SSH.NET/Renci.SshClient/Renci.SshNet/Common/ASCIIEncoding.cs

/*
 * ASCIIEncoding.cs - Implementation of the "System.Text.ASCIIEncoding" class.
 *
 * Copyright (C) 2001  Southern Storm Software, Pty Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

using System;
using System.Text;

namespace Renci.SshNet.Common
{
    /// <summary>
    /// Represents an ASCII character encoding of Unicode characters.
    /// </summary>
    public partial class ASCIIEncoding : Encoding
    {
        // Magic number used by Windows for "ASCII".
        internal const int ASCII_CODE_PAGE = 20127;

        private static ASCIIEncoding _current = new ASCIIEncoding();
        /// <summary>
        /// Gets the current encoding.
        /// </summary>
        public static ASCIIEncoding Current
        {
            get
            {
                return _current;
            }
        }

        /// <summary>
        /// Calculates the number of bytes produced by encoding a set of characters from the specified character array.
        /// </summary>
        /// <param name="chars">The character array containing the set of characters to encode.</param>
        /// <param name="index">The index of the first character to encode.</param>
        /// <param name="count">The number of characters to encode.</param>
        /// <returns>
        /// The number of bytes produced by encoding the specified characters.
        /// </returns>
        /// <exception cref="T:System.ArgumentNullException">
        ///   <paramref name="chars"/> is null. </exception>
        ///   
        /// <exception cref="T:System.ArgumentOutOfRangeException">
        ///   <paramref name="index"/> or <paramref name="count"/> is less than zero.-or- <paramref name="index"/> and <paramref name="count"/> do not denote a valid range in <paramref name="chars"/>. </exception>
        ///   
        /// <exception cref="T:System.Text.EncoderFallbackException">A fallback occurred (see Understanding Encodings for complete explanation)-and-<see cref="P:System.Text.Encoding.EncoderFallback"/> is set to <see cref="T:System.Text.EncoderExceptionFallback"/>.</exception>
        public override int GetByteCount(char[] chars, int index, int count)
        {
            if (chars == null)
            {
                throw new ArgumentNullException("chars");
            }
            if (index < 0 || index > chars.Length)
            {
                throw new ArgumentOutOfRangeException("index");
            }
            if (count < 0 || count > (chars.Length - index))
            {
                throw new ArgumentOutOfRangeException("count");
            }
            return count;
        }

        /// <summary>
        /// Gets the byte count.
        /// </summary>
        /// <param name="chars">The chars.</param>
        /// <returns></returns>
        public override int GetByteCount(string chars)
        {
            if (chars == null)
            {
                throw new ArgumentNullException("chars");
            }
            return chars.Length;
        }

        /// <summary>
        /// Encodes a set of characters from the specified character array into the specified byte array.
        /// </summary>
        /// <param name="chars">The character array containing the set of characters to encode.</param>
        /// <param name="charIndex">The index of the first character to encode.</param>
        /// <param name="charCount">The number of characters to encode.</param>
        /// <param name="bytes">The byte array to contain the resulting sequence of bytes.</param>
        /// <param name="byteIndex">The index at which to start writing the resulting sequence of bytes.</param>
        /// <returns>
        /// The actual number of bytes written into <paramref name="bytes"/>.
        /// </returns>
        /// <exception cref="T:System.ArgumentNullException">
        ///   <paramref name="chars"/> is null.-or- <paramref name="bytes"/> is null. </exception>
        ///   
        /// <exception cref="T:System.ArgumentOutOfRangeException">
        ///   <paramref name="charIndex"/> or <paramref name="charCount"/> or <paramref name="byteIndex"/> is less than zero.-or- <paramref name="charIndex"/> and <paramref name="charCount"/> do not denote a valid range in <paramref name="chars"/>.-or- <paramref name="byteIndex"/> is not a valid index in <paramref name="bytes"/>. </exception>
        ///   
        /// <exception cref="T:System.ArgumentException">
        ///   <paramref name="bytes"/> does not have enough capacity from <paramref name="byteIndex"/> to the end of the array to accommodate the resulting bytes. </exception>
        ///   
        /// <exception cref="T:System.Text.EncoderFallbackException">A fallback occurred (see Understanding Encodings for complete explanation)-and-<see cref="P:System.Text.Encoding.EncoderFallback"/> is set to <see cref="T:System.Text.EncoderExceptionFallback"/>.</exception>
        public override int GetBytes(char[] chars, int charIndex, int charCount, byte[] bytes, int byteIndex)
        {
            if (chars == null)
            {
                throw new ArgumentNullException("chars");
            }
            if (bytes == null)
            {
                throw new ArgumentNullException("bytes");
            }
            if (charIndex < 0 || charIndex > chars.Length)
            {
                throw new ArgumentOutOfRangeException("charIndex");
            }
            if (charCount < 0 || charCount > (chars.Length - charIndex))
            {
                throw new ArgumentOutOfRangeException("charCount");
            }
            if (byteIndex < 0 || byteIndex > bytes.Length)
            {
                throw new ArgumentOutOfRangeException("byteIndex");
            }
            if ((bytes.Length - byteIndex) < charCount)
            {
                throw new ArgumentException();
            }
            int count = charCount;
            char ch;
            while (count-- > 0)
            {
                ch = chars[charIndex++];
                if (ch < (char)0x80)
                {
                    bytes[byteIndex++] = (byte)ch;
                }
                else
                {
                    bytes[byteIndex++] = (byte)'?';
                }
            }
            return charCount;
        }

