1.5 KiB
binary-parse-stream
Painless streaming binary protocol parsers using generators.
Installation
npm install binary-parse-stream
Synchronous
This module uses the exact same generator interface as binary-parse-stream, which presents a synchronous interface to a generator parser.
Usage
const BinaryParseStream = require('binary-parse-stream')
const {One} = BinaryParseStream // -1
BinaryParseStream is a TransformStream that consumes buffers and outputs objects on the other end.
It expects your subclass to implement a _parse method that is a generator.
When your generator yields a number, it'll be fed a buffer of that length from the input.
If it yields -1, it'll be given the value of the first byte instead of a single-byte buffer.
When your generator returns, the return value will be pushed to the output side.
Example
The following module parses a protocol that consists of a 32-bit unsigned big-endian type parameter, an unsigned 8-bit length parameter, and a buffer of the specified length.
It outputs {type, buf} objects.
class SillyProtocolParseStream extends BinaryParseStream {
constructor(options) {
super(options)
this.count = 0
}
*_parse() {
const type = (yield 4).readUInt32BE(0, true)
const length = yield -1
const buf = yield length
this.count++
return {type, buf}
}
}
There is also a shorter syntax for when you don't want to explicitly subclass: BinaryParseStream.extend(function*()).