Taskwarrior has historically been a C++ project, but as of taskwarrior-3.0.0, the storage backend is now provided by a Rust library called TaskChampion.
TaskChampion implements storage and access to "replicas" containing a user's tasks.
It defines an abstract model for this data, and also provides a simple Rust API for manipulating replicas.
It also defines a method of synchronizing replicas and provides an implementation of that method in the form of a sync server.
TaskChampion provides a C interface via the taskchampion-lib crate, at src/tc/lib.
Other applications, besides Taskwarrior, can use TaskChampion to manage tasks. Taskwarrior is just one application using the TaskChampion interface.
Taskwarrior's interface to TaskChampion has a few layers:
- A Rust library,
takschampion-lib, that presentsextern "C"functions for use from C++, essentially defining a C interface to TaskChampion. - C++ wrappers for the types from
taskchampion-lib, defined insrc/tc, ensuring memory safety (withunique_ptr) and adding methods corresponding to the Rust API's methods. The wrapper types are in the C++ namespace,tc.