Add ForElseNode

CHANGELOG

@@ -1,9 +1,9 @@
 # 3.19.0 (2025-XX-XX)
 
+ * Add `ForElseNode`
  * Deprecate `Twig\ExpressionParser::parseOnlyArguments()` and
   `Twig\ExpressionParser::parseArguments()` (use
   `Twig\ExpressionParser::parseNamedArguments()` instead)
-
  * Fix `constant()` behavior when used with `??`
  * Add the `invoke` filter
  * Make `{}` optional for the `types` tag

src/Node/ForElseNode.php

@@ -0,0 +1,41 @@
+<?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.
+ */
+
+namespace Twig\Node;
+
+use Twig\Attribute\YieldReady;
+use Twig\Compiler;
+
+/**
+ * Represents an else node in a for loop.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+#[YieldReady]
+class ForElseNode extends Node
+{
+    public function __construct(Node $body, int $lineno)
+    {
+        parent::__construct(['body' => $body], [], $lineno);
+    }
+
+    public function compile(Compiler $compiler): void
+    {
+        $compiler
+            ->addDebugInfo($this)
+            ->write("if (!\$context['_iterated']) {\n")
+            ->indent()
+            ->subcompile($this->getNode('body'))
+            ->outdent()
+            ->write("}\n")
+        ;
+    }
+}

src/Node/ForNode.php

@@ -35,6 +35,12 @@ class ForNode extends Node
             trigger_deprecation('twig/twig', '3.19', \sprintf('Passing not-null to the "ifexpr" argument of the "%s" constructor is deprecated.', static::class));
         }
 
+        if (null !== $else && !$else instanceof ForElseNode) {
+            trigger_deprecation('twig/twig', '3.19', \sprintf('Not passing an instance of "%s" to the "else" argument of the "%s" constructor is deprecated.', ForElseNode::class, static::class));
+
+            $else = new ForElseNode($else, $else->getTemplateLine());
+        }
+
         $nodes = ['key_target' => $keyTarget, 'value_target' => $valueTarget, 'seq' => $seq, 'body' => $body];
         if (null !== $else) {
             $nodes['else'] = $else;
@@ -93,13 +99,7 @@ class ForNode extends Node
         ;
 
         if ($this->hasNode('else')) {
-            $compiler
-                ->write("if (!\$context['_iterated']) {\n")
-                ->indent()
-                ->subcompile($this->getNode('else'))
-                ->outdent()
-                ->write("}\n")
-            ;
+            $compiler->subcompile($this->getNode('else'));
         }
 
         $compiler->write("\$_parent = \$context['_parent'];\n");

src/TokenParser/ForTokenParser.php

@@ -13,6 +13,7 @@
 namespace Twig\TokenParser;
 
 use Twig\Node\Expression\Variable\AssignContextVariable;
+use Twig\Node\ForElseNode;
 use Twig\Node\ForNode;
 use Twig\Node\Node;
 use Twig\Token;
@@ -42,7 +43,7 @@ final class ForTokenParser extends AbstractTokenParser
         $body = $this->parser->subparse([$this, 'decideForFork']);
         if ('else' == $stream->next()->getValue()) {
             $stream->expect(Token::BLOCK_END_TYPE);
-            $else = $this->parser->subparse([$this, 'decideForEnd'], true);
+            $else = new ForElseNode($this->parser->subparse([$this, 'decideForEnd'], true), $stream->getCurrent()->getLine());
         } else {
             $else = null;
         }

tests/Node/ForTest.php

@@ -13,6 +13,7 @@ namespace Twig\Tests\Node;
 
 use Twig\Node\Expression\Variable\AssignContextVariable;
 use Twig\Node\Expression\Variable\ContextVariable;
+use Twig\Node\ForElseNode;
 use Twig\Node\ForNode;
 use Twig\Node\Nodes;
 use Twig\Node\PrintNode;
@@ -36,7 +37,7 @@ class ForTest extends NodeTestCase
         $this->assertEquals($body, $node->getNode('body')->getNode('0'));
         $this->assertFalse($node->hasNode('else'));
 
-        $else = new PrintNode(new ContextVariable('foo', 1), 1);
+        $else = new ForElseNode(new PrintNode(new ContextVariable('foo', 1), 1), 5);
         $node = new ForNode($keyTarget, $valueTarget, $seq, null, $body, $else, 1);
         $node->setAttribute('with_loop', false);
         $this->assertEquals($else, $node->getNode('else'));
@@ -159,7 +160,7 @@ EOF
         $valueTarget = new AssignContextVariable('v', 1);
         $seq = new ContextVariable('values', 1);
         $body = new Nodes([new PrintNode(new ContextVariable('foo', 1), 1)], 1);
-        $else = new PrintNode(new ContextVariable('foo', 1), 1);
+        $else = new ForElseNode(new PrintNode(new ContextVariable('foo', 6), 6), 5);
         $node = new ForNode($keyTarget, $valueTarget, $seq, null, $body, $else, 1);
         $node->setAttribute('with_loop', true);
 
@@ -193,7 +194,9 @@ foreach (\$context['_seq'] as \$context["k"] => \$context["v"]) {
         \$context['loop']['last'] = 0 === \$context['loop']['revindex0'];
     }
 }
+// line 5
 if (!\$context['_iterated']) {
+    // line 6
     yield $fooGetter;
 }
 \$_parent = \$context['_parent'];