Function apply_v_lag

nodedb-query/src/window/value_eval.rs:398–417

(
    rows: &mut [Vec<Value>],
    indices: &[usize],
    column_index: &HashMap<String, usize>,
    spec: &WindowFuncSpec,
    write_col: usize,
)

}

fn apply_v_lag(
    rows: &mut [Vec<Value>],
    indices: &[usize],
    column_index: &HashMap<String, usize>,
    spec: &WindowFuncSpec,
    write_col: usize,
) -> Result<(), WindowError> {
    let offset = usize_arg(spec, 1, 1);
    let default = default_arg_value(spec, 2);
    let values = collect_arg_values(rows, indices, column_index, spec);
    for (pos, &i) in indices.iter().enumerate() {
        let val = if pos >= offset {
            values[pos - offset].clone()
        } else {
            default.clone()
        };
        set_cell(rows, i, write_col, val);
    }
    Ok(())
}

fn apply_v_lead(
    rows: &mut [Vec<Value>],