Expose diesel_cli's functionality as a library

[jimmycuadra]

Would it be possible to expose the functionality of diesel_cli as a Rust library? I'd like to be able to programmatically perform diesel database setup from Rust without shelling out.

[sgrif]

It would probably make sense for CLI to expose a reasonable public API there. /cc @mcasper

[travismiller]

Would something like this work?

This PoC just exposes a run function where you can send arguments directly to the Clap Application.

// diesel database setup
diesel_cli::run(vec!["database", "setup"]);

The crux of this uses https://docs.rs/clap/2.32.0/clap/struct.App.html#method.get_matches_from

It probably makes more sense to use https://docs.rs/clap/2.32.0/clap/struct.App.html#method.get_matches_from_safe so that an API user could handle a result.

[sgrif]

That would certainly be the easiest to implement, but I'd rather just have a more static API akin to libgit2 vs git