EncodingProvider.cs

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using System.Collections.Generic;
using System.Threading;
 
namespace System.Text;
 
public abstract class EncodingProvider
{
    private static volatile EncodingProvider[] s_providers;
 
    public EncodingProvider()
    {
    }
 
    public abstract Encoding? GetEncoding(string name);
 
    public abstract Encoding? GetEncoding(int codepage);
 
    public virtual Encoding? GetEncoding(string name, EncoderFallback encoderFallback, DecoderFallback decoderFallback)
    {
        Encoding encoding = GetEncoding(name);
        if (encoding != null)
        {
            encoding = (Encoding)encoding.Clone();
            encoding.EncoderFallback = encoderFallback;
            encoding.DecoderFallback = decoderFallback;
        }
        return encoding;
    }
 
    public virtual Encoding? GetEncoding(int codepage, EncoderFallback encoderFallback, DecoderFallback decoderFallback)
    {
        Encoding encoding = GetEncoding(codepage);
        if (encoding != null)
        {
            encoding = (Encoding)encoding.Clone();
            encoding.EncoderFallback = encoderFallback;
            encoding.DecoderFallback = decoderFallback;
        }
        return encoding;
    }
 
    public virtual IEnumerable<EncodingInfo> GetEncodings()
    {
        return Array.Empty<EncodingInfo>();
    }
 
    internal static void AddProvider(EncodingProvider provider)
    {
        if (provider == null)
        {
            throw new ArgumentNullException("provider");
        }
        if (s_providers == null && Interlocked.CompareExchange(ref s_providers, new EncodingProvider[1] { provider }, null) == null)
        {
            return;
        }
        EncodingProvider[] array;
        EncodingProvider[] array2;
        do
        {
            array = s_providers;
            if (Array.IndexOf(array, provider) >= 0)
            {
                break;
            }
            array2 = new EncodingProvider[array.Length + 1];
            Array.Copy(array, array2, array.Length);
            array2[^1] = provider;
        }
        while (Interlocked.CompareExchange(ref s_providers, array2, array) != array);
    }
 
    internal static Encoding GetEncodingFromProvider(int codepage)
    {
        EncodingProvider[] array = s_providers;
        if (array == null)
        {
            return null;
        }
        EncodingProvider[] array2 = array;
        foreach (EncodingProvider encodingProvider in array2)
        {
            Encoding encoding = encodingProvider.GetEncoding(codepage);
            if (encoding != null)
            {
                return encoding;
            }
        }
        return null;
    }
 
    internal static Dictionary<int, EncodingInfo> GetEncodingListFromProviders()
    {
        EncodingProvider[] array = s_providers;
        if (array == null)
        {
            return null;
        }
        Dictionary<int, EncodingInfo> dictionary = new Dictionary<int, EncodingInfo>();
        EncodingProvider[] array2 = array;
        foreach (EncodingProvider encodingProvider in array2)
        {
            IEnumerable<EncodingInfo> encodings = encodingProvider.GetEncodings();
            if (encodings == null)
            {
                continue;
            }
            foreach (EncodingInfo item in encodings)
            {
                dictionary.TryAdd(item.CodePage, item);
            }
        }
        return dictionary;
    }
 
    internal static Encoding GetEncodingFromProvider(string encodingName)
    {
        if (s_providers == null)
        {
            return null;
        }
        EncodingProvider[] array = s_providers;
        EncodingProvider[] array2 = array;
        foreach (EncodingProvider encodingProvider in array2)
        {
            Encoding encoding = encodingProvider.GetEncoding(encodingName);
            if (encoding != null)
            {
                return encoding;
            }
        }
        return null;
    }
 
    internal static Encoding GetEncodingFromProvider(int codepage, EncoderFallback enc, DecoderFallback dec)
    {
        if (s_providers == null)
        {
            return null;
        }
        EncodingProvider[] array = s_providers;
        EncodingProvider[] array2 = array;
        foreach (EncodingProvider encodingProvider in array2)
        {
            Encoding encoding = encodingProvider.GetEncoding(codepage, enc, dec);
            if (encoding != null)
            {
                return encoding;
            }
        }
        return null;
    }
 
    internal static Encoding GetEncodingFromProvider(string encodingName, EncoderFallback enc, DecoderFallback dec)
    {
        if (s_providers == null)
        {
            return null;
        }
        EncodingProvider[] array = s_providers;
        EncodingProvider[] array2 = array;
        foreach (EncodingProvider encodingProvider in array2)
        {
            Encoding encoding = encodingProvider.GetEncoding(encodingName, enc, dec);
            if (encoding != null)
            {
                return encoding;
            }
        }
        return null;
    }
}