src/ServiceStack.Text/JsonSerializer.cs

//
// https://github.com/ServiceStack/ServiceStack.Text
// ServiceStack.Text: .NET C# POCO JSON, JSV and CSV Text Serializers.
//
// Authors:
//   Demis Bellot (demis.bellot@gmail.com)
//
// Copyright 2012 ServiceStack, Inc. All Rights Reserved.
//
// Licensed under the same terms of ServiceStack.
//

using System;
using System.IO;
using System.Net;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using ServiceStack.Text.Common;
using ServiceStack.Text.Json;

namespace ServiceStack.Text
{
    /// <summary>
    /// Creates an instance of a Type from a string value
    /// </summary>
    public static class JsonSerializer
    {
        static JsonSerializer()
        {
            JsConfig.InitStatics();
        }

        public static int BufferSize = 1024;

        [Obsolete("Use JsConfig.UTF8Encoding")]
        public static UTF8Encoding UTF8Encoding
        {
            get => JsConfig.UTF8Encoding;
            set => JsConfig.UTF8Encoding = value;
        }

        public static Action<object> OnSerialize { get; set; }

        public static T DeserializeFromString<T>(string value)
        {
            return JsonReader<T>.Parse(value) is T obj ? obj : default(T);
        }

        public static T DeserializeFromSpan<T>(ReadOnlySpan<char> value)
        {
            return JsonReader<T>.Parse(value) is T obj ? obj : default(T);
        }

        public static T DeserializeFromReader<T>(TextReader reader)
        {
            return DeserializeFromString<T>(reader.ReadToEnd());
        }

        public static object DeserializeFromSpan(Type type, ReadOnlySpan<char> value)
        {
            return value.IsEmpty
                ? null
                : JsonReader.GetParseSpanFn(type)(value);
        }

        public static object DeserializeFromString(string value, Type type)
        {
            return string.IsNullOrEmpty(value)
                ? null
                : JsonReader.GetParseFn(type)(value);
        }

        public static object DeserializeFromReader(TextReader reader, Type type)
        {
            return DeserializeFromString(reader.ReadToEnd(), type);
        }
        
        public static string SerializeToString<T>(T value)
        {
            if (value == null || value is Delegate) return null;
            if (typeof(T) == typeof(object))
            {
                return SerializeToString(value, value.GetType());
            }
            if (typeof(T).IsAbstract || typeof(T).IsInterface)
            {
                var prevState = JsState.IsWritingDynamic;
                JsState.IsWritingDynamic = true;
                var result = SerializeToString(value, value.GetType());
                JsState.IsWritingDynamic = prevState;
                return result;
            }

            var writer = StringWriterThreadStatic.Allocate();
            if (typeof(T) == typeof(string))
            {
                JsonUtils.WriteString(writer, value as string);
            }
            else
            {
                WriteObjectToWriter(value, JsonWriter<T>.GetRootObjectWriteFn(value), writer);
            }
            return StringWriterThreadStatic.ReturnAndFree(writer);
        }

        public static string SerializeToString(object value, Type type)
        {
            if (value == null) return null;

            var writer = StringWriterThreadStatic.Allocate();
            if (type == typeof(string))
            {
                JsonUtils.WriteString(writer, value as string);
            }
            else
            {
                OnSerialize?.Invoke(value);
                WriteObjectToWriter(value, JsonWriter.GetWriteFn(type), writer);
            }
            return StringWriterThreadStatic.ReturnAndFree(writer);
        }

        public static void SerializeToWriter<T>(T value, TextWriter writer)
        {
            if (value == null) return;
            if (typeof(T) == typeof(string))
            {
                JsonUtils.WriteString(writer, value as string);
            }
            else if (typeof(T) == typeof(object))
            {
                SerializeToWriter(value, value.GetType(), writer);
            }
            else if (typeof(T).IsAbstract || typeof(T).IsInterface)
            {
                var prevState = JsState.IsWritingDynamic;
                JsState.IsWritingDynamic = false;
                SerializeToWriter(value, value.GetType(), writer);
                JsState.IsWritingDynamic = prevState;
            }
            else
            {
                WriteObjectToWriter(value, JsonWriter<T>.GetRootObjectWriteFn(value), writer);
            }
        }

        public static void SerializeToWriter(object value, Type type, TextWriter writer)
        {
            if (value == null) return;
            if (type == typeof(string))
            {
                JsonUtils.WriteString(writer, value as string);
                return;
            }

