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/*global Blob,File*/
/**
* Module requirements
*/
var isArray = require('isarray');
var isBuf = require('./is-buffer');
var toString = Object.prototype.toString;
var withNativeBlob = typeof global.Blob === 'function' || toString.call(global.Blob) === '[object BlobConstructor]';
var withNativeFile = typeof global.File === 'function' || toString.call(global.File) === '[object FileConstructor]';
/**
* Replaces every Buffer | ArrayBuffer in packet with a numbered placeholder.
* Anything with blobs or files should be fed through removeBlobs before coming
* here.
*
* @param {Object} packet - socket.io event packet
* @return {Object} with deconstructed packet and list of buffers
* @api public
*/
exports.deconstructPacket = function(packet) {
var buffers = [];
var packetData = packet.data;
var pack = packet;
pack.data = _deconstructPacket(packetData, buffers);
pack.attachments = buffers.length; // number of binary 'attachments'
return {packet: pack, buffers: buffers};
};
function _deconstructPacket(data, buffers) {
if (!data) return data;
if (isBuf(data)) {
var placeholder = { _placeholder: true, num: buffers.length };
buffers.push(data);
return placeholder;
} else if (isArray(data)) {
var newData = new Array(data.length);
for (var i = 0; i < data.length; i++) {
newData[i] = _deconstructPacket(data[i], buffers);
}
return newData;
} else if (typeof data === 'object' && !(data instanceof Date)) {
var newData = {};
for (var key in data) {
newData[key] = _deconstructPacket(data[key], buffers);
}
return newData;
}
return data;
}
/**
* Reconstructs a binary packet from its placeholder packet and buffers
*
* @param {Object} packet - event packet with placeholders
* @param {Array} buffers - binary buffers to put in placeholder positions
* @return {Object} reconstructed packet
* @api public
*/
exports.reconstructPacket = function(packet, buffers) {
packet.data = _reconstructPacket(packet.data, buffers);
packet.attachments = undefined; // no longer useful
return packet;
};
function _reconstructPacket(data, buffers) {
if (!data) return data;
if (data && data._placeholder) {
return buffers[data.num]; // appropriate buffer (should be natural order anyway)
} else if (isArray(data)) {
for (var i = 0; i < data.length; i++) {
data[i] = _reconstructPacket(data[i], buffers);
}
} else if (typeof data === 'object') {
for (var key in data) {
data[key] = _reconstructPacket(data[key], buffers);
}
}
return data;
}
/**
* Asynchronously removes Blobs or Files from data via
* FileReader's readAsArrayBuffer method. Used before encoding
* data as msgpack. Calls callback with the blobless data.
*
* @param {Object} data
* @param {Function} callback
* @api private
*/
exports.removeBlobs = function(data, callback) {
function _removeBlobs(obj, curKey, containingObject) {
if (!obj) return obj;
// convert any blob
if ((withNativeBlob && obj instanceof Blob) ||
(withNativeFile && obj instanceof File)) {
pendingBlobs++;
// async filereader
var fileReader = new FileReader();
fileReader.onload = function() { // this.result == arraybuffer
if (containingObject) {
containingObject[curKey] = this.result;
}
else {
bloblessData = this.result;
}
// if nothing pending its callback time
if(! --pendingBlobs) {
callback(bloblessData);
}
};
fileReader.readAsArrayBuffer(obj); // blob -> arraybuffer
} else if (isArray(obj)) { // handle array
for (var i = 0; i < obj.length; i++) {
_removeBlobs(obj[i], i, obj);
}
} else if (typeof obj === 'object' && !isBuf(obj)) { // and object
for (var key in obj) {
_removeBlobs(obj[key], key, obj);
}
}
}
var pendingBlobs = 0;
var bloblessData = data;
_removeBlobs(bloblessData);
if (!pendingBlobs) {
callback(bloblessData);
}
};
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