Function unproject_window_exprs

datafusion/sql/src/unparser/utils.rs:253–266

Recursively identify all Column expressions and transform them into the appropriate window expression contained in window. For example, if expr contains the column expr "COUNT(*) PARTITION BY id" it will be transformed into an actual window expression as identified in the window node.

(expr: Expr, windows: &[&Window])

/// For example, if expr contains the column expr "COUNT(*) PARTITION BY id" it will be transformed
/// into an actual window expression as identified in the window node.
pub(crate) fn unproject_window_exprs(expr: Expr, windows: &[&Window]) -> Result<Expr> {
    expr.transform(|sub_expr| {
        if let Expr::Column(c) = sub_expr {
            if let Some(unproj) = find_window_expr(windows, &c.name) {
                Ok(Transformed::yes(unproj.clone()))
            } else {
                Ok(Transformed::no(Expr::Column(c)))
            }
        } else {
            Ok(Transformed::no(sub_expr))
        }
    })
    .map(|e| e.data)
}

fn find_agg_expr<'a>(agg: &'a Aggregate, column: &Column) -> Result<Option<&'a Expr>> {
    if let Ok(index) = agg.schema.index_of_column(column) {