JSON Prettifier

This is a simple class I wrote to nicely format a JSON string. Just call it with JsonFormatter.PrettyPrint(yourJsonString)

public static class JsonFormatter
{
    public static string Indent = "    ";

    public static void AppendIndent(StringBuilder sb, int count)
    {
        for (; count > 0; --count) sb.Append(Indent);
    }

    public static bool IsEscaped(StringBuilder sb, int index)
    {
        bool escaped = false;
        while (index > 0 && sb[--index] == '\\') escaped = !escaped;
        return escaped;
    }

    public static string PrettyPrint(string input)
    {
        var output = new StringBuilder(input.Length * 2);
        char? quote = null;
        int depth = 0;

        for(int i=0; i<input.Length; ++i)
        {
            char ch = input[i];

            switch (ch)
            {
                case '{':
                case '[':
                    output.Append(ch);
                    if (!quote.HasValue)
                    {
                        output.AppendLine();
                        AppendIndent(output, ++depth);
                    }
                    break;
                case '}':
                case ']':
                    if (quote.HasValue)  
                        output.Append(ch);
                    else
                    {
                        output.AppendLine();
                        AppendIndent(output, --depth);
                        output.Append(ch);
                    }
                    break;
                case '"':
                case '\'':
                    output.Append(ch);
                    if (quote.HasValue)
                    {
                        if (!IsEscaped(output, i))
                            quote = null;
                    }
                    else quote = ch;
                    break;
                case ',':
                    output.Append(ch);
                    if (!quote.HasValue)
                    {
                        output.AppendLine();
                        AppendIndent(output, depth);
                    }
                    break;
                case ':':
                    if (quote.HasValue) output.Append(ch);
                    else output.Append(" : ");
                    break;
                default:
                    if (quote.HasValue || !char.IsWhiteSpace(ch)) 
                        output.Append(ch);
                    break;
            }
        }

        return output.ToString();
    }
}