RDF Formatter for Math data type

Bug: T126349
Change-Id: I15fbeec282868b4267a3e3d15740f2c3ff37ea48

MathMLRdfBuilder.php

@@ -0,0 +1,35 @@
+<?php
+
+use Wikibase\DataModel\Snak\PropertyValueSnak;
+use Wikibase\Rdf\ValueSnakRdfBuilder;
+use Wikimedia\Purtle\RdfWriter;
+
+class MathMLRdfBuilder implements ValueSnakRdfBuilder {
+
+	/**
+	 * Adds a value
+	 *
+	 * @param RdfWriter $writer
+	 * @param string $propertyValueNamespace Property value relation namespace
+	 * @param string $propertyValueLName Property value relation name
+	 * @param string $dataType Property data type
+	 * @param PropertyValueSnak $snak
+	 */
+	public function addValue(
+		RdfWriter $writer,
+		$propertyValueNamespace,
+		$propertyValueLName,
+		$dataType,
+		PropertyValueSnak $snak
+	) {
+		$renderer = new MathMathML( $snak->getDataValue()->getValue() );
+		if ( $renderer->checkTeX() && $renderer->render() ) {
+			$mml = $renderer->getMathml();
+		} else {
+			$err = $renderer->getLastError();
+			$mml = "<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><merror>$err</merror></math>";
+		}
+		$writer->say( $propertyValueNamespace, $propertyValueLName )
+			->value( $mml, 'http://www.w3.org/1998/Math/MathML' );
+	}
+}

MathWikidataHook.php

@@ -2,8 +2,12 @@
 
 use ValueFormatters\FormatterOptions;
 use ValueParsers\StringParser;
+use Wikibase\Rdf\DedupeBag;
+use Wikibase\Rdf\EntityMentionListener;
+use Wikibase\Rdf\RdfVocabulary;
 use Wikibase\Repo\Parsers\WikibaseStringValueNormalizer;
 use Wikibase\Repo\WikibaseRepo;
+use Wikimedia\Purtle\RdfWriter;
 
 class MathWikidataHook {
 
@@ -41,6 +45,15 @@ class MathWikidataHook {
 				$wgOut->addModuleStyles( $styles );
 				return new MathFormatter( $format );
 			},
+			'rdf-builder-factory-callback' => function (
+				$mode,
+				RdfVocabulary $vocab,
+				RdfWriter $writer,
+				EntityMentionListener $tracker,
+				DedupeBag $dedupe
+			) {
+				return new MathMLRdfBuilder();
+			},
 		);
 	}
 

extension.json

@@ -28,7 +28,8 @@
 		"SpecialMathStatus": "SpecialMathStatus.php",
 		"MathValidator": "MathValidator.php",
 		"MathFormatter": "MathFormatter.php",
-		"MathWikidataHook": "MathWikidataHook.php"
+		"MathWikidataHook": "MathWikidataHook.php",
+		"MathMLRdfBuilder": "MathMLRdfBuilder.php"
 	},
 	"DefaultUserOptions": {
 		"math": "png"

tests/MathMLRdfBuilderTest.php

@@ -0,0 +1,72 @@
+<?php
+/**
+ * Test the MathML RDF formatter
+ *
+ * @group Math
+ * @covers MathMLRdfBuilder
+ * @author Moritz Schubotz (physikerwelt)
+ */
+
+use DataValues\StringValue;
+use Wikibase\DataModel\Entity\PropertyId;
+use Wikibase\DataModel\Snak\PropertyValueSnak;
+use Wikimedia\Purtle\NTriplesRdfWriter;
+
+class MathMLRdfBuilderTest extends MediaWikiTestCase {
+	const ACME_PREFIX_URL = 'http://acme/';
+	const ACME_REF = 'testing';
+	protected static $hasRestbase;
+
+	public static function setUpBeforeClass() {
+		$rbi = new MathRestbaseInterface();
+		self::$hasRestbase = $rbi->checkBackend( true );
+	}
+
+	/**
+	 * Sets up the fixture, for example, opens a network connection.
+	 * This method is called before a test is executed.
+	 */
+	protected function setUp() {
+		parent::setUp();
+		if ( !self::$hasRestbase ) {
+			$this->markTestSkipped( "Can not connect to Restbase Math interface." );
+		}
+	}
+
+	/**
+	 *
+	 * @param string $test
+	 * @return string
+	 */
+	private function makeCase( $test ) {
+		$builder = new MathMLRdfBuilder();
+		$writer = new NTriplesRdfWriter();
+		$writer->prefix( 'www', "http://www/" );
+		$writer->prefix( 'acme', self::ACME_PREFIX_URL );
+
+		$writer->start();
+		$writer->about( 'www', 'Q1' );
+
+		$snak = new PropertyValueSnak( new PropertyId( 'P1' ), new StringValue( $test ) );
+		$builder->addValue( $writer, 'acme', self::ACME_REF, 'DUMMY', $snak );
+
+		return trim( $writer->drain() );
+	}
+
+	public function testValidInput() {
+		$triples = $this->makeCase( 'a^2' );
+		$this->assertContains( self::ACME_PREFIX_URL . self::ACME_REF . '> "<math', $triples );
+		$this->assertContains( '<mi>a</mi>\n', $triples );
+		$this->assertContains( '<mn>2</mn>\n', $triples );
+		$this->assertContains( 'a^{2}', $triples );
+		$this->assertContains( '^^<http://www.w3.org/1998/Math/MathML> .', $triples );
+	}
+
+	public function testInvalidInput() {
+		$triples = $this->makeCase( '\notExists' );
+		$this->assertContains( '<math', $triples );
+		$this->assertContains( 'unknown function', $triples );
+		$this->assertContains( 'notExists', $triples );
+		$this->assertContains( '^^<http://www.w3.org/1998/Math/MathML> .', $triples );
+	}
+}