mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-29 07:04:09 +08:00
Chris Tate
da89261676
Array.prototype.sort and toSorted with a comparator now run V8's TimSort (array-sort.tq) step for step in the runtime, in the generated sort for booleans and unions with undefined, and in the checked-value sort. The comparator is called as f(x, y) < 0 in Node's argument order, so a comparator sees Node's calls in Node's order and an inconsistent comparator yields Node's permutation. Undefined values, including a union's undefined arm, are set aside before sorting and never reach the comparator, and a checked comparator's result converts with ToNumber. Structured inputs take fewer comparator calls than the previous merge sort. Each thread reuses one sort buffer of up to 1 MiB.
45 lines
1.8 KiB
TypeScript
45 lines
1.8 KiB
TypeScript
// Comparator sorts over element types the compiler sorts in generated code
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// (booleans, unions with an undefined member) make Node's comparator calls:
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// undefined values move to the end without reaching the comparator.
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let seed = 5;
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function random(): number {
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seed = (Math.imul(seed, 1103515245) + 12345) >>> 0;
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return seed / 4294967296;
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}
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function mix(h: number, x: number): number {
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return Math.imul(h ^ x, 16777619) >>> 0;
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}
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for (const n of [2, 9, 33, 70, 400]) {
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const maybe: (number | undefined)[] = [];
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for (let i = 0; i < n; i++) maybe.push(random() < 0.2 ? undefined : Math.floor(random() * 30));
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let calls = 0;
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let log = 2166136261;
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const sorted = maybe.slice().sort((x, y) => {
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calls++;
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log = mix(mix(log, x ?? -1), y ?? -1);
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return (x as number) - (y as number);
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});
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const copy = maybe.toSorted((x, y) => (y as number) - (x as number));
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console.log(n, calls, log.toString(16), sorted.slice(0, 10).join(","), sorted.slice(-3).join(","), copy.slice(0, 6).join(","));
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const flags: boolean[] = [];
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for (let i = 0; i < n; i++) flags.push(random() < 0.5);
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let flagCalls = 0;
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const flagOrder: string[] = [];
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flags.sort((x, y) => {
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if (flagOrder.length < 8) flagOrder.push(`${x ? 1 : 0}${y ? 1 : 0}`);
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flagCalls++;
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return (x ? 1 : 0) - (y ? 1 : 0);
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});
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console.log(flagCalls, flagOrder.join(" "), flags.indexOf(true));
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const mixed: (string | undefined)[] = [];
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for (let i = 0; i < n; i++) mixed.push(random() < 0.15 ? undefined : "w" + Math.floor(random() * 12));
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const seen: string[] = [];
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mixed.sort((x, y) => {
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if (seen.length < 10) seen.push(`${x}/${y}`);
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return x! < y! ? -1 : x! > y! ? 1 : 0;
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});
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console.log(seen.join(" "), mixed.filter((x): boolean => x === undefined).length, mixed[mixed.length - 1]);
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}
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