QEncoder.cs

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namespace System.Net.Mime;
 
internal sealed class QEncoder : ByteEncoder
{
    private readonly WriteStateInfoBase _writeState;
 
    internal override WriteStateInfoBase WriteState => _writeState;
 
    protected override bool HasSpecialEncodingForCRLF => true;
 
    internal QEncoder(WriteStateInfoBase wsi)
    {
        _writeState = wsi;
    }
 
    protected override void AppendEncodedCRLF()
    {
        WriteState.Append(61, 48, 68, 61, 48, 65);
    }
 
    protected override bool LineBreakNeeded(byte b)
    {
        int num = WriteState.CurrentLineLength + 3 + WriteState.FooterLength;
        bool flag = b == 32 || b == 9 || b == 13 || b == 10;
        if (num >= WriteState.MaxLineLength && flag)
        {
            return true;
        }
        int num2 = WriteState.CurrentLineLength + WriteState.FooterLength;
        if (num2 >= WriteState.MaxLineLength)
        {
            return true;
        }
        return false;
    }
 
    protected override bool LineBreakNeeded(byte[] bytes, int count)
    {
        if (count == 1 || IsCRLF(bytes, count))
        {
            return LineBreakNeeded(bytes[0]);
        }
        int num = count * 3;
        return WriteState.CurrentLineLength + num + _writeState.FooterLength > WriteState.MaxLineLength;
    }
 
    protected override int GetCodepointSize(string value, int i)
    {
        if (value[i] == '\r' && i + 1 < value.Length && value[i + 1] == '\n')
        {
            return 2;
        }
        if (IsSurrogatePair(value, i))
        {
            return 2;
        }
        return 1;
    }
 
    public override void AppendPadding()
    {
    }
 
    protected override void ApppendEncodedByte(byte b)
    {
        if (b == 32)
        {
            WriteState.Append(95);
            return;
        }
        if (IsAsciiLetterOrDigit((char)b))
        {
            WriteState.Append(b);
            return;
        }
        WriteState.Append(61);
        WriteState.Append((byte)System.HexConverter.ToCharUpper(b >> 4));
        WriteState.Append((byte)System.HexConverter.ToCharUpper(b));
    }
 
    private static bool IsAsciiLetterOrDigit(char character)
    {
        if (!IsAsciiLetter(character))
        {
            if (character >= '0')
            {
                return character <= '9';
            }
            return false;
        }
        return true;
    }
 
    private static bool IsAsciiLetter(char character)
    {
        if (character < 'a' || character > 'z')
        {
            if (character >= 'A')
            {
                return character <= 'Z';
            }
            return false;
        }
        return true;
    }
}