annotate vendor/guzzlehttp/promises/src/Promise.php @ 19:fa3358dc1485 tip

Add ndrum files
author Chris Cannam
date Wed, 28 Aug 2019 13:14:47 +0100
parents 4c8ae668cc8c
children
rev   line source
Chris@0 1 <?php
Chris@0 2 namespace GuzzleHttp\Promise;
Chris@0 3
Chris@0 4 /**
Chris@0 5 * Promises/A+ implementation that avoids recursion when possible.
Chris@0 6 *
Chris@0 7 * @link https://promisesaplus.com/
Chris@0 8 */
Chris@0 9 class Promise implements PromiseInterface
Chris@0 10 {
Chris@0 11 private $state = self::PENDING;
Chris@0 12 private $result;
Chris@0 13 private $cancelFn;
Chris@0 14 private $waitFn;
Chris@0 15 private $waitList;
Chris@0 16 private $handlers = [];
Chris@0 17
Chris@0 18 /**
Chris@0 19 * @param callable $waitFn Fn that when invoked resolves the promise.
Chris@0 20 * @param callable $cancelFn Fn that when invoked cancels the promise.
Chris@0 21 */
Chris@0 22 public function __construct(
Chris@0 23 callable $waitFn = null,
Chris@0 24 callable $cancelFn = null
Chris@0 25 ) {
Chris@0 26 $this->waitFn = $waitFn;
Chris@0 27 $this->cancelFn = $cancelFn;
Chris@0 28 }
Chris@0 29
Chris@0 30 public function then(
Chris@0 31 callable $onFulfilled = null,
Chris@0 32 callable $onRejected = null
Chris@0 33 ) {
Chris@0 34 if ($this->state === self::PENDING) {
Chris@0 35 $p = new Promise(null, [$this, 'cancel']);
Chris@0 36 $this->handlers[] = [$p, $onFulfilled, $onRejected];
Chris@0 37 $p->waitList = $this->waitList;
Chris@0 38 $p->waitList[] = $this;
Chris@0 39 return $p;
Chris@0 40 }
Chris@0 41
Chris@0 42 // Return a fulfilled promise and immediately invoke any callbacks.
Chris@0 43 if ($this->state === self::FULFILLED) {
Chris@0 44 return $onFulfilled
Chris@0 45 ? promise_for($this->result)->then($onFulfilled)
Chris@0 46 : promise_for($this->result);
Chris@0 47 }
Chris@0 48
Chris@0 49 // It's either cancelled or rejected, so return a rejected promise
Chris@0 50 // and immediately invoke any callbacks.
Chris@0 51 $rejection = rejection_for($this->result);
Chris@0 52 return $onRejected ? $rejection->then(null, $onRejected) : $rejection;
Chris@0 53 }
Chris@0 54
Chris@0 55 public function otherwise(callable $onRejected)
Chris@0 56 {
Chris@0 57 return $this->then(null, $onRejected);
Chris@0 58 }
Chris@0 59
Chris@0 60 public function wait($unwrap = true)
Chris@0 61 {
Chris@0 62 $this->waitIfPending();
Chris@0 63
Chris@0 64 $inner = $this->result instanceof PromiseInterface
Chris@0 65 ? $this->result->wait($unwrap)
Chris@0 66 : $this->result;
Chris@0 67
Chris@0 68 if ($unwrap) {
Chris@0 69 if ($this->result instanceof PromiseInterface
Chris@0 70 || $this->state === self::FULFILLED
Chris@0 71 ) {
Chris@0 72 return $inner;
Chris@0 73 } else {
Chris@0 74 // It's rejected so "unwrap" and throw an exception.
