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[RFC] Remove some(), map(), reduce() functions #219

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Jun 1, 2022
Merged

[RFC] Remove some(), map(), reduce() functions #219

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9b2c528
Remove `some()` function
clue May 16, 2022
51638e7
Remove `reduce()` function
clue May 16, 2022
5137c81
Remove `map()` function
clue May 16, 2022
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51 changes: 2 additions & 49 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -42,9 +42,6 @@ Table of Contents
* [all()](#all)
* [race()](#race)
* [any()](#any)
* [some()](#some)
* [map()](#map)
* [reduce()](#reduce)
4. [Examples](#examples)
* [How to use Deferred](#how-to-use-deferred)
* [How promise forwarding works](#how-promise-forwarding-works)
Expand Down Expand Up @@ -365,10 +362,9 @@ once all consumers called the `cancel()` method of the promise.

### Functions

Useful functions for creating, joining, mapping and reducing collections of
promises.
Useful functions for creating and joining collections of promises.

All functions working on promise collections (like `all()`, `race()`, `some()`
All functions working on promise collections (like `all()`, `race()`,
etc.) support cancellation. This means, if you call `cancel()` on the returned
promise, all promises in the collection are cancelled.

Expand Down Expand Up @@ -442,49 +438,6 @@ which holds all rejection reasons. The rejection reasons can be obtained with
The returned promise will also reject with a `React\Promise\Exception\LengthException`
if `$promisesOrValues` contains 0 items.

#### some()

```php
$promise = React\Promise\some(array $promisesOrValues, integer $howMany);
```

Returns a promise that will resolve when at least `$howMany` of the supplied items in
`$promisesOrValues` fulfill. The resolution value of the returned promise
will be an array of length `$howMany` containing the resolution values of
`$howMany` fulfilled promises that were resolved first.

The returned promise will reject if it becomes impossible for `$howMany` items
to resolve (that is, when `(count($promisesOrValues) - $howMany) + 1` items
reject). The rejection value will be a `React\Promise\Exception\CompositeException`
which holds `(count($promisesOrValues) - $howMany) + 1` rejection reasons.
The rejection reasons can be obtained with `CompositeException::getExceptions()`.

The returned promise will also reject with a `React\Promise\Exception\LengthException`
if `$promisesOrValues` contains less items than `$howMany`.

#### map()

```php
$promise = React\Promise\map(array $promisesOrValues, callable $mapFunc);
```

Traditional map function, similar to `array_map()`, but allows input to contain
promises and/or values, and `$mapFunc` may return either a value or a promise.

The map function receives each item as argument, where item is a fully resolved
value of a promise or value in `$promisesOrValues`.

#### reduce()

```php
$promise = React\Promise\reduce(array $promisesOrValues, callable $reduceFunc, $initialValue = null);
```

Traditional reduce function, similar to `array_reduce()`, but input may contain
promises and/or values, and `$reduceFunc` may return either a value or a
promise, *and* `$initialValue` may be a promise or a value for the starting
value.

Examples
--------

Expand Down
173 changes: 35 additions & 138 deletions src/functions.php
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Original file line number Diff line number Diff line change
Expand Up @@ -73,9 +73,33 @@ function reject(\Throwable $reason): PromiseInterface
*/
function all(array $promisesOrValues): PromiseInterface
{
return map($promisesOrValues, function ($val) {
return $val;
});
if (!$promisesOrValues) {
return resolve([]);
}

$cancellationQueue = new Internal\CancellationQueue();

return new Promise(function ($resolve, $reject) use ($promisesOrValues, $cancellationQueue): void {
$toResolve = \count($promisesOrValues);
$values = [];

foreach ($promisesOrValues as $i => $promiseOrValue) {
$cancellationQueue->enqueue($promiseOrValue);
$values[$i] = null;

resolve($promiseOrValue)
->done(
function ($mapped) use ($i, &$values, &$toResolve, $resolve): void {
$values[$i] = $mapped;

if (0 === --$toResolve) {
$resolve($values);
}
},
$reject
);
}
}, $cancellationQueue);
}

/**
Expand Down Expand Up @@ -122,45 +146,13 @@ function race(array $promisesOrValues): PromiseInterface
*/
function any(array $promisesOrValues): PromiseInterface
{
return some($promisesOrValues, 1)
->then(function ($val) {
return \array_shift($val);
});
}

/**
* Returns a promise that will resolve when `$howMany` of the supplied items in
* `$promisesOrValues` resolve. The resolution value of the returned promise
* will be an array of length `$howMany` containing the resolution values of the
* triggering items.
*
* The returned promise will reject if it becomes impossible for `$howMany` items
* to resolve (that is, when `(count($promisesOrValues) - $howMany) + 1` items
* reject). The rejection value will be an array of
* `(count($promisesOrValues) - $howMany) + 1` rejection reasons.
*
* The returned promise will also reject with a `React\Promise\Exception\LengthException`
* if `$promisesOrValues` contains less items than `$howMany`.
*
* @param array $promisesOrValues
* @param int $howMany
* @return PromiseInterface
*/
function some(array $promisesOrValues, int $howMany): PromiseInterface
{
if ($howMany < 1) {
return resolve([]);
}

