lighthouse/eth2/utils/ssz/examples/struct_definition.rs

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use ssz::{Decode, DecodeError, Encode, SszDecoderBuilder, SszEncoder};
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#[derive(Debug, PartialEq)]
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pub struct Foo {
a: u16,
b: Vec<u8>,
c: u16,
}
impl Encode for Foo {
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fn is_ssz_fixed_len() -> bool {
<u16 as Encode>::is_ssz_fixed_len() && <Vec<u16> as Encode>::is_ssz_fixed_len()
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}
fn ssz_bytes_len(&self) -> usize {
<u16 as Encode>::ssz_fixed_len()
+ ssz::BYTES_PER_LENGTH_OFFSET
+ <u16 as Encode>::ssz_fixed_len()
+ self.b.ssz_bytes_len()
}
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fn ssz_append(&self, buf: &mut Vec<u8>) {
let offset = <u16 as Encode>::ssz_fixed_len()
+ <Vec<u16> as Encode>::ssz_fixed_len()
+ <u16 as Encode>::ssz_fixed_len();
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let mut encoder = SszEncoder::container(buf, offset);
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encoder.append(&self.a);
encoder.append(&self.b);
encoder.append(&self.c);
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encoder.finalize();
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}
}
impl Decode for Foo {
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fn is_ssz_fixed_len() -> bool {
<u16 as Decode>::is_ssz_fixed_len() && <Vec<u16> as Decode>::is_ssz_fixed_len()
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}
fn from_ssz_bytes(bytes: &[u8]) -> Result<Self, DecodeError> {
let mut builder = SszDecoderBuilder::new(bytes);
builder.register_type::<u16>()?;
builder.register_type::<Vec<u8>>()?;
builder.register_type::<u16>()?;
let mut decoder = builder.build()?;
Ok(Self {
a: decoder.decode_next()?,
b: decoder.decode_next()?,
c: decoder.decode_next()?,
})
}
}
fn main() {
let my_foo = Foo {
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a: 42,
b: vec![0, 1, 2, 3],
c: 11,
};
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let bytes = vec![42, 0, 8, 0, 0, 0, 11, 0, 0, 1, 2, 3];
assert_eq!(my_foo.as_ssz_bytes(), bytes);
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let decoded_foo = Foo::from_ssz_bytes(&bytes).unwrap();
assert_eq!(my_foo, decoded_foo);
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}