Function extract_equality_with_residual

nodedb-sql/src/engine_rules/mod.rs:294–309

Pull `(column_name, equality_value, residual_expr)` out of a filter expression if it contains a column-equals-literal predicate that can drive an index lookup. Returns `None` if no usable equality is present. The returned residual is the rest of the conjunction with the equality removed — `None` when the filter was a bare equality.

(
    expr: &FilterExpr,
)

/// present. The returned residual is the rest of the conjunction with
/// the equality removed — `None` when the filter was a bare equality.
fn extract_equality_with_residual(
    expr: &FilterExpr,
) -> Option<(String, SqlValue, Option<SqlExpr>)> {
    match expr {
        FilterExpr::Comparison {
            field,
            op: CompareOp::Eq,
            value,
        } => Some((field.clone(), value.clone(), None)),
        FilterExpr::Expr(sql_expr) => {
            let (col, lit, residual) = split_equality_from_expr(sql_expr)?;
            Some((col, lit, residual))
        }
        _ => None,
    }
}

/// Return `(column, literal, residual_expr)` for an equality found
/// anywhere in a right-leaning AND conjunction tree, or `None` if no