Add traversable paginator (#3783)

CHANGELOG.md

@@ -5,6 +5,7 @@
 * Doctrine: Better exception to find which resource is linked to an exception (#3965)
 * Doctrine: Allow mixed type value for date filter (notice if invalid) (#3870)
 * MongoDB: `date_immutable` support (#3940)
+* Add `TraversablePaginator` (#3783)
 
 ## 2.6.3
 

src/DataProvider/TraversablePaginator.php

@@ -0,0 +1,90 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <dunglas@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Core\DataProvider;
+
+final class TraversablePaginator implements \IteratorAggregate, PaginatorInterface
+{
+    private $traversable;
+    private $currentPage;
+    private $itemsPerPage;
+    private $totalItems;
+
+    public function __construct(\Traversable $iterator, float $currentPage, float $itemsPerPage, float $totalItems)
+    {
+        $this->traversable = $iterator;
+        $this->currentPage = $currentPage;
+        $this->itemsPerPage = $itemsPerPage;
+        $this->totalItems = $totalItems;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getCurrentPage(): float
+    {
+        return $this->currentPage;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getLastPage(): float
+    {
+        if (0. >= $this->itemsPerPage) {
+            return 1.;
+        }
+
+        return max(ceil($this->totalItems / $this->itemsPerPage) ?: 1., 1.);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getItemsPerPage(): float
+    {
+        return $this->itemsPerPage;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getTotalItems(): float
+    {
+        return $this->totalItems;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function count(): int
+    {
+        if ($this->getCurrentPage() < $this->getLastPage()) {
+            return (int) ceil($this->itemsPerPage);
+        }
+
+        if (0. >= $this->itemsPerPage) {
+            return (int) ceil($this->totalItems);
+        }
+
+        return $this->totalItems % $this->itemsPerPage;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getIterator(): \Traversable
+    {
+        return $this->traversable;
+    }
+}

tests/DataProvider/TraversablePaginatorTest.php

@@ -0,0 +1,56 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <dunglas@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Core\Tests\DataProvider;
+
+use ApiPlatform\Core\DataProvider\TraversablePaginator;
+use ArrayIterator;
+use PHPUnit\Framework\TestCase;
+
+class TraversablePaginatorTest extends TestCase
+{
+    /**
+     * @dataProvider initializeProvider
+     */
+    public function testInitialize(
+        array $results,
+        float $currentPage,
+        float $perPage,
+        float $totalItems,
+        float $lastPage,
+        float $currentItems
+    ): void {
+        $traversable = new ArrayIterator($results);
+
+        $paginator = new TraversablePaginator($traversable, $currentPage, $perPage, $totalItems);
+
+        self::assertEquals($totalItems, $paginator->getTotalItems());
+        self::assertEquals($currentPage, $paginator->getCurrentPage());
+        self::assertEquals($lastPage, $paginator->getLastPage());
+        self::assertEquals($perPage, $paginator->getItemsPerPage());
+        self::assertEquals($currentItems, $paginator->count());
+
+        self::assertSame($results, iterator_to_array($paginator));
+    }
+
+    public function initializeProvider(): array
+    {
+        return [
+            'First of three pages of 3 items each' => [[0, 1, 2, 3, 4, 5, 6], 1, 3, 7, 3, 3],
+            'Second of two pages of 3 items for the first page and 2 for the second' => [[0, 1, 2, 3, 4], 2, 3, 5, 2, 2],
+            'Empty results' => [[], 1, 2, 0, 1, 0],
+            '0 items per page' => [[0, 1, 2, 3], 1, 0, 4, 1, 4],
+            'Total items less than items per page' => [[0, 1, 2], 1, 4, 3, 1, 3],
+        ];
+    }
+}