Support predicates in function arguments

[cpsievert]

Closes #456.

Summary

This PR improves SQL parsing inside function arguments.

The first commit takes the minimal step needed for the original issue by allowing AND / OR in function arguments.

The second commit expands that same area to support additional predicate forms in function arguments and named function-argument values:

• NOT
• IN (...)
• BETWEEN ... AND ...
• IS NULL
• LIKE / ILIKE

Examples that now parse include:

SELECT IFF(x = 'a' OR x = 'b', 1, 0) AS rate FROM t
VISUALISE rate AS x
DRAW point

SELECT IFF(NOT x = 'a', 1, 0) AS flag FROM t
VISUALISE flag AS x
DRAW point

SELECT IFF(x IN ('a', 'b'), 1, 0) AS flag FROM t
VISUALISE flag AS x
DRAW point

SELECT IFF(x BETWEEN 1 AND 10, 1, 0) AS flag FROM t
VISUALISE flag AS x
DRAW point

Scope

The richer predicate grammar is still scoped to function arguments rather than being applied to position_arg more generally. This keeps the change focused on the parser gap addressed by this PR instead of turning it into a broader SQL expression refactor.

Verification

• cargo test -p ggsql function_args -- --nocapture
• cd tree-sitter-ggsql && tree-sitter generate && tree-sitter test

[georgestagg]

How much more complex would it be to organise the grammar to also add the extra keywords and allow for the proposed predicates,

not_predicate
in_predicate
between_predicate
is_predicate
like_predicate

IMO if it is not too more more complex we may as well just do it now. Let me know. If you'd prefer to defer it I'll approve and merge.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.