[12.x] create new @hasStack Blade directive (#57788)

* create new `@hasStack` Blade directive

this new `@hasStack` directive can be used to wrap `@stack` directives for conditional output depending on if the stack is empty or not. this can be useful if you want some wrapping code around the stack only if it is not empty.

mimicked the `@hasSection` directive for naming.

* minor formatting

Author: browner12

src/Illuminate/View/Compilers/Concerns/CompilesConditionals.php

@@ -137,6 +137,17 @@ protected function compileHasSection($expression)
         return "<?php if (! empty(trim(\$__env->yieldContent{$expression}))): ?>";
     }
 
+    /**
+     * Compile the has-stack statements into valid PHP.
+     *
+     * @param  string  $expression
+     * @return string
+     */
+    protected function compileHasStack($expression)
+    {
+        return "<?php if (! \$__env->isStackEmpty{$expression}): ?>";
+    }
+
     /**
      * Compile the section-missing statements into valid PHP.
      *

src/Illuminate/View/Concerns/ManagesStacks.php

@@ -148,7 +148,7 @@ protected function extendPrepend($section, $content)
      */
     public function yieldPushContent($section, $default = '')
     {
-        if (! isset($this->pushes[$section]) && ! isset($this->prepends[$section])) {
+        if ($this->isStackEmpty($section)) {
             return $default;
         }
 
@@ -165,6 +165,14 @@ public function yieldPushContent($section, $default = '')
         return $output;
     }
 
+    /**
+     * Determine if the stack has any content in it.
+     */
+    public function isStackEmpty(string $section): bool
+    {
+        return ! isset($this->pushes[$section]) && ! isset($this->prepends[$section]);
+    }
+
     /**
      * Flush all of the stacks.
      *

tests/View/Blade/BladeHasStackTest.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Illuminate\Tests\View\Blade;
+
+class BladeHasStackTest extends AbstractBladeTestCase
+{
+    public function testHasStackStatementsAreCompiled()
+    {
+        $string = '@hasStack("stack")
+breeze
+@endif';
+        $expected = '<?php if (! $__env->isStackEmpty("stack")): ?>
+breeze
+<?php endif; ?>';
+        $this->assertEquals($expected, $this->compiler->compileString($string));
+    }
+}

tests/View/Concerns/ManagesStacksTest.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace Illuminate\Tests\View\Concerns;
+
+use Illuminate\View\Concerns\ManagesStacks;
+use PHPUnit\Framework\TestCase;
+
+class ManagesStacksTest extends TestCase
+{
+    public function testStackIsEmpty()
+    {
+        $this->assertTrue((new FakeViewFactory)->isStackEmpty('my-stack'));
+    }
+
+    public function testStackIsNotEmptyWithPushedContent()
+    {
+        $object = new FakeViewFactory;
+        $object->startPush('my-stack', 'some pushed content');
+
+        $this->assertFalse($object->isStackEmpty('my-stack'));
+    }
+
+    public function testStackIsNotEmptyWithPrependedContent()
+    {
+        $object = new FakeViewFactory;
+        $object->startPrepend('my-stack', 'some prepended content');
+
+        $this->assertFalse($object->isStackEmpty('my-stack'));
+    }
+}
+
+class FakeViewFactory
+{
+    use ManagesStacks;
+
+    protected int $renderCount = 0;
+}