Subrepo

Central.Subrepo.t identifies one of the sub-repos vendored under repo/ in the enclosing monorepo. It isn’t a fixed, hand-maintained enum: it’s just a validated string (the directory name under repo/), and the set of known sub-repos is discovered dynamically by walking the filesystem.

Discovery

all walks repo/’s direct children and keeps the ones that contain a .gitrepo file, sorted by name:

find_on_disk looks a sub-repo name up against all - unlike of_string, it validates that the name actually names a vendored sub-repo, not merely that it has the right shape:

Manipulating paths

Unlike all and find_on_disk above, everything in this section is pure path manipulation: none of it reads the filesystem, or confirms that anything it is given actually exists on disk.

root and gitrepo_file_path locate a sub-repo’s own directory, and its .gitrepo file, as paths in the enclosing monorepo:

central_path and subrepo_path convert a path back and forth between the two frames of reference a path can be expressed in: relative to the sub-repo’s own root (what the sub-repo’s standalone checkout sees), or relative to the enclosing monorepo (prefixed with root, what the monorepo checkout sees):

repo/widget/src/dune

subrepo_path returns None for a path that doesn’t belong to the sub-repo at all - and, since a path in the sub-repo’s own repo is never empty, for the sub-repo’s root itself: