Enforce return type hints on all functions and require PHP 7.1+ as a consequence

.travis.yml

@@ -1,7 +1,6 @@
 language: php
 
 php:
-  - 7.0
   - 7.1
   - 7.2
   - 7.3

composer.json

@@ -6,7 +6,7 @@
         {"name": "Jan Sorgalla", "email": "[email protected]"}
     ],
     "require": {
-        "php": ">=7.0.0"
+        "php": ">=7.1.0"
     },
     "require-dev": {
         "phpunit/phpunit": "~6.4"

src/Deferred.php

@@ -14,13 +14,13 @@ public function __construct(callable $canceller = null)
         $this->canceller = $canceller;
     }
 
-    public function promise()
+    public function promise(): PromiseInterface
     {
         if (null === $this->promise) {
             $canceller = $this->canceller;
             $this->canceller = null;
 
-            $this->promise = new Promise(function ($resolve, $reject) {
+            $this->promise = new Promise(function ($resolve, $reject): void {
                 $this->resolveCallback = $resolve;
                 $this->rejectCallback  = $reject;
             }, $canceller);
@@ -29,14 +29,14 @@ public function promise()
         return $this->promise;
     }
 
-    public function resolve($value = null)
+    public function resolve($value = null): void
     {
         $this->promise();
 
         \call_user_func($this->resolveCallback, $value);
     }
 
-    public function reject(\Throwable $reason)
+    public function reject(\Throwable $reason): void
     {
         $this->promise();
 

src/Exception/CompositeException.php

@@ -23,7 +23,7 @@ public function __construct(array $throwables, $message = '', $code = 0, $previo
     /**
      * @return \Throwable[]
      */
-    public function getThrowables()
+    public function getThrowables(): array
     {
         return $this->throwables;
     }

src/FulfilledPromise.php

@@ -15,14 +15,14 @@ public function __construct($value = null)
         $this->value = $value;
     }
 
-    public function then(callable $onFulfilled = null, callable $onRejected = null)
+    public function then(callable $onFulfilled = null, callable $onRejected = null): PromiseInterface
     {
         if (null === $onFulfilled) {
             return $this;
         }
 
-        return new Promise(function (callable $resolve, callable $reject) use ($onFulfilled) {
-            enqueue(function () use ($resolve, $reject, $onFulfilled) {
+        return new Promise(function (callable $resolve, callable $reject) use ($onFulfilled): void {
+            enqueue(function () use ($resolve, $reject, $onFulfilled): void {
                 try {
                     $resolve($onFulfilled($this->value));
                 } catch (\Throwable $exception) {
@@ -32,7 +32,7 @@ public function then(callable $onFulfilled = null, callable $onRejected = null)
         });
     }
 
-    public function done(callable $onFulfilled = null, callable $onRejected = null)
+    public function done(callable $onFulfilled = null, callable $onRejected = null): void
     {
         if (null === $onFulfilled) {
             return;
@@ -51,21 +51,21 @@ public function done(callable $onFulfilled = null, callable $onRejected = null)
         });
     }
 
-    public function otherwise(callable $onRejected)
+    public function otherwise(callable $onRejected): PromiseInterface
     {
         return $this;
     }
 
-    public function always(callable $onFulfilledOrRejected)
+    public function always(callable $onFulfilledOrRejected): PromiseInterface
     {
-        return $this->then(function ($value) use ($onFulfilledOrRejected) {
+        return $this->then(function ($value) use ($onFulfilledOrRejected): PromiseInterface {
             return resolve($onFulfilledOrRejected())->then(function () use ($value) {
                 return $value;
             });
         });
     }
 
-    public function cancel()
+    public function cancel(): void
     {
     }
 }

src/Internal/CancellationQueue.php

@@ -10,7 +10,7 @@ final class CancellationQueue
     private $started = false;
     private $queue = [];
 
-    public function __invoke()
+    public function __invoke(): void
     {
         if ($this->started) {
             return;
@@ -20,7 +20,7 @@ public function __invoke()
         $this->drain();
     }
 
-    public function enqueue($cancellable)
+    public function enqueue($cancellable): void
     {
         if (!\method_exists($cancellable, 'then') || !\method_exists($cancellable, 'cancel')) {
             return;
@@ -33,7 +33,7 @@ public function enqueue($cancellable)
         }
     }
 