        /// <summary>
        /// Encodes a set of characters from the specified <see cref="T:System.String"/> into the specified byte array.
        /// </summary>
        /// <param name="s">The <see cref="T:System.String"/> containing the set of characters to encode.</param>
        /// <param name="charIndex">The index of the first character to encode.</param>
        /// <param name="charCount">The number of characters to encode.</param>
        /// <param name="bytes">The byte array to contain the resulting sequence of bytes.</param>
        /// <param name="byteIndex">The index at which to start writing the resulting sequence of bytes.</param>
        /// <returns>
        /// The actual number of bytes written into <paramref name="bytes"/>.
        /// </returns>
        /// <exception cref="T:System.ArgumentNullException">
        ///   <paramref name="s"/> is null.-or- <paramref name="bytes"/> is null. </exception>
        ///   
        /// <exception cref="T:System.ArgumentOutOfRangeException">
        ///   <paramref name="charIndex"/> or <paramref name="charCount"/> or <paramref name="byteIndex"/> is less than zero.-or- <paramref name="charIndex"/> and <paramref name="charCount"/> do not denote a valid range in <paramref name="bytes"/>.-or- <paramref name="byteIndex"/> is not a valid index in <paramref name="bytes"/>. </exception>
        ///   
        /// <exception cref="T:System.ArgumentException">
        ///   <paramref name="bytes"/> does not have enough capacity from <paramref name="byteIndex"/> to the end of the array to accommodate the resulting bytes. </exception>
        ///   
        /// <exception cref="T:System.Text.EncoderFallbackException">A fallback occurred (see Understanding Encodings for complete explanation)-and-<see cref="P:System.Text.Encoding.EncoderFallback"/> is set to <see cref="T:System.Text.EncoderExceptionFallback"/>.</exception>
        public override int GetBytes(String s, int charIndex, int charCount, byte[] bytes, int byteIndex)
        {
            if (s == null)
            {
                throw new ArgumentNullException("s");
            }
            if (bytes == null)
            {
                throw new ArgumentNullException("bytes");
            }
            if (charIndex < 0 || charIndex > s.Length)
            {
                throw new ArgumentOutOfRangeException("charIndex");
            }
            if (charCount < 0 || charCount > (s.Length - charIndex))
            {
                throw new ArgumentOutOfRangeException("charCount");
            }
            if (byteIndex < 0 || byteIndex > bytes.Length)
            {
                throw new ArgumentOutOfRangeException("byteIndex");
            }
            if ((bytes.Length - byteIndex) < charCount)
            {
                throw new ArgumentException();
            }
            int count = charCount;
            char ch;
            while (count-- > 0)
            {
                ch = s[charIndex++];
                if (ch < (char)0x80)
                {
                    bytes[byteIndex++] = (byte)ch;
                }
                else
                {
                    bytes[byteIndex++] = (byte)'?';
                }
            }
            return charCount;
        }

