lighthouse/eth2/utils/ssz/examples/struct_definition.rs
2019-05-06 09:01:28 +10:00

67 lines
1.6 KiB
Rust

use ssz::{Decodable, DecodeError, Encodable, SszDecoderBuilder, SszEncoder, SszStream};
#[derive(Debug, PartialEq)]
pub struct Foo {
a: u16,
b: Vec<u8>,
c: u16,
}
impl Encodable for Foo {
fn is_ssz_fixed_len() -> bool {
<u16 as Encodable>::is_ssz_fixed_len() && <Vec<u16> as Encodable>::is_ssz_fixed_len()
}
fn ssz_append(&self, buf: &mut Vec<u8>) {
let offset = <u16 as Encodable>::ssz_fixed_len()
+ <Vec<u16> as Encodable>::ssz_fixed_len()
+ <u16 as Encodable>::ssz_fixed_len();
let mut encoder = SszEncoder::container(offset);
encoder.append(&self.a);
encoder.append(&self.b);
encoder.append(&self.c);
buf.append(&mut encoder.drain());
}
}
impl Decodable for Foo {
fn is_ssz_fixed_len() -> bool {
<u16 as Decodable>::is_ssz_fixed_len() && <Vec<u16> as Decodable>::is_ssz_fixed_len()
}
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 foo = Foo {
a: 42,
b: vec![0, 1, 2, 3],
c: 11,
};
let bytes = vec![42, 0, 8, 0, 0, 0, 11, 0, 0, 1, 2, 3];
assert_eq!(foo.as_ssz_bytes(), bytes);
let decoded_foo = Foo::from_ssz_bytes(&bytes).unwrap();
assert_eq!(foo, decoded_foo);
}