-    private function drain()
+    private function drain(): void
     {
         for ($i = \key($this->queue); isset($this->queue[$i]); $i++) {
             $cancellable = $this->queue[$i];

src/Internal/Queue.php

@@ -9,14 +9,14 @@ final class Queue
 {
     private $queue = [];
 
-    public function enqueue(callable $task)
+    public function enqueue(callable $task): void
     {
         if (1 === \array_push($this->queue, $task)) {
             $this->drain();
         }
     }
 
-    private function drain()
+    private function drain(): void
     {
         for ($i = \key($this->queue); isset($this->queue[$i]); $i++) {
             $task = $this->queue[$i];

src/Promise.php

@@ -17,7 +17,7 @@ public function __construct(callable $resolver, callable $canceller = null)
         $this->call($resolver);
     }
 
-    public function then(callable $onFulfilled = null, callable $onRejected = null)
+    public function then(callable $onFulfilled = null, callable $onRejected = null): PromiseInterface
     {
         if (null !== $this->result) {
             return $this->result->then($onFulfilled, $onRejected);
@@ -38,10 +38,11 @@ public function then(callable $onFulfilled = null, callable $onRejected = null)
         });
     }
 
-    public function done(callable $onFulfilled = null, callable $onRejected = null)
+    public function done(callable $onFulfilled = null, callable $onRejected = null): void
     {
         if (null !== $this->result) {
-            return $this->result->done($onFulfilled, $onRejected);
+            $this->result->done($onFulfilled, $onRejected);
+            return;
         }
 
         $this->handlers[] = function (PromiseInterface $promise) use ($onFulfilled, $onRejected) {
@@ -50,7 +51,7 @@ public function done(callable $onFulfilled = null, callable $onRejected = null)
         };
     }
 
-    public function otherwise(callable $onRejected)
+    public function otherwise(callable $onRejected): PromiseInterface
     {
         return $this->then(null, function ($reason) use ($onRejected) {
             if (!_checkTypehint($onRejected, $reason)) {
@@ -61,7 +62,7 @@ public function otherwise(callable $onRejected)
         });
     }
 
-    public function always(callable $onFulfilledOrRejected)
+    public function always(callable $onFulfilledOrRejected): PromiseInterface
     {
         return $this->then(function ($value) use ($onFulfilledOrRejected) {
             return resolve($onFulfilledOrRejected())->then(function () use ($value) {
@@ -74,7 +75,7 @@ public function always(callable $onFulfilledOrRejected)
         });
     }
 
-    public function cancel()
+    public function cancel(): void
     {
         $canceller = $this->canceller;
         $this->canceller = null;
@@ -109,7 +110,7 @@ public function cancel()
         }
     }
 
-    private function resolver(callable $onFulfilled = null, callable $onRejected = null)
+    private function resolver(callable $onFulfilled = null, callable $onRejected = null): callable
     {
         return function ($resolve, $reject) use ($onFulfilled, $onRejected) {
             $this->handlers[] = function (PromiseInterface $promise) use ($onFulfilled, $onRejected, $resolve, $reject) {
@@ -120,7 +121,7 @@ private function resolver(callable $onFulfilled = null, callable $onRejected = n
         };
     }
 
-    private function resolve($value = null)
+    private function resolve($value = null): void
     {
         if (null !== $this->result) {
             return;
@@ -129,7 +130,7 @@ private function resolve($value = null)
         $this->settle(resolve($value));
     }
 
-    private function reject(\Throwable $reason)
+    private function reject(\Throwable $reason): void
     {
         if (null !== $this->result) {
             return;
@@ -138,7 +139,7 @@ private function reject(\Throwable $reason)
         $this->settle(reject($reason));
     }
 
-    private function settle(PromiseInterface $result)
+    private function settle(PromiseInterface $result): void
     {
         $result = $this->unwrap($result);
 
@@ -165,7 +166,7 @@ private function settle(PromiseInterface $result)
         }
     }
 
-    private function unwrap($promise)
+    private function unwrap($promise): PromiseInterface
     {
         while ($promise instanceof self && null !== $promise->result) {
             $promise = $promise->result;
@@ -174,7 +175,7 @@ private function unwrap($promise)
         return $promise;
     }
 