Chris@0 75 throw exception_for($inner);
Chris@0 76 }
Chris@0 77 }
Chris@0 78 }
Chris@0 79
Chris@0 80 public function getState()
Chris@0 81 {
Chris@0 82 return $this->state;
Chris@0 83 }
Chris@0 84
Chris@0 85 public function cancel()
Chris@0 86 {
Chris@0 87 if ($this->state !== self::PENDING) {
Chris@0 88 return;
Chris@0 89 }
Chris@0 90
Chris@0 91 $this->waitFn = $this->waitList = null;
Chris@0 92
Chris@0 93 if ($this->cancelFn) {
Chris@0 94 $fn = $this->cancelFn;
Chris@0 95 $this->cancelFn = null;
Chris@0 96 try {
Chris@0 97 $fn();
Chris@0 98 } catch (\Throwable $e) {
Chris@0 99 $this->reject($e);
Chris@0 100 } catch (\Exception $e) {
Chris@0 101 $this->reject($e);
Chris@0 102 }
Chris@0 103 }
Chris@0 104
Chris@0 105 // Reject the promise only if it wasn't rejected in a then callback.
Chris@0 106 if ($this->state === self::PENDING) {
Chris@0 107 $this->reject(new CancellationException('Promise has been cancelled'));
Chris@0 108 }
Chris@0 109 }
Chris@0 110
Chris@0 111 public function resolve($value)
Chris@0 112 {
Chris@0 113 $this->settle(self::FULFILLED, $value);
Chris@0 114 }
Chris@0 115
Chris@0 116 public function reject($reason)
Chris@0 117 {
Chris@0 118 $this->settle(self::REJECTED, $reason);
Chris@0 119 }
Chris@0 120
Chris@0 121 private function settle($state, $value)
Chris@0 122 {
Chris@0 123 if ($this->state !== self::PENDING) {
Chris@0 124 // Ignore calls with the same resolution.
Chris@0 125 if ($state === $this->state && $value === $this->result) {
Chris@0 126 return;
Chris@0 127 }
Chris@0 128 throw $this->state === $state
Chris@0 129 ? new \LogicException("The promise is already {$state}.")
Chris@0 130 : new \LogicException("Cannot change a {$this->state} promise to {$state}");
Chris@0 131 }
Chris@0 132
Chris@0 133 if ($value === $this) {
Chris@0 134 throw new \LogicException('Cannot fulfill or reject a promise with itself');
Chris@0 135 }
Chris@0 136
Chris@0 137 // Clear out the state of the promise but stash the handlers.
Chris@0 138 $this->state = $state;
Chris@0 139 $this->result = $value;
Chris@0 140 $handlers = $this->handlers;
Chris@0 141 $this->handlers = null;
Chris@0 142 $this->waitList = $this->waitFn = null;
Chris@0 143 $this->cancelFn = null;
Chris@0 144
Chris@0 145 if (!$handlers) {
Chris@0 146 return;
Chris@0 147 }
Chris@0 148
Chris@0 149 // If the value was not a settled promise or a thenable, then resolve
Chris@0 150 // it in the task queue using the correct ID.
Chris@0 151 if (!method_exists($value, 'then')) {
Chris@0 152 $id = $state === self::FULFILLED ? 1 : 2;
Chris@0 153 // It's a success, so resolve the handlers in the queue.
Chris@0 154 queue()->add(static function () use ($id, $value, $handlers) {
Chris@0 155 foreach ($handlers as $handler) {
Chris@0 156 self::callHandler($id, $value, $handler);
Chris@0 157 }
Chris@0 158 });
Chris@0 159 } elseif ($value instanceof Promise
Chris@0 160 && $value->getState() === self::PENDING
Chris@0 161 ) {
Chris@0 162 // We can just merge our handlers onto the next promise.
Chris@0 163 $value->handlers = array_merge($value->handlers, $handlers);
Chris@0 164 } else {
Chris@0 165 // Resolve the handlers when the forwarded promise is resolved.
Chris@0 166 $value->then(
Chris@0 167 static function ($value) use ($handlers) {
Chris@0 168 foreach ($handlers as $handler) {
Chris@0 169 self::callHandler(1, $value, $handler);
Chris@0 170 }
Chris@0 171 },
Chris@0 172 static function ($reason) use ($handlers) {
Chris@0 173 foreach ($handlers as $handler) {
Chris@0 174 self::callHandler(2, $reason, $handler);
Chris@0 175 }
Chris@0 176 }
Chris@0 177 );
Chris@0 178 }
Chris@0 179 }
Chris@0 180
Chris@0 181 /**
Chris@0 182 * Call a stack of handlers using a specific callback index and value.
