How to convert between `boost::filesystem::path` and `QString`?

Question

When wrapping a Qt UI around back-end code using boost::filesystem one frequently needs to convert boost::filesystem::path to QString and vice versa.

What is the best way way to do these conversions that:

1. Is cross-platform
2. Losslessly preserves encoding
3. Produces QStrings containing regular slashes on all platforms, as is Qt's policy.
4. Is efficient and avoids unnecessary copies

Answer 1

This is what I'm currently using, but suggestions for improvements are very much welcome.

boost::filesystem::path PathFromQString(const QString & filePath)
{
#ifdef _WIN32
    auto * wptr = reinterpret_cast<const wchar_t*>(filePath.utf16());
    return boost::filesystem::path(wptr, wptr + filePath.size());
#else
    return boost::filesystem::path(filePath.toStdString());
#endif
}

QString QStringFromPath(const boost::filesystem::path & filePath)
{
#ifdef _WIN32
    return QString::fromStdWString(filePath.generic_wstring());
#else
    return QString::fromStdString(filePath.native());
#endif
}