AggregateException.php
1 week ago
CancellationException.php
1 week ago
Coroutine.php
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Create.php
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Each.php
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EachPromise.php
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FulfilledPromise.php
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Is.php
1 week ago
Promise.php
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PromiseInterface.php
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PromisorInterface.php
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RejectedPromise.php
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RejectionException.php
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TaskQueue.php
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TaskQueueInterface.php
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Utils.php
1 week ago
Promise.php
282 lines
| 1 | <?php |
| 2 | |
| 3 | declare(strict_types=1); |
| 4 | |
| 5 | namespace GuzzleHttp\Promise; |
| 6 | |
| 7 | /** |
| 8 | * Promises/A+ implementation that avoids recursion when possible. |
| 9 | * |
| 10 | * @see https://promisesaplus.com/ |
| 11 | * |
| 12 | * @final |
| 13 | */ |
| 14 | class Promise implements PromiseInterface |
| 15 | { |
| 16 | private $state = self::PENDING; |
| 17 | private $result; |
| 18 | private $cancelFn; |
| 19 | private $waitFn; |
| 20 | private $waitList; |
| 21 | private $handlers = []; |
| 22 | |
| 23 | /** |
| 24 | * @param callable $waitFn Fn that when invoked resolves the promise. |
| 25 | * @param callable $cancelFn Fn that when invoked cancels the promise. |
| 26 | */ |
| 27 | public function __construct( |
| 28 | ?callable $waitFn = null, |
| 29 | ?callable $cancelFn = null |
| 30 | ) { |
| 31 | $this->waitFn = $waitFn; |
| 32 | $this->cancelFn = $cancelFn; |
| 33 | } |
| 34 | |
| 35 | public function then( |
| 36 | ?callable $onFulfilled = null, |
| 37 | ?callable $onRejected = null |
| 38 | ): PromiseInterface { |
| 39 | if ($this->state === self::PENDING) { |
| 40 | $p = new Promise(null, [$this, 'cancel']); |
| 41 | $this->handlers[] = [$p, $onFulfilled, $onRejected]; |
| 42 | $p->waitList = $this->waitList; |
| 43 | $p->waitList[] = $this; |
| 44 | |
| 45 | return $p; |
| 46 | } |
| 47 | |
| 48 | // Return a fulfilled promise and immediately invoke any callbacks. |
| 49 | if ($this->state === self::FULFILLED) { |
| 50 | $promise = Create::promiseFor($this->result); |
| 51 | |
| 52 | return $onFulfilled ? $promise->then($onFulfilled) : $promise; |
| 53 | } |
| 54 | |
| 55 | // It's either cancelled or rejected, so return a rejected promise |
| 56 | // and immediately invoke any callbacks. |
| 57 | $rejection = Create::rejectionFor($this->result); |
| 58 | |
| 59 | return $onRejected ? $rejection->then(null, $onRejected) : $rejection; |
| 60 | } |
| 61 | |
| 62 | public function otherwise(callable $onRejected): PromiseInterface |
| 63 | { |
| 64 | return $this->then(null, $onRejected); |
| 65 | } |
| 66 | |
| 67 | public function wait(bool $unwrap = true) |
| 68 | { |
| 69 | $this->waitIfPending(); |
| 70 | |
| 71 | if ($this->result instanceof PromiseInterface) { |
| 72 | return $this->result->wait($unwrap); |
| 73 | } |
| 74 | if ($unwrap) { |
| 75 | if ($this->state === self::FULFILLED) { |
| 76 | return $this->result; |
| 77 | } |
| 78 | // It's rejected so "unwrap" and throw an exception. |
| 79 | throw Create::exceptionFor($this->result); |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | public function getState(): string |
| 84 | { |
| 85 | return $this->state; |
| 86 | } |
| 87 | |
| 88 | public function cancel(): void |
| 89 | { |
| 90 | if ($this->state !== self::PENDING) { |
| 91 | return; |
| 92 | } |
| 93 | |
| 94 | $this->waitFn = $this->waitList = null; |
| 95 | |
| 96 | if ($this->cancelFn) { |
| 97 | $fn = $this->cancelFn; |
| 98 | $this->cancelFn = null; |
| 99 | try { |
| 100 | $fn(); |
| 101 | } catch (\Throwable $e) { |
| 102 | $this->reject($e); |
| 103 | } |
| 104 | } |
| 105 | |
| 106 | // Reject the promise only if it wasn't rejected in a then callback. |
| 107 | /** @psalm-suppress RedundantCondition */ |
| 108 | if ($this->state === self::PENDING) { |
| 109 | $this->reject(new CancellationException('Promise has been cancelled')); |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | public function resolve($value): void |
| 114 | { |
| 115 | $this->settle(self::FULFILLED, $value); |
| 116 | } |
| 117 | |
| 118 | public function reject($reason): void |
| 119 | { |
| 120 | $this->settle(self::REJECTED, $reason); |
| 121 | } |
| 122 | |
| 123 | private function settle(string $state, $value): void |
| 124 | { |
| 125 | if ($this->state !== self::PENDING) { |
| 126 | // Ignore calls with the same resolution. |
| 127 | if ($state === $this->state && $value === $this->result) { |
| 128 | return; |
| 129 | } |
| 130 | throw $this->state === $state |
| 131 | ? new \LogicException("The promise is already {$state}.") |
| 132 | : new \LogicException("Cannot change a {$this->state} promise to {$state}"); |
| 133 | } |
| 134 | |
| 135 | if ($value === $this) { |
