bitbag

这个crate提供BitBag，一种用于跟踪在无字段的枚举中定义的位标志的类型。开始如下

use bitbag::{BitBag, BitBaggable};
use strum::EnumIter;

#[derive(BitBaggable, EnumIter, Clone, Copy)]
#[repr(u8)]
enum Flags {
    A = 0b0001,
    B = 0b0010,
    C = 0b0100,
}

BitBag提供基本功能

let mut bag = BitBag::<Flags>::new_unchecked(0b0011);
assert!(bag.is_set(Flags::A));
assert!(bag.is_set(Flags::B));
assert!(!bag.is_set(Flags::C));

bag.set(Flags::C);
assert_eq!(*bag, 0b0111);

通过推导BitBaggable，你还可以获得非常便利的构造函数

use Flags::*;
let bag = A | B | C;
assert!(bag.is_set(Flags::A));
assert!(bag.is_set(Flags::B));
assert!(bag.is_set(Flags::C));

此外，通过推导EnumIter和Copy，将允许创建和迭代集合标志

//                                  ⬇ this bit is not defined in Flags
let result = BitBag::<Flags>::new(0b1000);
assert!(matches!(
    result,
    Err(e) if e.given() == 0b1000
));

let bag = BitBag::<Flags>::new_unchecked(0b0110);
for flag in &bag {
    match flag {
        Flags::A => println!("Flag A was set"),
        Flags::B => println!("Flag B was set"),
        Flags::C => println!("Flag C was set"),
    }
};