Refactor reducer callbacks.

loophp · Sep 7, 2020 · 9d1e176 · 9d1e176
1 parent 1bb45f2
commit 9d1e176
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Showing 2 changed files with 49 additions and 38 deletions.
diff --git a/src/Operation/Group.php b/src/Operation/Group.php
@@ -16,13 +16,13 @@
 final class Group extends AbstractOperation
 {
     /**
-     * @psalm-return Closure(null|callable(TKey, T):(TKey)): Closure(Iterator<TKey, T>): Generator<int, list<T>>
+     * @psalm-return Closure(null|callable(TKey, T):(TKey|null)): Closure(Iterator<TKey, T>): Generator<int, T|list<T>>
      */
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param null|callable(TKey, T):(T|TKey) $callable
+             * @psalm-param null|callable(TKey, T):(TKey|null) $callable
              */
             static function (?callable $callable = null): Closure {
                 return
@@ -32,45 +32,54 @@ static function (?callable $callable = null): Closure {
                      * @psalm-return Generator<int, list<T>>
                      */
                     static function (Iterator $iterator) use ($callable): Generator {
+                        /** @psalm-var callable(T, TKey): (TKey|null) $callable */
                         $callable = $callable ??
                             /**
-                             * @param mixed $key
-                             * @psalm-param TKey $key
-                             *
                              * @param mixed $value
                              * @psalm-param T $value
                              *
+                             * @param mixed $key
+                             * @psalm-param TKey $key
+                             *
                              * @return mixed
                              * @psalm-return TKey
                              */
                             static function ($value, $key) {
                                 return $key;
                             };
 
-                        $callback =
+                        $reducerFactory =
                             /**
-                             * @psalm-param array<TKey, list<T>> $collect
-                             *
-                             * @param mixed $value
-                             * @psalm-param T $value
-                             *
-                             * @param mixed $key
-                             * @psalm-param TKey $key
+                             * @psalm-param callable(T, TKey): (TKey|null) $callback
                              *
-                             * @psalm-return array<TKey, list<T>>
+                             * @psalm-return Closure(array<TKey, T|list<T>>, T, TKey): array<TKey, T|list<T>>
                              */
-                            static function (array $collect, $value, $key) use ($callable): array {
-                                if (null !== $groupKey = $callable($value, $key)) {
-                                    $collect[$groupKey][] = $value;
-                                } else {
-                                    $collect[$key] = $value;
-                                }
+                            static function (callable $callback): Closure {
+                                return
+                                    /**
+                                     * @psalm-param array<TKey, list<T>> $collect
+                                     *
+                                     * @param mixed $value
+                                     * @psalm-param T $value
+                                     *
+                                     * @param mixed $key
+                                     * @psalm-param TKey $key
+                                     *
+                                     * @psalm-return non-empty-array<TKey, T|list<T>>
+                                     */
+                                    static function (array $collect, $value, $key) use ($callback): array {
+                                        if (null !== $groupKey = $callback($value, $key)) {
+                                            $collect[$groupKey][] = $value;
+                                        } else {
+                                            $collect[$key] = $value;
+                                        }
 
-                                return $collect;
+                                        return $collect;
+                                    };
                             };
 
                         /** @psalm-var callable(Iterator<TKey, T>): Generator<TKey, T> $foldLeft */
-                        $foldLeft = FoldLeft::of()($callback)([]);
+                        $foldLeft = FoldLeft::of()($reducerFactory($callable))([]);
 
                         return yield from ($foldLeft($iterator))->current();
                     };

diff --git a/src/Operation/Implode.php b/src/Operation/Implode.php
@@ -13,32 +13,34 @@
  * @psalm-template TKey
  * @psalm-template TKey of array-key
  * @psalm-template T
+ *
+ * phpcs:disable Generic.Files.LineLength.TooLong
  */
 final class Implode extends AbstractOperation
 {
     public function __invoke(): Closure
     {
         return static function (string $glue): Closure {
             return static function (Iterator $iterator) use ($glue): Generator {
-                $callback =
-                    /**
-                     * @psalm-param TKey $key
-                     * @psalm-param CachingIterator $iterator
-                     *
-                     * @param mixed $key
-                     * @param mixed $iterator
-                     */
-                    static function (string $carry, string $item, $key, CachingIterator $iterator) use ($glue): string {
-                        $carry .= $item;
+                $reducerFactory = static function (string $glue): Closure {
+                    return
+                        /**
+                         * @psalm-param TKey $key
+                         *
+                         * @param mixed $key
+                         */
+                        static function (string $carry, string $item, $key, CachingIterator $iterator) use ($glue): string {
+                            $carry .= $item;
 
-                        if ($iterator->hasNext()) {
-                            $carry .= $glue;
-                        }
+                            if ($iterator->hasNext()) {
+                                $carry .= $glue;
+                            }
 
-                        return $carry;
-                    };
+                            return $carry;
+                        };
+                };
 
-                return yield from FoldLeft::of()($callback)('')(new CachingIterator($iterator));
+                return yield from FoldLeft::of()($reducerFactory($glue))('')(new CachingIterator($iterator));
             };
         };
     }