--- /dev/null
+// https://d3js.org/d3-queue/ Version 3.0.5. Copyright 2017 Mike Bostock.
+(function (global, factory) {
+ typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
+ typeof define === 'function' && define.amd ? define(['exports'], factory) :
+ (factory((global.d3 = global.d3 || {})));
+}(this, (function (exports) { 'use strict';
+
+var slice = [].slice;
+
+var noabort = {};
+
+function Queue(size) {
+ if (!(size >= 1)) throw new Error;
+ this._size = size;
+ this._call =
+ this._error = null;
+ this._tasks = [];
+ this._data = [];
+ this._waiting =
+ this._active =
+ this._ended =
+ this._start = 0; // inside a synchronous task callback?
+}
+
+Queue.prototype = queue.prototype = {
+ constructor: Queue,
+ defer: function(callback) {
+ if (typeof callback !== "function" || this._call) throw new Error;
+ if (this._error != null) return this;
+ var t = slice.call(arguments, 1);
+ t.push(callback);
+ ++this._waiting, this._tasks.push(t);
+ poke(this);
+ return this;
+ },
+ abort: function() {
+ if (this._error == null) abort(this, new Error("abort"));
+ return this;
+ },
+ await: function(callback) {
+ if (typeof callback !== "function" || this._call) throw new Error;
+ this._call = function(error, results) { callback.apply(null, [error].concat(results)); };
+ maybeNotify(this);
+ return this;
+ },
+ awaitAll: function(callback) {
+ if (typeof callback !== "function" || this._call) throw new Error;
+ this._call = callback;
+ maybeNotify(this);
+ return this;
+ }
+};
+
+function poke(q) {
+ if (!q._start) {
+ try { start(q); } // let the current task complete
+ catch (e) {
+ if (q._tasks[q._ended + q._active - 1]) abort(q, e); // task errored synchronously
+ else if (!q._data) throw e; // await callback errored synchronously
+ }
+ }
+}
+
+function start(q) {
+ while (q._start = q._waiting && q._active < q._size) {
+ var i = q._ended + q._active,
+ t = q._tasks[i],
+ j = t.length - 1,
+ c = t[j];
+ t[j] = end(q, i);
+ --q._waiting, ++q._active;
+ t = c.apply(null, t);
+ if (!q._tasks[i]) continue; // task finished synchronously
+ q._tasks[i] = t || noabort;
+ }
+}
+
+function end(q, i) {
+ return function(e, r) {
+ if (!q._tasks[i]) return; // ignore multiple callbacks
+ --q._active, ++q._ended;
+ q._tasks[i] = null;
+ if (q._error != null) return; // ignore secondary errors
+ if (e != null) {
+ abort(q, e);
+ } else {
+ q._data[i] = r;
+ if (q._waiting) poke(q);
+ else maybeNotify(q);
+ }
+ };
+}
+
+function abort(q, e) {
+ var i = q._tasks.length, t;
+ q._error = e; // ignore active callbacks
+ q._data = undefined; // allow gc
+ q._waiting = NaN; // prevent starting
+
+ while (--i >= 0) {
+ if (t = q._tasks[i]) {
+ q._tasks[i] = null;
+ if (t.abort) {
+ try { t.abort(); }
+ catch (e) { /* ignore */ }
+ }
+ }
+ }
+
+ q._active = NaN; // allow notification
+ maybeNotify(q);
+}
+
+function maybeNotify(q) {
+ if (!q._active && q._call) {
+ var d = q._data;
+ q._data = undefined; // allow gc
+ q._call(q._error, d);
+ }
+}
+
+function queue(concurrency) {
+ return new Queue(arguments.length ? +concurrency : Infinity);
+}
+
+exports.queue = queue;
+
+Object.defineProperty(exports, '__esModule', { value: true });
+
+})));