const Transform = require('stream').Transform;
/**
* A transform stream that emits data each time a byte sequence is received.
* @extends Transform
* @summary To use the `Delimiter` parser, provide a delimiter as a string, buffer, or array of bytes. Runs in O(n) time.
* @example
const SerialPort = require('serialport')
const Delimiter = require('@serialport/parser-delimiter')
const port = new SerialPort('/dev/tty-usbserial1')
const parser = port.pipe(new Delimiter({ delimiter: '\n' }))
parser.on('data', console.log)
*/
class DelimiterParser extends Transform {
constructor(options) {
options = options || {};
super(options);
if (options.delimiter === undefined) {
throw new TypeError('"delimiter" is not a bufferable object');
}
if (options.delimiter.length === 0) {
throw new TypeError('"delimiter" has a 0 or undefined length');
}
this.includeDelimiter = options.includeDelimiter !== undefined ? options.includeDelimiter : false;
this.delimiter = Buffer.from(options.delimiter);
this.buffer = Buffer.alloc(0);
}
_transform(chunk, encoding, cb) {
let data = Buffer.concat([this.buffer, chunk]);
let position;
while ((position = data.indexOf(this.delimiter)) !== -1) {
this.push(data.slice(0, position + (this.includeDelimiter ? this.delimiter.length : 0)));
data = data.slice(position + this.delimiter.length);
}
this.buffer = data;
cb();
}
_flush(cb) {
this.push(this.buffer);
this.buffer = Buffer.alloc(0);
cb();
}
}
module.exports = DelimiterParser;