Crate convute

The purpose of convute is to let you convert between types of the same size with overlapping valid bit patterns. To do so, you must implement the unsafe convute::marker::Transmute or convute::marker::TryTransmute traits on your types. The great thing about these markers is that we can derive conversions between arrays, vecs and slices of those types.

// Import the traits which implement the conversions.
use convute::convert::*;

// This type represents a value in the range 0..9.
struct Lt9(u8);

impl Lt9 {
    #[inline]
    fn new(val: u8) -> Option<Self> {
        if val < 9 { Some(Lt9(val)) } else { None }
    }
}

// Let convute know every Lt9 is a valid u8.
unsafe impl convute::marker::Transmute<u8> for Lt9 {}

// Let convute know some u8 are valid Lt9.
unsafe impl convute::marker::TryTransmute<Lt9> for u8 {
    #[inline]
    fn can_transmute(&self) -> bool {
        Lt9::new(*self).is_some()
    }
}

fn main() {
    let numbers = [1, 6, 10, 5];
    let all_lt9: Result<[Lt9; 4], [u8; 4]> = numbers.try_transmute_each();
    // Because of the 10, the conversion will fail.
    assert!(all_lt9.is_err());
}

Check out the tests in convert.rs for more examples.

Modules

convert
marker