Merge pull request #214 from wmde/SeekableEntityIdPager

Add SeekableEntityIdPager

src/EntityId/InMemoryEntityIdPager.php

@@ -0,0 +1,61 @@
+<?php
+
+namespace Wikibase\DataModel\Services\EntityId;
+
+use Wikibase\DataModel\Entity\EntityId;
+
+/**
+ * The position markers are implementation dependent and are not
+ * interchangeable between different implementations.
+ *
+ * @since 3.14
+ *
+ * @author Addshore
+ * @author Jeroen De Dauw
+ * @license GPL-2.0-or-later
+ */
+class InMemoryEntityIdPager implements SeekableEntityIdPager {
+
+	/**
+	 * @var EntityId[]
+	 */
+	private $entityIds = [];
+
+	/**
+	 * @var int
+	 */
+	private $offset = 0;
+
+	/**
+	 * @param EntityId ...$ids
+	 */
+	public function __construct( ...$ids ) {
+		$this->entityIds = $ids;
+	}
+
+	public function addEntityId( EntityId $entityId ) {
+		$this->entityIds[] = $entityId;
+	}
+
+	/**
+	 * @see EntityIdPager::fetchIds
+	 *
+	 * @param int $limit
+	 *
+	 * @return EntityId[]
+	 */
+	public function fetchIds( $limit ) {
+		$entityIds = array_slice( $this->entityIds, $this->offset, $limit );
+		$this->offset += count( $entityIds );
+		return $entityIds;
+	}
+
+	public function getPosition() {
+		return $this->offset;
+	}
+
+	public function setPosition( $position ) {
+		$this->offset = $position;
+	}
+
+}

src/EntityId/SeekableEntityIdPager.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace Wikibase\DataModel\Services\EntityId;
+
+/**
+ * The position markers are implementation dependent and are not
+ * interchangeable between different implementations.
+ *
+ * @since 3.14
+ *
+ * @license GPL-2.0-or-later
+ */
+interface SeekableEntityIdPager extends EntityIdPager {
+
+	/**
+	 * @return mixed Round trips with method setPosition
+	 */
+	public function getPosition();
+
+	/**
+	 * @param mixed $position Round trips with method getPosition
+	 */
+	public function setPosition( $position );
+
+}

tests/unit/EntityId/InMemoryEntityIdPagerTest.php

@@ -0,0 +1,121 @@
+<?php
+
+namespace Wikibase\DataModel\Services\Tests\EntityId;
+
+use PHPUnit\Framework\TestCase;
+use Wikibase\DataModel\Entity\ItemId;
+use Wikibase\DataModel\Services\EntityId\InMemoryEntityIdPager;
+
+/**
+ * @covers \Wikibase\DataModel\Services\EntityId\InMemoryEntityIdPager
+ *
+ * @license GPL-2.0-or-later
+ */
+class InMemoryEntityIdPagerTest extends TestCase {
+
+	public function testReturnsEmptyArrayWhenThereAreNoIds() {
+		$this->assertSame(
+			[],
+			( new InMemoryEntityIdPager() )->fetchIds( 10 )
+		);
+	}
+
+	public function testReturnsTheFirstIdsUpToLimit() {
+		$pager = new InMemoryEntityIdPager(
+			new ItemId( 'Q1' ),
+			new ItemId( 'Q2' ),
+			new ItemId( 'Q3' ),
+			new ItemId( 'Q4' ),
+			new ItemId( 'Q5' )
+		);
+
+		$this->assertEquals(
+			[
+				new ItemId( 'Q1' ),
+				new ItemId( 'Q2' ),
+			],
+			$pager->fetchIds( 2 )
+		);
+	}
+
+	public function testReturnsLessItemsIfThereAreFew() {
+		$pager = new InMemoryEntityIdPager(
+			new ItemId( 'Q1' ),
+			new ItemId( 'Q2' )
+		);
+
+		$this->assertEquals(
+			[
+				new ItemId( 'Q1' ),
+				new ItemId( 'Q2' ),
+			],
+			$pager->fetchIds( 5 )
+		);
+	}
+
+	public function testReturnsNextBatch() {
+		$pager = new InMemoryEntityIdPager(
+			new ItemId( 'Q1' ),
+			new ItemId( 'Q2' ),
+			new ItemId( 'Q3' ),
+			new ItemId( 'Q4' ),
+			new ItemId( 'Q5' )
+		);
+
+		$pager->fetchIds( 2 );
+
+		$this->assertEquals(
+			[
+				new ItemId( 'Q3' ),
+				new ItemId( 'Q4' ),
+			],
+			$pager->fetchIds( 2 )
+		);
+	}
+
+	public function testCanResumeFromPosition() {
+		$firstPager = new InMemoryEntityIdPager(
+			new ItemId( 'Q1' ),
+			new ItemId( 'Q2' ),
+			new ItemId( 'Q3' ),
+			new ItemId( 'Q4' ),
+			new ItemId( 'Q5' )
+		);
+
+		$secondPager = new InMemoryEntityIdPager(
+			new ItemId( 'Q1' ),
+			new ItemId( 'Q2' ),
+			new ItemId( 'Q3' ),
+			new ItemId( 'Q4' ),
+			new ItemId( 'Q5' )
+		);
+
+		$firstPager->fetchIds( 2 );
+		$secondPager->setPosition( $firstPager->getPosition() );
+
+		$this->assertEquals(
+			[
+				new ItemId( 'Q3' ),
+				new ItemId( 'Q4' ),
+			],
+			$secondPager->fetchIds( 2 )
+		);
+	}
+
+	public function testCanAddIds() {
+		$pager = new InMemoryEntityIdPager(
+			new ItemId( 'Q1' )
+		);
+
+		$pager->addEntityId( new ItemId( 'Q2' ) );
+
+		$this->assertEquals(
+			[
+				new ItemId( 'Q1' ),
+				new ItemId( 'Q2' ),
+			],
+			$pager->fetchIds( 2 )
+		);
+	}
+
+}