lowercasetokenizer.cs

Lucene.Net 版本源码 测试通过

/*
 * 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.
 */

using System;

namespace Lucene.Net.Analysis
{
	
    /// <summary> LowerCaseTokenizer performs the function of LetterTokenizer
    /// and LowerCaseFilter together.  It divides text at non-letters and converts
    /// them to lower case.  While it is functionally equivalent to the combination
    /// of LetterTokenizer and LowerCaseFilter, there is a performance advantage
    /// to doing the two tasks at once, hence this (redundant) implementation.
    /// <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.
    /// </summary>
    public sealed class LowerCaseTokenizer : LetterTokenizer
    {
        /// <summary>Construct a new LowerCaseTokenizer. </summary>
        public LowerCaseTokenizer(System.IO.TextReader in_Renamed) : base(in_Renamed)
        {
        }
		
        /// <summary>Collects only characters which satisfy
        /// {@link Character#isLetter(char)}.
        /// </summary>
        protected internal override char Normalize(char c)
        {
            return System.Char.ToLower(c);
        }
    }
}