Enhance Message::parse() to support nested placeholders

CHANGELOG.md

@@ -3,7 +3,7 @@
 ## 2.2.1 under development
 
 - Bug #130: Updated `Message::parse()` to correctly support multiple placeholders (@technicated)
-- Chg #130: Changed `Message::parse()` to conform to PSR-3, removing support for placeholders with arbitrary names and nested placeholders (@technicated)
+- Chg #130, #133: Changed `Message::parse()` to conform to PSR-3 (@technicated, @vjik)
 
 ## 2.2.0 December 13, 2025
 

src/Message.php

@@ -208,7 +208,7 @@ private function parse(string|Stringable $message, array $context): string
 
         /** @var string */
         return preg_replace_callback(
-            '/\{([\w\._]+)\}/',
+            '/\{([\w\.\\\\_]+)\}/',
             static function (array $matches) use ($context) {
                 [$exist, $value] = ContextValueExtractor::extract($context, $matches[1]);
                 if ($exist) {

tests/MessageTest.php

@@ -122,6 +122,46 @@ public function dataParseMessage(): array
                 ['p1' => 'hello', 'p2' => 'world'],
                 'Placeholder 1: hello - Placeholder 2: world',
             ],
+            'nested-quoted' => [
+                'has "{foo\.ba\\\\r}" placeholder',
+                ['foo.ba\\r' => 'test'],
+                'has "test" placeholder',
+            ],
+            'nested-extended-1' => [
+                'has "{foo\\\.bar}" placeholder',
+                ['foo\\' => ['bar' => 'test']],
+                'has "test" placeholder',
+            ],
+            'nested-extended-2' => [
+                'has "{foo\\\\\\\\.bar}" placeholder',
+                ['foo\\\\' => ['bar' => 'test']],
+                'has "test" placeholder',
+            ],
+            'nested-extended-3' => [
+                'has "{foo\\\.}" placeholder',
+                ['foo\\' => ['' => 'test']],
+                'has "test" placeholder',
+            ],
+            'nested-extended-4' => [
+                'has "{foo\\\\}" placeholder',
+                ['foo\\' => 'test'],
+                'has "test" placeholder',
+            ],
+            'nested-extended-5' => [
+                'has "{foo\.bar.a}" placeholder',
+                ['foo.bar' => ['a' => 'test']],
+                'has "test" placeholder',
+            ],
+            'nested-extended-6' => [
+                'has "{key1\..\.key2\..\.key3}" placeholder',
+                ['key1.' => ['.key2.' => ['.key3' => 'test']]],
+                'has "test" placeholder',
+            ],
+            'nested-extended-7' => [
+                'has "{key1\..\.key2\..\.key3}" placeholder',
+                ['key1.' => ['.key2.' => ['.key3' => 'test']]],
+                'has "test" placeholder',
+            ],
         ];
     }