src/Lucene.Net.Analysis.Common/Analysis/No/NorwegianMinimalStemFilter.cs

using Lucene.Net.Analysis.TokenAttributes;

namespace Lucene.Net.Analysis.No
{
    /*
     * 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="TokenFilter"/> that applies <see cref="NorwegianMinimalStemmer"/> to stem Norwegian
    /// words.
    /// <para>
    /// To prevent terms from being stemmed use an instance of
    /// <see cref="Miscellaneous.SetKeywordMarkerFilter"/> or a custom <see cref="TokenFilter"/> that sets
    /// the <see cref="KeywordAttribute"/> before this <see cref="TokenStream"/>.
    /// </para>
    /// </summary>
    public sealed class NorwegianMinimalStemFilter : TokenFilter
    {
        private readonly NorwegianMinimalStemmer stemmer;
        private readonly ICharTermAttribute termAtt;
        private readonly IKeywordAttribute keywordAttr;

        /// <summary>
        /// Calls <see cref="NorwegianLightStemFilter.NorwegianLightStemFilter(TokenStream, NorwegianStandard)"/> -
        /// NorwegianMinimalStemFilter(input, BOKMAAL)
        /// </summary>
        public NorwegianMinimalStemFilter(TokenStream input)
            : this(input, NorwegianStandard.BOKMAAL)
        {
        }

        /// <summary>
        /// Creates a new <see cref="NorwegianLightStemFilter"/> </summary>
        /// <param name="input"> the source <see cref="TokenStream"/> to filter </param>
        /// <param name="flags"> set to <see cref="NorwegianStandard.BOKMAAL"/>, 
        ///                     <see cref="NorwegianStandard.NYNORSK"/>, or both. </param>
        public NorwegianMinimalStemFilter(TokenStream input, NorwegianStandard flags)
            : base(input)
        {
            this.stemmer = new NorwegianMinimalStemmer(flags);
            termAtt = AddAttribute<ICharTermAttribute>();
            keywordAttr = AddAttribute<IKeywordAttribute>();
        }

        public override bool IncrementToken()
        {
            if (m_input.IncrementToken())
            {
                if (!keywordAttr.IsKeyword)
                {
                    int newlen = stemmer.Stem(termAtt.Buffer, termAtt.Length);
                    termAtt.Length = newlen;
                }
                return true;
            }
            else
            {
                return false;
            }
        }
    }
}