content: package org.apache.lucene.analysis;
  
  /**
   * 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.
   */
  
  import java.io.Reader;
  
  import org.apache.lucene.util.AttributeSource;
  import org.apache.lucene.util.Version;
  
  /**
   * 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>
   * <p>
   * <a name="version"/>
   * You must specify the required {@link Version} compatibility when creating
   * {@link LetterTokenizer}:
   * <ul>
   * <li>As of 3.1, {@link CharTokenizer} uses an int based API to normalize and
   * detect token characters. See {@link CharTokenizer#isTokenChar(int)} and
   * {@link CharTokenizer#normalize(int)} for details.</li>
   * </ul>
   * </p>
   */
  
  public class LetterTokenizer extends CharTokenizer {
    
    /**
     * Construct a new LetterTokenizer.
     * 
     * @param matchVersion
     *          Lucene version to match See {@link <a href="#version">above</a>}
     * @param in
     *          the input to split up into tokens
     */
    public LetterTokenizer(Version matchVersion, Reader in) {
      super(matchVersion, in);
    }
    
    /**
     * Construct a new LetterTokenizer using a given {@link AttributeSource}.
     * 
     * @param matchVersion
     *          Lucene version to match See {@link <a href="#version">above</a>}
     * @param source
     *          the attribute source to use for this {@link Tokenizer}
     * @param in
     *          the input to split up into tokens
     */
    public LetterTokenizer(Version matchVersion, AttributeSource source, Reader in) {
      super(matchVersion, source, in);
    }
    
    /**
     * Construct a new LetterTokenizer using a given
     * {@link org.apache.lucene.util.AttributeSource.AttributeFactory}.
     * 
     * @param matchVersion
     *          Lucene version to match See {@link <a href="#version">above</a>}
     * @param factory
     *          the attribute factory to use for this {@link Tokenizer}
     * @param in
     *          the input to split up into tokens
     */
    public LetterTokenizer(Version matchVersion, AttributeFactory factory, Reader in) {
      super(matchVersion, factory, in);
    }
    
    /**
     * Construct a new LetterTokenizer.
     * 
     * @deprecated use {@link #LetterTokenizer(Version, Reader)} instead. This
     *             will be removed in Lucene 4.0.
     */
    @Deprecated
    public LetterTokenizer(Reader in) {
      super(Version.LUCENE_30, in);
    }
    
    /**
     * Construct a new LetterTokenizer using a given {@link AttributeSource}. 
     * @deprecated
     * use {@link #LetterTokenizer(Version, AttributeSource, Reader)} instead.
     * This will be removed in Lucene 4.0.
     */
    @Deprecated
    public LetterTokenizer(AttributeSource source, Reader in) {
      super(Version.LUCENE_30, source, in);
    }
    
    /**
     * Construct a new LetterTokenizer using a given
     * {@link org.apache.lucene.util.AttributeSource.AttributeFactory}.
     * 
     * @deprecated use {@link #LetterTokenizer(Version, AttributeSource.AttributeFactory, Reader)}
     *             instead. This will be removed in Lucene 4.0.
     */
    @Deprecated
    public LetterTokenizer(AttributeFactory factory, Reader in) {
      super(Version.LUCENE_30, factory, in);
    }
    
    /** Collects only characters which satisfy
     * {@link Character#isLetter(int)}.*/
    @Override
    protected boolean isTokenChar(int c) {
      return Character.isLetter(c);
    }
  }
  