63 lines
2.0 KiB
JavaScript
63 lines
2.0 KiB
JavaScript
import { EndOfStreamError } from './Errors.js';
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import { AbstractStreamReader } from "./AbstractStreamReader.js";
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export class WebStreamDefaultReader extends AbstractStreamReader {
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constructor(reader) {
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super();
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this.reader = reader;
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this.buffer = null; // Internal buffer to store excess data
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}
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/**
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* Copy chunk to target, and store the remainder in this.buffer
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*/
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writeChunk(target, chunk) {
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const written = Math.min(chunk.length, target.length);
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target.set(chunk.subarray(0, written));
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// Adjust the remainder of the buffer
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if (written < chunk.length) {
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this.buffer = chunk.subarray(written);
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}
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else {
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this.buffer = null;
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}
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return written;
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}
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/**
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* Read from stream
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* @param buffer - Target Uint8Array (or Buffer) to store data read from stream in
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* @param mayBeLess - If true, may fill the buffer partially
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* @protected Bytes read
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*/
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async readFromStream(buffer, mayBeLess) {
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if (buffer.length === 0)
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return 0;
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let totalBytesRead = 0;
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// Serve from the internal buffer first
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if (this.buffer) {
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totalBytesRead += this.writeChunk(buffer, this.buffer);
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}
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// Continue reading from the stream if more data is needed
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while (totalBytesRead < buffer.length && !this.endOfStream) {
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const result = await this.reader.read();
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if (result.done) {
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this.endOfStream = true;
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break;
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}
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if (result.value) {
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totalBytesRead += this.writeChunk(buffer.subarray(totalBytesRead), result.value);
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}
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}
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if (!mayBeLess && totalBytesRead === 0 && this.endOfStream) {
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throw new EndOfStreamError();
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}
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return totalBytesRead;
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}
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abort() {
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this.interrupted = true;
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return this.reader.cancel();
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}
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async close() {
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await this.abort();
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this.reader.releaseLock();
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}
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}
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