codeconvert.cpp

#include <codecvt>
#include <cstdlib>
#include <iomanip>
#include <iostream>
#include <locale>
#include <string>
#include <system_error>
#include <vector>
#include <Windows.h>

std::wstring multi_to_wide_capi(std::string const& src)
{
    std::size_t converted{};
    std::vector<wchar_t> dest(src.size(), L'\0');
    if (::_mbstowcs_s_l(&converted, dest.data(), dest.size(), src.data(), _TRUNCATE, ::_create_locale(LC_ALL, "jpn")) != 0) {
        throw std::system_error{errno, std::system_category()};
    }
    dest.resize(std::char_traits<wchar_t>::length(dest.data()));
    dest.shrink_to_fit();
    return std::wstring(dest.begin(), dest.end());
}

std::wstring multi_to_wide_winapi(std::string const& src)
{
    auto const dest_size = ::MultiByteToWideChar(CP_ACP, 0U, src.data(), -1, nullptr, 0U);
    std::vector<wchar_t> dest(dest_size, L'\0');
    if (::MultiByteToWideChar(CP_ACP, 0U, src.data(), -1, dest.data(), dest.size()) == 0) {
        throw std::system_error{static_cast<int>(::GetLastError()), std::system_category()};
    }
    dest.resize(std::char_traits<wchar_t>::length(dest.data()));
    dest.shrink_to_fit();
    return std::wstring(dest.begin(), dest.end());
}

std::string wide_to_multi_capi(std::wstring const& src)
{
    std::size_t converted{};
    std::vector<char> dest(src.size() * sizeof(wchar_t) + 1, '\0');
    if (::_wcstombs_s_l(&converted, dest.data(), dest.size(), src.data(), _TRUNCATE, ::_create_locale(LC_ALL, "jpn")) != 0) {
        throw std::system_error{errno, std::system_category()};
    }
    dest.resize(std::char_traits<char>::length(dest.data()));
    dest.shrink_to_fit();
    return std::string(dest.begin(), dest.end());
}

std::string wide_to_multi_winapi(std::wstring const& src)
{
    auto const dest_size = ::WideCharToMultiByte(CP_ACP, 0U, src.data(), -1, nullptr, 0, nullptr, nullptr);
    std::vector<char> dest(dest_size, '\0');
    if (::WideCharToMultiByte(CP_ACP, 0U, src.data(), -1, dest.data(), dest.size(), nullptr, nullptr) == 0) {
        throw std::system_error{static_cast<int>(::GetLastError()), std::system_category()};
    }
    dest.resize(std::char_traits<char>::length(dest.data()));
    dest.shrink_to_fit();
    return std::string(dest.begin(), dest.end());
}

std::string wide_to_utf8_cppapi(std::wstring const& src)
{
    std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> converter;
    return converter.to_bytes(src);
}

std::string wide_to_utf8_winapi(std::wstring const& src)
{
    auto const dest_size = ::WideCharToMultiByte(CP_UTF8, 0U, src.data(), -1, nullptr, 0, nullptr, nullptr);
    std::vector<char> dest(dest_size, '\0');
    if (::WideCharToMultiByte(CP_UTF8, 0U, src.data(), -1, dest.data(), dest.size(), nullptr, nullptr) == 0) {
        throw std::system_error{static_cast<int>(::GetLastError()), std::system_category()};
    }
    dest.resize(std::char_traits<char>::length(dest.data()));
    dest.shrink_to_fit();
    return std::string(dest.begin(), dest.end());
}

std::wstring utf8_to_wide_cppapi(std::string const& src)
{
    std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> converter;
    return converter.from_bytes(src);
}

std::wstring utf8_to_wide_winapi(std::string const& src)
{
    auto const dest_size = ::MultiByteToWideChar(CP_UTF8, 0U, src.data(), -1, nullptr, 0U);
    std::vector<wchar_t> dest(dest_size, L'\0');
    if (::MultiByteToWideChar(CP_UTF8, 0U, src.data(), -1, dest.data(), dest.size()) == 0) {
        throw std::system_error{static_cast<int>(::GetLastError()), std::system_category()};
    }
    dest.resize(std::char_traits<wchar_t>::length(dest.data()));
    dest.shrink_to_fit();
    return std::wstring(dest.begin(), dest.end());
}

