binary-packer.js
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// Copyright IBM Corp. 2014,2016. All Rights Reserved.
// Node module: loopback-connector
// This file is licensed under the MIT License.
// License text available at https://opensource.org/licenses/MIT
'use strict';
var createPromiseCallback = require('./utils').createPromiseCallback;
var msgpack = require('msgpack5');
module.exports = BinaryPacker;
/**
* Create a new Packer instance that can be used to convert between JavaScript
* objects and a binary representation in a Buffer.
*
* Compared to JSON, this encoding preserves the following JavaScript types:
* - Date
*/
function BinaryPacker() {
this._packer = msgpack({ forceFloat64: true });
this._packer.register(1, Date, encodeDate, decodeDate);
}
/**
* Encode the provided value to a `Buffer`.
*
* @param {*} value Any value (string, number, object)
* @callback {Function} cb The callback to receive the parsed result.
* @param {Error} err
* @param {Buffer} data The encoded value
* @promise
*/
BinaryPacker.prototype.encode = function(value, cb) {
cb = cb || createPromiseCallback();
try {
// msgpack5 returns https://www.npmjs.com/package/bl instead of Buffer
// use .slice() to convert to a Buffer
var data = this._packer.encode(value).slice();
setImmediate(function() {
cb(null, data);
});
} catch (err) {
setImmediate(function() {
cb(err);
});
}
return cb.promise;
};
/**
* Decode the binary value back to a JavaScript value.
* @param {Buffer} binary The binary input.
* @callback {Function} cb The callback to receive the composed value.
* @param {Error} err
* @param {*} value Decoded value.
* @promise
*/
BinaryPacker.prototype.decode = function(binary, cb) {
cb = cb || createPromiseCallback();
try {
var value = this._packer.decode(binary);
setImmediate(function() {
cb(null, value);
});
} catch (err) {
setImmediate(function() {
cb(err);
});
}
return cb.promise;
};
function encodeDate(obj) {
return new Buffer(obj.toISOString(), 'utf8');
}
function decodeDate(buf) {
return new Date(buf.toString('utf8'));
}