Function coalesce_replace

atomic-core/src/merge/three_way.rs:238–265

Turn adjacent Delete / Insert pairs at the same position into Replace.

(ops: &mut Vec<EditOp>)

/// Turn adjacent Delete / Insert pairs at the same position into Replace.
fn coalesce_replace(ops: &mut Vec<EditOp>) {
    let mut i = 0;
    while i + 1 < ops.len() {
        let is_pair = {
            if let (EditOp::Delete(del_idx), EditOp::Insert(ins_after, _)) = (&ops[i], &ops[i + 1])
            {
                // The insert sits right after the deleted index.
                *ins_after == *del_idx || (*del_idx == 0 && *ins_after == usize::MAX)
            } else {
                false
            }
        };

        if is_pair {
            let content = match &ops[i + 1] {
                EditOp::Insert(_, c) => c.clone(),
                _ => unreachable!(),
            };
            let idx = match &ops[i] {
                EditOp::Delete(idx) => *idx,
                _ => unreachable!(),
            };
            ops[i] = EditOp::Replace(idx, content);
            ops.remove(i + 1);
        }
        i += 1;
    }
}

// ---------------------------------------------------------------------------
// Helpers: analyse edit scripts