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51 lines
1.7 KiB
JavaScript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.ReadyParser = void 0;
const stream_1 = require("stream");
/**
* A transform stream that waits for a sequence of "ready" bytes before emitting a ready event and emitting data events
*
* 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.
*/
class ReadyParser extends stream_1.Transform {
constructor({ delimiter, ...options }) {
if (delimiter === undefined) {
throw new TypeError('"delimiter" is not a bufferable object');
}
if (delimiter.length === 0) {
throw new TypeError('"delimiter" has a 0 or undefined length');
}
super(options);
this.delimiter = Buffer.from(delimiter);
this.readOffset = 0;
this.ready = false;
}
_transform(chunk, encoding, cb) {
if (this.ready) {
this.push(chunk);
return cb();
}
const delimiter = this.delimiter;
let chunkOffset = 0;
while (this.readOffset < delimiter.length && chunkOffset < chunk.length) {
if (delimiter[this.readOffset] === chunk[chunkOffset]) {
this.readOffset++;
}
else {
this.readOffset = 0;
}
chunkOffset++;
}
if (this.readOffset === delimiter.length) {
this.ready = true;
this.emit('ready');
const chunkRest = chunk.slice(chunkOffset);
if (chunkRest.length > 0) {
this.push(chunkRest);
}
}
cb();
}
}
exports.ReadyParser = ReadyParser;