org.apache.lucene.analysis.core.LetterTokenizer.java Source code

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Here is the source code for org.apache.lucene.analysis.core.LetterTokenizer.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.core;

import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.util.CharTokenizer;
import org.apache.lucene.util.AttributeFactory;

/**
 * A LetterTokenizer is a tokenizer that divides text at non-letters. That's to
 * say, it defines tokens as maximal strings of adjacent letters, as defined by
 * java.lang.Character.isLetter() predicate.
 * <p>
 * Note: this does a decent job for most European languages, but does a terrible
 * job for some Asian languages, where words are not separated by spaces.
 * </p>
 */

public class LetterTokenizer extends CharTokenizer {

    /**
     * Construct a new LetterTokenizer.
     */
    public LetterTokenizer() {
    }

    /**
     * Construct a new LetterTokenizer using a given
     * {@link org.apache.lucene.util.AttributeFactory}.
     * 
     * @param factory
     *          the attribute factory to use for this {@link Tokenizer}
     */
    public LetterTokenizer(AttributeFactory factory) {
        super(factory);
    }

    /**
     * Construct a new LetterTokenizer using a given
     * {@link org.apache.lucene.util.AttributeFactory}.
     *
     * @param factory the attribute factory to use for this {@link Tokenizer}
     * @param maxTokenLen maximum token length the tokenizer will emit. 
     *        Must be greater than 0 and less than MAX_TOKEN_LENGTH_LIMIT (1024*1024)
     * @throws IllegalArgumentException if maxTokenLen is invalid.
        
     */
    public LetterTokenizer(AttributeFactory factory, int maxTokenLen) {
        super(factory, maxTokenLen);
    }

    /** Collects only characters which satisfy
     * {@link Character#isLetter(int)}.*/
    @Override
    protected boolean isTokenChar(int c) {
        return Character.isLetter(c);
    }
}