Package Exports
- binary-data
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Readme
binary-data
Declarative encoder/decoder of various binary data. This module works almost like as binary
or restructure
but provided modern and clean api.
Usage
decode
const { decode, createDecodeStream, types: { uint8, array, string } } = require('binary-data')
// 1.1 define your own schema as plain object
const protocol = {
type: uint8,
value: array(string(null), uint8)
}
socket.on('message', (message) => {
// 1.2 decode message
const packet = decode(message, protocol)
})
// 2.1 also you can decode messages from streams
const unicast = require('unicast')
const socket = unicast.createSocket({ /* options */ })
// 2.2 create stream
const decodeStream = createDecodeStream()
// 2.3 connect streams
socket.pipe(decodeStream)
// 2.4. decode messages chunk by chunk or what you want
socket.on('data', () => {
const packet = decode(decodeStream, protocol)
})
encode
const { encode, createEncodeStream, types: { uint8, buffer } } = require('binary-data')
// 1. define schema
const helloPacket = {
type: uint8,
data: buffer(uint8)
}
// 2. create data object (string, array - what you want)
const hello = {
type: 12,
data: Buffer.from('my random data')
}
// 3. create encode stream
const wstream = createEncodeStream()
// 4. connect streams
wstream.pipe(socket)
// 5. encode all your data multiple times
encode(hello, wstream, helloPacket)
// or convert to a buffer
const buf = wstream.slice()
See stun module for complete example.
API
decode(rstream: DecodeStream|Buffer, type: PrimitiveType|Object): any
encode(item: any, wstream: EncodeStream, type: PrimitiveType|Object): void
encodingLength(item: any, type: PrimitiveType|Object): Number
createEncodeStream(): EncodeStream
createDecodeStream([buf: Buffer]): DecodeStream
- Types
decode(rstream: DecodeStream|Buffer, type: PrimitiveType|Object): any
Reads any data from stream rstream
using data type type
. See examples above.
encode(item: any, wstream: EncodeStream, type: PrimitiveType|Object): void
Writes any data item
to stream wstream
using data type type
. See examples above.
encodingLength(item: any, type: PrimitiveType|Object): Number
Return the amount of bytes needed to encode item
using type
.
createEncodeStream(): EncodeStream
Create instance of EncodeStream.
createDecodeStream([buf: Buffer]): DecodeStream
Create instance of DecodeStream using buffer buf
.
types: Object
Contains all primitive data types.
Types
(u)int(8, 16, 24, 32, 40, 48)(be, le)
Low-level integer types.
const schema = {
type: int8
}
// define int64 as buffer and use your loved library for big numbers
const int64 = buffer(8)
(double, float)(be, le)
Low-level floating-point types.
const schema = {
size: doublele
}
array(type: Object, length: number|Object|Function, lengthType: string)
Array of low-level or user defined types. Argument type
should be primitive type or user defined scheme. Argument length
should be a number, number type or function. Argument lengthType
should be bytes
or count
(default).
array(uint8, 3) // 3 x uint8
const schema = {
length: uint8,
type: uint32be,
items: array(uint16, ({node}) => node.length, 'bytes')
}
// difference between `bytes` or `count`
array(uint16, uint8)
// | 0x2 | 0x0 0x1 | 0x0 0x2 |
// | length | item 1 | item 2 |
// bytes = 1 + 4, length = 2
array(uint16, uint8, 'bytes')
// | 0x4 | 0x0 0x1 | 0x0 0x2 |
// | length | item 1 | item 2 |
// bytes = 1 + 4, length = 4
string(length)
Low-level string type. Argument length
can be number, null for C - strings, type for size-prefixed data or function.
bool(type: any)
Convert provided type to / from boolean. Argument type
should be an number type.
const schema = bool(uint8)
const rstream = createDecodeStream(buf) // 0x01 0
decode(rstream, schema) // return true
decode(rstream, schema) // return false
buffer(length)
Low-level buffer type. Argument length
can be number, number type for size-prefixed data or function.
buffer(5) // buffer should be 5 bytes
buffer(uint8) // length prefixed buffer
// | 0x3 | 0xa 0xb 0xc
// | length | data
const packet = {
header: {
length: uint16be
},
data: buffer(({node}) => node.header.length % 2) // function should return actual length
}
reserved(type, count)
Special type to skip any data. Argument count
should be a number, number type or function.
const packet = {
type: uint8,
_padding: reserved(uint8, 3)
}
decode(rstream, packet) // return { type }
when(fn: function(context): boolean, type)
Special type for conditions. Argument fn
should be a function and should return boolean value. The type
argument will be evaluated when the first one returns positive value.
const schema = {
type: uint8,
bytes: when(({ node }) => node.type === 1, string(uint16be)),
list: when(({ node }) => node.type === 2, array(uint32be, uint8))
}
License
MIT, 2017 (c) Dmitriy Tsvettsikh