rust/rhg/src/main.rs

extern crate log;
use clap::App;
use clap::AppSettings;
use clap::Arg;
use clap::ArgMatches;
use format_bytes::format_bytes;
use std::path::Path;

mod error;
mod exitcode;
mod ui;
use error::CommandError;

fn add_global_args<'a, 'b>(app: App<'a, 'b>) -> App<'a, 'b> {
    app.arg(
        Arg::with_name("repository")
            .help("repository root directory")
            .short("-R")
            .long("--repository")
            .value_name("REPO")
            .takes_value(true),
    )
    .arg(
        Arg::with_name("config")
            .help("set/override config option (use 'section.name=value')")
            .long("--config")
            .value_name("CONFIG")
            .takes_value(true)
            // Ok: `--config section.key1=val --config section.key2=val2`
            .multiple(true)
            // Not ok: `--config section.key1=val section.key2=val2`
            .number_of_values(1),
    )
}

fn main() {
    env_logger::init();
    let app = App::new("rhg")
        .setting(AppSettings::AllowInvalidUtf8)
        .setting(AppSettings::SubcommandRequired)
        .setting(AppSettings::VersionlessSubcommands)
        .version("0.0.1");
    let app = add_global_args(app);
    let app = add_subcommand_args(app);

    let ui = ui::Ui::new();

    let matches = app.clone().get_matches_safe().unwrap_or_else(|err| {
        let _ = ui.writeln_stderr_str(&err.message);
        std::process::exit(exitcode::UNIMPLEMENTED)
    });

    let (subcommand_name, subcommand_matches) = matches.subcommand();
    let run = subcommand_run_fn(subcommand_name)
        .expect("unknown subcommand name from clap despite AppSettings::SubcommandRequired");
    let args = subcommand_matches
        .expect("no subcommand arguments from clap despite AppSettings::SubcommandRequired");

    // Global arguments can be in either based on e.g. `hg -R ./foo log` v.s.
    // `hg log -R ./foo`
    let value_of_global_arg =
        |name| args.value_of_os(name).or_else(|| matches.value_of_os(name));
    // For arguments where multiple occurences are allowed, return a
    // possibly-iterator of all values.
    let values_of_global_arg = |name: &str| {
        let a = matches.values_of_os(name).into_iter().flatten();
        let b = args.values_of_os(name).into_iter().flatten();
        a.chain(b)
    };

    let repo_path = value_of_global_arg("repository").map(Path::new);
    let result = (|| -> Result<(), CommandError> {
        let config_args = values_of_global_arg("config")
            // `get_bytes_from_path` works for OsStr the same as for Path
            .map(hg::utils::files::get_bytes_from_path);
        let config = hg::config::Config::load(config_args)?;
        run(&ui, &config, repo_path, args)
    })();

    let exit_code = match result {
        Ok(_) => exitcode::OK,

        // Exit with a specific code and no error message to let a potential
        // wrapper script fallback to Python-based Mercurial.
        Err(CommandError::Unimplemented) => exitcode::UNIMPLEMENTED,

        Err(CommandError::Abort { message }) => {
            if !message.is_empty() {
                // Ignore errors when writing to stderr, we’re already exiting
                // with failure code so there’s not much more we can do.
                let _ =
                    ui.write_stderr(&format_bytes!(b"abort: {}\n", message));
            }
            exitcode::ABORT
        }
    };
    std::process::exit(exit_code)
}

macro_rules! subcommands {
    ($( $command: ident )+) => {
        mod commands {
            $(
                pub mod $command;
            )+
        }

        fn add_subcommand_args<'a, 'b>(app: App<'a, 'b>) -> App<'a, 'b> {
            app
            $(
                .subcommand(add_global_args(commands::$command::args()))
            )+
        }

        fn subcommand_run_fn(name: &str) -> Option<fn(
            &ui::Ui,
            &hg::config::Config,
            Option<&Path>,
            &ArgMatches,
        ) -> Result<(), CommandError>> {
            match name {
                $(
                    stringify!($command) => Some(commands::$command::run),
                )+
                _ => None,
            }
        }
    };
}

subcommands! {
    cat
    debugdata
    debugrequirements
    files
    root
    config
}