Chris@0 183 *
Chris@0 184 * @param int $index 1 (resolve) or 2 (reject).
Chris@0 185 * @param mixed $value Value to pass to the callback.
Chris@0 186 * @param array $handler Array of handler data (promise and callbacks).
Chris@0 187 *
Chris@0 188 * @return array Returns the next group to resolve.
Chris@0 189 */
Chris@0 190 private static function callHandler($index, $value, array $handler)
Chris@0 191 {
Chris@0 192 /** @var PromiseInterface $promise */
Chris@0 193 $promise = $handler[0];
Chris@0 194
Chris@0 195 // The promise may have been cancelled or resolved before placing
Chris@0 196 // this thunk in the queue.
Chris@0 197 if ($promise->getState() !== self::PENDING) {
Chris@0 198 return;
Chris@0 199 }
Chris@0 200
Chris@0 201 try {
Chris@0 202 if (isset($handler[$index])) {
Chris@0 203 $promise->resolve($handler[$index]($value));
Chris@0 204 } elseif ($index === 1) {
Chris@0 205 // Forward resolution values as-is.
Chris@0 206 $promise->resolve($value);
Chris@0 207 } else {
Chris@0 208 // Forward rejections down the chain.
Chris@0 209 $promise->reject($value);
Chris@0 210 }
Chris@0 211 } catch (\Throwable $reason) {
Chris@0 212 $promise->reject($reason);
Chris@0 213 } catch (\Exception $reason) {
Chris@0 214 $promise->reject($reason);
Chris@0 215 }
Chris@0 216 }
Chris@0 217
Chris@0 218 private function waitIfPending()
Chris@0 219 {
Chris@0 220 if ($this->state !== self::PENDING) {
Chris@0 221 return;
Chris@0 222 } elseif ($this->waitFn) {
Chris@0 223 $this->invokeWaitFn();
Chris@0 224 } elseif ($this->waitList) {
Chris@0 225 $this->invokeWaitList();
Chris@0 226 } else {
Chris@0 227 // If there's not wait function, then reject the promise.
Chris@0 228 $this->reject('Cannot wait on a promise that has '
Chris@0 229 . 'no internal wait function. You must provide a wait '
Chris@0 230 . 'function when constructing the promise to be able to '
Chris@0 231 . 'wait on a promise.');
Chris@0 232 }
Chris@0 233
Chris@0 234 queue()->run();
Chris@0 235
Chris@0 236 if ($this->state === self::PENDING) {
Chris@0 237 $this->reject('Invoking the wait callback did not resolve the promise');
Chris@0 238 }
Chris@0 239 }
Chris@0 240
Chris@0 241 private function invokeWaitFn()
Chris@0 242 {
Chris@0 243 try {
Chris@0 244 $wfn = $this->waitFn;
Chris@0 245 $this->waitFn = null;
Chris@0 246 $wfn(true);
Chris@0 247 } catch (\Exception $reason) {
Chris@0 248 if ($this->state === self::PENDING) {
Chris@0 249 // The promise has not been resolved yet, so reject the promise
Chris@0 250 // with the exception.
Chris@0 251 $this->reject($reason);
Chris@0 252 } else {
Chris@0 253 // The promise was already resolved, so there's a problem in
Chris@0 254 // the application.
Chris@0 255 throw $reason;
Chris@0 256 }
Chris@0 257 }
Chris@0 258 }
Chris@0 259
Chris@0 260 private function invokeWaitList()
Chris@0 261 {
Chris@0 262 $waitList = $this->waitList;
Chris@0 263 $this->waitList = null;
Chris@0 264
Chris@0 265 foreach ($waitList as $result) {
Chris@0 266 while (true) {
Chris@0 267 $result->waitIfPending();
Chris@0 268
Chris@0 269 if ($result->result instanceof Promise) {
Chris@0 270 $result = $result->result;
Chris@0 271 } else {
Chris@0 272 if ($result->result instanceof PromiseInterface) {
Chris@0 273 $result->result->wait(false);
Chris@0 274 }
Chris@0 275 break;
Chris@0 276 }
Chris@0 277 }
Chris@0 278 }
Chris@0 279 }
Chris@0 280 }