netcore/System.Private.CoreLib/shared/System/Text/DecoderExceptionFallback.cs

   1 // Licensed to the .NET Foundation under one or more agreements.
   2 // The .NET Foundation licenses this file to you under the MIT license.
   3 // See the LICENSE file in the project root for more information.
   4
   5 using System.Diagnostics.CodeAnalysis;
   6 using System.Globalization;
   7 using System.Runtime.Serialization;
   8
   9 namespace System.Text
  10 {
  11     public sealed class DecoderExceptionFallback : DecoderFallback
  12     {
  13         public override DecoderFallbackBuffer CreateFallbackBuffer() =>
  14             new DecoderExceptionFallbackBuffer();
  15
  16         // Maximum number of characters that this instance of this fallback could return
  17         public override int MaxCharCount => 0;
  18
  19         public override bool Equals(object? value) =>
  20             value is DecoderExceptionFallback;
  21
  22         public override int GetHashCode() => 879;
  23     }
  24
  25
  26     public sealed class DecoderExceptionFallbackBuffer : DecoderFallbackBuffer
  27     {
  28         public override bool Fallback(byte[] bytesUnknown, int index)
  29         {
  30             Throw(bytesUnknown, index);
  31             return true;
  32         }
  33
  34         public override char GetNextChar() => (char)0;
  35
  36         // Exception fallback doesn't have anywhere to back up to.
  37         public override bool MovePrevious() => false;
  38
  39         // Exceptions are always empty
  40         public override int Remaining => 0;
  41
  42         [DoesNotReturn]
  43         private void Throw(byte[] bytesUnknown, int index)
  44         {
  45             bytesUnknown ??= Array.Empty<byte>();
  46
  47             // Create a string representation of our bytes.
  48             StringBuilder strBytes = new StringBuilder(bytesUnknown.Length * 4);
  49
  50             const int MaxLength = 20;
  51             for (int i = 0; i < bytesUnknown.Length && i < MaxLength; i++)
  52             {
  53                 strBytes.Append('[');
  54                 strBytes.Append(bytesUnknown[i].ToString("X2", CultureInfo.InvariantCulture));
  55                 strBytes.Append(']');
  56             }
  57
  58             // In case the string's really long
  59             if (bytesUnknown.Length > MaxLength)
  60             {
  61                 strBytes.Append(" ...");
  62             }
  63
  64             // Known index
  65             throw new DecoderFallbackException(
  66                 SR.Format(SR.Argument_InvalidCodePageBytesIndex,
  67                    strBytes, index), bytesUnknown, index);
  68         }
  69     }
  70
  71     // Exception for decoding unknown byte sequences.
  72     [Serializable]
  73     [System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
  74     public sealed class DecoderFallbackException : ArgumentException
  75     {
  76         private readonly byte[]? _bytesUnknown = null;
  77         private readonly int _index = 0;
  78
  79         public DecoderFallbackException()
  80             : base(SR.Arg_ArgumentException)
  81         {
  82             HResult = HResults.COR_E_ARGUMENT;
  83         }
  84
  85         public DecoderFallbackException(string? message)
  86             : base(message)
  87         {
  88             HResult = HResults.COR_E_ARGUMENT;
  89         }
  90
  91         public DecoderFallbackException(string? message, Exception? innerException)
  92             : base(message, innerException)
  93         {
  94             HResult = HResults.COR_E_ARGUMENT;
  95         }
  96
  97         public DecoderFallbackException(string? message, byte[]? bytesUnknown, int index)
  98             : base(message)
  99         {
 100             _bytesUnknown = bytesUnknown;
 101             _index = index;
 102         }
 103
 104         private DecoderFallbackException(SerializationInfo serializationInfo, StreamingContext streamingContext)
 105             : base(serializationInfo, streamingContext)
 106         {
 107         }
 108
 109         public byte[]? BytesUnknown => _bytesUnknown;
 110
 111         public int Index => _index;
 112     }
 113 }