Function extract_window_functions

nodedb-sql/src/planner/window/extract.rs:28–47

Extract window function specifications from a SELECT's projection.

(
    select: &ast::Select,
    functions: &FunctionRegistry,
)

/// Extract window function specifications from a SELECT's projection.
pub fn extract_window_functions(
    select: &ast::Select,
    functions: &FunctionRegistry,
) -> Result<Vec<WindowSpec>> {
    let named = collect_named_windows(&select.named_window)?;
    let mut specs = Vec::new();
    for item in &select.projection {
        let (expr, alias) = match item {
            ast::SelectItem::UnnamedExpr(e) => (e, format!("{e}")),
            ast::SelectItem::ExprWithAlias { expr, alias } => (expr, normalize_ident(alias)),
            _ => continue,
        };
        if let ast::Expr::Function(func) = expr
            && func.over.is_some()
        {
            specs.push(convert_window_spec(func, &alias, functions, &named)?);
        }
    }
    Ok(specs)
}

fn convert_window_spec(
    func: &ast::Function,