Struct ssz::SszEncoder

pub struct SszEncoder<'a> { /* private fields */ }

Allow for encoding an ordered series of distinct or indistinct objects as SSZ bytes.

You must call finalize(..) after the final append(..) call to ensure the bytes are written to buf.

Example

Use SszEncoder to produce identical output to foo.as_ssz_bytes():

use ssz_derive::{Encode, Decode};
use ssz::{Decode, Encode, SszEncoder};

#[derive(PartialEq, Debug, Encode, Decode)]
struct Foo {
    a: u64,
    b: Vec<u16>,
}

fn ssz_encode_example() {
    let foo = Foo {
        a: 42,
        b: vec![1, 3, 3, 7]
    };

    let mut buf: Vec<u8> = vec![];
    let offset = <u64 as Encode>::ssz_fixed_len() + <Vec<u16> as Encode>::ssz_fixed_len();

    let mut encoder = SszEncoder::container(&mut buf, offset);

    encoder.append(&foo.a);
    encoder.append(&foo.b);

    encoder.finalize();

    assert_eq!(foo.as_ssz_bytes(), buf);
}

Implementations

impl<'a> SszEncoder<'a>

pub fn container(buf: &'a mut Vec<u8>, num_fixed_bytes: usize) -> Self

Instantiate a new encoder for encoding a SSZ container.

pub fn append<T: Encode>(&mut self, item: &T)

Append some item to the SSZ bytes.

pub fn append_parameterized<F>(&mut self, is_ssz_fixed_len: bool, ssz_append: F)

where F: Fn(&mut Vec<u8>),

Uses ssz_append to append the encoding of some item to the SSZ bytes.

pub fn finalize(&mut self) -> &mut Vec<u8>

Write the variable bytes to self.bytes.

This method must be called after the final append(..) call when serializing variable-length items.