[1.x] Allow setting title using a closure (#79)

functions.php

@@ -96,7 +96,7 @@ function layout(string $layout): void
 /**
  * Define the component's title.
  */
-function title(string $title): void
+function title(Closure|string $title): void
 {
     CompileContext::instance()->title = $title;
 }

src/Actions/ReturnTitle.php

@@ -2,6 +2,8 @@
 
 namespace Livewire\Volt\Actions;
 
+use Closure;
+use Illuminate\Container\Container;
 use Livewire\Volt\CompileContext;
 use Livewire\Volt\Component;
 use Livewire\Volt\Contracts\Action;
@@ -13,6 +15,12 @@ class ReturnTitle implements Action
      */
     public function execute(CompileContext $context, Component $component, array $arguments): ?string
     {
+        if ($context->title instanceof Closure) {
+            return Container::getInstance()->call(
+                Closure::bind($context->title, $component, $component::class),
+            );
+        }
+
         return $context->title;
     }
 }

src/CompileContext.php

@@ -20,7 +20,7 @@ public function __construct(
         public array $variables,
         public array $state,
         public ?string $layout,
-        public ?string $title,
+        public Closure|string|null $title,
         public ?Closure $listeners,
         public array $inlineListeners,
         public Closure|array $rules,

tests/Feature/Actions/ReturnTitleTest.php

@@ -17,3 +17,32 @@
 
     expect($result)->toBe('my title');
 });
+
+it('returns a static title using a closure', function () {
+    $context = CompileContext::make();
+
+    $context->title = fn () => 'my title from a closure';
+
+    $component = new class extends Component
+    {
+    };
+
+    $result = (new ReturnTitle)->execute($context, $component, []);
+
+    expect($result)->toBe('my title from a closure');
+});
+
+it('returns a computed title using a closure', function () {
+    $context = CompileContext::make();
+
+    $context->title = fn () => "welcome back $this->username";
+
+    $component = new class extends Component
+    {
+        public string $username = 'Tom';
+    };
+
+    $result = (new ReturnTitle)->execute($context, $component, []);
+
+    expect($result)->toBe('welcome back Tom');
+});

tests/Feature/CompilerContext/TitleTest.php

@@ -17,3 +17,15 @@
 
     expect($context->title)->toBe('my custom title');
 });
+
+it('may be set using closures', function () {
+    $context = CompileContext::instance();
+
+    title(fn () => 'my custom title from a closure');
+
+    expect($context->title)
+        ->toBeCallable()
+        ->and($context->title)
+        ->resolve()
+        ->toBe('my custom title from a closure');
+});