mirror of
https://github.com/vercel-labs/scriptc.git
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Malte Ubl
ae76fa85a3
An overflow map stores a nullable union's unit arm as NULL, which the keyed-read path took for a missing key (trapping where the result has no undefined arm, e.g. a stored null in Record<string, C | null>). Presence now comes from scr_map_has_str for nullable value unions; corpus 4413/4414 pin present-null index reads.
87 lines
3.8 KiB
TypeScript
87 lines
3.8 KiB
TypeScript
// `string | undefined`, `string | null` and `string | null | undefined` are the
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// string pointer itself (NULL / the null sentinel for the unit arms), retained
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// through a NULL-skipping wrapper. Strings compare by content and are falsy
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// when empty, so equality and truthiness keep their per-arm semantics. Pins
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// locals, returns, narrowing, ??, ||, ?., typeof, equality against literals
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// and computed strings, templates, JSON, inspect, Map values (typed and
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// missing-key results), sorting and joining `(string | null)[]`, optional
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// record fields, checked casts, unknown, captures, class fields, generators,
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// async payloads, and a hot loop.
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function pick(xs: string[], i: number): string | undefined {
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return i < xs.length ? xs[i] : undefined;
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}
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function show(s: string | undefined): string {
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return s === undefined ? "<u>" : `[${s}]`;
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}
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const xs = ["a", "", "ccc"];
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const vals: (string | undefined)[] = [pick(xs, 0), pick(xs, 1), pick(xs, 5), "lit", undefined];
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console.log(vals.map(show).join(","), vals.map((v) => (v ? "T" : "F")).join(""), vals.map((v) => typeof v).join(","));
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console.log(vals.map((v) => v ?? "dflt").join(","), vals.map((v) => v || "falsy").join(","), vals.map((v) => v?.length ?? -1).join(","));
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const a: string | undefined = pick(xs, 0);
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const b: string | undefined = "a" + "";
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const c: string | undefined = pick(xs, 9);
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console.log(a === b, a !== b, a === "a", c === undefined, a === c, a == "a", b === "ab".slice(0, 1));
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console.log(`${a}-${c}`, String(c), JSON.stringify({ a, c, n: null }), JSON.stringify(vals), vals);
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const m = new Map<string, string | undefined>();
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m.set("x", "1");
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m.set("u", undefined);
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console.log(show(m.get("x")), show(m.get("u")), show(m.get("zz")), m.has("u"));
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const plain = new Map<number, string>();
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plain.set(1, "one");
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console.log(show(plain.get(1)), show(plain.get(2)), plain.get(1) ?? "none", plain.get(3) ?? "none");
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const nn: (string | null)[] = ["q", null, "r"];
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nn.sort((p, q) => (p ?? "").localeCompare(q ?? ""));
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console.log(nn.map((s) => (s === null ? "null" : s)).join(","), nn.join("|"), nn.indexOf(null), nn.includes("r"));
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const three: (string | null | undefined)[] = ["s", null, undefined, ""];
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console.log(three.map((s) => (s === null ? "N" : s === undefined ? "U" : s === "" ? "E" : s)).join(""), three.map((s) => s == null).join(","), three.map((s) => (s ? 1 : 0)).join(""));
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console.log(JSON.stringify(three), three);
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interface Opt {
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name?: string;
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title: string | null;
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}
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const o1: Opt = { title: null };
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const o2: Opt = { name: "n", title: "t" };
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console.log(JSON.stringify([o1, o2]), o1, o2, "name" in o1, o2.name?.toUpperCase());
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const parsed = JSON.parse('{"title":"x"}') as Opt;
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console.log(show(parsed.name), parsed.title, "name" in parsed);
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const u: unknown = c;
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const u2: unknown = a;
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console.log(u === undefined, u2 === "a", typeof u2);
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let cap: string | undefined;
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const setCap = (s: string | undefined) => {
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cap = s ?? cap;
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};
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setCap("one");
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setCap(undefined);
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console.log(show(cap));
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class Holder {
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label: string | undefined;
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alt: string | null = null;
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}
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const h = new Holder();
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h.label = pick(xs, 2);
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h.alt = h.label ?? null;
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console.log(show(h.label), h.alt, h);
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function* gen(): Generator<string | undefined> {
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yield "g";
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yield undefined;
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}
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const gs: string[] = [];
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for (const g of gen()) gs.push(show(g));
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console.log(gs.join(","));
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async function later(i: number): Promise<string | undefined> {
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await null;
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return pick(xs, i);
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}
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const ps: Promise<string | undefined>[] = [later(0), later(7)];
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Promise.all(ps).then((r) => console.log("async", r.map(show).join(",")));
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let total = 0;
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for (let i = 0; i < 20000; i++) {
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const s = pick(xs, i % 4);
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if (s !== undefined) total += s.length;
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}
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console.log("total", total);
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const labels: Record<string, string | null> = { a: "A", n: null };
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for (const key of ["a", "n"]) console.log("index", key, labels[key] ?? "null", labels[key] === null);
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