GermanDIN2Stemmer.cs

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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
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*/

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Lucene.Net.Analysis.De
{
    /// <summary>
    /// A stemmer for the german language that uses the
    /// DIN-5007-2 "Phone Book" rules for handling
    /// umlaut characters.
    /// </summary>
    public sealed class GermanDIN2Stemmer : GermanStemmer
    {
        protected override void Substitute(StringBuilder buffer)
        {
            for (int c = 0; c < buffer.Length; c++)
            {
                if (buffer[c] == 'e')
                {
                    switch (buffer[c - 1])
                    {
                        case 'a':
                        case 'o':
                        case 'u':
                            buffer.Remove(c, 1);
                            break;
                    }
                }
            }
            base.Substitute(buffer);
        }
    }
}