mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-11-01 07:33:12 +08:00
Chris Tate
5f602ff3b8
`decoder.decode(view!)` on a `Uint16Array | undefined` (or another typed array that may be undefined) was refused with SC2020: the assertion keeps the undefined arm for decode, and the decode input only read the undefined arm of `Uint8Array | undefined`. The undefined arm of any typed array that may be undefined now reads as an empty array of the same type, so a defined input decodes its bytes and an undefined one decodes no bytes, as in Node.
39 lines
1.8 KiB
TypeScript
39 lines
1.8 KiB
TypeScript
// TextDecoder.decode(undefined) decodes no bytes, as decode() does: it
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// returns "" and, after streamed input, flushes the pending bytes.
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const decoder = new TextDecoder();
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const encoded = new TextEncoder().encode("bytes");
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const inputs = new Map<string, Uint8Array | undefined>([
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["present", encoded],
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["absent", undefined],
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]);
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console.log(JSON.stringify(decoder.decode(undefined)));
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console.log(JSON.stringify(decoder.decode(inputs.get("present"))), JSON.stringify(decoder.decode(inputs.get("absent"))));
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console.log(JSON.stringify(decoder.decode(inputs.get("absent")!)), JSON.stringify(decoder.decode(inputs.get("missing")!)));
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console.log(JSON.stringify(new TextDecoder("utf-8").decode(undefined)));
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console.log(JSON.stringify(new TextDecoder("utf-8").decode(inputs.get("absent"))));
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let calls = 0;
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function nothing(): undefined {
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calls++;
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return undefined;
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}
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console.log(JSON.stringify(decoder.decode(nothing())), calls);
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interface Chunk {
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done: boolean;
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value?: Uint8Array;
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}
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const chunks: Chunk[] = [{ done: false, value: new Uint8Array([0xe2, 0x82]) }, { done: true }];
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const streaming = new TextDecoder();
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let text = "";
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for (const chunk of chunks) text += streaming.decode(chunk.value, { stream: !chunk.done });
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console.log(JSON.stringify(text), text.length);
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// Other typed arrays decode their bytes, with or without the assertion.
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const wide = new Map<string, Uint16Array | undefined>([["present", new Uint16Array([0x6968])]]);
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const asserted = wide.get("present")!;
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console.log(JSON.stringify(decoder.decode(asserted)), JSON.stringify(decoder.decode(wide.get("present")!)));
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console.log(JSON.stringify(decoder.decode(wide.get("present"))), JSON.stringify(decoder.decode(wide.get("absent"))));
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console.log(JSON.stringify(new TextDecoder("utf-8").decode(wide.get("absent")!)));
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