-    private function call(callable $callback)
+    private function call(callable $callback): void
     {
         // Use reflection to inspect number of arguments expected by this callback.
         // We did some careful benchmarking here: Using reflection to avoid unneeded

src/PromiseInterface.php

@@ -32,7 +32,7 @@ interface PromiseInterface
      * @param callable|null $onRejected
      * @return PromiseInterface
      */
-    public function then(callable $onFulfilled = null, callable $onRejected = null);
+    public function then(?callable $onFulfilled = null, ?callable $onRejected = null): PromiseInterface;
 
     /**
      * Consumes the promise's ultimate value if the promise fulfills, or handles the
@@ -48,7 +48,7 @@ public function then(callable $onFulfilled = null, callable $onRejected = null);
      * @param callable|null $onRejected
      * @return void
      */
-    public function done(callable $onFulfilled = null, callable $onRejected = null);
+    public function done(callable $onFulfilled = null, callable $onRejected = null): void;
 
     /**
      * Registers a rejection handler for promise. It is a shortcut for:
@@ -63,7 +63,7 @@ public function done(callable $onFulfilled = null, callable $onRejected = null);
      * @param callable $onRejected
      * @return PromiseInterface
      */
-    public function otherwise(callable $onRejected);
+    public function otherwise(callable $onRejected): PromiseInterface;
 
     /**
      * Allows you to execute "cleanup" type tasks in a promise chain.
@@ -110,7 +110,7 @@ public function otherwise(callable $onRejected);
      * @param callable $onFulfilledOrRejected
      * @return PromiseInterface
      */
-    public function always(callable $onFulfilledOrRejected);
+    public function always(callable $onFulfilledOrRejected): PromiseInterface;
 
     /**
      * The `cancel()` method notifies the creator of the promise that there is no
@@ -121,5 +121,5 @@ public function always(callable $onFulfilledOrRejected);
      *
      * @return void
      */
-    public function cancel();
+    public function cancel(): void;
 }

src/PromisorInterface.php

@@ -9,5 +9,5 @@ interface PromisorInterface
      *
      * @return PromiseInterface
      */
-    public function promise();
+    public function promise(): PromiseInterface;
 }

src/RejectedPromise.php

@@ -11,14 +11,14 @@ public function __construct(\Throwable $reason)
         $this->reason = $reason;
     }
 
-    public function then(callable $onFulfilled = null, callable $onRejected = null)
+    public function then(callable $onFulfilled = null, callable $onRejected = null): PromiseInterface
     {
         if (null === $onRejected) {
             return $this;
         }
 
-        return new Promise(function (callable $resolve, callable $reject) use ($onRejected) {
-            enqueue(function () use ($resolve, $reject, $onRejected) {
+        return new Promise(function (callable $resolve, callable $reject) use ($onRejected): void {
+            enqueue(function () use ($resolve, $reject, $onRejected): void {
                 try {
                     $resolve($onRejected($this->reason));
                 } catch (\Throwable $exception) {
@@ -28,7 +28,7 @@ public function then(callable $onFulfilled = null, callable $onRejected = null)
         });
     }
 
-    public function done(callable $onFulfilled = null, callable $onRejected = null)
+    public function done(callable $onFulfilled = null, callable $onRejected = null): void
     {
         enqueue(function () use ($onRejected) {
             if (null === $onRejected) {
@@ -51,7 +51,7 @@ public function done(callable $onFulfilled = null, callable $onRejected = null)
         });
     }
 
-    public function otherwise(callable $onRejected)
+    public function otherwise(callable $onRejected): PromiseInterface
     {
         if (!_checkTypehint($onRejected, $this->reason)) {
             return $this;
@@ -60,16 +60,16 @@ public function otherwise(callable $onRejected)
         return $this->then(null, $onRejected);
     }
 
-    public function always(callable $onFulfilledOrRejected)
+    public function always(callable $onFulfilledOrRejected): PromiseInterface
     {
-        return $this->then(null, function (\Throwable $reason) use ($onFulfilledOrRejected) {
-            return resolve($onFulfilledOrRejected())->then(function () use ($reason) {
+        return $this->then(null, function (\Throwable $reason) use ($onFulfilledOrRejected): PromiseInterface {
+            return resolve($onFulfilledOrRejected())->then(function () use ($reason): PromiseInterface {
                 return new RejectedPromise($reason);
             });
         });
     }
 
-    public function cancel()
+    public function cancel(): void
     {
     }
 }