$len = \count($promisesOrValues);

if ($len < $howMany) {
if (!$promisesOrValues) {
return reject(
new Exception\LengthException(
\sprintf(
'Input array must contain at least %d item%s but contains only %s item%s.',
$howMany,
1 === $howMany ? '' : 's',
'Input array must contain at least 1 item but contains only %s item%s.',
$len,
1 === $len ? '' : 's'
)
Expand All @@ -170,37 +162,23 @@ function some(array $promisesOrValues, int $howMany): PromiseInterface

$cancellationQueue = new Internal\CancellationQueue();

return new Promise(function ($resolve, $reject) use ($len, $promisesOrValues, $howMany, $cancellationQueue): void {
$toResolve = $howMany;
$toReject = ($len - $toResolve) + 1;
$values = [];
return new Promise(function ($resolve, $reject) use ($len, $promisesOrValues, $cancellationQueue): void {
$toReject = $len;
$reasons = [];

foreach ($promisesOrValues as $i => $promiseOrValue) {
$fulfiller = function ($val) use ($i, &$values, &$toResolve, $toReject, $resolve): void {
if ($toResolve < 1 || $toReject < 1) {
return;
}

$values[$i] = $val;

if (0 === --$toResolve) {
$resolve($values);
}
$fulfiller = function ($val) use ($resolve): void {
$resolve($val);
};

$rejecter = function (\Throwable $reason) use ($i, &$reasons, &$toReject, $toResolve, $reject): void {
if ($toResolve < 1 || $toReject < 1) {
return;
}

$rejecter = function (\Throwable $reason) use ($i, &$reasons, &$toReject, $reject): void {
$reasons[$i] = $reason;

if (0 === --$toReject) {
$reject(
new CompositeException(
$reasons,
'Too many promises rejected.'
'All promises rejected.'
)
);
}
Expand All @@ -214,87 +192,6 @@ function some(array $promisesOrValues, int $howMany): PromiseInterface
}, $cancellationQueue);
}

/**
* Traditional map function, similar to `array_map()`, but allows input to contain
* promises and/or values, and `$mapFunc` may return either a value or a promise.
*
* The map function receives each item as argument, where item is a fully resolved
* value of a promise or value in `$promisesOrValues`.
*
* @param array $promisesOrValues
* @param callable $mapFunc
* @return PromiseInterface
*/
function map(array $promisesOrValues, callable $mapFunc): PromiseInterface
{
if (!$promisesOrValues) {
return resolve([]);
}

$cancellationQueue = new Internal\CancellationQueue();

return new Promise(function ($resolve, $reject) use ($promisesOrValues, $mapFunc, $cancellationQueue): void {
$toResolve = \count($promisesOrValues);
$values = [];

foreach ($promisesOrValues as $i => $promiseOrValue) {
$cancellationQueue->enqueue($promiseOrValue);
$values[$i] = null;

resolve($promiseOrValue)
->then($mapFunc)
->done(
function ($mapped) use ($i, &$values, &$toResolve, $resolve): void {
$values[$i] = $mapped;

if (0 === --$toResolve) {
$resolve($values);
}
},
$reject
);
}
}, $cancellationQueue);
}

/**
* Traditional reduce function, similar to `array_reduce()`, but input may contain
* promises and/or values, and `$reduceFunc` may return either a value or a
* promise, *and* `$initialValue` may be a promise or a value for the starting
* value.
*
* @param array $promisesOrValues
* @param callable $reduceFunc
* @param mixed $initialValue
* @return PromiseInterface
*/
function reduce(array $promisesOrValues, callable $reduceFunc, $initialValue = null): PromiseInterface
{
$cancellationQueue = new Internal\CancellationQueue();

return new Promise(function ($resolve, $reject) use ($promisesOrValues, $reduceFunc, $initialValue, $cancellationQueue): void {
$total = \count($promisesOrValues);
$i = 0;

$wrappedReduceFunc = function ($current, $val) use ($reduceFunc, $cancellationQueue, $total, &$i): PromiseInterface {
$cancellationQueue->enqueue($val);

return $current
->then(function ($c) use ($reduceFunc, $total, &$i, $val) {
return resolve($val)
->then(function ($value) use ($reduceFunc, $total, &$i, $c) {
return $reduceFunc($c, $value, $i++, $total);
});
});
};

$cancellationQueue->enqueue($initialValue);

\array_reduce($promisesOrValues, $wrappedReduceFunc, resolve($initialValue))
->done($resolve, $reject);
}, $cancellationQueue);
}

/**
* @internal
*/
Expand Down
4 changes: 2 additions & 2 deletions tests/FunctionAnyTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -61,7 +61,7 @@ public function shouldRejectWithAllRejectedInputValuesIfAllInputsAreRejected()

$compositeException = new CompositeException(
[0 => $exception1, 1 => $exception2, 2 => $exception3],
'Too many promises rejected.'
'All promises rejected.'
);

$mock = $this->createCallableMock();
Expand Down Expand Up @@ -126,6 +126,6 @@ public function shouldNotCancelOtherPendingInputArrayPromisesIfOnePromiseFulfill

$promise2 = new Promise(function () {}, $this->expectCallableNever());

some([$deferred->promise(), $promise2], 1)->cancel();
any([$deferred->promise(), $promise2], 1)->cancel();
}
}
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