alamb commented on code in PR #10405:
URL: https://github.com/apache/datafusion/pull/10405#discussion_r1592578860
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datafusion/expr/src/expr.rs:
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@@ -1087,13 +1087,60 @@ impl Expr {
}
/// Remove an alias from an expression if one exists.
+ ///
+ /// If the expression is not an alias, the expression is returned
unchanged.
+ /// This method does not remove aliases from nested expressions.
+ ///
+ /// # Example
+ /// ```
+ /// # use datafusion_expr::col;
+ /// // `foo as "bar"` is unaliased to `foo`
+ /// let expr = col("foo").alias("bar");
+ /// assert_eq!(expr.unalias(), col("foo"));
+ ///
+ /// // `foo as "bar" + baz` is not unaliased
+ /// let expr = col("foo").alias("bar") + col("baz");
+ /// assert_eq!(expr.clone().unalias(), expr);
+ ///
+ /// // `foo as "bar" as "baz" is unalaised to foo as "bar"
+ /// let expr = col("foo").alias("bar").alias("baz");
+ /// assert_eq!(expr.unalias(), col("foo").alias("bar"));
+ /// ```
pub fn unalias(self) -> Expr {
match self {
Expr::Alias(alias) => *alias.expr,
_ => self,
}
}
+ /// Recursively potentially multiple aliases from an expression.
Review Comment:
This is `trim_expr` renamed and with examples
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