84 lines
2.4 KiB
Plaintext
84 lines
2.4 KiB
Plaintext
import { AbortError, } from './Errors.js';
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import { Deferred } from './Deferred.js';
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import { AbstractStreamReader } from "./AbstractStreamReader.js";
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/**
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* Node.js Readable Stream Reader
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* Ref: https://nodejs.org/api/stream.html#readable-streams
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*/
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export class StreamReader extends AbstractStreamReader {
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constructor(s) {
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super();
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this.s = s;
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/**
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* Deferred used for postponed read request (as not data is yet available to read)
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*/
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this.deferred = null;
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if (!s.read || !s.once) {
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throw new Error('Expected an instance of stream.Readable');
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}
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this.s.once('end', () => {
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this.endOfStream = true;
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if (this.deferred) {
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this.deferred.resolve(0);
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}
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});
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this.s.once('error', err => this.reject(err));
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this.s.once('close', () => this.abort());
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}
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/**
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* Read chunk 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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* @returns Number of 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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const readBuffer = this.s.read(buffer.length);
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if (readBuffer) {
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buffer.set(readBuffer);
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return readBuffer.length;
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}
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const request = {
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buffer,
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mayBeLess,
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deferred: new Deferred()
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};
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this.deferred = request.deferred;
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this.s.once('readable', () => {
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this.readDeferred(request);
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});
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return request.deferred.promise;
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}
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/**
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* Process deferred read request
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* @param request Deferred read request
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*/
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readDeferred(request) {
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const readBuffer = this.s.read(request.buffer.length);
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if (readBuffer) {
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request.buffer.set(readBuffer);
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request.deferred.resolve(readBuffer.length);
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this.deferred = null;
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}
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else {
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this.s.once('readable', () => {
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this.readDeferred(request);
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});
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}
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}
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reject(err) {
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this.interrupted = true;
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if (this.deferred) {
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this.deferred.reject(err);
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this.deferred = null;
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}
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}
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async abort() {
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this.reject(new AbortError());
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}
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async close() {
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return this.abort();
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}
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}
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