slopgobblercobbler opened a new pull request, #2791:
URL: https://github.com/apache/datafusion-sqlparser-rs/pull/2791
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Dialects: mysql, generic
### Description
Fixes #2760.
In `Parser::parse_subexpr`, when matching infix operators (`NOT`, `IN`,
`BETWEEN`, `LIKE`, `ILIKE`, `SIMILAR`, `REGEXP`, `RLIKE`), the parser
previously parsed `Keyword::NULL` eagerly into a `null` boolean before checking
if a `REGEXP` or `RLIKE` operator matched:
```rust
let negated = self.parse_keyword(Keyword::NOT);
let regexp = self.parse_keyword(Keyword::REGEXP);
let rlike = self.parse_keyword(Keyword::RLIKE);
let null = if !self.in_column_definition_state() {
self.parse_keyword(Keyword::NULL)
} else {
false
};
```
When an expression contained `REGEXP NULL` or `RLIKE NULL` (with or without
`NOT`), `self.parse_keyword(Keyword::REGEXP)` (or `RLIKE`) consumed the
operator token, placing the parser cursor directly at `NULL`. The subsequent
`self.parse_keyword(Keyword::NULL)` call then consumed the `NULL` token under
the assumption that it was part of a `NOT NULL` expression.
Consequently, when `Expr::RLike` went to parse its `pattern` operand with
`self.parse_subexpr(Precedence::Like)`, the `NULL` token was already consumed:
- `SELECT 'abc' REGEXP NULL` failed with `ParserError("Expected: an
expression, found: EOF")`.
- `SELECT a RLIKE NULL FROM t` consumed `FROM` as the pattern identifier.
- `SELECT a NOT REGEXP NULL OR b FROM t` consumed `OR` as the pattern
identifier.
This PR defers the `Keyword::NULL` check so it is only evaluated when
checking for `NOT NULL` in the `else if negated &&
!self.in_column_definition_state() && self.parse_keyword(Keyword::NULL)`
branch, ensuring `REGEXP` and `RLIKE` pattern expressions retain access to
`NULL` literals.
### Tests
- Extended `parse_rlike_and_regexp` in `tests/sqlparser_mysql.rs` with:
- `SELECT 'abc' REGEXP NULL`
- `SELECT a RLIKE NULL FROM t`
- `SELECT a NOT REGEXP NULL OR b FROM t`
- `SELECT a NOT RLIKE NULL FROM t`
- Explicit AST verification that `Expr::RLike` pattern contains
`Value(Null)`.
- Verified `cargo test --test sqlparser_mysql`, `cargo test --test
sqlparser_common`, and `cargo test --lib` all pass.
- Verified `cargo fmt --check` and `cargo clippy --all-targets -- -D
warnings` pass with 0 warnings.
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