CodePagesEncodingProvider
Provides access to an encoding provider for code pages that otherwise are available only in the desktop .NET Framework.
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Threading;
namespace System.Text
{
[System.Runtime.CompilerServices.NullableContext(1)]
[System.Runtime.CompilerServices.Nullable(0)]
public sealed class CodePagesEncodingProvider : EncodingProvider
{
private static readonly EncodingProvider s_singleton = new CodePagesEncodingProvider();
private readonly Dictionary<int, Encoding> _encodings = new Dictionary<int, Encoding>();
private readonly ReaderWriterLockSlim _cacheLock = new ReaderWriterLockSlim();
private const int ISCIIAssemese = 57006;
private const int ISCIIBengali = 57003;
private const int ISCIIDevanagari = 57002;
private const int ISCIIGujarathi = 57010;
private const int ISCIIKannada = 57008;
private const int ISCIIMalayalam = 57009;
private const int ISCIIOriya = 57007;
private const int ISCIIPanjabi = 57011;
private const int ISCIITamil = 57004;
private const int ISCIITelugu = 57005;
private const int ISOKorean = 50225;
private const int ChineseHZ = 52936;
private const int ISO2022JP = 50220;
private const int ISO2022JPESC = 50221;
private const int ISO2022JPSISO = 50222;
private const int ISOSimplifiedCN = 50227;
private const int EUCJP = 51932;
private const int CodePageMacGB2312 = 10008;
private const int CodePageMacKorean = 10003;
private const int CodePageGB2312 = 20936;
private const int CodePageDLLKorean = 20949;
private const int GB18030 = 54936;
private const int DuplicateEUCCN = 51936;
private const int EUCKR = 51949;
private const int EUCCN = 936;
private const int ISO_8859_8I = 38598;
private const int ISO_8859_8_Visual = 28598;
public static EncodingProvider Instance => s_singleton;
private static int SystemDefaultCodePage {
get {
if (!global::Interop.Kernel32.TryGetACPCodePage(out int codePage))
return 0;
return codePage;
}
}
internal CodePagesEncodingProvider()
{
}
[System.Runtime.CompilerServices.NullableContext(2)]
public override Encoding GetEncoding(int codepage)
{
if (codepage < 0 || codepage > 65535)
return null;
if (codepage != 0) {
Encoding value = null;
_cacheLock.EnterUpgradeableReadLock();
try {
if (!_encodings.TryGetValue(codepage, out value)) {
switch (BaseCodePageEncoding.GetCodePageByteSize(codepage)) {
case 1:
value = new SBCSCodePageEncoding(codepage);
break;
case 2:
value = new DBCSCodePageEncoding(codepage);
break;
default:
value = GetEncodingRare(codepage);
if (value == null)
return null;
break;
}
_cacheLock.EnterWriteLock();
try {
if (!_encodings.TryGetValue(codepage, out Encoding value2)) {
_encodings.Add(codepage, value);
return value;
}
return value2;
} finally {
_cacheLock.ExitWriteLock();
}
}
return value;
} finally {
_cacheLock.ExitUpgradeableReadLock();
}
}
int systemDefaultCodePage = SystemDefaultCodePage;
if (systemDefaultCodePage == 0)
return null;
return GetEncoding(systemDefaultCodePage);
}
[return: System.Runtime.CompilerServices.Nullable(2)]
public override Encoding GetEncoding(string name)
{
int codePageFromName = System.Text.EncodingTable.GetCodePageFromName(name);
if (codePageFromName == 0)
return null;
return GetEncoding(codePageFromName);
}
private static Encoding GetEncodingRare(int codepage)
{
Encoding result = null;
if (codepage <= 51932) {
switch (codepage) {
case 10008:
result = new DBCSCodePageEncoding(10008, 20936);
goto IL_011a;
case 10003:
result = new DBCSCodePageEncoding(10003, 20949);
goto IL_011a;
case 50220:
case 50221:
case 50222:
case 50225:
break;
case 50227:
goto IL_00ea;
case 51932:
result = new EUCJPEncoding();
goto IL_011a;
case 38598:
result = new SBCSCodePageEncoding(codepage, 28598);
goto IL_011a;
default:
goto IL_011a;
}
goto IL_00e1;
}
if (codepage <= 51949) {
switch (codepage) {
case 51936:
break;
case 51949:
result = new DBCSCodePageEncoding(codepage, 20949);
goto IL_011a;
default:
goto IL_011a;
}
goto IL_00ea;
}
switch (codepage) {
case 54936:
goto IL_00d9;
case 52936:
goto IL_00e1;
}
if ((uint)(codepage - 57002) <= 9)
result = new ISCIIEncoding(codepage);
goto IL_011a;
IL_00e1:
result = new ISO2022Encoding(codepage);
goto IL_011a;
IL_00ea:
result = new DBCSCodePageEncoding(codepage, 936);
goto IL_011a;
IL_011a:
return result;
IL_00d9:
result = new GB18030Encoding();
goto IL_011a;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal unsafe static ref T GetNonNullPinnableReference<T>(T[] array) where T : struct
{
if (array.Length == 0)
return ref Unsafe.AsRef<T>((void*)1);
return ref array[0];
}
}
}