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.Runtime.InteropServices;
using System.Threading;
namespace System.Text
{
[NullableContext(1)]
[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();
public static EncodingProvider Instance => s_singleton;
internal CodePagesEncodingProvider()
{
}
[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 num = 0;
return null;
}
[return: 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 static ref T GetNonNullPinnableReference<T>(T[] array) where T : struct
{
return ref MemoryMarshal.GetArrayDataReference(array);
}
public override IEnumerable<EncodingInfo> GetEncodings()
{
return BaseCodePageEncoding.GetEncodings(this);
}
}
}