Add ??? Empty Coalesce Operator

lib/Twig/Extension/Core.php

@@ -251,6 +251,7 @@ public function getOperators()
                 'is not' => array('precedence' => 100, 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
                 '**' => array('precedence' => 200, 'class' => 'Twig_Node_Expression_Binary_Power', 'associativity' => Twig_ExpressionParser::OPERATOR_RIGHT),
                 '??' => array('precedence' => 300, 'class' => 'Twig_Node_Expression_NullCoalesce', 'associativity' => Twig_ExpressionParser::OPERATOR_RIGHT),
+                '???' => array('precedence' => 300, 'class' => 'Twig_Node_Expression_EmptyCoalesce', 'associativity' => Twig_ExpressionParser::OPERATOR_RIGHT),
             ),
         );
     }

lib/Twig/Node/Expression/EmptyCoalesce.php

@@ -0,0 +1,44 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+class Twig_Node_Expression_EmptyCoalesce extends \Twig_Node_Expression
+{
+
+    public function __construct(Twig_Node $left, Twig_Node $right, $lineno)
+    {
+        $left->setAttribute('ignore_strict_check', true);
+        $left->setAttribute('is_defined_test', false);
+        $right->setAttribute('ignore_strict_check', true);
+        $right->setAttribute('is_defined_test', false);
+        parent::__construct(
+            ['left' => $left, 'right' => $right],
+            ['ignore_strict_check' => true, 'is_defined_test' => false],
+            $lineno
+        );
+    }
+
+    public function compile(\Twig_Compiler $compiler)
+    {
+            $compiler
+                ->raw('((empty(')
+                ->subcompile($this->getNode('left'))
+                ->raw(') ? null : ')
+                ->subcompile($this->getNode('left'))
+                ->raw(') ?? (empty(')
+                ->subcompile($this->getNode('right'))
+                ->raw(') ? null : ')
+                ->subcompile($this->getNode('right'))
+                ->raw('))')
+            ;
+    }
+}
+
+class_alias('Twig_Node_Expression_EmptyCoalesce', 'Twig\Node\Expression\EmptyCoalesceExpression', false);

src/Node/Expression/EmptyCoalesceExpression.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Twig\Node\Expression;
+
+class_exists('Twig_Node_Expression_EmptyCoalesce');
+
+if (\false) {
+    class EmptyCoalesceExpression extends \Twig_Node_Expression_EmptyCoalesce
+    {
+    }
+}

test/Twig/Tests/Node/Expression/EmptyCoalesceTest.php

@@ -0,0 +1,22 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+class Twig_Tests_Node_Expression_EmptyCoalesceTest extends Twig_Test_NodeTestCase
+{
+    public function getTests()
+    {
+        $left = new Twig_Node_Expression_Name('foo', 1);
+        $right = new Twig_Node_Expression_Constant(2, 1);
+        $node = new Twig_Node_Expression_EmptyCoalesce($left, $right, 1);
+
+        return array(array($node, "((empty(// line 1\n(\$context[\"foo\"] ?? null)) ? null : (\$context[\"foo\"] ?? null)) ?? (empty(2) ? null : 2))"));
+    }
+}