[GitHub] [arrow] alamb commented on a change in pull request #9364: ARROW-11431: [Rust][DataFusion] Support the HAVING clause.

[GitBox <gi...@apache.org>]

alamb commented on a change in pull request #9364:
URL: https://github.com/apache/arrow/pull/9364#discussion_r567415267



##########
File path: rust/datafusion/src/sql/utils.rs
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@@ -335,3 +336,35 @@ where
         },
     }
 }
+
+/// Returns mapping of each alias (`String`) to the expression (`Expr`) it is
+/// aliasing.
+pub(crate) fn extract_aliases(exprs: &Vec<Expr>) -> HashMap<String, Expr> {

Review comment:
       This can probably be something like the following if you wanted more idomatic rust style (I don't think it really matters in this case)
   
   ```suggestion
   pub(crate) fn extract_aliases(exprs: &[Expr]) -> HashMap<String, Expr> {
   ```
   
   Maybe even something fancier like anything that can become an iterator:
   
   ```
   pub(crate) fn extract_aliases(exprs: impl Iterator<Item=&Expr>) -> HashMap<String, Expr> {
   ```




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