32 lines
865 B
TypeScript
32 lines
865 B
TypeScript
// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
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// This module is browser compatible.
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/**
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* A `LimitedReader` reads from `reader` but limits the amount of data returned to just `limit` bytes.
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* Each call to `read` updates `limit` to reflect the new amount remaining.
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* `read` returns `null` when `limit` <= `0` or
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* when the underlying `reader` returns `null`.
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*/
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import type { Reader } from "../types.d.ts";
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export class LimitedReader implements Reader {
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constructor(public reader: Reader, public limit: number) {}
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async read(p: Uint8Array): Promise<number | null> {
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if (this.limit <= 0) {
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return null;
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}
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if (p.length > this.limit) {
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p = p.subarray(0, this.limit);
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}
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const n = await this.reader.read(p);
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if (n == null) {
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return null;
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}
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this.limit -= n;
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return n;
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}
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}
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