[7.x] Once Blocks (#33812)

Once blocks for Blade.

Author: taylorotwell

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

@@ -2,6 +2,8 @@
 
 namespace Illuminate\View\Compilers\Concerns;
 
+use Illuminate\Support\Str;
+
 trait CompilesConditionals
 {
     /**
@@ -279,4 +281,26 @@ protected function compileEndSwitch()
     {
         return '<?php endswitch; ?>';
     }
+
+    /**
+     * Compile an once block into valid PHP.
+     *
+     * @return string
+     */
+    protected function compileOnce($id = null)
+    {
+        $id = $id ? $this->stripParentheses($id) : "'".(string) Str::uuid()."'";
+
+        return '<?php if (! $__env->hasRenderedOnce('.$id.')): $__env->markAsRenderedOnce('.$id.'); ?>';
+    }
+
+    /**
+     * Compile an end-once block into valid PHP.
+     *
+     * @return string
+     */
+    public function compileEndOnce()
+    {
+        return '<?php endif; ?>';
+    }
 }

src/Illuminate/View/Factory.php

@@ -83,6 +83,13 @@ class Factory implements FactoryContract
      */
     protected $renderCount = 0;
 
+    /**
+     * The "once" block IDs that have been rendered.
+     *
+     * @var array
+     */
+    protected $renderedOnce = [];
+
     /**
      * Create a new view factory instance.
      *
@@ -352,6 +359,28 @@ public function doneRendering()
         return $this->renderCount == 0;
     }
 
+    /**
+     * Determine if the given once token has been rendered.
+     *
+     * @param  string  $id
+     * @return bool
+     */
+    public function hasRenderedOnce(string $id)
+    {
+        return isset($this->renderedOnce[$id]);
+    }
+
+    /**
+     * Mark the given once token as having been rendered.
+     *
+     * @param  string  $id
+     * @return void
+     */
+    public function markAsRenderedOnce(string $id)
+    {
+        $this->renderedOnce[$id] = true;
+    }
+
     /**
      * Add a location to the array of view locations.
      *
@@ -434,6 +463,7 @@ public function addExtension($extension, $engine, $resolver = null)
     public function flushState()
     {
         $this->renderCount = 0;
+        $this->renderedOnce = [];
 
         $this->flushSections();
         $this->flushStacks();

tests/View/ViewFactoryTest.php

@@ -59,6 +59,16 @@ public function testExistsPassesAndFailsViews()
         $this->assertTrue($factory->exists('bar'));
     }
 
+    public function testRenderingOnceChecks()
+    {
+        $factory = $this->getFactory();
+        $this->assertFalse($factory->hasRenderedOnce('foo'));
+        $factory->markAsRenderedOnce('foo');
+        $this->assertTrue($factory->hasRenderedOnce('foo'));
+        $factory->flushState();
+        $this->assertFalse($factory->hasRenderedOnce('foo'));
+    }
+
     public function testFirstCreatesNewViewInstanceWithProperPath()
     {
         unset($_SERVER['__test.view']);