[Feature Request] ref::cli::read wchar_t **argv[] support

[levicki]

Please add wchar_t support for argument parsing.

[liuzicheng1987]

@levicki this is a bit trickier than I originally thought. I will think about an elegant solution

[levicki]

Yes I know, especially if you want to keep multi-platform support.

Do you think something like this would work?

#include <codecvt>
#include <concepts>
#include <locale>
#include <string>
#include <vector>

template <typename CharT>
inline std::string to_utf8(const CharT* Str)
{
	if constexpr (std::same_as<CharT, char>) {
		return std::string(Str);
	} else {
		std::wstring_convert<std::codecvt_utf8<CharT>, CharT> Converter;
		return Converter.to_bytes(Str);
	}
}

template <typename CharT>
inline rfl::Result<ParsedArgs> parse_argv(int Argc, CharT* Argv[])
{
	std::vector<std::string> Args;
	Args.reserve(static_cast<size_t>(Argc));

	for (int i = 0; i < Argc; ++i) {
		Args.push_back(to_utf8(Argv[i]));
	}

	// rest of the code...
}

And also:

template <class CharT, class T, class... Ps>
rfl::Result<T> read(int Argc, CharT* Argv[])
...

Of course if you want to avoid wstring_convert then it gets even more complicated :-)

Not sure how much sense it makes though — for string arguments app may still expect wide strings. Main issue of working with Win32 API is it exclusively uses wchar_t and having to juggle back and forth is a big mess.

[liuzicheng1987]

@levicki we will have to avoid wstring_convert. It is deprecated and will be removed in C++ 26.
https://en.cppreference.com/cpp/locale/wstring_convert

[liuzicheng1987]

@levicki I have an idea. The PR will come later today.

[levicki]

@levicki I have an idea. The PR will come later today.

Can you please clarify if you plan to change storage and return type for string arguments also (so that we can parse them into std::wstring for example) or just convert on input?

[liuzicheng1987]

@levicki I will convert on input, but it is absolutely possible to parse into std::wstring, as you can see from the tests I have added in the relevant PR:

#709