c++11: json library that implements two simple requirements

I want c++11 json library with such two simple features:

1. For output allow code like this(usage of json11), with help of std::initializer_list:

   std::cout << json11::Json{
       json11::Json::object {
           { "Key4", json11::Json::object{
                   {"sub key", "data"}
               }}}}
   .dump();
   
   

2. Allow parse such input data "{\"test1\": \"test1 value\"} {", for example picojson:

   std::string json = "{\"test1\": \"test1 value\"} {";
   picojson::value v;
   std::string err;
   auto it = picojson::parse(v, json.begin(), json.end(), &err);
   
   

as result it(picojson) parse "{\"test1\": \"test1 value\"}" and it point to last symbol('{')

Simple enough requirement I think, but

• Qt 5 not supported (2),

• json11 not support (2),

• picojson not support (1)

• jsoncpp not support (1)

So anybody know opensource c++11 library that support these two simple requirements?