expected.h

 
 
#pragma once
 
#define GHPL_LATEST_MSVC_VERSION_WITH_EXPECTED_BUGS 1939 
#if __has_include(<expected>) && (_MSC_VER > GHPL_LATEST_MSVC_VERSION_WITH_EXPECTED_BUGS)
#include <expected>
namespace ghassanpl
{
    using std::expected;
    using std::unexpected;
 
    static_assert(std::is_swappable_v<std::string>);
    static_assert(std::is_swappable_v<std::error_code>);
}
#elif __has_include(<tl/expected.hpp>)
#include <tl/expected.hpp> 
namespace ghassanpl
{
    using tl::expected;
    using tl::unexpected;
}
#elif defined(GHPL_EXPECTED_HEADER)
#include GHPL_EXPECTED_HEADER
#else
#error "No expected implementation found"
#endif
 
namespace ghassanpl
{
 
    template <typename FUNC, typename... ARGS>
    inline auto call_with_expected_ec(FUNC&& func, ARGS&&... args) noexcept(noexcept(func(std::forward<ARGS>(args)...)))
        -> expected<std::invoke_result_t<FUNC, ARGS&&...>, std::error_code>
    {
        std::error_code ec{};
        if constexpr (std::is_void_v<std::invoke_result_t<FUNC, ARGS&&...>>)
        {
            func(std::forward<ARGS>(args)..., ec);
            if (ec)
                return unexpected(ec);
            return {};
        }
        else
        {
            auto result = func(std::forward<ARGS>(args)..., ec);
            if (ec)
                return unexpected(ec);
            return result;
        }
    }
 
}