Add VariableOptimizerNodeVisitor

src/NodeVisitor/VariableOptimizerNodeVisitor.php

@@ -0,0 +1,56 @@
+<?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\NodeVisitor;
+
+use Twig\Environment;
+use Twig\Node\Expression\NameExpression;
+use Twig\Node\ModuleNode;
+use Twig\Node\Node;
+use Twig\Node\TypesNode;
+
+/**
+ * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @internal
+ */
+final class VariableOptimizerNodeVisitor implements NodeVisitorInterface
+{
+    private array $types = [];
+
+    public function enterNode(Node $node, Environment $env): Node
+    {
+        if ($node instanceof TypesNode) {
+            $this->types = array_merge($this->types, $node->getAttribute('mapping'));
+        }
+
+        // A NameExpression is always defined if the variable is typed and not optional
+        if ($node instanceof NameExpression && isset($this->types[$node->getAttribute('name')]) && !$this->types[$node->getAttribute('name')]['optional']) {
+            $node->setAttribute('always_defined', true);
+        }
+
+        return $node;
+    }
+
+    public function leaveNode(Node $node, Environment $env): ?Node
+    {
+        if ($node instanceof ModuleNode) {
+            $this->types = [];
+        }
+
+        return $node;
+    }
+
+    public function getPriority(): int
+    {
+        return 255;
+    }
+}

tests/NodeVisitor/VariableOptimizerNodeVisitorTest.php

@@ -0,0 +1,51 @@
+<?php
+
+namespace Twig\Tests\NodeVisitor;
+
+/*
+ * 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.
+ */
+
+use PHPUnit\Framework\TestCase;
+use Twig\Environment;
+use Twig\Loader\ArrayLoader;
+use Twig\NodeTraverser;
+use Twig\NodeVisitor\VariableOptimizerNodeVisitor;
+use Twig\Source;
+
+class VariableOptimizerNodeVisitorTest extends TestCase
+{
+    /**
+     * @dataProvider getTypedVariablesData
+     */
+    public function testTypedVariables(string $template, string $expected)
+    {
+        $env = new Environment(new ArrayLoader(), ['autoescape' => false]);
+        $node = $env->parse($env->tokenize(new Source($template, 'index')));
+        $traverser = new NodeTraverser($env, [new VariableOptimizerNodeVisitor()]);
+        $node = $traverser->traverse($node);
+
+        $this->assertSame($expected, $this->stripCode($env->compile($node->getNode('body'))));
+    }
+
+    public function getTypedVariablesData()
+    {
+        yield 'regular' => ['{{ foo }}', 'yield ($context["foo"] ?? null);'];
+        yield 'typed_optional' => ['{% types { foo?: "string" } %}{{ foo }}', 'yield ($context["foo"] ?? null);'];
+        yield 'typed' => ['{% types { foo: "string" } %}{{ foo }}', 'yield $context["foo"];'];
+
+        yield 'is_defined_test' => ['{{ foo is defined }}', 'yield array_key_exists("foo", $context);'];
+        yield 'is_defined_test_typed_optional' => ['{% types { foo?: "string" } %}{{ foo is defined }}', 'yield array_key_exists("foo", $context);'];
+        yield 'is_defined_test_typed' => ['{% types { foo: "string" } %}{{ foo is defined }}', 'yield true;'];
+    }
+
+    private function stripCode(string $code): string
+    {
+        return trim(preg_replace("{^//.*\n}", '', $code));
+    }
+}