feat: add new function to output registered languages as list

to do:
- add documentation
- maybe add other output formats

src/Extension.php

@@ -17,6 +17,7 @@
 use Psr\Log\NullLogger;
 use Twig\Extension\AbstractExtension;
 use Twig\TwigFilter;
+use Twig\TwigFunction;
 
 /**
  * @see \Brotkrueml\TwigCodeHighlight\Tests\ExtensionTest
@@ -49,6 +50,9 @@ public function __construct(
         }
     }
 
+    /**
+     * @return list<TwigFilter>
+     */
     public function getFilters(): array
     {
         return [
@@ -62,6 +66,19 @@ public function getFilters(): array
         ];
     }
 
+    /**
+     * @return list<TwigFunction>
+     */
+    public function getFunctions(): array
+    {
+        return [
+            new TwigFunction(
+                'codehighlight_languages',
+                $this->languages(...),
+            ),
+        ];
+    }
+
     private function highlight(
         string $code,
         ?string $language,
@@ -160,4 +177,16 @@ private function addEmphasizeLines(string $code): string
 
         return \implode("\n", $newLines);
     }
+
+    private function languages(): string
+    {
+        $registeredLanguages = Highlighter::listRegisteredLanguages();
+
+        \sort($registeredLanguages);
+
+        return \implode(
+            "\n",
+            \array_map(static fn(string $language): string => '* ' . $language, $registeredLanguages),
+        );
+    }
 }

tests/ExtensionTest.php

@@ -32,11 +32,17 @@ protected function setUp(): void
     }
 
     #[Test]
-    public function getNameReturnExtensionName(): void
+    public function registeredFiltersAreAvailable(): void
     {
         self::assertSame('codehighlight', $this->subject->getFilters()[0]->getName());
     }
 
+    #[Test]
+    public function registeredFunctionsAreAvailable(): void
+    {
+        self::assertSame('codehighlight_languages', $this->subject->getFunctions()[0]->getName());
+    }
+
     #[Test]
     #[DataProvider('providerForHighlightThroughTwigTemplate')]
     public function highlightThroughTwigTemplate(string $filterArguments, string $code, string $expected): void
@@ -322,4 +328,28 @@ public function instantiatedWithClassesAndClassesGivenViaFilter(): void
 
         self::assertSame('<pre class="some-default-class some-special-class"><code class="hljs plaintext">some text</code></pre>', $template->render());
     }
+
+    #[Test]
+    public function registeredLanguagesAreReturnedCorrectly(): void
+    {
+        $loader = new ArrayLoader([
+            'index' => '{{ codehighlight_languages() }}',
+        ]);
+        $twig = new Environment($loader, [
+            'debug' => true,
+            'cache' => false,
+        ]);
+        $twig->addExtension($this->subject);
+
+        $template = $twig->load('index');
+
+        // Validate sorting
+        $actual = $template->render();
+        self::assertStringStartsWith('* 1c', $actual);
+        self::assertStringEndsWith('* zephir', $actual);
+
+        // Validate random language is available and languages are separated by a line feed
+        $actualAsArray = \explode("\n", $actual);
+        self::assertContains('* php', $actualAsArray);
+    }
 }