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https://github.com/vercel-labs/scriptc.git
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Chris Tate
94fd361b54
Represent ordinary JavaScript arrays with hole, value, and explicit-undefined states; add sparse side storage and carry missing values through the frontend, native backends, runtime, and Node-facing consumers.
49 lines
2.2 KiB
TypeScript
49 lines
2.2 KiB
TypeScript
// Holes are skipped by the HasProperty family and visited by value iterators.
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// Copying methods materialize holes as present undefined without changing the
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// original number[] payload ABI.
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const sparse: number[] = [];
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sparse[2] = 7;
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sparse.length = 4;
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function kind(value: number): string {
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return typeof value;
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}
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const kindAlias = kind;
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console.log("map", sparse.map(kindAlias).join("|"));
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console.log("flat-scalar", sparse.flatMap((_value, index) => index).join(","));
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console.log("find-hole", sparse.findIndex((value) => typeof value === "undefined"));
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console.log("find-last-hole", sparse.findLastIndex((value) => typeof value === "undefined"));
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console.log("some", sparse.some((value) => typeof value === "undefined"));
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console.log("every", sparse.every((value) => typeof value === "number"));
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const dense = sparse.toReversed();
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console.log("dense-map", dense.map(kindAlias).join("|"));
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console.log("dense-some", dense.some((value) => typeof value === "undefined"));
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const selected = dense.filter((value) => typeof value === "undefined");
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console.log("selected", selected.length, selected.map(kind).join("|"));
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const flattened = sparse.flatMap(() => dense);
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console.log("flattened", flattened.length, flattened.map(kind).join("|"));
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console.log("preserved-inner-holes", dense.flatMap(() => sparse).join(","));
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for (const value of sparse) console.log("value", typeof value, value);
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for (const [index, value] of sparse.entries()) console.log("entry", index, typeof value, value);
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for (const pair of dense.entries()) console.log("pair", pair[0], typeof pair[1], pair[1]);
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console.log("reduce", sparse.reduce((acc, value) => acc + value, 3));
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console.log("reduce-seed", sparse.reduce((acc, value) => acc + value));
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console.log("reduce-right", sparse.reduceRight((acc, value) => acc + value));
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console.log("dense-reduce", dense.reduce((acc, value) => acc + value, 0));
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const holes: number[] = [];
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holes.length = 2;
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try {
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console.log(holes.reduce((acc, value) => acc + value));
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} catch (error) {
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if (error instanceof Error) console.log("empty-reduce", error.name, error.message);
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}
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const changed = [1, 2, 3];
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changed.find((value, index) => {
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console.log("find-mutation", index, typeof value);
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if (index === 0) changed.length = 1;
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return false;
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});
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