static string EncodeRFC5987(string value)
{
var encoding = Encoding.UTF8;
StringBuilder sb = new StringBuilder(value.Length + 11);
sb.Append(encoding.WebName);
sb.Append('\'');
sb.Append('\'');
for (int i = 0; i < value.Length; ++i)
{
var ch = value[i];
if (ch > 127)
{
foreach (var b in encoding.GetBytes(new[] { ch }))
{
sb.Append('%');
sb.Append(b.ToString("X2"));
}
continue;
}
if (!Lexer.IsValidCharacter(ch) || ch == '*' || ch == '?' || ch == '%')
{
sb.Append(Uri.HexEscape(ch));
continue;
}
sb.Append(ch);
}
return(sb.ToString());
}
