jsonfx reader for emoji

gistfile1.txt

						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;
								int utf16_pair;
								// tsteil - added
								// see if we have another \u char (surrogate pair)
								if (this.index+6 < this.SourceLength &&
									Int32.TryParse(
										this.Source.Substring(this.index+3, 4),
										NumberStyles.AllowHexSpecifier,
										NumberFormatInfo.InvariantInfo,
										out utf16_pair))
								{
									this.index += 5;
									var utf32 = Char.ConvertToUtf32((char)utf16, (char)utf16_pair);
									builder.Append(Char.ConvertFromUtf32(utf32));
								} else {
									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;
						}