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argp_version.rs
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63 lines (57 loc) · 2.24 KB
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// Originally from https://gist.github.com/suluke/e0c672492126be0a4f3b4f0e1115d77c
//! Extend `argp` to be better integrated with the `cargo` ecosystem
//!
//! For now, this only adds a --version/-V option which causes early-exit.
use std::ffi::OsStr;
use argp::{parser::ParseGlobalOptions, EarlyExit, FromArgs, TopLevelCommand};
struct ArgsOrVersion<T>(T)
where T: FromArgs;
impl<T> TopLevelCommand for ArgsOrVersion<T> where T: FromArgs {}
impl<T> FromArgs for ArgsOrVersion<T>
where T: FromArgs
{
fn _from_args(
command_name: &[&str],
args: &[&OsStr],
parent: Option<&mut dyn ParseGlobalOptions>,
) -> Result<Self, EarlyExit> {
/// Also use argp for catching `--version`-only invocations
#[derive(FromArgs)]
struct Version {
/// Print version information and exit.
#[argp(switch, short = 'V')]
pub version: bool,
}
match Version::from_args(command_name, args) {
Ok(v) => {
if v.version {
println!(
"{} {}",
command_name.first().unwrap_or(&""),
env!("CARGO_PKG_VERSION"),
);
std::process::exit(0);
} else {
// Pass through empty arguments
T::_from_args(command_name, args, parent).map(Self)
}
}
Err(exit) => match exit {
EarlyExit::Help(_help) => {
// TODO: Chain help info from Version
// For now, we just put the switch on T as well
T::from_args(command_name, &["--help"]).map(Self)
}
EarlyExit::Err(_) => T::_from_args(command_name, args, parent).map(Self),
},
}
}
}
/// Create a `FromArgs` type from the current process’s `env::args`.
///
/// This function will exit early from the current process if argument parsing was unsuccessful or if information like `--help` was requested.
/// Error messages will be printed to stderr, and `--help` output to stdout.
pub fn from_env<T>() -> T
where T: TopLevelCommand {
argp::parse_args_or_exit::<ArgsOrVersion<T>>(argp::DEFAULT).0
}