Add null-safe operator

extra/intl-extra/Tests/Fixtures/script_names.test

@@ -2,15 +2,15 @@
 "script_names" function
 --TEMPLATE--
 {{ script_names('UNKNOWN')|length }}
-{{ script_names()|length }}
-{{ script_names('fr')|length }}
+{{ script_names()|length > 200 ? 'more than 200' : 'less than 200' }}
+{{ script_names('fr')|length > 200 ? 'more than 200' : 'less than 200' }}
 {{ script_names()['Marc'] }}
 {{ script_names('fr')['Marc'] }}
 --DATA--
 return [];
 --EXPECT--
 0
-208
-208
+more than 200
+more than 200
 Marchen
 Marchen

src/ExpressionParser/Infix/DotExpressionParser.php

@@ -37,6 +37,7 @@ final class DotExpressionParser extends AbstractExpressionParser implements Infi
 
     public function parse(Parser $parser, AbstractExpression $expr, Token $token): AbstractExpression
     {
+        $nullSafe = '?.' === $token->getValue();
         $stream = $parser->getStream();
         $token = $stream->getCurrent();
         $lineno = $token->getLine();
@@ -55,7 +56,7 @@ public function parse(Parser $parser, AbstractExpression $expr, Token $token): A
             ) {
                 $attribute = new ConstantExpression($token->getValue(), $token->getLine());
             } else {
-                throw new SyntaxError(\sprintf('Expected name or number, got value "%s" of type %s.', $token->getValue(), $token->toEnglish()), $token->getLine(), $stream->getSourceContext());
+                throw new SyntaxError(\sprintf('Expected name or number, got value "%s" of type "%s".', $token->getValue(), $token->toEnglish()), $token->getLine(), $stream->getSourceContext());
             }
         }
 
@@ -74,14 +75,19 @@ public function parse(Parser $parser, AbstractExpression $expr, Token $token): A
             return new MacroReferenceExpression(new TemplateVariable($expr->getAttribute('name'), $expr->getTemplateLine()), 'macro_'.$attribute->getAttribute('value'), $arguments, $expr->getTemplateLine());
         }
 
-        return new GetAttrExpression($expr, $attribute, $arguments, $type, $lineno);
+        return new GetAttrExpression($expr, $attribute, $arguments, $type, $lineno, $nullSafe);
     }
 
     public function getName(): string
     {
         return '.';
     }
 
+    public function getAliases(): array
+    {
+        return ['?.'];
+    }
+
     public function getDescription(): string
     {
         return 'Get an attribute on a variable';

src/Node/Expression/GetAttrExpression.php

@@ -4,7 +4,6 @@
  * This file is part of Twig.
  *
  * (c) Fabien Potencier
- * (c) Armin Ronacher
  *
  * For the full copyright and license information, please view the LICENSE
  * file that was distributed with this source code.
@@ -25,7 +24,7 @@ class GetAttrExpression extends AbstractExpression implements SupportDefinedTest
     /**
      * @param ArrayExpression|NameExpression|null $arguments
      */
-    public function __construct(AbstractExpression $node, AbstractExpression $attribute, ?AbstractExpression $arguments, string $type, int $lineno)
+    public function __construct(AbstractExpression $node, AbstractExpression $attribute, ?AbstractExpression $arguments, string $type, int $lineno, bool $nullSafe = false)
     {
         $nodes = ['node' => $node, 'attribute' => $attribute];
         if (null !== $arguments) {
@@ -36,7 +35,7 @@ public function __construct(AbstractExpression $node, AbstractExpression $attrib
             trigger_deprecation('twig/twig', '3.15', \sprintf('Not passing a "%s" instance as the "arguments" argument of the "%s" constructor is deprecated ("%s" given).', ArrayExpression::class, static::class, $arguments::class));
         }
 
-        parent::__construct($nodes, ['type' => $type, 'ignore_strict_check' => false, 'optimizable' => true], $lineno);
+        parent::__construct($nodes, ['type' => $type, 'ignore_strict_check' => false, 'optimizable' => !$nullSafe, 'null_safe' => $nullSafe], $lineno);
     }
 
     public function enableDefinedTest(): void
@@ -49,6 +48,8 @@ public function compile(Compiler $compiler): void
     {
         $env = $compiler->getEnvironment();
         $arrayAccessSandbox = false;
+        $nullSafe = $this->getAttribute('null_safe');
+        $objectVar = null;
 
         // optimize array calls
         if (
@@ -93,14 +94,27 @@ public function compile(Compiler $compiler): void
             ;
         }
 
-        $compiler->raw('CoreExtension::getAttribute($this->env, $this->source, ');
-
         if ($this->getAttribute('ignore_strict_check')) {
             $this->getNode('node')->setAttribute('ignore_strict_check', true);
         }
 
