<?php
declare(strict_types=1);
namespace GuzzleHttp\Promise;
/**
* Promises/A+ implementation that avoids recursion when possible.
*
* @see https://promisesaplus.com/
*
* @final
*/
class Promise implements PromiseInterface
{
private $state = self::PENDING;
private $result;
private $cancelFn;
private $waitFn;
private $waitList;
private $handlers = [];
/**
* @param callable $waitFn Fn that when invoked resolves the promise.
* @param callable $cancelFn Fn that when invoked cancels the promise.
*/
public function __construct(
callable $waitFn = null,
callable $cancelFn = null
) {
$this->waitFn = $waitFn;
$this->cancelFn = $cancelFn;
}
public function then(
callable $onFulfilled = null,
callable $onRejected = null
): PromiseInterface {
if ($this->state === self::PENDING) {
$p = new Promise(null, [$this, 'cancel']);
$this->handlers[] = [$p, $onFulfilled, $onRejected];
$p->waitList = $this->waitList;
$p->waitList[] = $this;
return $p;
}
// Return a fulfilled promise and immediately invoke any callbacks.
if ($this->state === self::FULFILLED) {
$promise = Create::promiseFor($this->result);
return $onFulfilled ? $promise->then($onFulfilled) : $promise;
}
// It's either cancelled or rejected, so return a rejected promise
// and immediately invoke any callbacks.
$rejection = Create::rejectionFor($this->result);
return $onRejected ? $rejection->then(null, $onRejected) : $rejection;
}
public function otherwise(callable $onRejected): PromiseInterface
{
return $this->then(null, $onRejected);
}
public function wait(bool $unwrap = true)
{
$this->waitIfPending();
if ($this->result instanceof PromiseInterface) {
return $this->result->wait($unwrap);
}
if ($unwrap) {
if ($this->state === self::FULFILLED) {
return $this->result;
}
// It's rejected so "unwrap" and throw an exception.
throw Create::exceptionFor($this->result);
}
}
public function getState(): string
{
return $this->state;
}
public function cancel(): void
{
if ($this->state !== self::PENDING) {
return;
}
$this->waitFn = $this->waitList = null;
if ($this->cancelFn) {
$fn = $this->cancelFn;
$this->cancelFn = null;
try {
$fn();
} catch (\Throwable $e) {
$this->reject($e);
}
}
// Reject the promise only if it wasn't rejected in a then callback.
/** @psalm-suppress RedundantCondition */
if ($this->state === self::PENDING) {
$this->reject(new CancellationException('Promise has been cancelled'));
}
}
public function resolve($value): void
{
$this->settle(self::FULFILLED, $value);
}
public function reject($reason): void
{
$this->settle(self::REJECTED, $reason);
}
private function settle(string $state, $value): void
{
if ($this->state !== self::PENDING) {
// Ignore calls with the same resolution.
if ($state === $this->state && $value === $this->result) {
return;
}
throw $this->state === $state
? new \LogicException("The promise is already {$state}.")
: new \LogicException("Cannot change a {$this->state} promise to {$state}");
}
if ($value === $this) {
throw new \LogicException('Cannot fulfill or reject a promise with itself');
}
// Clear out the state of the promise but stash the handlers.
$this->state = $state;
$this->result = $value;
$handlers = $this->handlers;
$this->handlers = null;
$this->waitList = $this->waitFn = null;
$this->cancelFn = null;
if (!$handlers) {
return;
}
// If the value was not a settled promise or a thenable, then resolve
// it in the task queue using the correct ID.
if (!is_object($value) || !method_exists($value, 'then')) {
$id = $state === self::FULFILLED ? 1 : 2;
// It's a success, so resolve the handlers in the queue.
Utils::queue()->add(static function () use ($id, $value, $handlers): void {
foreach ($handlers as $handler) {
self::callHandler($id, $value, $handler);
}
});
} elseif ($value instanceof Promise && Is::pending($value)) {
// We can just merge our handlers onto the next promise.
$value->handlers = array_merge($value->handlers, $handlers);
} else {
// Resolve the handlers when the forwarded promise is resolved.
$value->then(
static function ($value) use ($handlers): void {
foreach ($handlers as $handler) {
self::callHandler(1, $value, $handler);
}
},
static function ($reason) use ($handlers): void {
foreach ($handlers as $handler) {
self::callHandler(2, $reason, $handler);
}
}
);
}
}
/**
* Call a stack of handlers using a specific callback index and value.
