DecoderReplacementFallback.cs

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using System.Diagnostics.CodeAnalysis;
 
namespace System.Text;
 
public sealed class DecoderReplacementFallback : DecoderFallback
{
    internal static readonly DecoderReplacementFallback s_default = new DecoderReplacementFallback();
 
    private readonly string _strDefault;
 
    public string DefaultString => _strDefault;
 
    public override int MaxCharCount => _strDefault.Length;
 
    public DecoderReplacementFallback()
        : this("?")
    {
    }
 
    public DecoderReplacementFallback(string replacement)
    {
        if (replacement == null)
        {
            throw new ArgumentNullException("replacement");
        }
        bool flag = false;
        foreach (char c in replacement)
        {
            if (char.IsSurrogate(c))
            {
                if (char.IsHighSurrogate(c))
                {
                    if (flag)
                    {
                        break;
                    }
                    flag = true;
                    continue;
                }
                if (!flag)
                {
                    flag = true;
                    break;
                }
                flag = false;
            }
            else if (flag)
            {
                break;
            }
        }
        if (flag)
        {
            throw new ArgumentException(SR.Format(SR.Argument_InvalidCharSequenceNoIndex, "replacement"));
        }
        _strDefault = replacement;
    }
 
    public override DecoderFallbackBuffer CreateFallbackBuffer()
    {
        return new DecoderReplacementFallbackBuffer(this);
    }
 
    public override bool Equals([NotNullWhen(true)] object? value)
    {
        if (value is DecoderReplacementFallback decoderReplacementFallback)
        {
            return _strDefault == decoderReplacementFallback._strDefault;
        }
        return false;
    }
 
    public override int GetHashCode()
    {
        return _strDefault.GetHashCode();
    }
}