+        if ($nullSafe) {
+            $objectVar = '$'.$compiler->getVarName();
+            $compiler
+                ->raw('((null === ('.$objectVar.' = ')
+                ->subcompile($this->getNode('node'))
+                ->raw(')) ? null : ');
+        }
+
+        $compiler->raw('CoreExtension::getAttribute($this->env, $this->source, ');
+
+        if ($nullSafe) {
+            $compiler->raw($objectVar);
+        } else {
+            $compiler->subcompile($this->getNode('node'));
+        }
+
         $compiler
-            ->subcompile($this->getNode('node'))
             ->raw(', ')
             ->subcompile($this->getNode('attribute'))
         ;
@@ -123,6 +137,10 @@ public function compile(Compiler $compiler): void
         if ($arrayAccessSandbox) {
             $compiler->raw(')');
         }
+
+        if ($nullSafe) {
+            $compiler->raw(')');
+        }
     }
 
     private function changeIgnoreStrictCheck(self $node): void

tests/ExpressionParserTest.php

@@ -288,6 +288,62 @@ public static function getTestsForString()
         ];
     }
 
+    /**
+     * @dataProvider getTestsForNullSafeOperator
+     */
+    public function testNullSafeOperator($template, $data, $expected)
+    {
+        $env = new Environment(new ArrayLoader(['template' => $template]));
+
+        $this->assertSame($expected, $env->render('template', $data));
+    }
+
+    public static function getTestsForNullSafeOperator()
+    {
+        return [
+            [
+                '{{ foo?.bar }}',
+                ['foo' => (object) ['bar' => 'baz']],
+                'baz',
+            ],
+            [
+                '{{ foo?.bar }}',
+                ['foo' => null],
+                '',
+            ],
+            [
+                '{{ foo?.bar?.baz }}',
+                ['foo' => (object) ['bar' => (object) ['baz' => 'qux']]],
+                'qux',
+            ],
+            [
+                '{{ foo?.bar?.baz }}',
+                ['foo' => (object) ['bar' => null]],
+                '',
+            ],
+            [
+                '{{ foo?.bar?.baz }}',
+                ['foo' => null],
+                '',
+            ],
+            [
+                '{{ foo?.bar?.baz ?? "qux" }}',
+                ['foo' => null],
+                'qux',
+            ],
+            [
+                '{{ foo?.bar ?? "qux" }}',
+                ['foo' => (object) ['bar' => 0]],
+                '0',
+            ],
+            [
+                '{{ foo?.bar ?? "qux" }}',
+                ['foo' => (object) ['bar' => false]],
+                '',
+            ],
+        ];
+    }
+
     public function testMacroDefinitionDoesNotSupportNonNameVariableName()
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);

tests/Fixtures/expressions/dot_as_concatenation.test

@@ -5,4 +5,4 @@ Twig does not support using . for concatenation
 --DATA--
 return []
 --EXCEPTION--
-Twig\Error\SyntaxError: Expected name or number, got value "b" of type string in "index.twig" at line 2.
+Twig\Error\SyntaxError: Expected name or number, got value "b" of type "string" in "index.twig" at line 2.

tests/Node/Expression/GetAttrTest.php

@@ -42,6 +42,7 @@ public function testConstructor()
         $this->assertEquals($attr, $node->getNode('attribute'));
         $this->assertEquals($args, $node->getNode('arguments'));
         $this->assertEquals(Template::ARRAY_CALL, $node->getAttribute('type'));
+        $this->assertFalse($node->getAttribute('null_safe'));
     }
 
     public static function provideTests(): iterable
@@ -51,9 +52,13 @@ public static function provideTests(): iterable
         $expr = new ContextVariable('foo', 1);
         $attr = new ConstantExpression('bar', 1);
         $args = new ArrayExpression([], 1);
+
         $node = new GetAttrExpression($expr, $attr, $args, Template::ANY_CALL, 1);
         $tests[] = [$node, \sprintf('%s%s, "bar", [], "any", false, false, false, 1)', self::createAttributeGetter(), self::createVariableGetter('foo', 1))];
 
+        $node = new GetAttrExpression($expr, $attr, $args, Template::ANY_CALL, 1, true);
+        $tests[] = [$node, '((null === ($_v%s = // line 1'."\n".'($context["foo"] ?? null))) ? null : '.self::createAttributeGetter().'$_v%s, "bar", [], "any", false, false, false, 1))', null, true];
+
         $node = new GetAttrExpression($expr, $attr, $args, Template::ARRAY_CALL, 1);
         $tests[] = [$node, '(($_v%s = // line 1'."\n".
             '($context["foo"] ?? null)) && is_array($_v%s) || $_v%s instanceof ArrayAccess ? ($_v%s["bar"] ?? null) : null)', null, true, ];