Analyzer.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 specific language governing permissions and
 * limitations under the License.
 */

using System;
using Lucene.Net.Documents;
using Lucene.Net.Store;
using Lucene.Net.Util;

namespace Lucene.Net.Analysis
{
    public abstract class Analyzer : IDisposable
    {
        public abstract TokenStream TokenStream(String fieldName, System.IO.TextReader reader);
        
        public virtual TokenStream ReusableTokenStream(String fieldName, System.IO.TextReader reader)
        {
            return TokenStream(fieldName, reader);
        }
        
        private CloseableThreadLocal<Object> tokenStreams = new CloseableThreadLocal<Object>();
        private bool isDisposed;

        protected internal virtual object PreviousTokenStream
        {
            get
            {
                if (tokenStreams == null)
                {
                    throw new AlreadyClosedException("this Analyzer is closed");
                }
                return tokenStreams.Get();
            }
            set
            {
                if (tokenStreams == null)
                {
                    throw new AlreadyClosedException("this Analyzer is closed");
                }
                tokenStreams.Set(value);
            }
        }

        [Obsolete()]
        protected internal bool overridesTokenStreamMethod = false;
        
        [Obsolete("This is only present to preserve back-compat of classes that subclass a core analyzer and override tokenStream but not reusableTokenStream ")]
        protected internal virtual void SetOverridesTokenStreamMethod<TClass>()
            where TClass : Analyzer
        {
            try
            {
                System.Reflection.MethodInfo m = this.GetType().GetMethod("TokenStream", new[] { typeof(string), typeof(System.IO.TextReader) });
                overridesTokenStreamMethod = m.DeclaringType != typeof(TClass);
            }
            catch (MethodAccessException)
            {
                // can't happen, as baseClass is subclass of Analyzer
                overridesTokenStreamMethod = false;
            }
        }
        
        
        public virtual int GetPositionIncrementGap(String fieldName)
        {
            return 0;
        }
        
        public virtual int GetOffsetGap(IFieldable field)
        {
            return field.IsTokenized ? 1 : 0;
        }

        public void  Close()
        {
            Dispose();
        }

        public virtual void Dispose()
        {
            Dispose(true);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (isDisposed) return;

            if (disposing)
            {
                if (tokenStreams != null)
                {
                    tokenStreams.Close();
                    tokenStreams = null;
                }
            }
            isDisposed = true;
        }
    }
}