Tokenizer.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
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using AttributeSource = Lucene.Net.Util.AttributeSource;

namespace Lucene.Net.Analysis
{
    
    /// <summary> A Tokenizer is a TokenStream whose input is a Reader.
    /// <p/>
    /// This is an abstract class; subclasses must override <see cref="TokenStream.IncrementToken()" />
    /// <p/>
    /// NOTE: Subclasses overriding <see cref="TokenStream.IncrementToken()" /> must call
    /// <see cref="AttributeSource.ClearAttributes()" /> before setting attributes.
    /// </summary>
    
    public abstract class Tokenizer:TokenStream
    {
        /// <summary>The text source for this Tokenizer. </summary>
        protected internal System.IO.TextReader input;

        private bool isDisposed;
        
        /// <summary>Construct a tokenizer with null input. </summary>
        protected internal Tokenizer()
        {
        }
        
        /// <summary>Construct a token stream processing the given input. </summary>
        protected internal Tokenizer(System.IO.TextReader input)
        {
            this.input = CharReader.Get(input);
        }
        
        /// <summary>Construct a tokenizer with null input using the given AttributeFactory. </summary>
        protected internal Tokenizer(AttributeFactory factory):base(factory)
        {
        }
        
        /// <summary>Construct a token stream processing the given input using the given AttributeFactory. </summary>
        protected internal Tokenizer(AttributeFactory factory, System.IO.TextReader input):base(factory)
        {
            this.input = CharReader.Get(input);
        }
        
        /// <summary>Construct a token stream processing the given input using the given AttributeSource. </summary>
        protected internal Tokenizer(AttributeSource source):base(source)
        {
        }
        
        /// <summary>Construct a token stream processing the given input using the given AttributeSource. </summary>
        protected internal Tokenizer(AttributeSource source, System.IO.TextReader input):base(source)
        {
            this.input = CharReader.Get(input);
        }
        
        protected override void Dispose(bool disposing)
        {
            if (isDisposed) return;

            if (disposing)
            {
                if (input != null)
                {
                    input.Close();
                }
            }

            // LUCENE-2387: don't hold onto Reader after close, so
            // GC can reclaim
            input = null;
            isDisposed = true;
        }
  
        /// <summary>Return the corrected offset. If <see cref="input" /> is a <see cref="CharStream" /> subclass
        /// this method calls <see cref="CharStream.CorrectOffset" />, else returns <c>currentOff</c>.
        /// </summary>
        /// <param name="currentOff">offset as seen in the output
        /// </param>
        /// <returns> corrected offset based on the input
        /// </returns>
        /// <seealso cref="CharStream.CorrectOffset">
        /// </seealso>
        protected internal int CorrectOffset(int currentOff)
        {
            return (input is CharStream)?((CharStream) input).CorrectOffset(currentOff):currentOff;
        }
        
        /// <summary>Expert: Reset the tokenizer to a new reader.  Typically, an
        /// analyzer (in its reusableTokenStream method) will use
        /// this to re-use a previously created tokenizer. 
        /// </summary>
        public virtual void  Reset(System.IO.TextReader input)
        {
            this.input = input;
        }
    }
}