EnumFlags

EnumFlags 是一个类似于 C# 的枚举标志实现。

示例

由于使用功能 arbitrary_enum_discriminant，需要使用 nightly 频道。

#![feature(arbitrary_enum_discriminant)]
use enum_flags::enum_flags;

#[repr(u8)]  // default: #[repr(usize)]
#[enum_flags]
#[derive(Copy, Clone, PartialEq)] // can be omitted
enum Flags{
    None = 0,
    A = 1,
    B, // 2
    C = 4
}
fn main() {
    let e1: Flags = Flags::A | Flags::C;
    let e2 = Flags::B | Flags::C;

    assert_eq!(e1 | e2, Flags::A | Flags::B | Flags::C); // union
    assert_eq!(e1 & e2, Flags::C); // intersection
    assert_eq!(e1 ^ e2, Flags::A | Flags::B); // toggle
    assert_eq!(e1 & (!Flags::C), Flags::A); // deletion
    assert_eq!(e1 - Flags::C, Flags::A); // deletion

    assert_eq!(format!("{:?}", e1).as_str(), "(Flags::A | Flags::C)");
    assert!(e1.has_a());
    assert!(!e1.has_b());
    assert!(e1.has_flag(Flags::C));
    assert!(e1.contains(Flags::C));
    assert_eq!(match Flags::A | Flags::C {
        Flags::None => "None",
        Flags::A => "A",
        Flags::B => "B",
        Flags::C => "C",
        Flags::__Composed__(v) if v == Flags::A | Flags::B => "A and B",
        Flags::__Composed__(v) if v == Flags::A | Flags::C => "A and C",
        _ => "Others"
    }, "A and C")
}

重大变更

• 在版本 0.18 之前

  #[derive(Copy, EnumFlags, Clone, PartialEq)]
  enum Flags {
      None = 0,
      A = 1,
      B = 2,
      C = 4
  }
  

• 从版本 0.30 开始

  #[enum_flags] 
  #[derive(Copy, Clone, PartialEq)]
  enum Flags {
      None = 0,
      A = 1,
      B = 2,
      C = 4
  }