private function emit($value) : Promise
{
if ($this->resolved) {
throw new \Error("The observable has been resolved; cannot emit more values");
}
if ($value instanceof Promise) {
$deferred = new Deferred();
$value->when(function ($e, $v) use($deferred) {
if ($this->resolved) {
$deferred->fail(new \Error("The observable was resolved before the promise result could be emitted"));
return;
}
if ($e) {
$this->fail($e);
$deferred->fail($e);
return;
}
$deferred->resolve($this->emit($v));
});
return $deferred->promise();
}
$promises = [];
foreach ($this->subscribers as $onNext) {
try {
$result = $onNext($value);
if ($result instanceof Promise) {
$promises[] = $result;
}
} catch (\Throwable $e) {
Loop::defer(static function () use($e) {
throw $e;
});
}
}
if (!$promises) {
return new Success($value);
}
$deferred = new Deferred();
$count = \count($promises);
$f = static function ($e) use($deferred, $value, &$count) {
if ($e) {
Loop::defer(static function () use($e) {
throw $e;
});
}
if (!--$count) {
$deferred->resolve($value);
}
};
foreach ($promises as $promise) {
$promise->when($f);
}
return $deferred->promise();
}
