mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-26 06:34:20 +08:00
Chris Tate
9843f8efd2
Interface dispatch now unboxes a receiver it has matched by key with one load and no reference count change, and keeps its checked fallback out of line so the key tests inline at each call site. A loop over an array of interface values lends each element to a dispatch whose implementing methods cannot release it; the fallback, which can run any code, takes its own reference to the receiver.
46 lines
1.2 KiB
TypeScript
46 lines
1.2 KiB
TypeScript
// Arrays of interface values with holes and undefined entries written by
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// untyped code, read by loops, index reads and array methods.
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interface Shape {
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area(): number;
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}
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class Square implements Shape {
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side: number;
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constructor(side: number) {
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this.side = side;
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}
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area(): number {
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return this.side * this.side;
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}
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}
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const shapes: Shape[] = [new Square(1), new Square(2)];
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function extend(view: unknown): void {
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const array = view as unknown[];
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array.length = 5;
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array[3] = undefined;
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array[4] = new Square(4);
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}
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extend(shapes);
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let present = 0;
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let missing = 0;
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for (const shape of shapes) {
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if (shape === undefined) missing++;
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else present += shape.area();
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}
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console.log(shapes.length, present, missing);
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console.log(2 in shapes, 3 in shapes, shapes[2] === undefined, shapes[4]!.area());
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console.log(shapes.filter((s) => s !== undefined).length);
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const areas: number[] = [];
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shapes.forEach((s) => areas.push(s === undefined ? -1 : s.area()));
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console.log(areas.join(","));
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console.log(JSON.stringify(shapes));
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function areaSum(list: Shape[]): number {
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let sum = 0;
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for (const shape of list) sum += shape === undefined ? -1 : shape.area();
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return sum;
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}
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console.log(areaSum(shapes));
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