Character.class.getFields()) {
if (!field.getName().startsWith("DIRECTIONALITY")
&& Modifier.isPublic(field.getModifiers())
&& Modifier.isStatic(field.getModifiers())
&& field.getType() == byte.class) {
try {
builder.put(field.getName().toLowerCase(Locale.ROOT), CharMatcher.ByUnicodeCategory.of(field.getByte(null)));
} catch (Exception e) {
// just ignore
continue;
}
}
}
MATCHERS = builder.build();
}
static CharMatcher parseTokenChars(String[] characterClasses) {
if (characterClasses == null || characterClasses.length == 0) {
return null;
}
CharMatcher.Builder builder = new CharMatcher.Builder();
for (String characterClass : characterClasses) {
characterClass = characterClass.toLowerCase(Locale.ROOT).trim();
CharMatcher matcher = MATCHERS.get(characterClass);
if (matcher == null) {
throw new ElasticSearchIllegalArgumentException("Unknown token type: '" + characterClass + "', must be one of " + MATCHERS.keySet());
}
builder.or(matcher);
}
return builder.build();
}
@Inject
public NGramTokenizerFactory(Index index, @IndexSettings Settings indexSettings, @Assisted String name, @Assisted Settings settings) {
super(index, indexSettings, name, settings);
this.minGram = settings.getAsInt("min_gram", NGramTokenizer.DEFAULT_MIN_NGRAM_SIZE);
this.maxGram = settings.getAsInt("max_gram", NGramTokenizer.DEFAULT_MAX_NGRAM_SIZE);
this.matcher = parseTokenChars(settings.getAsArray("token_chars"));
}
@Override
public Tokenizer create(Reader reader) {
if (this.version.onOrAfter(Version.LUCENE_43)) {
// LUCENE MONITOR: this token filter is a copy from lucene trunk and should go away once we upgrade to lucene 4.4
if (matcher == null) {
return new XNGramTokenizer(version, reader, minGram, maxGram);
} else {
return new XNGramTokenizer(version, reader, minGram, maxGram) {
@Override
protected boolean isTokenChar(int chr) {
return matcher.isTokenChar(chr);
}
};
}
}
return new NGramTokenizer(reader, minGram, maxGram);
}
}