donglora/vendor/bitflags/examples/fmt.rs

//! An example of implementing Rust's standard formatting and parsing traits for flags types.

use core::{fmt, str};

bitflags::bitflags! {
    // You can `#[derive]` the `Debug` trait, but implementing it manually
    // can produce output like `A | B` instead of `Flags(A | B)`.
    // #[derive(Debug)]
    #[derive(PartialEq, Eq)]
    pub struct Flags: u32 {
        const A = 1;
        const B = 2;
        const C = 4;
        const D = 8;
    }
}

impl fmt::Debug for Flags {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        bitflags::parser::to_writer(self, f)
    }
}

impl fmt::Display for Flags {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        bitflags::parser::to_writer(self, f)
    }
}

impl str::FromStr for Flags {
    type Err = bitflags::parser::ParseError;

    fn from_str(flags: &str) -> Result<Self, Self::Err> {
        bitflags::parser::from_str(flags)
    }
}

fn main() -> Result<(), bitflags::parser::ParseError> {
    let flags = Flags::A | Flags::B;

    println!("{}", flags);

    let formatted = flags.to_string();
    let parsed: Flags = formatted.parse()?;

    assert_eq!(flags, parsed);

    Ok(())
}