alrevuelta commented on code in PR #2333:
URL:
https://github.com/apache/datafusion-sqlparser-rs/pull/2333#discussion_r3235396708
##########
src/parser/mod.rs:
##########
@@ -14639,6 +14639,33 @@ impl<'a> Parser<'a> {
Ok(cte)
}
+ /// Parse a single item in a `WITH` clause.
+ ///
+ /// In standard SQL this is always a CTE (`name [(cols)] AS (query)`).
+ /// Dialects that enable
[`Dialect::supports_with_clause_scalar_expression`]
+ /// — currently only ClickHouse — also accept the reversed form
+ /// `<expression> AS <identifier>`, which can be freely interleaved with
+ /// CTEs in the same comma-separated list.
+ pub fn parse_with_item(&mut self) -> Result<WithItem, ParserError> {
+ if !self.dialect.supports_with_clause_scalar_expression() {
+ return self.parse_cte().map(WithItem::Cte);
+ }
+
+ // CTE form must start with an identifier. If the leading token
+ // can't begin one (e.g. `42`, `(SELECT …)`, `(x, y) -> …`), this
+ // is unambiguously the named-expression form.
+ if matches!(self.peek_token().token, Token::Word(_)) {
+ if let Some(cte) = self.maybe_parse(|p| p.parse_cte())? {
+ return Ok(WithItem::Cte(cte));
+ }
+ }
Review Comment:
right, i was mixing things up. can you confirm this `WITH (SELECT max(x)
FROM t) AS m SELECT m` will work with your approach? i tried and seems that the
first tokens `(SELECT` make peek_subquery_or_cte_start return true, which
routes to parse_cte, but parse_cte immediately fails on ( since it expects an
identifier.
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