ADR-0030 §3 commissioned a focused ADR for the stratified SQL
expression grammar fragment. ADR-0031 records the decisions:
- One unified precedence ladder (OR/AND/NOT, comparison/LIKE/IN/
BETWEEN/IS NULL predicates, arithmetic incl. `||`, function
calls, CASE) — SQL treats booleans as values, so unlike
ADR-0026's bool/scalar split this is a single ladder.
- No AST — every Phase-1 consumer (SELECT projection, WHERE)
runs validated SQL as text per ADR-0030 §4/§6; CHECK/DEFAULT
in Phase 4 store text too. The fragment's job is accept /
reject + the matched-terminal path + a source span.
- Recursion via Subgrammar with ADR-0026's depth cap reused.
- A parallel `grammar/sql_expr.rs` — separate from `expr.rs` so
simple mode's 1240-test surface is untouched by construction.
- Subquery expressions and qualified `t.c` column refs deferred
to ADR-0030 Phase 2 (they need the recursive SELECT grammar).
`%` modulo is included alongside `+ - * /` and `||` — it isn't
ISO SQL but is near-universal across mainstream engines and
matches learner expectations (pedagogy wins ties, ADR-0030).
Status: Accepted. The implementation lands in subsequent
commits.
claude@clouddev1
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