Function evaluate_window_functions_value

nodedb-query/src/window/value_eval.rs:36–89

Evaluate window functions over a `Vec >` result set. `column_index` maps column name → position in each row slice. For each spec, one `Value` is appended to every row. Returns the list of new column names, one per spec in spec order.

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

/// For each spec, one `Value` is appended to every row. Returns the list of
/// new column names, one per spec in spec order.
pub fn evaluate_window_functions_value(
    rows: &mut [Vec<Value>],
    column_index: &HashMap<String, usize>,
    specs: &[WindowFuncSpec],
) -> Result<Vec<String>, WindowError> {
    let mut new_cols: Vec<String> = Vec::with_capacity(specs.len());

    for spec in specs {
        let partitions = build_value_partitions(rows, column_index, spec)?;
        let write_col = rows.first().map(|r| r.len()).unwrap_or(0);

        for row in rows.iter_mut() {
            row.push(Value::Null);
        }

        for partition_indices in &partitions {
            match spec.func_name.as_str() {
                "row_number" => apply_v_row_number(rows, partition_indices, write_col),
                "rank" => apply_v_rank(rows, partition_indices, column_index, spec, write_col),
                "dense_rank" => {
                    apply_v_dense_rank(rows, partition_indices, column_index, spec, write_col)
                }
                "ntile" => apply_v_ntile(rows, partition_indices, spec, write_col)?,
                "percent_rank" => {
                    apply_v_percent_rank(rows, partition_indices, column_index, spec, write_col)
                }
                "cume_dist" => {
                    apply_v_cume_dist(rows, partition_indices, column_index, spec, write_col)
                }
                "lag" => apply_v_lag(rows, partition_indices, column_index, spec, write_col)?,
                "lead" => apply_v_lead(rows, partition_indices, column_index, spec, write_col)?,
                "nth_value" => {
                    apply_v_nth_value(rows, partition_indices, column_index, spec, write_col)?
                }
                "sum" | "count" | "avg" | "min" | "max" | "first_value" | "last_value" => {
                    apply_v_aggregate(rows, partition_indices, column_index, spec, write_col)
                }
                other => {
                    return Err(WindowError::ArgEval {
                        detail: format!(
                            "unknown window function '{other}'; valid names: row_number, rank, \
                             dense_rank, ntile, percent_rank, cume_dist, lag, lead, nth_value, \
                             sum, count, avg, min, max, first_value, last_value"
                        ),
                    });
                }
            }
        }

        new_cols.push(spec.alias.clone());
    }

    Ok(new_cols)
}

// ── Partition building ────────────────────────────────────────────────────────