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

   1 <?php
   2
   3 namespace seekat\API;
   4
   5 use Generator;
   6 use http\Client;
   7 use React\Promise\Deferred;
   8 use React\Promise\PromiseInterface;
   9 use React\Promise\ExtendedPromiseInterface;
  10
  11 use function React\Promise\all;
  12
  13 class Invoker extends Deferred
  14 {
  15         /**
  16          * The HTTP client
  17          * @var Client
  18          */
  19         private $client;
  20
  21         /**
  22          * The return value of the generator
  23          * @var mixed
  24          */
  25         private $result;
  26
  27         /**
  28          * Cancellation flag
  29          * @var bool
  30          */
  31         private $cancelled = false;
  32
  33         /**
  34          * Create a new generator invoker
  35          * @param \http\Client $client
  36          */
  37         function __construct(Client $client) {
  38                 $this->client = $client;
  39
  40                 parent::__construct(function($resolve, $reject) {
  41                         return $this->cancel($resolve, $reject);
  42                 });
  43         }
  44
  45         /**
  46          * Invoke $generator to create a \Generator which yields promises
  47          *
  48          * @param callable $generator as function() : \Generator, creating a generator yielding promises
  49          * @return \seekat\API\Invoker
  50          */
  51         function invoke(callable $generator) : Invoker {
  52                 $this->iterate($generator());
  53                 return $this;
  54         }
  55
  56         /**
  57          * Iterate over $gen, a \Generator yielding promises
  58          *
  59          * @param \Generator $gen
  60          * @return \seekat\API\Invoker
  61          */
  62         function iterate(Generator $gen) : Invoker {
  63                 $this->cancelled = false;
  64
  65                 foreach ($gen as $promise) {
  66                         if ($this->cancelled) {
  67                                 break;
  68                         }
  69                         $this->queue($promise, $gen);
  70                 }
  71
  72                 if (!$this->cancelled) {
  73                         $this->resolve($this->result = $gen->getReturn());
  74                 }
  75                 return $this;
  76         }
  77
  78         /**
  79          * Get the generator's result
  80          *
  81          * @return \React\Promise\ExtendedPromiseInterface
  82          */
  83         function result() : ExtendedPromiseInterface {
  84                 return $this->promise();
  85         }
  86
  87         /**
  88          * Promise handler
  89          *
  90          * @param \React\Promise\PromiseInterface $promise
  91          * @param \Generator $to
  92          */
  93         private function give(PromiseInterface $promise, Generator $to) {
  94                 $promise->then(function($result) use($to) {
  95                         if (($promise = $to->send($result))) {
  96                                 $this->queue($promise, $to);
  97                         }
  98                 });
  99         }
 100
 101         private function queue($promise, Generator $gen) {
 102                 if ($promise instanceof PromiseInterface) {
 103                                 $this->give($promise, $gen);
 104                 } else {
 105                         all($promise)->then(function($results) use($gen) {
 106                                 if (($promise = $gen->send($results))) {
 107                                         $this->queue($promise, $gen);
 108                                 }
 109                         });
 110                 }
 111                 $this->client->send();
 112         }
 113
 114         /**
 115          * Cancellation callback
 116          *
 117          * @param callable $resolve
 118          * @param callable $reject
 119          */
 120         private function cancel(callable $resolve, callable $reject) {
 121                 $this->cancelled = true;
 122
 123                 /* did we finish in the meantime? */
 124                 if ($this->result) {
 125                         $resolve($this->result);
 126                 } else {
 127                         $reject("Cancelled");
 128                 }
 129         }
 130 }