@siftql/core

The controls live in the card above, beside the query they affect. This is the explanation, and the resolved shape the engine is actually running with.

dateFormat

A non-ISO layout, declared rather than guessed. 01-06-2020 is 1 June under DD-MM-YYYY and 6 January under MM-DD-YYYY; siftql will never pick for you. Tokens are YYYY MM DD HH mm ss SSS and everything else in the layout is matched literally. Engine-level only.

tolerant

For search-as-you-type, where the query is malformed on almost every keystroke. Holes are repaired and marked instead of thrown. Structural limits still throw — this forgives half-typed syntax, not unbounded input. Engine-level only: passing it per call does nothing at all.

matchKeys

A bare term may match a field NAME as well as its contents. Off by default.

regexGuard

On, a pattern that cannot be matched in guaranteed linear time is refused — backreferences, lookaround, a quantifier whose body can match empty, the u/v flags. Off, those run on RegExp instead, and you get three things: the pattern works, you lose highlight positions for it, and unbounded backtracking is back.

onValueError

What a bad VALUE in the data does — not a bad query, which always throws. skip drops the row; throw raises a SiftQLValueError naming the path and the value.

maxPatternLength

Longest accepted regex source, default 1000.

Resolved options

Note temporal.dateFormat: it is flat going in and nested coming out, which is the kind of thing a demo gets wrong quietly.

Two public functions, run live. detectTemporalFormat asks does this match one of the built-in ISO shapes; resolveTemporal asks does it resolve to a real instant — and it also applies any dateFormat you declare, which detect never sees. So the two disagree in both directions, and each disagreement means something different:

• ISO-shaped, resolves — an ordinary date.
• ISO-shaped, does not resolve — 2021-02-29. This is the gap the whole design rests on: siftql refuses the query rather than falling back to comparing it as text, where new Date() would hand you 1 March.
• Not ISO-shaped, resolves — 01-06-2020 once you pick a layout below. Declared layouts live inside resolveTemporal, so detect returns null for them. Change the layout and watch that row's answer move between June and January.
• Neither — not a date under any rule currently in force.

The AST is a documented public contract and pure JSON — no RegExp, no Date, no functions — so it survives structuredClone, a cache key, or a worker boundary.

serialize(parse(query))

JSON round trip

Tree (locations stripped)

^(a+)+$ against "a".repeat(n) + "!" — the classic catastrophic pattern. siftql matches it on a linear-time automaton. The native RegExp runs in a Web Worker with a hard timeout, because otherwise it would freeze this tab and you would never see the result.

Editable. One caveat worth stating plainly: the seed is built in JavaScript so that created can hold an ISO string, epoch milliseconds and a real Date across different rows. JSON cannot express the third, so anything you paste here loses Date objects — the ISO strings and epoch numbers still behave identically.