[10.x] Add Blade @session Directive (#49339)

* Add Blade `@session` Directive

* Fix test

* Refactor to `$__sessionPrevious` array for nesting

* Unset `$__sessionPrevious` if it is set and empty.

* use value

---------

Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/Illuminate/View/Compilers/BladeCompiler.php

@@ -30,6 +30,7 @@ class BladeCompiler extends Compiler implements CompilerInterface
         Concerns\CompilesLayouts,
         Concerns\CompilesLoops,
         Concerns\CompilesRawPhp,
+        Concerns\CompilesSessions,
         Concerns\CompilesStacks,
         Concerns\CompilesStyles,
         Concerns\CompilesTranslations,

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

@@ -0,0 +1,37 @@
+<?php
+
+namespace Illuminate\View\Compilers\Concerns;
+
+trait CompilesSessions
+{
+    /**
+     * Compile the session statements into valid PHP.
+     *
+     * @param  string  $expression
+     * @return string
+     */
+    protected function compileSession($expression)
+    {
+        $expression = $this->stripParentheses($expression);
+
+        return '<?php $__sessionArgs = ['.$expression.'];
+if (session()->has($__sessionArgs[0])) :
+if (isset($value)) { $__sessionPrevious[] = $value; }
+$value = session()->get($__sessionArgs[0]); ?>';
+    }
+
+    /**
+     * Compile the endsession statements into valid PHP.
+     *
+     * @param  string  $expression
+     * @return string
+     */
+    protected function compileEndsession($expression)
+    {
+        return '<?php unset($value);
+if (isset($__sessionPrevious) && !empty($__sessionPrevious)) { $value = array_pop($__sessionPrevious); }
+if (isset($__sessionPrevious) && empty($__sessionPrevious)) { unset($__sessionPrevious); }
+endif;
+unset($__sessionArgs); ?>';
+    }
+}

tests/View/Blade/BladeSessionTest.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace Illuminate\Tests\View\Blade;
+
+class BladeSessionTest extends AbstractBladeTestCase
+{
+    public function testSessionsAreCompiled()
+    {
+        $string = '
+@session(\'status\')
+    <span>{{ $value }}</span>
+@endsession';
+        $expected = '
+<?php $__sessionArgs = [\'status\'];
+if (session()->has($__sessionArgs[0])) :
+if (isset($value)) { $__sessionPrevious[] = $value; }
+$value = session()->get($__sessionArgs[0]); ?>
+    <span><?php echo e($value); ?></span>
+<?php unset($value);
+if (isset($__sessionPrevious) && !empty($__sessionPrevious)) { $value = array_pop($__sessionPrevious); }
+if (isset($__sessionPrevious) && empty($__sessionPrevious)) { unset($__sessionPrevious); }
+endif;
+unset($__sessionArgs); ?>';
+
+        $this->assertEquals($expected, $this->compiler->compileString($string));
+    }
+}