usage_rs/

lib.rs

//! The facade for building compiled Rust CLIs with usage.
//!
//! Depend on `usage-rs` under the short crate name `usage`. That is the one package an
//! application needs: derive macros, the argv runtime, help, and clap-shaped errors ship in the
//! defaults. Completions stay behind a feature; low-level adopters that want only the binding
//! runtime keep depending on `usage-argv` directly.
//!
//! ```toml
//! [dependencies]
//! usage = { package = "usage-rs", version = "6" }
//! ```
//!
//! # Smaller binaries
//!
//! CLIs without `flatten_help` or `HelpAll` actions can omit `help-advanced`:
//!
//! ```toml
//! usage = { package = "usage-rs", version = "6", default-features = false, features = ["help", "diagnostics", "completions"] }
//! ```
//!
//! Advanced help remains enabled by default. Declaring those actions without its feature
//! fails at compile time; hand-written metadata requesting advanced help panics when rendered.
//! Cargo features are additive: another dependency enabling it restores advanced help.
//!
//! To keep the spec endpoint without linking the KDL writer, use
//! `#[usage(spec_endpoint_file = "cli.usage.kdl")]`. The file is included at compile time,
//! relative to the declaring crate. Generate it with `Cli::to_kdl()` in a development tool,
//! and test that `Cli::spec_request(&[usage::SPEC_REQUEST.as_ref()])` equals `Cli::to_kdl()`.
//! Regenerate after changing CLI metadata or its version. `to_kdl()` still uses the live
//! metadata, including settings and `spec_extra`; only the endpoint uses the file.
//!
//! What happens after a parse can come from the same declaration: a command implements [`Run`],
//! the subcommand enum says `#[usage(run)]`, and the `match` that routes argv to the code
//! carrying it out is generated rather than written. [`RunWith`] under `#[usage(run_with)]` hands
//! each command shared state, and [`RunAsync`] / [`RunAsyncWith`] under `#[usage(run_async)]` /
//! `#[usage(run_async_with)]` are the async pair. Nothing about any of it reaches the spec.
//!
//! Enable portable expression validation only when a CLI declares `validate` rules:
//!
//! ```toml
//! usage = { package = "usage-rs", version = "6", features = ["validation"] }
//! ```
//!
//! ```
//! use usage_rs as usage;
//! # #[cfg(feature = "spec")]
//! use usage::Cli;
//!
//! # #[cfg(not(feature = "spec"))]
//! # fn main() {}
//! # #[cfg(feature = "spec")]
//! # fn main() {
//! #[derive(Cli)]
//! #[usage(bin = "ex")]
//! struct Ex {
//!     #[usage(long, value_hint = usage::ValueHint::FilePath)]
//!     file: Option<std::path::PathBuf>,
//! }
//!
//! let argv = [std::ffi::OsStr::new("--file"), std::ffi::OsStr::new("input.txt")];
//! let ex = Ex::parse_from(&argv).expect("valid command line");
//! assert_eq!(ex.file.as_deref(), Some(std::path::Path::new("input.txt")));
//! # }
//! ```
//!
//! A derived [`Args`] type can also be parsed on its own. This lets an adapter
//! reuse one command's exact argument contract without constructing or parsing
//! the application's root CLI:
//!
//! ```
//! use usage_rs as usage;
//! # #[cfg(feature = "spec")]
//! use usage::Args;
//! #
//! # #[cfg(not(feature = "spec"))]
//! # fn main() {}
//! # #[cfg(feature = "spec")]
//! # fn main() {
//!
//! #[derive(Debug, Args)]
//! struct Install {
//!     #[usage(short, long)]
//!     force: bool,
//!     tools: Vec<String>,
//! }
//!
//! let argv = ["--force", "node@24"].map(std::ffi::OsStr::new);
//! let install = usage::parse_args_from::<Install>(&argv).unwrap();
//! assert!(install.force);
//! assert_eq!(install.tools, ["node@24"]);
//! # }
//! ```

#![forbid(unsafe_code)]

