| Leo Repp | 58b9f11 | 2021-11-22 11:57:47 +0100 | [diff] [blame^] | 1 | 'use strict'; |
| 2 | |
| 3 | var PENDING = 'pending'; |
| 4 | var SETTLED = 'settled'; |
| 5 | var FULFILLED = 'fulfilled'; |
| 6 | var REJECTED = 'rejected'; |
| 7 | var NOOP = function () {}; |
| 8 | var isNode = typeof global !== 'undefined' && typeof global.process !== 'undefined' && typeof global.process.emit === 'function'; |
| 9 | |
| 10 | var asyncSetTimer = typeof setImmediate === 'undefined' ? setTimeout : setImmediate; |
| 11 | var asyncQueue = []; |
| 12 | var asyncTimer; |
| 13 | |
| 14 | function asyncFlush() { |
| 15 | // run promise callbacks |
| 16 | for (var i = 0; i < asyncQueue.length; i++) { |
| 17 | asyncQueue[i][0](asyncQueue[i][1]); |
| 18 | } |
| 19 | |
| 20 | // reset async asyncQueue |
| 21 | asyncQueue = []; |
| 22 | asyncTimer = false; |
| 23 | } |
| 24 | |
| 25 | function asyncCall(callback, arg) { |
| 26 | asyncQueue.push([callback, arg]); |
| 27 | |
| 28 | if (!asyncTimer) { |
| 29 | asyncTimer = true; |
| 30 | asyncSetTimer(asyncFlush, 0); |
| 31 | } |
| 32 | } |
| 33 | |
| 34 | function invokeResolver(resolver, promise) { |
| 35 | function resolvePromise(value) { |
| 36 | resolve(promise, value); |
| 37 | } |
| 38 | |
| 39 | function rejectPromise(reason) { |
| 40 | reject(promise, reason); |
| 41 | } |
| 42 | |
| 43 | try { |
| 44 | resolver(resolvePromise, rejectPromise); |
| 45 | } catch (e) { |
| 46 | rejectPromise(e); |
| 47 | } |
| 48 | } |
| 49 | |
| 50 | function invokeCallback(subscriber) { |
| 51 | var owner = subscriber.owner; |
| 52 | var settled = owner._state; |
| 53 | var value = owner._data; |
| 54 | var callback = subscriber[settled]; |
| 55 | var promise = subscriber.then; |
| 56 | |
| 57 | if (typeof callback === 'function') { |
| 58 | settled = FULFILLED; |
| 59 | try { |
| 60 | value = callback(value); |
| 61 | } catch (e) { |
| 62 | reject(promise, e); |
| 63 | } |
| 64 | } |
| 65 | |
| 66 | if (!handleThenable(promise, value)) { |
| 67 | if (settled === FULFILLED) { |
| 68 | resolve(promise, value); |
| 69 | } |
| 70 | |
| 71 | if (settled === REJECTED) { |
| 72 | reject(promise, value); |
| 73 | } |
| 74 | } |
| 75 | } |
| 76 | |
| 77 | function handleThenable(promise, value) { |
| 78 | var resolved; |
| 79 | |
| 80 | try { |
| 81 | if (promise === value) { |
| 82 | throw new TypeError('A promises callback cannot return that same promise.'); |
| 83 | } |
| 84 | |
| 85 | if (value && (typeof value === 'function' || typeof value === 'object')) { |
| 86 | // then should be retrieved only once |
| 87 | var then = value.then; |
| 88 | |
| 89 | if (typeof then === 'function') { |
| 90 | then.call(value, function (val) { |
| 91 | if (!resolved) { |
| 92 | resolved = true; |
| 93 | |
| 94 | if (value === val) { |
| 95 | fulfill(promise, val); |
| 96 | } else { |
| 97 | resolve(promise, val); |
| 98 | } |
| 99 | } |
| 100 | }, function (reason) { |
| 101 | if (!resolved) { |
| 102 | resolved = true; |
| 103 | |
| 104 | reject(promise, reason); |
| 105 | } |
| 106 | }); |
| 107 | |
| 108 | return true; |
| 109 | } |
| 110 | } |
| 111 | } catch (e) { |
| 112 | if (!resolved) { |
| 113 | reject(promise, e); |
| 114 | } |
| 115 | |
| 116 | return true; |
| 117 | } |
| 118 | |
| 119 | return false; |
| 120 | } |
| 121 | |
| 122 | function resolve(promise, value) { |
| 123 | if (promise === value || !handleThenable(promise, value)) { |
| 124 | fulfill(promise, value); |
| 125 | } |
| 126 | } |
| 127 | |
| 128 | function fulfill(promise, value) { |
| 129 | if (promise._state === PENDING) { |
| 130 | promise._state = SETTLED; |
| 131 | promise._data = value; |
| 132 | |
| 133 | asyncCall(publishFulfillment, promise); |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | function reject(promise, reason) { |
| 138 | if (promise._state === PENDING) { |
| 139 | promise._state = SETTLED; |
| 140 | promise._data = reason; |
| 141 | |
| 142 | asyncCall(publishRejection, promise); |
| 143 | } |
| 144 | } |
| 145 | |
| 146 | function publish(promise) { |
| 147 | promise._then = promise._then.forEach(invokeCallback); |
| 148 | } |
| 149 | |
| 150 | function publishFulfillment(promise) { |
