lighthouse/eth2/utils/ssz/src/encode/impls.rs

use super::*;
use ethereum_types::H256;

macro_rules! impl_encodable_for_uint {
    ($type: ident, $bit_size: expr) => {
        impl Encode for $type {
            fn is_ssz_fixed_len() -> bool {
                true
            }

            fn ssz_fixed_len() -> usize {
                $bit_size / 8
            }

            fn ssz_append(&self, buf: &mut Vec<u8>) {
                buf.extend_from_slice(&self.to_le_bytes());
            }
        }
    };
}

impl_encodable_for_uint!(u8, 8);
impl_encodable_for_uint!(u16, 16);
impl_encodable_for_uint!(u32, 32);
impl_encodable_for_uint!(u64, 64);
impl_encodable_for_uint!(usize, 64);

impl<T: Encode> Encode for Vec<T> {
    fn is_ssz_fixed_len() -> bool {
        false
    }

    fn ssz_append(&self, buf: &mut Vec<u8>) {
        if T::is_ssz_fixed_len() {
            buf.reserve(T::ssz_fixed_len() * self.len());

            for item in self {
                item.ssz_append(buf);
            }
        } else {
            let mut encoder = SszEncoder::list(buf, self.len() * BYTES_PER_LENGTH_OFFSET);

            for item in self {
                encoder.append(item);
            }

            encoder.finalize();
        }
    }
}

impl Encode for bool {
    fn is_ssz_fixed_len() -> bool {
        true
    }

    fn ssz_fixed_len() -> usize {
        1
    }

    fn ssz_append(&self, buf: &mut Vec<u8>) {
        buf.extend_from_slice(&(*self as u8).to_le_bytes());
    }
}

impl Encode for H256 {
    fn is_ssz_fixed_len() -> bool {
        true
    }

    fn ssz_fixed_len() -> usize {
        32
    }

    fn ssz_append(&self, buf: &mut Vec<u8>) {
        buf.extend_from_slice(self.as_bytes());
    }
}

macro_rules! impl_encodable_for_u8_array {
    ($len: expr) => {
        impl Encode for [u8; $len] {
            fn is_ssz_fixed_len() -> bool {
                true
            }

            fn ssz_fixed_len() -> usize {
                $len
            }

            fn ssz_append(&self, buf: &mut Vec<u8>) {
                buf.extend_from_slice(&self[..]);
            }
        }
    };
}

impl_encodable_for_u8_array!(4);

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn vec_of_u8() {
        let vec: Vec<u8> = vec![];
        assert_eq!(vec.as_ssz_bytes(), vec![]);

        let vec: Vec<u8> = vec![1];
        assert_eq!(vec.as_ssz_bytes(), vec![1]);

        let vec: Vec<u8> = vec![0, 1, 2, 3];
        assert_eq!(vec.as_ssz_bytes(), vec![0, 1, 2, 3]);
    }

    #[test]
    fn vec_of_vec_of_u8() {
        let vec: Vec<Vec<u8>> = vec![];
        assert_eq!(vec.as_ssz_bytes(), vec![]);

        let vec: Vec<Vec<u8>> = vec![vec![]];
        assert_eq!(vec.as_ssz_bytes(), vec![4, 0, 0, 0]);

        let vec: Vec<Vec<u8>> = vec![vec![], vec![]];
        assert_eq!(vec.as_ssz_bytes(), vec![8, 0, 0, 0, 8, 0, 0, 0]);

        let vec: Vec<Vec<u8>> = vec![vec![0, 1, 2], vec![11, 22, 33]];
        assert_eq!(
            vec.as_ssz_bytes(),
            vec![8, 0, 0, 0, 11, 0, 0, 0, 0, 1, 2, 11, 22, 33]
        );
    }

    #[test]
    fn ssz_encode_u8() {
        assert_eq!(0_u8.as_ssz_bytes(), vec![0]);
        assert_eq!(1_u8.as_ssz_bytes(), vec![1]);
        assert_eq!(100_u8.as_ssz_bytes(), vec![100]);
        assert_eq!(255_u8.as_ssz_bytes(), vec![255]);
    }

    #[test]
    fn ssz_encode_u16() {
        assert_eq!(1_u16.as_ssz_bytes(), vec![1, 0]);
        assert_eq!(100_u16.as_ssz_bytes(), vec![100, 0]);
        assert_eq!((1_u16 << 8).as_ssz_bytes(), vec![0, 1]);
        assert_eq!(65535_u16.as_ssz_bytes(), vec![255, 255]);
    }

    #[test]
    fn ssz_encode_u32() {
        assert_eq!(1_u32.as_ssz_bytes(), vec![1, 0, 0, 0]);
        assert_eq!(100_u32.as_ssz_bytes(), vec![100, 0, 0, 0]);
        assert_eq!((1_u32 << 16).as_ssz_bytes(), vec![0, 0, 1, 0]);
        assert_eq!((1_u32 << 24).as_ssz_bytes(), vec![0, 0, 0, 1]);
        assert_eq!((!0_u32).as_ssz_bytes(), vec![255, 255, 255, 255]);
    }

    #[test]
    fn ssz_encode_u64() {
        assert_eq!(1_u64.as_ssz_bytes(), vec![1, 0, 0, 0, 0, 0, 0, 0]);
        assert_eq!(
            (!0_u64).as_ssz_bytes(),
            vec![255, 255, 255, 255, 255, 255, 255, 255]
        );
    }

    #[test]
    fn ssz_encode_usize() {
        assert_eq!(1_usize.as_ssz_bytes(), vec![1, 0, 0, 0, 0, 0, 0, 0]);
        assert_eq!(
            (!0_usize).as_ssz_bytes(),
            vec![255, 255, 255, 255, 255, 255, 255, 255]
        );
    }

    #[test]
    fn ssz_encode_bool() {
        assert_eq!(true.as_ssz_bytes(), vec![1]);
        assert_eq!(false.as_ssz_bytes(), vec![0]);
    }

    #[test]
    fn ssz_encode_h256() {
        assert_eq!(H256::from(&[0; 32]).as_ssz_bytes(), vec![0; 32]);
        assert_eq!(H256::from(&[1; 32]).as_ssz_bytes(), vec![1; 32]);

        let bytes = vec![
            1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0,
        ];

        assert_eq!(H256::from_slice(&bytes).as_ssz_bytes(), bytes);
    }

    #[test]
    fn ssz_encode_u8_array_4() {
        assert_eq!([0, 0, 0, 0].as_ssz_bytes(), vec![0; 4]);
        assert_eq!([1, 0, 0, 0].as_ssz_bytes(), vec![1, 0, 0, 0]);
        assert_eq!([1, 2, 3, 4].as_ssz_bytes(), vec![1, 2, 3, 4]);
    }
}