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encoder.js
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encoder.js
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'use strict'
const Buffer = require('safe-buffer').Buffer
const bl = require('bl')
const isFloat = require('./helpers.js').isFloat
module.exports = function buildEncode (encodingTypes, options) {
function encode (obj) {
if (obj === undefined) throw new Error('undefined is not encodable in msgpack!')
if (obj === null) return Buffer.from([0xc0])
if (obj === true) return Buffer.from([0xc3])
if (obj === false) return Buffer.from([0xc2])
if (obj instanceof Map) return encodeMap(obj, options, encode)
if (typeof obj === 'string') return encodeString(obj, options)
if (obj && (obj.readUInt32LE || obj instanceof Uint8Array)) {
if (obj instanceof Uint8Array) {
obj = Buffer.from(obj)
}
// weird hack to support Buffer
// and Buffer-like objects
const _getBufferHeader = options.compatibilityMode ? getCompatibleBufferHeader : getBufferHeader
return bl([_getBufferHeader(obj.length), obj])
}
if (Array.isArray(obj)) return encodeArray(obj, encode)
if (typeof obj === 'object') return encodeExt(obj, encodingTypes) || encodeObject(obj, options, encode)
if (typeof obj === 'number') return encodeNumber(obj, options)
throw new Error('not implemented yet')
}
return function (obj) {
return encode(obj).slice()
}
}
//
//
// === MENTAL SEPARATOR ===
//
//
function encodeArray (array, encode) {
const acc = [getHeader(array.length, 0x90, 0xdc)]
// This has to be forEach; Array.prototype.map preserves missing values and
// Array.prototype.values yields them as undefined
array.forEach(item => {
acc.push(encode(item))
})
if (acc.length !== array.length + 1) {
throw new Error('Sparse arrays are not encodable in msgpack')
}
return bl(acc)
}
function encodeMap (map, options, encode) {
const acc = [getHeader(map.size, 0x80, 0xde)]
const keys = [...map.keys()]
if (!options.preferMap) {
if (keys.every(item => typeof item === 'string')) {
console.warn('Map with string only keys will be deserialized as an object!')
}
}
keys.forEach(key => {
acc.push(encode(key), encode(map.get(key)))
})
return bl(acc)
}
function encodeObject (obj, options, encode) {
const keys = []
for (const key in obj) {
if (Object.prototype.hasOwnProperty.call(obj, key) &&
obj[key] !== undefined &&
typeof obj[key] !== 'function') {
keys.push(key)
}
}
const acc = [getHeader(keys.length, 0x80, 0xde)]
if (options.sortKeys) keys.sort()
keys.forEach(key => {
acc.push(encode(key), encode(obj[key]))
})
return bl(acc)
}
function write64BitUint (buf, offset, num) {
const lo = num % 4294967296
const hi = Math.floor(num / 4294967296)
buf.writeUInt32BE(hi, offset + 0)
buf.writeUInt32BE(lo, offset + 4)
}
function write64BitInt (buf, offset, num) {
const negate = num < 0
num = Math.abs(num)
write64BitUint(buf, offset, num)
if (negate) negate64BitInt(buf, offset)
}
function negate64BitInt (buf, offset) {
let i = offset + 8
// Optimization based on the fact that:
// buf[i] == 0x00 => (buf[i] ^ 0xff) + 1 = 0x100 = 0x00 + 1 curry
while (i-- > offset) {
if (buf[i] === 0x00) continue
buf[i] = (buf[i] ^ 0xff) + 1
break
}
while (i-- > offset) {
buf[i] = buf[i] ^ 0xff
}
}
const fround = Math.fround
function encodeFloat (obj, forceFloat64) {
let buf
if (forceFloat64 || !fround || !Object.is(fround(obj), obj)) {
buf = Buffer.allocUnsafe(9)
buf[0] = 0xcb
buf.writeDoubleBE(obj, 1)
} else {
buf = Buffer.allocUnsafe(5)
buf[0] = 0xca
buf.writeFloatBE(obj, 1)
}
return buf
}
function encodeExt (obj, encodingTypes) {
const codec = encodingTypes.find(codec => codec.check(obj))