            OnSerialize?.Invoke(value);
            WriteObjectToWriter(value, JsonWriter.GetWriteFn(type), writer);
        }

        public static void SerializeToStream<T>(T value, Stream stream)
        {
            if (value == null) return;
            if (typeof(T) == typeof(object))
            {
                SerializeToStream(value, value.GetType(), stream);
            }
            else if (typeof(T).IsAbstract || typeof(T).IsInterface)
            {
                var prevState = JsState.IsWritingDynamic;
                JsState.IsWritingDynamic = false;
                SerializeToStream(value, value.GetType(), stream);
                JsState.IsWritingDynamic = prevState;
            }
            else
            {
                var writer = new StreamWriter(stream, JsConfig.UTF8Encoding, BufferSize, leaveOpen:true);
                WriteObjectToWriter(value, JsonWriter<T>.GetRootObjectWriteFn(value), writer);
                writer.Flush();
            }
        }

        public static void SerializeToStream(object value, Type type, Stream stream)
        {
            OnSerialize?.Invoke(value);
            var writer = new StreamWriter(stream, JsConfig.UTF8Encoding, BufferSize, leaveOpen:true);
            WriteObjectToWriter(value, JsonWriter.GetWriteFn(type), writer);
            writer.Flush();
        }

        private static void WriteObjectToWriter(object value, WriteObjectDelegate serializeFn, TextWriter writer)
        {
            if (!JsConfig.Indent)
            {
                serializeFn(writer, value);
            }
            else
            {
                var sb = StringBuilderCache.Allocate();
                using var captureJson = new StringWriter(sb);
                serializeFn(captureJson, value);
                captureJson.Flush();
                var json = StringBuilderCache.ReturnAndFree(sb);
                var indentJson = json.IndentJson();
                writer.Write(indentJson);
            }
        }
        public static T DeserializeFromStream<T>(Stream stream)
        {
            return (T)MemoryProvider.Instance.Deserialize(stream, typeof(T), DeserializeFromSpan);
        }

        public static object DeserializeFromStream(Type type, Stream stream)
        {
            return MemoryProvider.Instance.Deserialize(stream, type, DeserializeFromSpan);
        }

        public static Task<object> DeserializeFromStreamAsync(Type type, Stream stream)
        {
            return MemoryProvider.Instance.DeserializeAsync(stream, type, DeserializeFromSpan);
        }

        public static async Task<T> DeserializeFromStreamAsync<T>(Stream stream)
        {
            var obj = await MemoryProvider.Instance.DeserializeAsync(stream, typeof(T), DeserializeFromSpan).ConfigAwait();
            return (T)obj;
        }

        public static T DeserializeResponse<T>(WebRequest webRequest)
        {
            using (var webRes = PclExport.Instance.GetResponse(webRequest))
            using (var stream = webRes.GetResponseStream())
            {
                return DeserializeFromStream<T>(stream);
            }
        }

        public static object DeserializeResponse<T>(Type type, WebRequest webRequest)
        {
            using (var webRes = PclExport.Instance.GetResponse(webRequest))
            using (var stream = webRes.GetResponseStream())
            {
                return DeserializeFromStream(type, stream);
            }
        }

        public static T DeserializeRequest<T>(WebRequest webRequest)
        {
            using (var webRes = PclExport.Instance.GetResponse(webRequest))
            {
                return DeserializeResponse<T>(webRes);
            }
        }

        public static object DeserializeRequest(Type type, WebRequest webRequest)
        {
            using (var webRes = PclExport.Instance.GetResponse(webRequest))
            {
                return DeserializeResponse(type, webRes);
            }
        }

        public static T DeserializeResponse<T>(WebResponse webResponse)
        {
            using (var stream = webResponse.GetResponseStream())
            {
                return DeserializeFromStream<T>(stream);
            }
        }

        public static object DeserializeResponse(Type type, WebResponse webResponse)
        {
            using (var stream = webResponse.GetResponseStream())
            {
                return DeserializeFromStream(type, stream);
            }
        }
    }

    public class JsonStringSerializer : IStringSerializer
    {
        public To DeserializeFromString<To>(string serializedText)
        {
            return JsonSerializer.DeserializeFromString<To>(serializedText);
        }

        public object DeserializeFromString(string serializedText, Type type)
        {
            return JsonSerializer.DeserializeFromString(serializedText, type);
        }

        public string SerializeToString<TFrom>(TFrom @from)
        {
            return JsonSerializer.SerializeToString(@from);
        }
    }
}