mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-21 05:50:55 +08:00
Chris Tate
b40a6f6079
- Keep generic bindings and short-circuit writes scoped to their native execution context. - Compile Map and Set copies, tuple callbacks and searches, and string-pattern replacement. - Exercise production frontend registries without Node and preserve mutation, identity, and evaluation order.
97 lines
3.2 KiB
TypeScript
97 lines
3.2 KiB
TypeScript
export {};
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let effects = "";
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function rhs(value: number): number { effects += "R"; return value; }
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let number = 0;
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console.log(number &&= rhs(1), number, effects);
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console.log(number ||= rhs(2), number, effects);
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console.log(number ||= rhs(3), number, effects);
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console.log(number &&= rhs(4), number, effects);
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number = NaN;
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console.log(number ||= rhs(5), number, effects);
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number = -0;
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console.log(number &&= rhs(6), Object.is(number, -0), effects);
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let text = "";
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console.log(text ||= "filled", text);
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console.log(text &&= "changed", text);
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let flag = false;
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console.log(flag &&= true, flag);
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console.log(flag ||= true, flag);
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console.log(flag &&= false, flag);
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function optional(value: string | undefined): string | undefined {
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value &&= "changed";
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console.log("and", value);
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value ||= "default";
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return value;
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}
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console.log(optional(undefined), optional(""), optional("present"));
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// Evaluation of the reference precedes its single read. The setter runs
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// only when the selected branch actually assigns, and the result is the
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// RHS value even when the setter stores a different value.
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class Cell {
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stored = 0;
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get value(): number { effects += "G"; return this.stored; }
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set value(value: number) { effects += "S"; this.stored = value + 10; }
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}
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const cell = new Cell();
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function receiver(): Cell { effects += "O"; return cell; }
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effects = "";
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console.log(receiver().value &&= rhs(1), cell.stored, effects);
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effects = "";
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console.log(receiver().value ||= rhs(2), cell.stored, effects);
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effects = "";
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console.log(receiver().value ||= rhs(3), cell.stored, effects);
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effects = "";
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console.log(receiver().value &&= rhs(4), cell.stored, effects);
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const values = [0, 2];
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function array(): number[] { effects += "A"; return values; }
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function key(value: number): number { effects += "K"; return value; }
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effects = "";
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console.log(array()[key(0)] ||= rhs(7), values[0], effects);
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effects = "";
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console.log(array()[key(1)] &&= rhs(8), values[1], effects);
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effects = "";
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console.log(array()[key(9)] &&= rhs(9), values.length, effects);
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effects = "";
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console.log(array()[key(9)] ||= rhs(10), values.length, effects);
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// The receiver remains the one evaluated before the RHS changes its alias.
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let active = [0];
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const original = active;
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function replace(): number { active = [20]; return 30; }
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console.log(active[0] ||= replace(), original[0], active[0]);
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function captured(): void {
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let value = "";
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const fill = (): string => value ||= "capture";
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console.log(fill(), fill(), value);
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}
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captured();
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function fail(): number { effects += "T"; throw new Error("rhs"); }
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let preserved = 0;
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effects = "";
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try { preserved ||= fail(); }
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catch (error) { if (error instanceof Error) console.log(error.message); }
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console.log(preserved, effects);
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preserved = 2;
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effects = "";
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console.log(preserved ||= fail(), effects);
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// A forward captured binding still checks TDZ before deciding whether to
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// evaluate the RHS. Neither logical operator can initialize its empty box.
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function forward(): void {
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const write = (): void => { value ||= rhs(40); };
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effects = "";
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try { write(); }
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catch (error) { if (error instanceof Error) console.log(error.name, effects); }
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let value = 0;
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write();
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console.log(value, effects);
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}
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forward();
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