LucaCappelletti94 commented on code in PR #2352:
URL:
https://github.com/apache/datafusion-sqlparser-rs/pull/2352#discussion_r3366832278
##########
src/parser/mod.rs:
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@@ -1717,6 +1748,31 @@ impl<'a> Parser<'a> {
return prefix;
}
+ // Memoize parse_prefix failures to break 2^N speculation when both
+ // prefix arms fail at every level (e.g. `IF(current_time(...x`).
+ // The per-arm cache in `parse_prefix_inner` complements this for
+ // chains where the reserved arm fails but the unreserved fallback
+ // succeeds (e.g. `case-case-...c`).
+ let start_index = self.index;
+ if let Some(&cached) = self.failed_prefix_positions.get(&start_index) {
+ return Err(self.cached_prefix_error(cached,
self.peek_token_ref()));
+ }
+ let result = self.parse_prefix_inner();
+ if let Err(ref e) = result {
+ self.failed_prefix_positions.insert(start_index, e.into());
+ }
+ result
+ }
+
+ /// Rebuild the error for a cached prefix failure at the `found` token.
+ fn cached_prefix_error(&self, cached: ExprPrefixError, found:
&TokenWithSpan) -> ParserError {
Review Comment:
Done!
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