[9.x] Add Str::lcfirst to support non-ascii characters (vs php's co…

…re lcfirst fct) and add DX consistency with ucfirst wrapper (#41384)

* Add the lcfirst function to the Str class

* formatting

Co-authored-by: Taylor Otwell <[email protected]>

src/Illuminate/Support/Str.php

@@ -987,6 +987,17 @@ public static function swap(array $map, $subject)
         return strtr($subject, $map);
     }
 
+    /**
+     * Make a string's first character lowercase.
+     *
+     * @param  string  $string
+     * @return string
+     */
+    public static function lcfirst($string)
+    {
+        return static::lower(static::substr($string, 0, 1)).static::substr($string, 1);
+    }
+
     /**
      * Make a string's first character uppercase.
      *

src/Illuminate/Support/Stringable.php

@@ -801,6 +801,16 @@ public function rtrim($characters = null)
         return new static(rtrim(...array_merge([$this->value], func_get_args())));
     }
 
+    /**
+     * Make a string's first character lowercase.
+     *
+     * @return static
+     */
+    public function lcfirst()
+    {
+        return new static(Str::lcfirst($this->value));
+    }
+
     /**
      * Make a string's first character uppercase.
      *

tests/Support/SupportStrTest.php

@@ -638,6 +638,14 @@ public function testSubstrReplace()
         $this->assertSame('Laravel – The PHP Framework for Web Artisans', Str::substrReplace('Laravel Framework', '– The PHP Framework for Web Artisans', 8));
     }
 
+    public function testLcfirst()
+    {
+        $this->assertSame('laravel', Str::lcfirst('Laravel'));
+        $this->assertSame('laravel framework', Str::lcfirst('Laravel framework'));
+        $this->assertSame('мама', Str::lcfirst('Мама'));
+        $this->assertSame('мама мыла раму', Str::lcfirst('Мама мыла раму'));
+    }
+
     public function testUcfirst()
     {
         $this->assertSame('Laravel', Str::ucfirst('laravel'));