rust/rhg/src/main.rs

rhg: Group values passed to every sub-command into a struct

The set of which values this is is evidently not stable yet,
so this will make changes easier. Also it is growing, and the function
signatures are getting out hand.

Differential Revision: https://phab.mercurial-scm.org/D10003

extern crate log;
use crate::ui::Ui;
use clap::App;
use clap::AppSettings;
use clap::Arg;
use clap::ArgMatches;
use format_bytes::format_bytes;
use hg::config::Config;
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_with_result(ui: &ui::Ui) -> Result<(), CommandError> {
    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 matches = app.clone().get_matches_safe()?;

    let (subcommand_name, subcommand_matches) = matches.subcommand();
    let run = subcommand_run_fn(subcommand_name)
        .expect("unknown subcommand name from clap despite AppSettings::SubcommandRequired");
    let subcommand_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| {
        subcommand_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 = subcommand_args.values_of_os(name).into_iter().flatten();
        a.chain(b)
    };

    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 non_repo_config = &hg::config::Config::load(config_args)?;

    let repo_path = value_of_global_arg("repository").map(Path::new);

    run(&CliInvocation {
        ui,
        subcommand_args,
        non_repo_config,
        repo_path,
    })
}

fn main() {
    let ui = Ui::new();

    let exit_code = match main_with_result(&ui) {
        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()))
            )+
        }

        pub type RunFn = fn(&CliInvocation) -> Result<(), CommandError>;

        fn subcommand_run_fn(name: &str) -> Option<RunFn> {
            match name {
                $(
                    stringify!($command) => Some(commands::$command::run),
                )+
                _ => None,
            }
        }
    };
}

subcommands! {
    cat
    debugdata
    debugrequirements
    files
    root
    config
}
pub struct CliInvocation<'a> {
    ui: &'a Ui,
    subcommand_args: &'a ArgMatches<'a>,
    non_repo_config: &'a Config,
    repo_path: Option<&'a Path>,
}