.
├── config         Configuration parsing
├── internal       Private packages and helpers
│   ├── cache
│   │   └── lru    Size-cost bounded LRU cache (e.g., for delta base caching)
│   └── testgit    Helpers for integration tests with upstream git(1)
├── object         Parse/serialize objects such as blob, tree, commit, tag
├── objectheader   Parse/serialize object headers ("type size\0")
├── objectid       Utilities aroud object IDs and hash algorithms
├── objectstore    Interfaces for object storage backends
│   ├── chain      Wrapper object storage backend to query a chain of backends
│   ├── loose      Loose object backend (objects/XX/YYYYY..)
│   └── packed     Packfiles reading, and associated indexes
├── objecttype     Object type constants and names
├── ref            General, detached, and symbolic references
└── refstore       Interfaces for reference storage backends
    ├── chain      Wrapper reference storage backend to query a chain of backends
    ├── loose      Loose ref backend (refs/... as a directory tree)
    ├── packed     Packed refs backend
    └── reftable   Experimental reftable backend