| using J2N; |
| using Lucene.Net.Analysis.Util; |
| using Lucene.Net.Util; |
| using System.IO; |
| |
| namespace Lucene.Net.Analysis.Core |
| { |
| /* |
| * 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. |
| */ |
| |
| /// <summary> |
| /// A <see cref="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 |
| /// <see cref="Character.IsLetter(int)"/> predicate. |
| /// <para> |
| /// 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. |
| /// </para> |
| /// <para> |
| /// You must specify the required <see cref="LuceneVersion"/> compatibility when creating |
| /// <see cref="LetterTokenizer"/>: |
| /// <list type="bullet"> |
| /// <item><description>As of 3.1, <see cref="CharTokenizer"/> uses an <see cref="int"/> based API to normalize and |
| /// detect token characters. See <see cref="CharTokenizer.IsTokenChar(int)"/> and |
| /// <see cref="CharTokenizer.Normalize(int)"/> for details.</description></item> |
| /// </list> |
| /// </para> |
| /// </summary> |
| public class LetterTokenizer : CharTokenizer |
| { |
| /// <summary> |
| /// Construct a new <see cref="LetterTokenizer"/>. |
| /// </summary> |
| /// <param name="matchVersion"> |
| /// <see cref="LuceneVersion"/> to match. </param> |
| /// <param name="in"> |
| /// the input to split up into tokens </param> |
| public LetterTokenizer(LuceneVersion matchVersion, TextReader @in) |
| : base(matchVersion, @in) |
| { |
| } |
| |
| /// <summary> |
| /// Construct a new <see cref="LetterTokenizer"/> using a given |
| /// <see cref="AttributeSource.AttributeFactory"/>. |
| /// </summary> |
| /// <param name="matchVersion"> |
| /// <see cref="LuceneVersion"/> to match</param> |
| /// <param name="factory"> |
| /// the attribute factory to use for this <see cref="Tokenizer"/> </param> |
| /// <param name="in"> |
| /// the input to split up into tokens </param> |
| public LetterTokenizer(LuceneVersion matchVersion, AttributeSource.AttributeFactory factory, TextReader @in) |
| : base(matchVersion, factory, @in) |
| { |
| } |
| |
| /// <summary> |
| /// Collects only characters which satisfy |
| /// <see cref="Character.IsLetter(int)"/>. |
| /// </summary> |
| protected override bool IsTokenChar(int c) |
| { |
| return Character.IsLetter(c); |
| } |
| } |
| } |