stockpack / vendor / guzzlehttp / promises / src / Promise.php

Promise.php in StockPack – Stock photos and AI images from Unsplash, Adobe Stock, Freepik and more 2.4.1, at vendor/guzzlehttp/promises/src/Promise.php

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