if (!codec) return null
const encoded = codec.encode(obj)
if (!encoded) return null
return bl([getExtHeader(encoded.length - 1), encoded])
}
function getExtHeader (length) {
if (length === 1) return Buffer.from([0xd4])
if (length === 2) return Buffer.from([0xd5])
if (length === 4) return Buffer.from([0xd6])
if (length === 8) return Buffer.from([0xd7])
if (length === 16) return Buffer.from([0xd8])
if (length < 256) return Buffer.from([0xc7, length])
if (length < 0x10000) return Buffer.from([0xc8, length >> 8, length & 0x00ff])
return Buffer.from([0xc9, length >> 24, (length >> 16) & 0x000000ff, (length >> 8) & 0x000000ff, length & 0x000000ff])
}
function getHeader (length, tag1, tag2) {
if (length < 16) return Buffer.from([tag1 | length])
const size = length < 0x10000 ? 2 : 4
const buf = Buffer.allocUnsafe(1 + size)
buf[0] = length < 0x10000 ? tag2 : tag2 + 1
buf.writeUIntBE(length, 1, size)
return buf
}
function encodeString (obj, options) {
const len = Buffer.byteLength(obj)
let buf
if (len < 32) {
buf = Buffer.allocUnsafe(1 + len)
buf[0] = 0xa0 | len
if (len > 0) {
buf.write(obj, 1)
}
} else if (len <= 0xff && !options.compatibilityMode) {
// str8, but only when not in compatibility mode
buf = Buffer.allocUnsafe(2 + len)
buf[0] = 0xd9
buf[1] = len
buf.write(obj, 2)
} else if (len <= 0xffff) {
buf = Buffer.allocUnsafe(3 + len)
buf[0] = 0xda
buf.writeUInt16BE(len, 1)
buf.write(obj, 3)
} else {
buf = Buffer.allocUnsafe(5 + len)
buf[0] = 0xdb
buf.writeUInt32BE(len, 1)
buf.write(obj, 5)
}
return buf
}
function getBufferHeader (length) {
let header
if (length <= 0xff) {
header = Buffer.allocUnsafe(2)
header[0] = 0xc4
header[1] = length
} else if (length <= 0xffff) {
header = Buffer.allocUnsafe(3)
header[0] = 0xc5
header.writeUInt16BE(length, 1)
} else {
header = Buffer.allocUnsafe(5)
header[0] = 0xc6
header.writeUInt32BE(length, 1)
}
return header
}
function getCompatibleBufferHeader (length) {
let header
if (length <= 0x1f) {
// fix raw header: 101XXXXX
header = Buffer.allocUnsafe(1)
header[0] = 0xa0 | length
} else if (length <= 0xffff) {
// raw 16 header: 0xda, XXXXXXXX, XXXXXXXX
header = Buffer.allocUnsafe(3)
header[0] = 0xda
header.writeUInt16BE(length, 1)
} else {
// raw 32 header: 0xdb, XXXXXXXX, XXXXXXXX, XXXXXXXX, XXXXXXXX
header = Buffer.allocUnsafe(5)
header[0] = 0xdb
header.writeUInt32BE(length, 1)
}
return header
}
function encodeNumber (obj, options) {
let buf
if (isFloat(obj)) return encodeFloat(obj, options.forceFloat64)
if (Math.abs(obj) > 9007199254740991) {
return encodeFloat(obj, true)
}
if (obj >= 0) {
if (obj < 128) {
return Buffer.from([obj])
} else if (obj < 256) {
return Buffer.from([0xcc, obj])
} else if (obj < 65536) {
return Buffer.from([0xcd, 0xff & (obj >> 8), 0xff & (obj)])
} else if (obj <= 0xffffffff) {
return Buffer.from([0xce, 0xff & (obj >> 24), 0xff & (obj >> 16), 0xff & (obj >> 8), 0xff & (obj)])
} else if (obj <= 9007199254740991) {
buf = Buffer.allocUnsafe(9)
buf[0] = 0xcf
write64BitUint(buf, 1, obj)
}
} else {
if (obj >= -32) {
buf = Buffer.allocUnsafe(1)
buf[0] = 0x100 + obj
} else if (obj >= -128) {
buf = Buffer.allocUnsafe(2)
buf[0] = 0xd0
buf.writeInt8(obj, 1)
} else if (obj >= -32768) {
buf = Buffer.allocUnsafe(3)
buf[0] = 0xd1
buf.writeInt16BE(obj, 1)
} else if (obj > -214748365) {
buf = Buffer.allocUnsafe(5)
buf[0] = 0xd2
buf.writeInt32BE(obj, 1)
} else if (obj >= -9007199254740991) {
buf = Buffer.allocUnsafe(9)
buf[0] = 0xd3
write64BitInt(buf, 1, obj)
}
}
return buf
}
// function order(num, n = 1, step = 2) {
// while (num = num >> step) n++;
// return n
// }