// Generated absolute paths must also work if a derive is used inside this crate. Integration
// targets already receive this name through Cargo; the library target needs the self alias.
extern crate self as usage_rs;

pub use usage_argv as argv;
pub use usage_argv::*;
#[cfg(feature = "config")]
pub use usage_config as config;
#[cfg(feature = "config")]
pub use usage_derive::Config;
#[cfg(feature = "spec")]
pub use usage_derive::{ArgGroup, Args, Cli, Subcommands, ValueEnum};
#[cfg(feature = "test")]
pub use usage_test as test;
#[cfg(feature = "validation")]
pub use usage_validation as validation;
#[cfg(feature = "response-files")]
pub mod response;

#[cfg(all(test, feature = "spec"))]
mod tests {
    #[derive(crate::Cli)]
    #[usage(bin = "internal")]
    struct Internal {}

    #[cfg(feature = "validation")]
    #[derive(Debug, crate::Cli)]
    #[usage(bin = "validated")]
    struct Validated {
        #[usage(
            long,
            validate = "int(value) >= 1 && int(value) <= 65535",
            validate_error = "must be a valid port"
        )]
        port: Option<u16>,
    }

    #[cfg(feature = "validation")]
    #[derive(Debug, crate::Args)]
    struct ValidatedArgs {
        #[usage(long, validate = "value == 'ok'", validate_error = "must be ok")]
        token: Option<String>,
    }

    #[cfg(feature = "validation")]
    #[derive(Debug, crate::Cli)]
    #[usage(bin = "validated-args")]
    struct ValidatedArgsCli {
        #[usage(flatten)]
        args: ValidatedArgs,
    }

    #[test]
    fn derives_resolve_the_facade_from_inside_the_facade() {
        assert_eq!(Internal::spec().bin, Some("internal"));
    }

    #[cfg(feature = "config")]
    #[derive(crate::Config)]
    struct InternalSettings {
        /// How many jobs to run at once
        #[usage(env = "INTERNAL_JOBS", default = 4)]
        jobs: u64,
    }

    #[cfg(feature = "config")]
    #[test]
    fn the_config_derive_resolves_the_facade_from_inside_the_facade() {
        let resolved = crate::config::resolve(
            InternalSettings::SETTINGS_REGISTRY,
            crate::config::Layers::new(),
        )
        .expect("resolves");
        let settings = InternalSettings::read(&resolved).expect("reads");
        assert_eq!(settings.jobs, 4);
        assert!(InternalSettings::spec_kdl().contains(r#"prop "jobs""#));
    }

    #[cfg(feature = "validation")]
    #[test]
    fn derives_evaluate_portable_validation_expressions() {
        let valid = [
            ::std::ffi::OsStr::new("--port"),
            ::std::ffi::OsStr::new("9229"),
        ];
        assert_eq!(Validated::parse_from(&valid).unwrap().port, Some(9229));

        let invalid = [
            ::std::ffi::OsStr::new("--port"),
            ::std::ffi::OsStr::new("0"),
        ];
        let crate::Error::InvalidValue(error) = Validated::parse_from(&invalid).unwrap_err() else {
            panic!("expected invalid value");
        };
        assert_eq!(error.reason, "must be a valid port");

        let invalid_args = [
            ::std::ffi::OsStr::new("--token"),
            ::std::ffi::OsStr::new("bad"),
        ];
        let crate::Error::InvalidValue(error) =
            ValidatedArgsCli::parse_from(&invalid_args).unwrap_err()
        else {
            panic!("expected invalid value from flattened Args");
        };
        assert_eq!(error.reason, "must be ok");

        let valid_args = [
            ::std::ffi::OsStr::new("--token"),
            ::std::ffi::OsStr::new("ok"),
        ];
        assert_eq!(
            ValidatedArgsCli::parse_from(&valid_args)
                .unwrap()
                .args
                .token
                .as_deref(),
            Some("ok")
        );

        let kdl = Validated::to_kdl();
        assert!(
            kdl.contains(r#"validate="int(value) >= 1 && int(value) <= 65535""#),
            "{kdl}"
        );
    }
}