The concept of mount points can be found in almost every modern filesystem. For a multi-platform C++ program, it is convenient to access files across heterogeneous storage devices in a unified way. For example, on Android, each read-only data file can be stored inside the .apk package and the developer is forced to use an Android-specific asset management API. On OSX and iOS, accessing program bundles requires yet another API, on Windows an application should store everything in its folder whose physical path also varies depending on where the application was installed.

To organize file access across different platforms, we propose a shallow class hierarchy that abstracts away the differences of file management, as shown in the following figure:

The virtual filesystem is a collection of mount points. Each mount point is an abstraction of a filesystem folder. This organization allows us to hide actual OS-specific file access routines and file name mapping from the application code...