TinyJsonSerializer - C# Json Serializer(serialize only)

TinyJsonSerializer.cs

using System;
using System.Collections;
using System.IO;
using System.Reflection;
using System.Text;

// serialize only:)
public static class TinyJsonSerializer
{
    static readonly Encoding bomlessUtf8 = new UTF8Encoding(false);

    public static string Serialize(object obj)
    {
        using (var ms = new MemoryStream())
        using (var sw = new StreamWriter(ms, bomlessUtf8))
        {
            Serialize(sw, obj);
            sw.Flush();

            return bomlessUtf8.GetString(ms.ToArray());
        }
    }

    public static void Serialize(TextWriter tw, object obj)
    {
        SerializeObject(tw, obj);
    }

    enum JsonType
    {
        @string, number, boolean, @object, array, @null
    }

    static JsonType GetJsonType(object obj)
    {
        if (obj == null) return JsonType.@null;

        switch (Type.GetTypeCode(obj.GetType()))
        {
            case TypeCode.Boolean:
                return JsonType.boolean;
            case TypeCode.String:
            case TypeCode.Char:
            case TypeCode.DateTime:
                return JsonType.@string;
            case TypeCode.Int16:
            case TypeCode.Int32:
            case TypeCode.Int64:
            case TypeCode.UInt16:
            case TypeCode.UInt32:
            case TypeCode.UInt64:
            case TypeCode.Single:
            case TypeCode.Double:
            case TypeCode.Decimal:
            case TypeCode.SByte:
            case TypeCode.Byte:
                return JsonType.number;
            case TypeCode.Object:
                // specialized for wellknown types
                if (obj is Uri || obj is DateTimeOffset || obj is Guid || obj is StringBuilder)
                {
                    return JsonType.@string;
                }
                else if (obj is IDictionary)
                {
                    return JsonType.@object;
                }

                return (obj is IEnumerable) ? JsonType.array : JsonType.@object;
            case TypeCode.DBNull:
            case TypeCode.Empty:
            default:
                return JsonType.@null;
        }
    }

    static void SerializeObject(TextWriter tw, object o)
    {
        switch (GetJsonType(o))
        {
            case JsonType.@string:
                if (o is string)
                {
                    WriteString(tw, (string)o);
                }
                else if (o is DateTime)
                {
                    var s = ((DateTime)o).ToString("o");
                    WriteString(tw, s);
                }
                else if (o is DateTimeOffset)
                {
                    var s = ((DateTimeOffset)o).ToString("o");
                    WriteString(tw, s);
                }
                else
                {
                    WriteString(tw, o.ToString());
                }
                break;
            case JsonType.number:
                WriteNumber(tw, o);
                break;
            case JsonType.boolean:
                WriteBoolean(tw, (bool)o);
                break;
            case JsonType.@object:
                WriteObject(tw, o);
                break;
            case JsonType.array:
                WriteArray(tw, (IEnumerable)o);
                break;
            case JsonType.@null:
                WriteNull(tw);
                break;
            default:
                break;
        }
    }

    static void WriteString(TextWriter tw, string o)
    {
        tw.Write('\"');

        for (int i = 0; i < o.Length; i++)
        {
            var c = o[i];
            switch (c)
            {
                case '"':
                    tw.Write("\\\"");
                    break;
                case '\\':
                    tw.Write("\\\\");
                    break;
                case '\b':
                    tw.Write("\\b");
                    break;
                case '\f':
                    tw.Write("\\f");
                    break;
                case '\n':
                    tw.Write("\\n");
                    break;
                case '\r':
                    tw.Write("\\r");
                    break;
                case '\t':
                    tw.Write("\\t");
                    break;
                default:
                    tw.Write(c);
                    break;
            }
        }

        tw.Write('\"');
    }

    static void WriteNumber(TextWriter tw, object o)
    {
        tw.Write(o.ToString());
    }

    static void WriteBoolean(TextWriter tw, bool o)
    {
        tw.Write(o ? "true" : "false");
    }

    static void WriteObject(TextWriter tw, object o)
    {
        tw.Write('{');

        var dict = o as IDictionary;
        if (dict != null)
        {
            // Dictionary
            var isFirst = true;
            foreach (DictionaryEntry item in dict)
            {
                if (!isFirst) tw.Write(",");
                else isFirst = false;

                tw.Write("\"" + item.Key + "\"");
                tw.Write(":");
                SerializeObject(tw, item.Value);
            }
        }
        else
        {
            // Object
            var isFirst = true;
            foreach (var item in o.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance | BindingFlags.GetProperty))
            {
                if (!isFirst) tw.Write(",");
                else isFirst = false;

                var key = item.Name;
                var value = item.GetGetMethod().Invoke(o, null); // safe reflection for unity
                tw.Write("\"" + key + "\"");
                tw.Write(":");
                SerializeObject(tw, value);
            }

            isFirst = true;
            foreach (var item in o.GetType().GetFields(BindingFlags.Public | BindingFlags.Instance | BindingFlags.GetField))
            {
                if (!isFirst) tw.Write(",");
                else isFirst = false;

                var key = item.Name;
                var value = item.GetValue(o);
                tw.Write("\"" + key + "\"");
                tw.Write(":");
                SerializeObject(tw, value);
            }
        }

        tw.Write('}');
    }

    static void WriteArray(TextWriter tw, IEnumerable o)
    {
        tw.Write("[");
        var isFirst = true;
        foreach (var item in o)
        {
            if (!isFirst) tw.Write(",");
            else isFirst = false;

            SerializeObject(tw, item);
        }
        tw.Write("]");
    }

    static void WriteNull(TextWriter tw)
    {
        tw.Write("null");
    }
}