browser.js 6.2 KB

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  1. 'use strict';
  2. var immediate = require('immediate');
  3. /* istanbul ignore next */
  4. function INTERNAL() {}
  5. var handlers = {};
  6. var REJECTED = ['REJECTED'];
  7. var FULFILLED = ['FULFILLED'];
  8. var PENDING = ['PENDING'];
  9. module.exports = Promise;
  10. function Promise(resolver) {
  11. if (typeof resolver !== 'function') {
  12. throw new TypeError('resolver must be a function');
  13. }
  14. this.state = PENDING;
  15. this.queue = [];
  16. this.outcome = void 0;
  17. if (resolver !== INTERNAL) {
  18. safelyResolveThenable(this, resolver);
  19. }
  20. }
  21. Promise.prototype["finally"] = function (callback) {
  22. if (typeof callback !== 'function') {
  23. return this;
  24. }
  25. var p = this.constructor;
  26. return this.then(resolve, reject);
  27. function resolve(value) {
  28. function yes () {
  29. return value;
  30. }
  31. return p.resolve(callback()).then(yes);
  32. }
  33. function reject(reason) {
  34. function no () {
  35. throw reason;
  36. }
  37. return p.resolve(callback()).then(no);
  38. }
  39. };
  40. Promise.prototype["catch"] = function (onRejected) {
  41. return this.then(null, onRejected);
  42. };
  43. Promise.prototype.then = function (onFulfilled, onRejected) {
  44. if (typeof onFulfilled !== 'function' && this.state === FULFILLED ||
  45. typeof onRejected !== 'function' && this.state === REJECTED) {
  46. return this;
  47. }
  48. var promise = new this.constructor(INTERNAL);
  49. if (this.state !== PENDING) {
  50. var resolver = this.state === FULFILLED ? onFulfilled : onRejected;
  51. unwrap(promise, resolver, this.outcome);
  52. } else {
  53. this.queue.push(new QueueItem(promise, onFulfilled, onRejected));
  54. }
  55. return promise;
  56. };
  57. function QueueItem(promise, onFulfilled, onRejected) {
  58. this.promise = promise;
  59. if (typeof onFulfilled === 'function') {
  60. this.onFulfilled = onFulfilled;
  61. this.callFulfilled = this.otherCallFulfilled;
  62. }
  63. if (typeof onRejected === 'function') {
  64. this.onRejected = onRejected;
  65. this.callRejected = this.otherCallRejected;
  66. }
  67. }
  68. QueueItem.prototype.callFulfilled = function (value) {
  69. handlers.resolve(this.promise, value);
  70. };
  71. QueueItem.prototype.otherCallFulfilled = function (value) {
  72. unwrap(this.promise, this.onFulfilled, value);
  73. };
  74. QueueItem.prototype.callRejected = function (value) {
  75. handlers.reject(this.promise, value);
  76. };
  77. QueueItem.prototype.otherCallRejected = function (value) {
  78. unwrap(this.promise, this.onRejected, value);
  79. };
  80. function unwrap(promise, func, value) {
  81. immediate(function () {
  82. var returnValue;
  83. try {
  84. returnValue = func(value);
  85. } catch (e) {
  86. return handlers.reject(promise, e);
  87. }
  88. if (returnValue === promise) {
  89. handlers.reject(promise, new TypeError('Cannot resolve promise with itself'));
  90. } else {
  91. handlers.resolve(promise, returnValue);
  92. }
  93. });
  94. }
  95. handlers.resolve = function (self, value) {
  96. var result = tryCatch(getThen, value);
  97. if (result.status === 'error') {
  98. return handlers.reject(self, result.value);
  99. }
  100. var thenable = result.value;
  101. if (thenable) {
  102. safelyResolveThenable(self, thenable);
  103. } else {
  104. self.state = FULFILLED;
  105. self.outcome = value;
  106. var i = -1;
  107. var len = self.queue.length;
  108. while (++i < len) {
  109. self.queue[i].callFulfilled(value);
  110. }
  111. }
  112. return self;
  113. };
