feat: Implement ArrayAccess for in-memory paginator.

This allows to use this paginator as a regular array.

Author: b00gizm

src/Infrastructure/InMemory/Paginator.php

@@ -4,13 +4,14 @@
 
 namespace GeekCell\Ddd\Infrastructure\InMemory;
 
+use ArrayAccess;
 use EmptyIterator;
 use GeekCell\Ddd\Contracts\Domain\Paginator as PaginatorInterface;
 use GeekCell\Ddd\Domain\Collection;
 use LimitIterator;
 use Traversable;
 
-class Paginator implements PaginatorInterface
+class Paginator implements PaginatorInterface, ArrayAccess
 {
     public function __construct(
         private readonly Collection $collection,
@@ -52,6 +53,57 @@ public function getTotalItems(): int
         return count($this->collection);
     }
 
+    /**
+     * @inheritDoc
+     */
+    public function offsetExists(mixed $offset): bool
+    {
+        if (!is_int($offset)) {
+            return false;
+        }
+
+        return $offset >= 0 && $offset < $this->count();
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function offsetGet(mixed $offset): mixed
+    {
+        if (!$this->offsetExists($offset)) {
+            return null;
+        }
+
+        $realOffset = $offset + $this->getCurrentPage();
+        foreach ($this->getIterator() as $index => $item) {
+            if ($index === $realOffset) {
+                return $item;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * This method is not supported since it is not appropriate for a paginator.
+     *
+     * @inheritDoc
+     */
+    public function offsetSet(mixed $offset, mixed $value): void
+    {
+        // Unsupported since it is not appropriate for a paginator.
+    }
+
+    /**
+     * This method is not supported since it is not appropriate for a paginator.
+     *
+     * @inheritDoc
+     */
+    public function offsetUnset(mixed $offset): void
+    {
+        // Unsupported since it is not appropriate for a paginator.
+    }
+
     /**
      * @inheritDoc
      */

tests/Fixtures/Counter.php

@@ -9,4 +9,9 @@ class Counter
     public function __construct(private int $value)
     {
     }
+
+    public function getValue(): int
+    {
+        return $this->value;
+    }
 }

tests/Infrastructure/InMemory/PaginatorTest.php

@@ -90,6 +90,70 @@ public function testGetTotalItems(): void
         $this->assertEquals(10, $result);
     }
 
+    public function testArrayAccess(): void
+    {
+        // Given
+        $items = [
+            new Counter(1),
+            new Counter(2),
+            new Counter(3),
+            new Counter(4),
+            new Counter(5),
+        ];
+
+        /** @var Mockery\MockInterface $collection */
+        $collection = Mockery::mock(Collection::class);
+        $collection
+            ->shouldReceive('getIterator')
+            ->andReturn(new ArrayIterator($items));
+        $collection
+            ->shouldReceive('count')
+            ->andReturn(count($items));
+
+        // When
+
+        /** @var Collection $collection */
+        $paginator = new InMemoryPaginator($collection, 2, 2);
+        $result1 = $paginator[0];
+        $result2 = $paginator[4];
+
+        // Then
+        $this->assertInstanceOf(Counter::class, $result1);
+        $this->assertEquals(3, $result1->getValue());
+        $this->assertNull($result2);
+    }
+
+    public function testArrayAccessWithInvalidOffset(): void
+    {
+        // Given
+        $items = [
+            new Counter(1),
+            new Counter(2),
+            new Counter(3),
+            new Counter(4),
+            new Counter(5),
+        ];
+
+        /** @var Mockery\MockInterface $collection */
+        $collection = Mockery::mock(Collection::class);
+        $collection
+            ->shouldReceive('getIterator')
+            ->andReturn(new ArrayIterator($items));
+        $collection
+            ->shouldReceive('count')
+            ->andReturn(count($items));
+
+        // When
+
+        /** @var Collection $collection */
+        $paginator = new InMemoryPaginator($collection, 2, 2);
+
+        // Then
+        $this->assertNull($paginator[-1]);
+        $this->assertNull($paginator[0.5]);
+        $this->assertNull($paginator['invalid']);
+    }
+
     /**
      * @covers \GeekCell\Ddd\Infrastructure\InMemoryPaginator::getIterator
      * @covers \GeekCell\Ddd\Infrastructure\InMemoryPaginator::count