src/Lucene.Net.Analysis.Common/Collation/TokenAttributes/CollatedTermAttributeImpl.cs

#if FEATURE_COLLATION
using Icu.Collation;
using Lucene.Net.Analysis.TokenAttributes;
using System;

namespace Lucene.Net.Collation.TokenAttributes
{
    /*
     * 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>
    /// Extension of <see cref="CharTermAttribute"/> that encodes the term
    /// text as a binary Unicode collation key instead of as UTF-8 bytes.
    /// </summary>
    public class CollatedTermAttributeImpl : CharTermAttribute
    {
        private readonly Collator collator;

        /// <summary>
        /// Create a new <see cref="CollatedTermAttributeImpl"/> </summary>
        /// <param name="collator"> Collation key generator </param>
        public CollatedTermAttributeImpl(Collator collator)
        {
            // clone in case JRE doesn't properly sync,
            // or to reduce contention in case they do
            this.collator = (Collator)collator.Clone();
        }

        public override void FillBytesRef()
        {
            var bytes = this.BytesRef;

            //LUCENENET TODO: Verify that this is correct. Java's byte[] is signed and Big Endian, .NET's is unsigned and Little Endian.
            bytes.Bytes = this.collator.GetSortKey(this.ToString()).KeyData;
            bytes.Offset = 0;
            bytes.Length = bytes.Bytes.Length;
        }
    }
}
#endif