mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-23 06:10:02 +08:00
Chris Tate
385b0a9199
- Destructuring assignment now takes nested patterns (`({ p: { q } } = src)`, `[[a], b] = t`) and property/element targets (`[c.x, box.vals[i]] = arr`, `({ a: rec.f } = o)`, rest into members) — receivers temp at their pattern position, JS's reference-before-read order; defaults on member targets test against the target's own type. Defaults on nested targets keep a named fence (no single binding type to test against).
- Class instances destructure in assignment position like they already did in declarations: field slots and getter calls per element via the same fieldGetExpr dispatch, defaults, renames, and member targets; methods and undeclared names keep their pointed fences.
- Rest over class-instance sources packs the remaining instance FIELDS into a fresh record (JS's CopyDataProperties copies own enumerable properties — never prototype methods/accessors, matching the checker's rest type), in declarations and assignments; non-public fields, runtime-provided chains (Error/EventEmitter/stream), and key orders the packed shape cannot reproduce fence instead of diverging.
- Defaults on destructured getter results now lower (record and class accessors alike), with the getter result temped so the default's undefined test never calls it twice; numeric-literal pattern keys (`const { 2: x } = o`) fold to JS's canonical property name.
- Corpus 2536-2540 pin the new forms byte-identically against Node on both backends; the destructuring-fences diagnostics program keeps the honest residue (method extraction, non-public rest fields, nested-target defaults, index-signature rest).
- The ts7 order-parity baseline re-record backfills the entries the released file was missing (2490-2500 included) alongside the new fixtures; no existing entry changed.
67 lines
1.4 KiB
TypeScript
67 lines
1.4 KiB
TypeScript
// Destructuring assignment FROM class instances: field reads, getter
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// calls at the element's pattern position, inherited members, defaults
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// against the target's own type, renames, and member targets fed from a
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// class source.
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class Base {
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root = "r";
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}
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class Item extends Base {
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id = 7;
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label = "seven";
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get loud(): string {
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return this.label.toUpperCase();
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}
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}
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const item = new Item();
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let id = 0;
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let label = "";
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({ id, label } = item);
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console.log(id, label);
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// Renames and getters.
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let shout = "";
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let from = "";
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({ loud: shout, root: from } = item);
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console.log(shout, from);
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// Defaults from undefined-armed class fields.
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class Sparse {
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hit?: number;
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miss?: number;
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constructor() {
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this.hit = 3;
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}
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}
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let hit = -1;
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let miss = -1;
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({ hit = -10, miss = -20 } = new Sparse());
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console.log(hit, miss);
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// A class source feeding MEMBER targets.
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const sink = { a: 0, b: "" };
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({ id: sink.a, label: sink.b } = item);
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console.log(sink.a, sink.b);
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// Getters run ONCE per element, at the element's position.
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const order: string[] = [];
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class Tracked {
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get first(): number {
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order.push("first");
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return 1;
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}
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get second(): number {
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order.push("second");
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return 2;
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}
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}
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let f = 0;
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let sec = 0;
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({ second: sec, first: f } = new Tracked());
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console.log(order.join(","), f, sec);
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// Expression-position class-source assignment keeps the RHS value.
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let again = 0;
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const same = ({ id: again } = item);
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console.log(again, same.label);
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