pub fn extract_window_functions(
items: &[SelectItem],
functions: &FunctionRegistry,
) -> Result<Vec<WindowSpec>>Expand description
Extract window function specifications from SELECT items.
Validates each <func>() OVER (...) against the function registry.
Names that are neither registered window functions nor aggregates
(PostgreSQL allows aggregates as windows) are rejected here so the
Data-Plane evaluator never receives an unrecognised verb.