  114. handlers.reject = function (self, error) {
  115. self.state = REJECTED;
  116. self.outcome = error;
  117. var i = -1;
  118. var len = self.queue.length;
  119. while (++i < len) {
  120. self.queue[i].callRejected(error);
  121. }
  122. return self;
  123. };
  124. function getThen(obj) {
  125. // Make sure we only access the accessor once as required by the spec
  126. var then = obj && obj.then;
  127. if (obj && (typeof obj === 'object' || typeof obj === 'function') && typeof then === 'function') {
  128. return function appyThen() {
  129. then.apply(obj, arguments);
  130. };
  131. }
  132. }
  133. function safelyResolveThenable(self, thenable) {
  134. // Either fulfill, reject or reject with error
  135. var called = false;
  136. function onError(value) {
  137. if (called) {
  138. return;
  139. }
  140. called = true;
  141. handlers.reject(self, value);
  142. }
  143. function onSuccess(value) {
  144. if (called) {
  145. return;
  146. }
  147. called = true;
  148. handlers.resolve(self, value);
  149. }
  150. function tryToUnwrap() {
  151. thenable(onSuccess, onError);
  152. }
  153. var result = tryCatch(tryToUnwrap);
  154. if (result.status === 'error') {
  155. onError(result.value);
  156. }
  157. }
  158. function tryCatch(func, value) {
  159. var out = {};
  160. try {
  161. out.value = func(value);
  162. out.status = 'success';
  163. } catch (e) {
  164. out.status = 'error';
  165. out.value = e;
  166. }
  167. return out;
  168. }
  169. Promise.resolve = resolve;
  170. function resolve(value) {
  171. if (value instanceof this) {
  172. return value;
  173. }
  174. return handlers.resolve(new this(INTERNAL), value);
  175. }
  176. Promise.reject = reject;
  177. function reject(reason) {
  178. var promise = new this(INTERNAL);
  179. return handlers.reject(promise, reason);
  180. }
  181. Promise.all = all;
  182. function all(iterable) {
  183. var self = this;
  184. if (Object.prototype.toString.call(iterable) !== '[object Array]') {
  185. return this.reject(new TypeError('must be an array'));
  186. }
  187. var len = iterable.length;
  188. var called = false;
  189. if (!len) {
  190. return this.resolve([]);
  191. }
  192. var values = new Array(len);
  193. var resolved = 0;
  194. var i = -1;
  195. var promise = new this(INTERNAL);
  196. while (++i < len) {
  197. allResolver(iterable[i], i);
  198. }
  199. return promise;
  200. function allResolver(value, i) {
  201. self.resolve(value).then(resolveFromAll, function (error) {
  202. if (!called) {
  203. called = true;
  204. handlers.reject(promise, error);
  205. }
  206. });
  207. function resolveFromAll(outValue) {
  208. values[i] = outValue;
  209. if (++resolved === len && !called) {
  210. called = true;
  211. handlers.resolve(promise, values);
  212. }
  213. }
  214. }
  215. }
  216. Promise.race = race;
  217. function race(iterable) {
  218. var self = this;
  219. if (Object.prototype.toString.call(iterable) !== '[object Array]') {
  220. return this.reject(new TypeError('must be an array'));
  221. }
  222. var len = iterable.length;
  223. var called = false;
  224. if (!len) {
  225. return this.resolve([]);
  226. }
  227. var i = -1;
  228. var promise = new this(INTERNAL);
  229. while (++i < len) {
  230. resolver(iterable[i]);
  231. }
  232. return promise;
  233. function resolver(value) {
  234. self.resolve(value).then(function (response) {
  235. if (!called) {
  236. called = true;
  237. handlers.resolve(promise, response);
  238. }
  239. }, function (error) {
  240. if (!called) {
  241. called = true;
  242. handlers.reject(promise, error);
  243. }
  244. });
  245. }
  246. }