git.m6w6.name Git - m6w6/seekat/blob - lib/API/Consumer.php

   1 <?php
   2
   3 namespace seekat\API;
   4
   5 use Exception;
   6 use Generator;
   7 use seekat\API;
   8 use seekat\Exception\{function exception};
   9
  10 final class Consumer {
  11         /**
  12          * The return value of the generator
  13          * @var mixed
  14          */
  15         private mixed $result = null;
  16
  17         /**
  18          * Cancellation flag
  19          */
  20         private bool $cancelled = false;
  21
  22         /**
  23          * Promise
  24          */
  25         private object $promise;
  26
  27         private \Closure $resolve;
  28         private \Closure $reject;
  29         private \Closure $reduce;
  30
  31         /**
  32          * Create a new generator consumer
  33          */
  34         function __construct(private readonly Future $future, private readonly \Closure $loop) {
  35                 $context = $future->createContext(function() {
  36                         $this->cancelled = true;
  37                 });
  38                 $this->promise = $future->getPromise($context);
  39                 $this->resolve = $future->resolver($context);
  40                 $this->reject = $future->rejecter($context);
  41                 $this->reduce = $future->reducer();
  42         }
  43
  44         /**
  45          * Iterate over $gen, a \Generator yielding promises
  46          *
  47          * @param Generator $gen
  48          * @return mixed promise
  49          */
  50         function __invoke(Generator $gen) : mixed {
  51                 $this->cancelled = false;
  52                 foreach ($gen as $promise) {
  53                         if ($this->cancelled) {
  54                                 break;
  55                         }
  56                         $this->give($promise, $gen);
  57                 }
  58
  59                 if ($this->cancelled) {
  60                         ($this->reject)("Cancelled");
  61                 } else if (!$gen->valid()) {
  62                         try {
  63                                 $this->result = $gen->getReturn();
  64                         } catch (Exception $e) {
  65                                 assert($e->getMessage() === "Cannot get return value of a generator that hasn't returned");
  66                         }
  67                 }
  68                 ($this->resolve)($this->result);
  69
  70                 return $this->promise;
  71         }
  72
  73         /**
  74          * Promise handler
  75          *
  76          * @param mixed $promise
  77          * @param Generator $gen
  78          */
  79         private function give(mixed $promise, Generator $gen) : void {
  80                 if ($promise instanceof \Traversable) {
  81                         $promise = iterator_to_array($promise);
  82                 }
  83                 if (is_array($promise)) {
  84                         $promise = ($this->reduce)($promise);
  85                 }
  86
  87                 $this->future->handlePromise($promise, function($result) use($gen) {
  88                         if (($promise = $gen->send($result))) {
  89                                 $this->give($promise, $gen);
  90                         }
  91                 }, function($error) use($gen) {
  92                         $gen->throw(exception($error));
  93                 });
  94
  95                 /* FIXME: external loop */
  96                 ($this->loop)();
  97         }
  98 }