feat(view): add view processors (#1011)

Author: brendt

src/Tempest/View/src/Renderers/TempestViewRenderer.php

@@ -5,12 +5,14 @@
 namespace Tempest\View\Renderers;
 
 use Stringable;
+use Tempest\Container\Container;
 use Tempest\Support\Html\HtmlString;
 use Tempest\View\Exceptions\ViewCompilationError;
 use Tempest\View\Exceptions\ViewVariableIsReserved;
 use Tempest\View\GenericView;
 use Tempest\View\View;
 use Tempest\View\ViewCache;
+use Tempest\View\ViewConfig;
 use Tempest\View\ViewRenderer;
 use Throwable;
 
@@ -24,6 +26,8 @@ final class TempestViewRenderer implements ViewRenderer
     public function __construct(
         private readonly TempestViewCompiler $compiler,
         private readonly ViewCache $viewCache,
+        private readonly ViewConfig $viewConfig,
+        private readonly Container $container,
     ) {
     }
 
@@ -48,6 +52,8 @@ public function render(string|View $view): string
             compiledView: fn () => $this->cleanupCompiled($this->compiler->compile($view)),
         );
 
+        $view = $this->processView($view);
+
         return $this->renderCompiled($view, $path);
     }
 
@@ -80,6 +86,18 @@ private function cleanupCompiled(string $compiled): string
         return $compiled->toString();
     }
 
+    private function processView(View $view): View
+    {
+        foreach ($this->viewConfig->viewProcessors as $viewProcessorClass) {
+            /** @var \Tempest\View\ViewProcessor $viewProcessor */
+            $viewProcessor = $this->container->get($viewProcessorClass);
+
+            $view = $viewProcessor->process($view);
+        }
+
+        return $view;
+    }
+
     private function renderCompiled(View $_view, string $_path): string
     {
         $this->currentView = $_view;

src/Tempest/View/src/ViewConfig.php

@@ -15,11 +15,19 @@ public function __construct(
         /** @var array<array-key, class-string<\Tempest\View\ViewComponent>|\Tempest\View\ViewComponent> */
         public array $viewComponents = [],
 
+        /** @var class-string<\Tempest\View\ViewProcessor>[] */
+        public array $viewProcessors = [],
+
         /** @var class-string<\Tempest\View\ViewRenderer> */
         public string $rendererClass = TempestViewRenderer::class,
     ) {
     }
 
+    public function addViewProcessor(ClassReflector $viewProcessor): void
+    {
+        $this->viewProcessors[] = $viewProcessor->getName();
+    }
+
     public function addViewComponent(string $name, ClassReflector|AnonymousViewComponent $viewComponent): void
     {
         if (! str_starts_with($name, 'x-')) {

src/Tempest/View/src/ViewProcessor.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace Tempest\View;
+
+interface ViewProcessor
+{
+    public function process(View $view): View;
+}

src/Tempest/View/src/ViewProcessorDiscovery.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace Tempest\View;
+
+use Tempest\Discovery\Discovery;
+use Tempest\Discovery\DiscoveryLocation;
+use Tempest\Discovery\IsDiscovery;
+use Tempest\Reflection\ClassReflector;
+
+final class ViewProcessorDiscovery implements Discovery
+{
+    use IsDiscovery;
+
+    public function __construct(
+        private readonly ViewConfig $viewConfig,
+    ) {
+    }
+
+    public function discover(DiscoveryLocation $location, ClassReflector $class): void
+    {
+        if (! $class->implements(ViewProcessor::class)) {
+            return;
+        }
+
+        $this->discoveryItems->add($location, [$class->getName()]);
+    }
+
+    public function apply(): void
+    {
+        foreach ($this->discoveryItems as [$className]) {
+            $viewProcessor = new ClassReflector($className);
+
+            $this->viewConfig->addViewProcessor($viewProcessor);
+        }
+    }
+}

tests/Fixtures/Views/TestViewProcessor.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Tests\Tempest\Fixtures\Views;
+
+use Tempest\View\View;
+use Tempest\View\ViewProcessor;
+
+final readonly class TestViewProcessor implements ViewProcessor
+{
+    public function process(View $view): View
+    {
+        return $view->data(global: 'test');
+    }
+}

tests/Integration/View/TempestViewRendererTest.php

@@ -514,4 +514,11 @@ public function test_html_tags(): void
         $this->assertStringContainsString('<body', $html);
         $this->assertStringContainsString('<!-- test comment -->', $html);
     }
+
+    public function test_view_processors(): void
+    {
+        $html = $this->render('<div>{{ $global }}</div>');
+
+        $this->assertStringEqualsStringIgnoringLineEndings('<div>test</div>', $html);
+    }
 }