GeezerVison

For DuckDB (operators, numeric, pattern matching).

• Exponentiation is a new BinaryExpression; ExpressionVisitor.visit(Exponentiation) is a default method, so existing visitors keep compiling. Its precedence matches DuckDB: above *, left-associative, below the unary sign (-2 ** 2 = 4). ^ stays BitwiseXor at the level of *, so 2^3**2 still differs from DuckDB's power ^.
• LikeExpression.setLikeOperator sets the keyword and NOT from the operator; the operator spelling is then derived from them, so later setNot/setLikeKeyWord calls print consistently (falling back to the keyword form, e.g. for NOT GLOB).
• A sign is separated from an operand starting with a sign when either is ~, or both are -: - -1 must not deparse as the comment --1, nor - ~1 / ~ ~a as the single operators -~ / ~~.
• Behaviour change: a ~~b and a !~~b used to parse as a regular expression match against ~b; they are now LIKE / NOT LIKE, as in PostgreSQL and DuckDB. Unspaced ~~a failed before and still does.
• Not included: DuckDB's integer division // (lexed as a Snowflake line comment), ^@ and postfix a NOT NULL.
• checkGrammarAmbiguity: no conflicts. ./gradlew check: 10,121 tests, 0 failures.
• DuckDB's own test suite (test/sql, 70,729 statements): 199 more parse, none less.