Minilase/src/ezcad/field_of.rs

use binrw::{binread, binwrite, BinRead, BinWrite};
use std::mem::size_of;

#[binwrite]
#[binread]
#[derive(Debug, PartialEq)]
struct FieldOf<T>
where
    T: for<'a> BinRead<Args<'a> = ()> + Default,
    T: for<'a> BinWrite<Args<'a> = ()> + Default,
{
    #[br(temp, assert(size == size_of::<T>().try_into().unwrap()))]
    #[bw(try_calc(u32::try_from(size_of::<T>())))]
    size: u32,
    pub value: T,
}

#[cfg(test)]
mod tests {
    use std::io::Cursor;

    use super::*;

    #[test]
    fn field_of_be() {
        #[derive(BinRead, BinWrite, Debug, PartialEq, Default)]
        struct Test {
            a: u32,
            b: u32,
        }

        let decoded: FieldOf<Test> = FieldOf {
            value: Test {
                a: 0x0A0B0C0D,
                b: 0x01020304,
            },
        };
        let encoded: Vec<u8> = vec![
            0x00, 0x00, 0x00, 0x08, 0x0A, 0x0B, 0x0C, 0x0D, 0x01, 0x02, 0x03, 0x04,
        ];

        let mut stream: Cursor<Vec<u8>> = Cursor::new(encoded.clone());
        assert_eq!(FieldOf::<Test>::read_be(&mut stream).unwrap(), decoded);

        let mut buffer: Cursor<Vec<u8>> = Cursor::new(vec![]);
        decoded.write_be(&mut buffer).unwrap();
        assert_eq!(buffer.into_inner(), encoded);
    }

    #[test]
    fn field_of_le() {
        #[derive(BinRead, BinWrite, Debug, PartialEq, Default)]
        struct Test {
            a: u32,
            b: u32,
        }

        let decoded: FieldOf<Test> = FieldOf {
            value: Test {
                a: 0x0A0B0C0D,
                b: 0x01020304,
            },
        };
        let encoded: Vec<u8> = vec![
            0x08, 0x00, 0x00, 0x00, 0x0D, 0x0C, 0x0B, 0x0A, 0x04, 0x03, 0x02, 0x01,
        ];

        let mut stream: Cursor<Vec<u8>> = Cursor::new(encoded.clone());
        assert_eq!(FieldOf::<Test>::read_le(&mut stream).unwrap(), decoded);

        let mut buffer: Cursor<Vec<u8>> = Cursor::new(vec![]);
        decoded.write_le(&mut buffer).unwrap();
        assert_eq!(buffer.into_inner(), encoded);
    }
}