org.apache.lucene.analysis.ko.KoreanAnalyzer.java Source code

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Here is the source code for org.apache.lucene.analysis.ko.KoreanAnalyzer.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.apache.lucene.analysis.ko;

import java.util.Set;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.LowerCaseFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.ko.KoreanTokenizer.DecompoundMode;
import org.apache.lucene.analysis.ko.dict.UserDictionary;

import static org.apache.lucene.analysis.TokenStream.DEFAULT_TOKEN_ATTRIBUTE_FACTORY;

/**
 * Analyzer for Korean that uses morphological analysis.
 * @see KoreanTokenizer
 * @lucene.experimental
 *
 * @since 7.4.0
 */
public class KoreanAnalyzer extends Analyzer {
    private final UserDictionary userDict;
    private final KoreanTokenizer.DecompoundMode mode;
    private final Set<POS.Tag> stopTags;
    private final boolean outputUnknownUnigrams;

    /**
     * Creates a new KoreanAnalyzer.
     */
    public KoreanAnalyzer() {
        this(null, KoreanTokenizer.DEFAULT_DECOMPOUND, KoreanPartOfSpeechStopFilter.DEFAULT_STOP_TAGS, false);
    }

    /**
     * Creates a new KoreanAnalyzer.
     *
     * @param userDict Optional: if non-null, user dictionary.
     * @param mode Decompound mode.
     * @param stopTags The set of part of speech that should be filtered.
     * @param outputUnknownUnigrams If true outputs unigrams for unknown words.
     */
    public KoreanAnalyzer(UserDictionary userDict, DecompoundMode mode, Set<POS.Tag> stopTags,
            boolean outputUnknownUnigrams) {
        super();
        this.userDict = userDict;
        this.mode = mode;
        this.stopTags = stopTags;
        this.outputUnknownUnigrams = outputUnknownUnigrams;
    }

    @Override
    protected TokenStreamComponents createComponents(String fieldName) {
        Tokenizer tokenizer = new KoreanTokenizer(DEFAULT_TOKEN_ATTRIBUTE_FACTORY, userDict, mode,
                outputUnknownUnigrams);
        TokenStream stream = new KoreanPartOfSpeechStopFilter(tokenizer, stopTags);
        stream = new KoreanReadingFormFilter(stream);
        stream = new LowerCaseFilter(stream);
        return new TokenStreamComponents(tokenizer, stream);
    }

    @Override
    protected TokenStream normalize(String fieldName, TokenStream in) {
        TokenStream result = new LowerCaseFilter(in);
        return result;
    }
}