*
* @param int $index 1 (resolve) or 2 (reject).
* @param mixed $value Value to pass to the callback.
* @param array $handler Array of handler data (promise and callbacks).
*/
private static function callHandler(int $index, $value, array $handler): void
{
/** @var PromiseInterface $promise */
$promise = $handler[0];
// The promise may have been cancelled or resolved before placing
// this thunk in the queue.
if (Is::settled($promise)) {
return;
}
try {
if (isset($handler[$index])) {
/*
* If $f throws an exception, then $handler will be in the exception
* stack trace. Since $handler contains a reference to the callable
* itself we get a circular reference. We clear the $handler
* here to avoid that memory leak.
*/
$f = $handler[$index];
unset($handler);
$promise->resolve($f($value));
} elseif ($index === 1) {
// Forward resolution values as-is.
$promise->resolve($value);
} else {
// Forward rejections down the chain.
$promise->reject($value);
}
} catch (\Throwable $reason) {
$promise->reject($reason);
}
}
private function waitIfPending(): void
{
if ($this->state !== self::PENDING) {
return;
} elseif ($this->waitFn) {
$this->invokeWaitFn();
} elseif ($this->waitList) {
$this->invokeWaitList();
} else {
// If there's no wait function, then reject the promise.
$this->reject('Cannot wait on a promise that has '
.'no internal wait function. You must provide a wait '
.'function when constructing the promise to be able to '
.'wait on a promise.');
}
Utils::queue()->run();
/** @psalm-suppress RedundantCondition */
if ($this->state === self::PENDING) {
$this->reject('Invoking the wait callback did not resolve the promise');
}
}
private function invokeWaitFn(): void
{
try {
$wfn = $this->waitFn;
$this->waitFn = null;
$wfn(true);
} catch (\Throwable $reason) {
if ($this->state === self::PENDING) {
// The promise has not been resolved yet, so reject the promise
// with the exception.
$this->reject($reason);
} else {
// The promise was already resolved, so there's a problem in
// the application.
throw $reason;
}
}
}
private function invokeWaitList(): void
{
$waitList = $this->waitList;
$this->waitList = null;
foreach ($waitList as $result) {
do {
$result->waitIfPending();
$result = $result->result;
} while ($result instanceof Promise);
if ($result instanceof PromiseInterface) {
$result->wait(false);
}
}
}
}
NFC Pay was founded with a vision to transform the way people handle transactions. Our journey is defined by a commitment to innovation, security, and convenience. We strive to deliver seamless, user-friendly payment solutions that make everyday transactions effortless and secure. Our mission is to empower you to pay with ease and confidence, anytime, anywhere.
Simplifying Payments, One Tap at a Time.
Reinventing Your Wallet for Modern Convenience.
Smart Payments for a Effortless Lifestyle.
Experience the Ease of Tap and Pay.
Innovative Solutions for Your Daily Transactions.
FAQ Section
Frequently Asked Questions About NFC Pay
Here are answers to some common questions about NFC Pay. We aim to provide clear and concise information to help you understand how our platform works and how it can benefit you. If you have any further inquiries, please don’t hesitate to contact our support team.
How do I register for NFC Pay?
Download the app and sign up using your email or phone number, then complete the verification process.
Is my payment information secure?
Yes, we use advanced encryption and security protocols to protect your payment details.
Can I add multiple cards to my NFC Pay wallet?
Absolutely, you can link multiple debit or credit cards to your wallet.
How do I transfer money to another user?
Go to the transfer section, select the recipient, enter the amount, and authorize the transfer.
What should I do if I forget my PIN?
Use the “Forgot PIN” feature in the app to reset it following the provided instructions.
How can I activate my merchant account?
Sign up for a merchant account through the app and follow the setup instructions to start accepting payments.
Can I track my payment status?
Yes, you can view and track your payment status in the account dashboard
In the digital age, privacy concerns have become increasingly paramount, prompting the European Union to enact the General Data Protection Regulation (GDPR) in 2018. Among its many provisions, GDPR sets strict guidelines for the collection and processing of personal data, including the use of cookies on websites. Privacy Policy