| 136 | throw new \LogicException('Cannot fulfill or reject a promise with itself'); |
| 137 | } |
| 138 | |
| 139 | // Clear out the state of the promise but stash the handlers. |
| 140 | $this->state = $state; |
| 141 | $this->result = $value; |
| 142 | $handlers = $this->handlers; |
| 143 | $this->handlers = null; |
| 144 | $this->waitList = $this->waitFn = null; |
| 145 | $this->cancelFn = null; |
| 146 | |
| 147 | if (!$handlers) { |
| 148 | return; |
| 149 | } |
| 150 | |
| 151 | // If the value was not a settled promise or a thenable, then resolve |
| 152 | // it in the task queue using the correct ID. |
| 153 | if (!is_object($value) || !method_exists($value, 'then')) { |
| 154 | $id = $state === self::FULFILLED ? 1 : 2; |
| 155 | // It's a success, so resolve the handlers in the queue. |
| 156 | Utils::queue()->add(static function () use ($id, $value, $handlers): void { |
| 157 | foreach ($handlers as $handler) { |
| 158 | self::callHandler($id, $value, $handler); |
| 159 | } |
| 160 | }); |
| 161 | } elseif ($value instanceof Promise && Is::pending($value)) { |
| 162 | // We can just merge our handlers onto the next promise. |
| 163 | $value->handlers = array_merge($value->handlers, $handlers); |
| 164 | } else { |
| 165 | // Resolve the handlers when the forwarded promise is resolved. |
| 166 | $value->then( |
| 167 | static function ($value) use ($handlers): void { |
| 168 | foreach ($handlers as $handler) { |
| 169 | self::callHandler(1, $value, $handler); |
| 170 | } |
| 171 | }, |
| 172 | static function ($reason) use ($handlers): void { |
| 173 | foreach ($handlers as $handler) { |
| 174 | self::callHandler(2, $reason, $handler); |
| 175 | } |
| 176 | } |
| 177 | ); |
| 178 | } |
| 179 | } |
| 180 | |
| 181 | /** |
| 182 | * Call a stack of handlers using a specific callback index and value. |
| 183 | * |
| 184 | * @param int $index 1 (resolve) or 2 (reject). |
| 185 | * @param mixed $value Value to pass to the callback. |
| 186 | * @param array $handler Array of handler data (promise and callbacks). |
| 187 | */ |
| 188 | private static function callHandler(int $index, $value, array $handler): void |
| 189 | { |
| 190 | /** @var PromiseInterface $promise */ |
| 191 | $promise = $handler[0]; |
| 192 | |
| 193 | // The promise may have been cancelled or resolved before placing |
| 194 | // this thunk in the queue. |
| 195 | if (Is::settled($promise)) { |
| 196 | return; |
| 197 | } |
| 198 | |
| 199 | try { |
| 200 | if (isset($handler[$index])) { |
| 201 | /* |
| 202 | * If $f throws an exception, then $handler will be in the exception |
| 203 | * stack trace. Since $handler contains a reference to the callable |
| 204 | * itself we get a circular reference. We clear the $handler |
| 205 | * here to avoid that memory leak. |
| 206 | */ |
| 207 | $f = $handler[$index]; |
| 208 | unset($handler); |
| 209 | $promise->resolve($f($value)); |
| 210 | } elseif ($index === 1) { |
| 211 | // Forward resolution values as-is. |
| 212 | $promise->resolve($value); |
| 213 | } else { |
| 214 | // Forward rejections down the chain. |
| 215 | $promise->reject($value); |
| 216 | } |
| 217 | } catch (\Throwable $reason) { |
| 218 | $promise->reject($reason); |
| 219 | } |
| 220 | } |
| 221 | |
| 222 | private function waitIfPending(): void |
| 223 | { |
| 224 | if ($this->state !== self::PENDING) { |
| 225 | return; |
| 226 | } elseif ($this->waitFn) { |
| 227 | $this->invokeWaitFn(); |
| 228 | } elseif ($this->waitList) { |
| 229 | $this->invokeWaitList(); |
| 230 | } else { |
| 231 | // If there's no wait function, then reject the promise. |
| 232 | $this->reject('Cannot wait on a promise that has ' |
| 233 | .'no internal wait function. You must provide a wait ' |
| 234 | .'function when constructing the promise to be able to ' |
| 235 | .'wait on a promise.'); |
| 236 | } |
| 237 | |
| 238 | Utils::queue()->run(); |
| 239 | |
| 240 | /** @psalm-suppress RedundantCondition */ |
| 241 | if ($this->state === self::PENDING) { |
| 242 | $this->reject('Invoking the wait callback did not resolve the promise'); |
| 243 | } |
| 244 | } |
| 245 | |
| 246 | private function invokeWaitFn(): void |
| 247 | { |
| 248 | try { |
| 249 | $wfn = $this->waitFn; |
| 250 | $this->waitFn = null; |
| 251 | $wfn(true); |
| 252 | } catch (\Throwable $reason) { |
| 253 | if ($this->state === self::PENDING) { |
| 254 | // The promise has not been resolved yet, so reject the promise |
| 255 | // with the exception. |
| 256 | $this->reject($reason); |
| 257 | } else { |
| 258 | // The promise was already resolved, so there's a problem in |
| 259 | // the application. |
| 260 | throw $reason; |
| 261 | } |
| 262 | } |
| 263 | } |
| 264 | |
| 265 | private function invokeWaitList(): void |
| 266 | { |
| 267 | $waitList = $this->waitList; |
| 268 | $this->waitList = null; |
| 269 | |
| 270 | foreach ($waitList as $result) { |
| 271 | do { |
| 272 | $result->waitIfPending(); |
| 273 | $result = $result->result; |
| 274 | } while ($result instanceof Promise); |
| 275 | |
| 276 | if ($result instanceof PromiseInterface) { |
| 277 | $result->wait(false); |
| 278 | } |
| 279 | } |
| 280 | } |
| 281 | } |
| 282 |