adriangb commented on code in PR #2458:
URL:
https://github.com/apache/datafusion-sqlparser-rs/pull/2458#discussion_r3889857013
##########
tests/sqlparser_derive_dialect.rs:
##########
@@ -121,3 +125,65 @@ fn test_identifier_quote_style_overrides() {
None
);
}
+
+#[test]
+fn test_lambda_keyword_syntax_on_postgres_derivative() {
+ // A PostgreSQL derivative can opt into the `LAMBDA` keyword spelling of
+ // lambda functions without giving up `->` as JSON member access. The two
+ // meet in a single expression below: a lambda whose body is a JSON access.
+ derive_dialect!(
+ LambdaPostgreSqlDialect,
+ PostgreSqlDialect,
+ overrides = { supports_lambda_keyword_syntax = true }
+ );
+ let dialect = LambdaPostgreSqlDialect::new();
+
+ // Only the keyword spelling is enabled; the arrow spelling stays off.
+ assert!(dialect.supports_lambda_keyword_syntax());
+ assert!(!dialect.supports_lambda_functions());
+
+ let sql = "SELECT transform(xs, lambda x : (x -> 'a')::INT + 1)";
+ let ast = Parser::parse_sql(&dialect, sql).unwrap();
+ assert_eq!(sql, ast[0].to_string());
+
+ // Round-tripping alone would not distinguish a JSON access from a nested
+ // lambda, since both print as `x -> 'a'`, so check the parsed shape.
+ let Statement::Query(query) = &ast[0] else {
+ panic!("unexpected statement {}", ast[0]);
+ };
+ let Expr::Function(func) =
+ expr_from_projection(only(&query.body.as_select().unwrap().projection))
+ else {
+ panic!("expected a function call");
+ };
+ let FunctionArguments::List(args) = &func.args else {
+ panic!("expected an argument list");
+ };
+ let [_, FunctionArg::Unnamed(FunctionArgExpr::Expr(Expr::Lambda(lambda)))]
= &args.args[..]
+ else {
+ panic!("expected the second argument to be a lambda");
+ };
+
+ // The lambda came from the `LAMBDA` keyword, not from `->`.
+ assert_eq!(LambdaSyntax::LambdaKeyword, lambda.syntax);
+
+ // And the `->` in its body is still JSON member access.
+ let Expr::BinaryOp {
+ left,
+ op: BinaryOperator::Plus,
+ ..
+ } = lambda.body.as_ref()
+ else {
+ panic!("expected the lambda body to be an addition");
+ };
+ let Expr::Cast { expr, .. } = left.as_ref() else {
+ panic!("expected the left operand to be a cast");
+ };
+ let Expr::Nested(json_access) = expr.as_ref() else {
+ panic!("expected the cast operand to be parenthesized");
+ };
+ let Expr::BinaryOp { op, .. } = json_access.as_ref() else {
+ panic!("expected `->` to stay a binary operator");
+ };
+ assert_eq!(&BinaryOperator::Arrow, op);
+}
Review Comment:
Thanks, added but in `sqlparser_custom_dialect.rs`
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