Function diff_attestations 

pub fn diff_attestations(base_ssz: &[u8], target_ssz: &[u8]) -> AttestationsDiff

Computes a compact delta between two serialized SSZ attestation lists.

The function automatically selects between the supported delta representations:

• If the lists are identical, AttestationsDiff::Unchanged is returned.
• If the target list starts with the exact byte sequence of the base list, only the trailing bytes are stored in AttestationsDiff::Append.
• Otherwise, the complete target list is stored in AttestationsDiff::FullReplacement.

This covers both append-only updates, such as growth of current_epoch_attestations, and epoch-boundary replacement of previous_epoch_attestations.

An empty base list is naturally represented as an append of the complete target list.

Arguments

• base_ssz - Serialized SSZ representation of the base attestation list.
• target_ssz - Serialized SSZ representation of the target attestation list.

Returns

A compact AttestationsDiff representing the transition from base_ssz to target_ssz.

Complexity

The prefix comparison takes O(min(n, m)) time, where n and m are the lengths of base_ssz and target_ssz, respectively. Additional space is proportional to the selected delta payload.

Example

let base = b"AAAA";

// Append case.
let target = b"AAAABBBB";
assert_eq!(
    diff_attestations(base, target),
    AttestationsDiff::Append(b"BBBB".to_vec())
);

// Replacement case.
let target = b"CCCC";
assert_eq!(
    diff_attestations(base, target),
    AttestationsDiff::FullReplacement(b"CCCC".to_vec())
);