std::string multi_to_utf8_cppapi(std::string const& src)
{
    auto const wide = multi_to_wide_capi(src);
    return wide_to_utf8_cppapi(wide);
}

std::string multi_to_utf8_winapi(std::string const& src)
{
    auto const wide = multi_to_wide_winapi(src);
    return wide_to_utf8_winapi(wide);
}

std::string utf8_to_multi_cppapi(std::string const& src)
{
    auto const wide = utf8_to_wide_cppapi(src);
    return wide_to_multi_capi(wide);
}

std::string utf8_to_multi_winapi(std::string const& src)
{
    auto const wide = utf8_to_wide_winapi(src);
    return wide_to_multi_winapi(wide);
}

//std::u16string utf8_to_utf16(std::string const& src)
//{
//    std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> converter;
//    return converter.from_bytes(src);
//}
//
//std::string utf16_to_utf8(std::u16string const& src)
//{
//    std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> converter;
//    return converter.to_bytes(src);
//}

template <typename OS, typename T>
void dump(OS& os, T const* t)
{
    bool is_first = true;
    auto const* byte = reinterpret_cast<unsigned char const*>(t);
    os << std::hex << std::uppercase << std::setfill('0') << std::setw(2);
    while (*byte) {
        if (!std::exchange(is_first, false)) {
            os << " ";
        }
        os << static_cast<unsigned int>(*byte);
        ++byte;
    }
    os << std::endl;
}

int main()
{
    {
        std::string const src = "あ";
        dump(std::cout, src.data());
        auto const dest = multi_to_wide_capi(src);
        dump(std::cout, dest.data());
    }
    {
        std::string const src = "あ";
        dump(std::cout, src.data());
        auto const dest = multi_to_wide_winapi(src);
        dump(std::cout, dest.data());
    }
    std::cout << std::endl;
    {
        std::wstring const src = L"あ";
        dump(std::cout, src.data());
        auto const dest = wide_to_multi_capi(src);
        dump(std::cout, dest.data());
    }
    {
        std::wstring const src = L"あ";
        dump(std::cout, src.data());
        auto const dest = wide_to_multi_winapi(src);
        dump(std::cout, dest.data());
    }
    std::cout << std::endl;
    {
        std::wstring const src = L"あ";
        dump(std::cout, src.data());
        auto const dest = wide_to_utf8_cppapi(src);
        dump(std::cout, dest.data());
    }
    {
        std::wstring const src = L"あ";
        dump(std::cout, src.data());
        auto const dest = wide_to_utf8_winapi(src);
        dump(std::cout, dest.data());
    }
    std::cout << std::endl;
    {
        std::string const src = u8"あ";
        dump(std::cout, src.data());
        auto const dest = utf8_to_wide_cppapi(src);
        dump(std::cout, dest.data());
    }
    {
        std::string const src = u8"あ";
        dump(std::cout, src.data());
        auto const dest = utf8_to_wide_winapi(src);
        dump(std::cout, dest.data());
    }
    std::cout << std::endl;
    {
        std::string const src = "あ";
        dump(std::cout, src.data());
        auto const dest = multi_to_utf8_cppapi(src);
        dump(std::cout, dest.data());
    }
    {
        std::string const src = "あ";
        dump(std::cout, src.data());
        auto const dest = multi_to_utf8_winapi(src);
        dump(std::cout, dest.data());
    }
    std::cout << std::endl;
    {
        std::string const src = u8"あ";
        dump(std::cout, src.data());
        auto const dest = utf8_to_multi_cppapi(src);
        dump(std::cout, dest.data());
    }
    {
        std::string const src = u8"あ";
        dump(std::cout, src.data());
        auto const dest = utf8_to_multi_winapi(src);
        dump(std::cout, dest.data());
    }
    std::cout << std::endl;
    //{
    //    std::string const src = u8"あ";
    //    dump(std::cout, src.data());
    //    auto const dest = utf8_to_utf16(src);
    //    dump(std::cout, dest.data());
    //}
    //{
    //    std::u16string const src = u"あ";
    //    dump(std::cout, src.data());
    //    auto const dest = utf16_to_utf8(src);
    //    dump(std::cout, dest.data());
    //}
}