[BUGFIX] Support escaped quotes selector in selectors (#1485)

Tailwind allows selectors that contain quotes like this one:
.before\:content-\[\'\'\]:before

Author: samuil-banti-wpenigne

CHANGELOG.md

@@ -10,6 +10,7 @@ Please also have a look at our
 
 ### Added
 
+- Add support for escaped quotes in the selectors (#1485)
 - Provide line number in exception message for mismatched parentheses in
   selector (#1435)
 - Add support for CSS container queries (#1400)

src/Property/Selector.php

@@ -95,10 +95,13 @@ public static function parse(ParserState $parserState, array &$comments = []): s
                 case '\'':
                     // The fallthrough is intentional.
                 case '"':
-                    if (!\is_string($stringWrapperCharacter)) {
-                        $stringWrapperCharacter = $nextCharacter;
-                    } elseif ($stringWrapperCharacter === $nextCharacter) {
-                        if (\substr(\end($selectorParts), -1) !== '\\') {
+                    $lastPart = \end($selectorParts);
+                    $backslashCount = \strspn(\strrev($lastPart), '\\');
+                    $quoteIsEscaped = ($backslashCount % 2 === 1);
+                    if (!$quoteIsEscaped) {
+                        if (!\is_string($stringWrapperCharacter)) {
+                            $stringWrapperCharacter = $nextCharacter;
+                        } elseif ($stringWrapperCharacter === $nextCharacter) {
                             $stringWrapperCharacter = null;
                         }
                     }

tests/Unit/Property/SelectorTest.php

@@ -369,4 +369,88 @@ public function getArrayRepresentationThrowsException(): void
 
         $subject->getArrayRepresentation();
     }
+
+    /**
+     * @return array<non-empty-string, array{0: non-empty-string}>
+     */
+    public static function provideSelectorsWithEscapedQuotes(): array
+    {
+        return [
+            'escaped double quote in double-quoted attribute' => ['a[href="test\\"value"]'],
+            'escaped single quote in single-quoted attribute' => ['a[href=\'test\\\'value\']'],
+            'multiple escaped double quotes in double-quoted attribute' => ['a[title="say \\"hello\\" world"]'],
+            'multiple escaped single quotes in single-quoted attribute' => ['a[title=\'say \\\'hello\\\' world\']'],
+            'escaped quote at start of attribute value' => ['a[data-test="\\"start"]'],
+            'escaped quote at end of attribute value' => ['a[data-test="end\\""]'],
+            'escaped backslash followed by quote' => ['a[data-test="test\\\\"]'],
+            'escaped backslash before escaped quote' => ['a[data-test="test\\\\\\"value"]'],
+            'triple backslash before quote' => ['a[data-test="test\\\\\\""]'],
+        ];
+    }
+
+    /**
+     * @test
+     *
+     * @param non-empty-string $selector
+     *
+     * @dataProvider provideSelectorsWithEscapedQuotes
+     */
+    public function parsesSelectorsWithEscapedQuotes(string $selector): void
+    {
+        $result = Selector::parse(new ParserState($selector, Settings::create()));
+
+        self::assertInstanceOf(Selector::class, $result);
+        self::assertSame($selector, $result->getSelector());
+    }
+
+    /**
+     * @test
+     *
+     * @param non-empty-string $selector
+     *
+     * @dataProvider provideSelectorsWithEscapedQuotes
+     */
+    public function isValidForSelectorsWithEscapedQuotesReturnsTrue(string $selector): void
+    {
+        self::assertTrue(Selector::isValid($selector));
+    }
+
+    /**
+     * @test
+     */
+    public function parsingAttributeWithEscapedQuoteDoesNotPrematurelyCloseString(): void
+    {
+        $selector = 'input[placeholder="Enter \\"quoted\\" text here"]';
+
+        $result = Selector::parse(new ParserState($selector, Settings::create()));
+
+        self::assertInstanceOf(Selector::class, $result);
+        self::assertSame($selector, $result->getSelector());
+    }
+
+    /**
+     * @test
+     */
+    public function parseDistinguishesEscapedFromUnescapedQuotes(): void
+    {
+        // One backslash = escaped quote (should not close string)
+        $selector = 'a[data-value="test\\"more"]';
+
+        $result = Selector::parse(new ParserState($selector, Settings::create()));
+
+        self::assertSame($selector, $result->getSelector());
+    }
+
+    /**
+     * @test
+     */
+    public function parseHandlesEvenNumberOfBackslashesBeforeQuote(): void
+    {
+        // Two backslashes = escaped backslash + unescaped quote (should close string)
+        $selector = 'a[data-value="test\\\\"]';
+
+        $result = Selector::parse(new ParserState($selector, Settings::create()));
+
+        self::assertSame($selector, $result->getSelector());
+    }
 }