[String] allow translit rules to be given as closure

AbstractUnicodeString.php

@@ -77,7 +77,7 @@ public static function fromCodePoints(int ...$codes): self
      *
      * Install the intl extension for best results.
      *
-     * @param string[]|\Transliterator[] $rules See "*-Latin" rules from Transliterator::listIDs()
+     * @param string[]|\Transliterator[]|\Closure[] $rules See "*-Latin" rules from Transliterator::listIDs()
      */
     public function ascii(array $rules = []): self
     {
@@ -107,6 +107,8 @@ public function ascii(array $rules = []): self
 
             if ($rule instanceof \Transliterator) {
                 $s = $rule->transliterate($s);
+            } elseif ($rule instanceof \Closure) {
+                $s = $rule($s);
             } elseif ($rule) {
                 if ('nfd' === $rule = strtolower($rule)) {
                     normalizer_is_normalized($s, self::NFD) ?: $s = normalizer_normalize($s, self::NFD);

Slugger/AsciiSlugger.php

@@ -66,8 +66,15 @@ class AsciiSlugger implements SluggerInterface, LocaleAwareInterface
      */
     private $transliterators = [];
 
-    public function __construct(string $defaultLocale = null, array $symbolsMap = null)
+    /**
+     * @param array|\Closure|null $symbolsMap
+     */
+    public function __construct(string $defaultLocale = null, $symbolsMap = null)
     {
+        if (null !== $symbolsMap && !\is_array($symbolsMap) && !$symbolsMap instanceof \Closure) {
+            throw new \TypeError(sprintf('Argument 2 passed to "%s()" must be array, Closure or null, "%s" given.', __METHOD__, \gettype($symbolMap)));
+        }
+
         $this->defaultLocale = $defaultLocale;
         $this->symbolsMap = $symbolsMap ?? $this->symbolsMap;
     }
@@ -103,9 +110,16 @@ public function slug(string $string, string $separator = '-', string $locale = n
             $transliterator = (array) $this->createTransliterator($locale);
         }
 
+        if ($this->symbolsMap instanceof \Closure) {
+            $symbolsMap = $this->symbolsMap;
+            array_unshift($transliterator, static function ($s) use ($symbolsMap, $locale) {
+                return $symbolsMap($s, $locale);
+            });
+        }
+
         $unicodeString = (new UnicodeString($string))->ascii($transliterator);
 
-        if (isset($this->symbolsMap[$locale])) {
+        if (\is_array($this->symbolsMap) && isset($this->symbolsMap[$locale])) {
             foreach ($this->symbolsMap[$locale] as $char => $replace) {
                 $unicodeString = $unicodeString->replace($char, ' '.$replace.' ');
             }

Tests/AbstractUnicodeTestCase.php

@@ -20,6 +20,16 @@ public function testAscii()
         $this->assertSame('Dieser Wert sollte groesser oder gleich', (string) $s->ascii(['de-ASCII']));
     }
 
+    public function testAsciiClosureRule()
+    {
+        $rule = function ($c) {
+            return str_replace('ö', 'OE', $c);
+        };
+
+        $s = static::createFromString('Dieser Wert sollte größer oder gleich');
+        $this->assertSame('Dieser Wert sollte grOEsser oder gleich', (string) $s->ascii([$rule]));
+    }
+
     public function provideCreateFromCodePoint(): array
     {
         return [

Tests/SluggerTest.php

@@ -64,4 +64,15 @@ public function testSlugCharReplacementLocaleMethod()
         $slug = (string) $slugger->slug('yo & tu a esta dirección [email protected]', '_', 'es');
         $this->assertSame('yo_y_tu_a_esta_direccion_slug_en_senal_test_es', $slug);
     }
+
+    public function testSlugClosure()
+    {
+        $slugger = new AsciiSlugger(null, function ($s, $locale) {
+            $this->assertSame('foo', $locale);
+
+            return str_replace('❤️', 'love', $s);
+        });
+
+        $this->assertSame('love', (string) $slugger->slug('❤️', '-', 'foo'));
+    }
 }