        /// <summary>
        /// Calculates the number of characters produced by decoding a sequence of bytes from the specified byte array.
        /// </summary>
        /// <param name="bytes">The byte array containing the sequence of bytes to decode.</param>
        /// <param name="index">The index of the first byte to decode.</param>
        /// <param name="count">The number of bytes to decode.</param>
        /// <returns>
        /// The number of characters produced by decoding the specified sequence of bytes.
        /// </returns>
        /// <exception cref="T:System.ArgumentNullException">
        ///   <paramref name="bytes"/> is null. </exception>
        ///   
        /// <exception cref="T:System.ArgumentOutOfRangeException">
        ///   <paramref name="index"/> or <paramref name="count"/> is less than zero.-or- <paramref name="index"/> and <paramref name="count"/> do not denote a valid range in <paramref name="bytes"/>. </exception>
        ///   
        /// <exception cref="T:System.Text.DecoderFallbackException">A fallback occurred (see Understanding Encodings for complete explanation)-and-<see cref="P:System.Text.Encoding.DecoderFallback"/> is set to <see cref="T:System.Text.DecoderExceptionFallback"/>.</exception>
        public override int GetCharCount(byte[] bytes, int index, int count)
        {
            if (bytes == null)
            {
                throw new ArgumentNullException("bytes");
            }
            if (index < 0 || index > bytes.Length)
            {
                throw new ArgumentOutOfRangeException("index");
            }
            if (count < 0 || count > (bytes.Length - index))
            {
                throw new ArgumentOutOfRangeException("count");
            }
            return count;
        }

        /// <summary>
        /// Decodes a sequence of bytes from the specified byte array into the specified character array.
        /// </summary>
        /// <param name="bytes">The byte array containing the sequence of bytes to decode.</param>
        /// <param name="byteIndex">The index of the first byte to decode.</param>
        /// <param name="byteCount">The number of bytes to decode.</param>
        /// <param name="chars">The character array to contain the resulting set of characters.</param>
        /// <param name="charIndex">The index at which to start writing the resulting set of characters.</param>
        /// <returns>
        /// The actual number of characters written into <paramref name="chars"/>.
        /// </returns>
        /// <exception cref="T:System.ArgumentNullException">
        ///   <paramref name="bytes"/> is null.-or- <paramref name="chars"/> is null. </exception>
        ///   
        /// <exception cref="T:System.ArgumentOutOfRangeException">
        ///   <paramref name="byteIndex"/> or <paramref name="byteCount"/> or <paramref name="charIndex"/> is less than zero.-or- <paramref name="byteIndex"/> and <paramref name="byteCount"/> do not denote a valid range in <paramref name="bytes"/>.-or- <paramref name="charIndex"/> is not a valid index in <paramref name="chars"/>. </exception>
        ///   
        /// <exception cref="T:System.ArgumentException">
        ///   <paramref name="chars"/> does not have enough capacity from <paramref name="charIndex"/> to the end of the array to accommodate the resulting characters. </exception>
        ///   
        /// <exception cref="T:System.Text.DecoderFallbackException">A fallback occurred (see Understanding Encodings for complete explanation)-and-<see cref="P:System.Text.Encoding.DecoderFallback"/> is set to <see cref="T:System.Text.DecoderExceptionFallback"/>.</exception>
        public override int GetChars(byte[] bytes, int byteIndex, int byteCount, char[] chars, int charIndex)
        {
            if (bytes == null)
            {
                throw new ArgumentNullException("bytes");
            }
            if (chars == null)
            {
                throw new ArgumentNullException("chars");
            }
            if (byteIndex < 0 || byteIndex > bytes.Length)
            {
                throw new ArgumentOutOfRangeException("byteIndex");
            }
            if (byteCount < 0 || byteCount > (bytes.Length - byteIndex))
            {
                throw new ArgumentOutOfRangeException("byteCount");
            }
            if (charIndex < 0 || charIndex > chars.Length)
            {
                throw new ArgumentOutOfRangeException("charIndex");
            }
            if ((chars.Length - charIndex) < byteCount)
            {
                throw new ArgumentException();
            }
            int count = byteCount;
            byte ch;
            while (count-- > 0)
            {
                ch = bytes[byteIndex++];
                if (ch < 0x80)
                {
                    chars[charIndex++] = (char)ch;
                }
                else
                {
                    chars[charIndex++] = '?';
                }
            }
            return byteCount;
        }

