// BufferedTextReader.cs
// 
// Copyright (C) 2003 Ryan Seghers
//
// This software is provided AS IS. No warranty is granted, 
// neither expressed nor implied. USE THIS SOFTWARE AT YOUR OWN RISK.
// NO REPRESENTATION OF MERCHANTABILITY or FITNESS FOR ANY 
// PURPOSE is given.
//
// License to use this software is limited by the following terms:
// 1) This code may be used in any program, including programs developed
//    for commercial purposes, provided that this notice is included verbatim.
//    
// Also, in return for using this code, please attempt to make your fixes and
// updates available in some way, such as by sending your updates to the
// author.

using System;
using System.IO;

namespace RTools_NTS.Util
{
    /// <summary>
    /// Wraps a TextReader with buffering for speed. This is not finished,
    /// and preliminary testing indicates it isn't faster than FCL implementation.
    /// </summary>
    public class BufferedTextReader
    {
        private static readonly int BlockSize = 1024;
        private readonly TextReader reader;
        private readonly char[] buffer;
        private CharBuffer cb;

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="reader">The TextReader to wrap.</param>
        public BufferedTextReader(TextReader reader)
        {
            this.reader = reader;
            buffer = new char[BlockSize];
            cb = new CharBuffer(0);
        }

        /// <summary>
        /// Read a single character.
        /// </summary>
        /// <returns>The character read.</returns>
        public char Read()
        {
            if (cb.Length == 0)
            {
                // read from underlying reader
                int readCount = reader.Read(buffer, 0, BlockSize);
                if (readCount == 0)
                {
                    throw new ApplicationException("End of stream.");
                }
                cb.SetBuffer(buffer, readCount);
            }

            char c = cb[0];
            cb.Remove(0);
            return (c);
        }

        /// <summary>
        /// Close the underlying reader.
        /// </summary>
        public void Close()
        {
            reader.Close();
            cb = null;
        }
    }
}