ConditionalExpression

A composable, parameterized boolean expression used by WHERE / HAVING / ON clauses.

Internally it is a thin wrapper around an immutable SqlNode tree (see com.zxhhyj.storm.sql). The infix operators (eq, and, or, not, gt, like, in, …) build new trees; the actual SQL text and bound arguments are produced on demand by buildFragment (which runs the tree through the Normalizer first, then the Renderer).

Why a tree of nodes instead of a flat list of SqlFragments? See the "AST 是什么" discussion — the tree lets us

• emit parens correctly (e.g. (a OR b) AND c instead of relying on SQL precedence),

• fix the NOT a > 5 misparse by always wrapping a NOT's operand,

• rewrite dialect quirks in one place (eq null → IS NULL, IN () → 0) instead of special-casing each call site.