[BUGFIX] Allow comma-separated arguments in selectors

CHANGELOG.md

@@ -110,6 +110,7 @@ Please also have a look at our
 
 ### Fixed
 
+- Parse selector functions (like `:not`) with comma-separated arguments (#1292)
 - Parse quoted attribute selector value containing comma (#1323)
 - Allow comma in selectors (e.g. `:not(html, body)`) (#1293)
 - Insert `Rule` before sibling even with different property name

src/RuleSet/DeclarationBlock.php

@@ -43,8 +43,9 @@ public static function parse(ParserState $parserState, ?CSSList $list = null): ?
             $selectors = [];
             $selectorParts = [];
             $stringWrapperCharacter = null;
+            $functionNestingLevel = 0;
             $consumedNextCharacter = false;
-            static $stopCharacters = ['{', '}', '\'', '"', ','];
+            static $stopCharacters = ['{', '}', '\'', '"', '(', ')', ','];
             do {
                 if (!$consumedNextCharacter) {
                     $selectorParts[] = $parserState->consume(1);
@@ -64,8 +65,21 @@ public static function parse(ParserState $parserState, ?CSSList $list = null): ?
                             }
                         }
                         break;
-                    case ',':
+                    case '(':
+                        if (!\is_string($stringWrapperCharacter)) {
+                            ++$functionNestingLevel;
+                        }
+                        break;
+                    case ')':
                         if (!\is_string($stringWrapperCharacter)) {
+                            if ($functionNestingLevel <= 0) {
+                                throw new UnexpectedTokenException('anything but', ')');
+                            }
+                            --$functionNestingLevel;
+                        }
+                        break;
+                    case ',':
+                        if (!\is_string($stringWrapperCharacter) && $functionNestingLevel === 0) {
                             $selectors[] = \implode('', $selectorParts);
                             $selectorParts = [];
                             $parserState->consume(1);

tests/Unit/RuleSet/DeclarationBlockTest.php

@@ -67,6 +67,7 @@ public static function provideSelector(): array
             'pseudo-class' => [':hover'],
             'type & pseudo-class' => ['a:hover'],
             '`not`' => [':not(#your-mug)'],
+            '`not` with multiple arguments' => [':not(#your-mug, .their-mug)'],
             'pseudo-element' => ['::before'],
             'attribute with `"`' => ['[alt="{}()[]\\"\',"]'],
             'attribute with `\'`' => ['[alt=\'{}()[]"\\\',\']'],