from_string should support wstring_view

[taocpp]

from_string should support wstring_view

[d-frey]

The overloads also need to be implemented, but our parser only supports UTF-8. I don't see any way to support this with reasonable effort. Plus JSON only requires support for UTF-8 anyways... hm...

@ColinH Any thoughts on this?

[matbech]

As an alternative: given a utf-8 encoded char* input, would it be possible to convert all value strings transparently from utf-8 to wstring?
The use case are Windows applications which for the majority work with wchar_t and not with utf-8 encoded strings.

[d-frey]

Storing UTF-16 encoded strings (wstring or even wstring_view) would be a lot of work, starting with extending tao::json::type and adding support for the two additional types almost everywhere, extending the Events interface and forcing every producer and consumer to handle wstring, then adding comparisons for string vs. wstring because they are just a different representations of the same conceptual type, ... - sorry, that's not going to happen :)

💡 You could try and specialize the traits (or create your own traits) for std::wstring. That would allow you to use std::wstring almost seamlessly with our library.

❗️A specialization for wstring_view would probably not make much sense as the JSON value nodes store UTF-8 internally which can't be used by a wstring_view.

[whiterabbit963]

It should also be noted that std::wstring (wchar_t) gets compiled as 4 bytes on linux and 2 bytes on windows.