GeezerVison

What

Allow a parametric (constructor-style) data type — including a nested one such as Nullable(Decimal(10, 2)) — to be used as the target type of a CAST.

Why

ClickHouse supports parametric data types as a CAST target, and they can be nested:

SELECT CAST(x AS Nullable(Decimal(10, 2))) FROM cast_demo;

JSQLParser failed on the inner opening bracket:

ParseException: Encountered: <OPENING_BRACKET> / "(", ... Was expecting ... <CLOSING_BRACKET>

Reported in #2441.

How

The argument production of ColDataType only accepted atomic tokens (S_LONG/K_MAX with optional BYTE/CHAR, S_CHAR_LITERAL, S_IDENTIFIER, K_CHAR), so a nested parametric type was unreachable.

This adds one alternative to the argument loop: when the next token is a DATA_TYPE or identifier immediately followed by (, parse the argument as a nested ColDataType (recursing through the existing production) and store its toString() rendering in the arguments string list. The new alternative is gated by an explicit LOOKAHEAD, so the existing atomic arguments are unaffected.

Kept intentionally narrow: only parametric arguments (a type immediately followed by its own argument list) are handled. A bare type-keyword argument (e.g. String in Nullable(String)) is a separate concern and out of scope for this issue.

Testing

• New regression test ClickHouseTest#testCastToNestedParametricTypeIssue2441 covering Nullable(Decimal(10, 2)) (the reported case) and LowCardinality(Decimal(10, 2)) (another ClickHouse parametric type wrapping a precision type). Both parse and round-trip.
• mvn clean test: 4647 tests, 0 failures, 0 errors (26 skipped) — no regressions on the shared ColDataType production.
• mvn spotless:check: clean.

Fixes #2441