commit	afffefb86127ead76f08687d821da9d85c03ae31	[log] [tgz]
author	Android Build Coastguard Worker <[email protected]>	Thu Oct 31 01:09:28 2024 +0000
committer	Android Build Coastguard Worker <[email protected]>	Thu Oct 31 01:09:28 2024 +0000
tree	b24fe0cc53b62e11ec4c01f78952839d80722c3c
parent	bc3b50d0d373b25d78aa8c3221bc546174f92238 [diff]
parent	6757853fcfa0404a685527c40eac8a6fe92c5b7a [diff]

tree: b24fe0cc53b62e11ec4c01f78952839d80722c3c

README.md

bitflags

License

bitflags generates flags enums with well-defined semantics and ergonomic end-user APIs.

You can use bitflags to:

provide more user-friendly bindings to C APIs where flags may or may not be fully known in advance.
generate efficient options types with string parsing and formatting support.

You can't use bitflags to:

guarantee only bits corresponding to defined flags will ever be set. bitflags allows access to the underlying bits type so arbitrary bits may be set.
define bitfields. bitflags only generates types where set bits denote the presence of some combination of flags.
Documentation
Specification
Release notes

Usage

Add this to your Cargo.toml:

[dependencies]
bitflags = "2.5.0"

and this to your source code:

use bitflags::bitflags;

Example

Generate a flags structure:

use bitflags::bitflags;

// The `bitflags!` macro generates `struct`s that manage a set of flags.
bitflags! {
    /// Represents a set of flags.
    #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
    struct Flags: u32 {
        /// The value `A`, at bit position `0`.
        const A = 0b00000001;
        /// The value `B`, at bit position `1`.
        const B = 0b00000010;
        /// The value `C`, at bit position `2`.
        const C = 0b00000100;

        /// The combination of `A`, `B`, and `C`.
        const ABC = Self::A.bits() | Self::B.bits() | Self::C.bits();
    }
}

fn main() {
    let e1 = Flags::A | Flags::C;
    let e2 = Flags::B | Flags::C;
    assert_eq!((e1 | e2), Flags::ABC);   // union
    assert_eq!((e1 & e2), Flags::C);     // intersection
    assert_eq!((e1 - e2), Flags::A);     // set difference
    assert_eq!(!e2, Flags::A);           // set complement
}

Rust Version Support

The minimum supported Rust version is documented in the Cargo.toml file. This may be bumped in minor releases as necessary.