Handle Escaped Quote in Format

Author: oleibman

src/PhpSpreadsheet/Style/NumberFormat/Formatter.php

@@ -126,7 +126,8 @@ public static function toFormattedString($value, string $format, ?array $callBac
         }
         // For now we do not treat strings in sections, although section 4 of a format code affects strings
         // Process a single block format code containing @ for text substitution
-        if (preg_match(self::SECTION_SPLIT, $format) === 0 && preg_match(self::SYMBOL_AT, $format) === 1) {
+        $formatx = str_replace('\\"', self::QUOTE_REPLACEMENT, $format);
+        if (preg_match(self::SECTION_SPLIT, $format) === 0 && preg_match(self::SYMBOL_AT, $formatx) === 1) {
             if (!str_contains($format, '"')) {
                 return str_replace('@', $value, $format);
             }
@@ -140,7 +141,7 @@ public static function toFormattedString($value, string $format, ?array $callBac
             return str_replace(
                 ['"', self::QUOTE_REPLACEMENT],
                 ['', '"'],
-                preg_replace(self::SYMBOL_AT, $value, $format) ?? $value
+                preg_replace(self::SYMBOL_AT, $value, $formatx) ?? $value
             );
         }
 

tests/data/Style/NumberFormat.php

@@ -1722,4 +1722,9 @@
         '"Hooray" for me',
         '"Text: "' . NumberFormat::FORMAT_TEXT,
     ],
+    'issue 4242 escaped quote in format' => [
+        '"Hello"',
+        'Hello',
+        '\\"@\\"',
+    ],
 ];