127 lines
4.2 KiB
JavaScript
127 lines
4.2 KiB
JavaScript
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// Copyright (c) Jupyter Development Team.
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// Distributed under the terms of the Modified BSD License.
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define([
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'underscore',
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], function (_) {
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"use strict";
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var _deserialize_array_buffer = function (buf) {
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var data = new DataView(buf);
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// read the header: 1 + nbufs 32b integers
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var nbufs = data.getUint32(0);
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var offsets = [];
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var i;
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for (i = 1; i <= nbufs; i++) {
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offsets.push(data.getUint32(i * 4));
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}
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var json_bytes = new Uint8Array(buf.slice(offsets[0], offsets[1]));
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var msg = JSON.parse(
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(new TextDecoder('utf8')).decode(json_bytes)
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);
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// the remaining chunks are stored as DataViews in msg.buffers
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msg.buffers = [];
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var start, stop;
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for (i = 1; i < nbufs; i++) {
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start = offsets[i];
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stop = offsets[i+1] || buf.byteLength;
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msg.buffers.push(new DataView(buf.slice(start, stop)));
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}
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return msg;
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};
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var _deserialize_binary = function(data) {
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/**
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* deserialize the binary message format
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* callback will be called with a message whose buffers attribute
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* will be an array of DataViews.
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*/
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if (data instanceof Blob) {
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// data is Blob, have to deserialize from ArrayBuffer in reader callback
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var reader = new FileReader();
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var promise = new Promise(function(resolve, reject) {
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reader.onload = function () {
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var msg = _deserialize_array_buffer(this.result);
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resolve(msg);
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};
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});
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reader.readAsArrayBuffer(data);
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return promise;
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} else {
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// data is ArrayBuffer, can deserialize directly
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var msg = _deserialize_array_buffer(data);
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return msg;
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}
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};
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var deserialize = function (data) {
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/**
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* deserialize a message and return a promise for the unpacked message
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*/
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if (typeof data === "string") {
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// text JSON message
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return Promise.resolve(JSON.parse(data));
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} else {
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// binary message
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return Promise.resolve(_deserialize_binary(data));
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}
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};
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var _serialize_binary = function (msg) {
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/**
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* implement the binary serialization protocol
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* serializes JSON message to ArrayBuffer
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*/
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msg = _.clone(msg);
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var offsets = [];
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var buffers = [];
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var i;
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for (i = 0; i < msg.buffers.length; i++) {
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// msg.buffers elements could be either views or ArrayBuffers
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// buffers elements are ArrayBuffers
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var b = msg.buffers[i];
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buffers.push(b.buffer instanceof ArrayBuffer ? b.buffer : b);
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}
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delete msg.buffers;
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var json_utf8 = (new TextEncoder('utf8')).encode(JSON.stringify(msg));
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buffers.unshift(json_utf8);
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var nbufs = buffers.length;
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offsets.push(4 * (nbufs + 1));
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for (i = 0; i + 1 < buffers.length; i++) {
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offsets.push(offsets[offsets.length-1] + buffers[i].byteLength);
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}
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var msg_buf = new Uint8Array(
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offsets[offsets.length-1] + buffers[buffers.length-1].byteLength
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);
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// use DataView.setUint32 for network byte-order
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var view = new DataView(msg_buf.buffer);
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// write nbufs to first 4 bytes
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view.setUint32(0, nbufs);
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// write offsets to next 4 * nbufs bytes
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for (i = 0; i < offsets.length; i++) {
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view.setUint32(4 * (i+1), offsets[i]);
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}
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// write all the buffers at their respective offsets
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for (i = 0; i < buffers.length; i++) {
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msg_buf.set(new Uint8Array(buffers[i]), offsets[i]);
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}
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// return raw ArrayBuffer
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return msg_buf.buffer;
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};
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var serialize = function (msg) {
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if (msg.buffers && msg.buffers.length) {
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return _serialize_binary(msg);
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} else {
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return JSON.stringify(msg);
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}
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};
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var exports = {
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deserialize : deserialize,
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serialize: serialize
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};
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return exports;
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});
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