cfg-expr

A parser and evaluator for Rust cfg() expressions. Targets as of Rust 1.58.0 are supported.

Latest version: 0.20.0 registry icon
Maintenance score
74
Safety score
100
Popularity score
72
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Stability
Latest release:

0.20.0 - This version is safe to use because it has no known security vulnerabilities at this time. Find out if your coding project uses this component and get notified of any reported security vulnerabilities with Meterian-X Open Source Security Platform

Licensing

Maintain your licence declarations and avoid unwanted licences to protect your IP the way you intended.

Apache-2.0   -   Apache License 2.0

Not a wildcard

Not proprietary

OSI Compliant


MIT   -   MIT License

Not a wildcard

Not proprietary

OSI Compliant



⚙️ cfg-expr

A parser and evaluator for Rust cfg() expressions. Builtin targets as of 1.87.0 are supported.

Build Status Crates.io Docs Minimum Stable Rust Version Rust Targets Contributor Covenant Embark

Alternatives

Usage

cfg-expr is a crate that can be used to parse and evaluate Rust cfg() expressions, both as declarable in Rust code itself, as well in cargo manifests' [target.'cfg()'.dependencies] sections.

It contains a list of all builtin targets known to rustc as of 1.87.0 that can be used to determine if a particular cfg expression is satisfiable.

use cfg_expr::{targets::get_builtin_target_by_triple, Expression, Predicate};

let specific = Expression::parse(
    r#"all(
        target_os = "windows",
        target_arch = "x86",
        windows,
        target_env = "msvc",
        target_feature = "fxsr",
        target_feature = "sse",
        target_feature = "sse2",
        target_pointer_width = "32",
        target_endian = "little",
        not(target_vendor = "uwp"),
        feature = "cool_thing",
    )"#,
).unwrap();

// cfg_expr includes a list of every builtin target in rustc
let x86_win = get_builtin_target_by_triple("i686-pc-windows-msvc").unwrap();
let uwp_win = get_builtin_target_by_triple("i686-uwp-windows-msvc").unwrap();
let mac = get_builtin_target_by_triple("x86_64-apple-darwin").unwrap();

let avail_target_feats = ["fxsr", "sse", "sse2"];

// This will satisfy all requirements
assert!(specific.eval(|pred| {
    match pred {
        Predicate::Target(tp) => tp.matches(x86_win),
        Predicate::TargetFeature(feat) => avail_target_feats.contains(feat),
        Predicate::Feature(feat) => *feat == "cool_thing",
        _ => false,
    }
}));

// This will *not* satisfy the vendor predicate
assert!(!specific.eval(|pred| {
    match pred {
        Predicate::Target(tp) => tp.matches(uwp_win),
        Predicate::TargetFeature(feat) => avail_target_feats.contains(feat),
        _ => false,
    }
}));

// This will *not* satisfy the vendor, os, or env predicates
assert!(!specific.eval(|pred| {
    match pred {
        Predicate::Target(tp) => tp.matches(mac),
        Predicate::TargetFeature(feat) => avail_target_feats.contains(feat),
        _ => false,
    }
}));

Contributing

We welcome community contributions to this project.

Please read our Contributor Guide for more information on how to get started.

License

Licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.