| 151 | promise._state = FULFILLED; |
| 152 | publish(promise); |
| 153 | } |
| 154 | |
| 155 | function publishRejection(promise) { |
| 156 | promise._state = REJECTED; |
| 157 | publish(promise); |
| 158 | if (!promise._handled && isNode) { |
| 159 | global.process.emit('unhandledRejection', promise._data, promise); |
| 160 | } |
| 161 | } |
| 162 | |
| 163 | function notifyRejectionHandled(promise) { |
| 164 | global.process.emit('rejectionHandled', promise); |
| 165 | } |
| 166 | |
| 167 | /** |
| 168 | * @class |
| 169 | */ |
| 170 | function Promise(resolver) { |
| 171 | if (typeof resolver !== 'function') { |
| 172 | throw new TypeError('Promise resolver ' + resolver + ' is not a function'); |
| 173 | } |
| 174 | |
| 175 | if (this instanceof Promise === false) { |
| 176 | throw new TypeError('Failed to construct \'Promise\': Please use the \'new\' operator, this object constructor cannot be called as a function.'); |
| 177 | } |
| 178 | |
| 179 | this._then = []; |
| 180 | |
| 181 | invokeResolver(resolver, this); |
| 182 | } |
| 183 | |
| 184 | Promise.prototype = { |
| 185 | constructor: Promise, |
| 186 | |
| 187 | _state: PENDING, |
| 188 | _then: null, |
| 189 | _data: undefined, |
| 190 | _handled: false, |
| 191 | |
| 192 | then: function (onFulfillment, onRejection) { |
| 193 | var subscriber = { |
| 194 | owner: this, |
| 195 | then: new this.constructor(NOOP), |
| 196 | fulfilled: onFulfillment, |
| 197 | rejected: onRejection |
| 198 | }; |
| 199 | |
| 200 | if ((onRejection || onFulfillment) && !this._handled) { |
| 201 | this._handled = true; |
| 202 | if (this._state === REJECTED && isNode) { |
| 203 | asyncCall(notifyRejectionHandled, this); |
| 204 | } |
| 205 | } |
| 206 | |
| 207 | if (this._state === FULFILLED || this._state === REJECTED) { |
| 208 | // already resolved, call callback async |
| 209 | asyncCall(invokeCallback, subscriber); |
| 210 | } else { |
| 211 | // subscribe |
| 212 | this._then.push(subscriber); |
| 213 | } |
| 214 | |
| 215 | return subscriber.then; |
| 216 | }, |
| 217 | |
| 218 | catch: function (onRejection) { |
| 219 | return this.then(null, onRejection); |
| 220 | } |
| 221 | }; |
| 222 | |
| 223 | Promise.all = function (promises) { |
| 224 | if (!Array.isArray(promises)) { |
| 225 | throw new TypeError('You must pass an array to Promise.all().'); |
| 226 | } |
| 227 | |
| 228 | return new Promise(function (resolve, reject) { |
| 229 | var results = []; |
| 230 | var remaining = 0; |
| 231 | |
| 232 | function resolver(index) { |
| 233 | remaining++; |
| 234 | return function (value) { |
| 235 | results[index] = value; |
| 236 | if (!--remaining) { |
| 237 | resolve(results); |
| 238 | } |
| 239 | }; |
| 240 | } |
| 241 | |
| 242 | for (var i = 0, promise; i < promises.length; i++) { |
| 243 | promise = promises[i]; |
| 244 | |
| 245 | if (promise && typeof promise.then === 'function') { |
| 246 | promise.then(resolver(i), reject); |
| 247 | } else { |
| 248 | results[i] = promise; |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | if (!remaining) { |
| 253 | resolve(results); |
| 254 | } |
| 255 | }); |
| 256 | }; |
| 257 | |
| 258 | Promise.race = function (promises) { |
| 259 | if (!Array.isArray(promises)) { |
| 260 | throw new TypeError('You must pass an array to Promise.race().'); |
| 261 | } |
| 262 | |
| 263 | return new Promise(function (resolve, reject) { |
| 264 | for (var i = 0, promise; i < promises.length; i++) { |
| 265 | promise = promises[i]; |
| 266 | |
| 267 | if (promise && typeof promise.then === 'function') { |
| 268 | promise.then(resolve, reject); |
| 269 | } else { |
| 270 | resolve(promise); |
| 271 | } |
| 272 | } |
| 273 | }); |
| 274 | }; |
| 275 | |
| 276 | Promise.resolve = function (value) { |
| 277 | if (value && typeof value === 'object' && value.constructor === Promise) { |
| 278 | return value; |
| 279 | } |
| 280 | |
| 281 | return new Promise(function (resolve) { |
| 282 | resolve(value); |
| 283 | }); |
| 284 | }; |
| 285 | |
| 286 | Promise.reject = function (reason) { |
| 287 | return new Promise(function (resolve, reject) { |
| 288 | reject(reason); |
| 289 | }); |
| 290 | }; |
| 291 | |
| 292 | module.exports = Promise; |