Function extract_aliases

datafusion/sql/src/utils.rs:195–203

Returns mapping of each alias (`String`) to the expression (`Expr`) it is aliasing.

(exprs: &[Expr])

/// Returns mapping of each alias (`String`) to the expression (`Expr`) it is
/// aliasing.
pub(crate) fn extract_aliases(exprs: &[Expr]) -> HashMap<String, Expr> {
    exprs
        .iter()
        .filter_map(|expr| match expr {
            Expr::Alias(Alias { expr, name, .. }) => Some((name.clone(), *expr.clone())),
            _ => None,
        })
        .collect::<HashMap<String, Expr>>()
}

/// Given an expression that's literal int encoding position, lookup the corresponding expression
/// in the select_exprs list, if the index is within the bounds and it is indeed a position literal,