jsonfx reader for emoji

gistfile1.cs

case 'u':
{
	// Unicode escape sequence
	// e.g. Copyright: "\u00A9"

	// unicode ordinal
	int utf16;
	if (this.index+4 < this.SourceLength &&
		Int32.TryParse(
			this.Source.Substring(this.index+1, 4),
			NumberStyles.AllowHexSpecifier,
			NumberFormatInfo.InvariantInfo,
			out utf16))
	{
		this.index += 4;
		// tsteil - added
		// see if we have another \u char (surrogate pair)
		int utf16_pair;
		if (this.index + 6 < this.SourceLength &&
			Int32.TryParse(
				this.Source.Substring(this.index+3, 4),
				NumberStyles.AllowHexSpecifier,
				NumberFormatInfo.InvariantInfo,
				out utf16_pair))
		{
			// make sure its actually a surrogate pair
			if (char.IsSurrogatePair((char)utf16, (char)utf16_pair)) {
				// looks like we have a surrogate pair
				this.index += 5;
				var utf32 = Char.ConvertToUtf32((char)utf16, (char)utf16_pair);
				builder.Append(Char.ConvertFromUtf32(utf32));
			} else {
				// its not a surrogate pair, so just add the original utf16 char
				builder.Append(Char.ConvertFromUtf32(utf16));
			}
		} else {
			// no additional \u char
			builder.Append(Char.ConvertFromUtf32(utf16));
		}
	}
	else
	{
		// using FireFox style recovery, if not a valid hex
		// escape sequence then treat as single escaped 'u'
		// followed by rest of string
		builder.Append(this.Source[this.index]);
	}
	break;
}