[8.x] Add Stringable::whenNotEmpty() (laravel#37080)

src/Illuminate/Support/Stringable.php

@@ -744,6 +744,23 @@ public function whenEmpty($callback)
         return $this;
     }
 
+    /**
+     * Execute the given callback if the string is not empty.
+     *
+     * @param  callable  $callback
+     * @return static
+     */
+    public function whenNotEmpty($callback)
+    {
+        if ($this->isNotEmpty()) {
+            $result = $callback($this);
+
+            return is_null($result) ? $this : $result;
+        }
+
+        return $this;
+    }
+
     /**
      * Limit the number of words in a string.
      *