39 lines
1.3 KiB
JavaScript
39 lines
1.3 KiB
JavaScript
import { Writable } from "stream";
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import { headStream as headWebStream } from "./headStream.browser";
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import { isReadableStream } from "./stream-type-check";
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export const headStream = (stream, bytes) => {
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if (isReadableStream(stream)) {
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return headWebStream(stream, bytes);
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}
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return new Promise((resolve, reject) => {
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const collector = new Collector();
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collector.limit = bytes;
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stream.pipe(collector);
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stream.on("error", (err) => {
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collector.end();
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reject(err);
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});
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collector.on("error", reject);
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collector.on("finish", function () {
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const bytes = new Uint8Array(Buffer.concat(this.buffers));
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resolve(bytes);
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});
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});
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};
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class Collector extends Writable {
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buffers = [];
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limit = Infinity;
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bytesBuffered = 0;
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_write(chunk, encoding, callback) {
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this.buffers.push(chunk);
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this.bytesBuffered += chunk.byteLength ?? 0;
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if (this.bytesBuffered >= this.limit) {
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const excess = this.bytesBuffered - this.limit;
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const tailBuffer = this.buffers[this.buffers.length - 1];
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this.buffers[this.buffers.length - 1] = tailBuffer.subarray(0, tailBuffer.byteLength - excess);
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this.emit("finish");
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}
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callback();
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}
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}
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