        /// <summary>
        /// Calculates the maximum number of bytes produced by encoding the specified number of characters.
        /// </summary>
        /// <param name="charCount">The number of characters to encode.</param>
        /// <returns>
        /// The maximum number of bytes produced by encoding the specified number of characters.
        /// </returns>
        /// <exception cref="T:System.ArgumentOutOfRangeException">
        ///   <paramref name="charCount"/> is less than zero. </exception>
        ///   
        /// <exception cref="T:System.Text.EncoderFallbackException">A fallback occurred (see Understanding Encodings for complete explanation)-and-<see cref="P:System.Text.Encoding.EncoderFallback"/> is set to <see cref="T:System.Text.EncoderExceptionFallback"/>.</exception>
        public override int GetMaxByteCount(int charCount)
        {
            if (charCount < 0)
            {
                throw new ArgumentOutOfRangeException("charCount");
            }

            return charCount;
        }

        /// <summary>
        /// Calculates the maximum number of characters produced by decoding the specified number of bytes.
        /// </summary>
        /// <param name="byteCount">The number of bytes to decode.</param>
        /// <returns>
        /// The maximum number of characters produced by decoding the specified number of bytes.
        /// </returns>
        /// <exception cref="T:System.ArgumentOutOfRangeException">
        ///   <paramref name="byteCount"/> is less than zero. </exception>
        ///   
        /// <exception cref="T:System.Text.DecoderFallbackException">A fallback occurred (see Understanding Encodings for complete explanation)-and-<see cref="P:System.Text.Encoding.DecoderFallback"/> is set to <see cref="T:System.Text.DecoderExceptionFallback"/>.</exception>
        public override int GetMaxCharCount(int byteCount)
        {
            if (byteCount < 0)
            {
                throw new ArgumentOutOfRangeException("byteCount");
            }
            return byteCount;
        }

        /// <summary>
        /// Decodes a sequence of bytes from the specified byte array into a string.
        /// </summary>
        /// <param name="bytes">The byte array containing the sequence of bytes to decode.</param>
        /// <param name="index">The index of the first byte to decode.</param>
        /// <param name="count">The number of bytes to decode.</param>
        /// <returns>
        /// A <see cref="T:System.String"/> containing the results of decoding the specified sequence of bytes.
        /// </returns>
        /// <exception cref="T:System.ArgumentException">The byte array contains invalid Unicode code points.</exception>
        ///   
        /// <exception cref="T:System.ArgumentNullException">
        ///   <paramref name="bytes"/> is null. </exception>
        ///   
        /// <exception cref="T:System.ArgumentOutOfRangeException">
        ///   <paramref name="index"/> or <paramref name="count"/> is less than zero.-or- <paramref name="index"/> and <paramref name="count"/> do not denote a valid range in <paramref name="bytes"/>. </exception>
        ///   
        /// <exception cref="T:System.Text.DecoderFallbackException">A fallback occurred (see Understanding Encodings for complete explanation)-and-<see cref="P:System.Text.Encoding.DecoderFallback"/> is set to <see cref="T:System.Text.DecoderExceptionFallback"/>.</exception>
        public override String GetString(byte[] bytes, int index, int count)
        {
            if (bytes == null)
            {
                throw new ArgumentNullException("bytes");
            }
            if (index < 0 || index > bytes.Length)
            {
                throw new ArgumentOutOfRangeException("index");
            }
            if (count < 0 || count > (bytes.Length - index))
            {
                throw new ArgumentOutOfRangeException("count");
            }
            if (count == 0)
            {
                return String.Empty;
            }

            char[] chars = new char[count];
            int posn = 0;
            while (count-- > 0)
            {
                chars[posn++] = (char)(bytes[index++]);
            }
            return new string(chars);
        }
    }; 
}