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51 lines
1.7 KiB
JavaScript
51 lines
1.7 KiB
JavaScript
5 months ago
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"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.ReadyParser = void 0;
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const stream_1 = require("stream");
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/**
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* A transform stream that waits for a sequence of "ready" bytes before emitting a ready event and emitting data events
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*
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* To use the `Ready` parser provide a byte start sequence. After the bytes have been received a ready event is fired and data events are passed through.
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*/
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class ReadyParser extends stream_1.Transform {
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constructor({ delimiter, ...options }) {
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if (delimiter === undefined) {
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throw new TypeError('"delimiter" is not a bufferable object');
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}
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if (delimiter.length === 0) {
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throw new TypeError('"delimiter" has a 0 or undefined length');
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}
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super(options);
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this.delimiter = Buffer.from(delimiter);
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this.readOffset = 0;
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this.ready = false;
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}
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_transform(chunk, encoding, cb) {
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if (this.ready) {
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this.push(chunk);
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return cb();
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}
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const delimiter = this.delimiter;
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let chunkOffset = 0;
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while (this.readOffset < delimiter.length && chunkOffset < chunk.length) {
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if (delimiter[this.readOffset] === chunk[chunkOffset]) {
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this.readOffset++;
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}
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else {
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this.readOffset = 0;
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}
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chunkOffset++;
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}
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if (this.readOffset === delimiter.length) {
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this.ready = true;
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this.emit('ready');
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const chunkRest = chunk.slice(chunkOffset);
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if (chunkRest.length > 0) {
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this.push(chunkRest);
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}
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}
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cb();
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}
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}
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exports.ReadyParser = ReadyParser;
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