// return: https://skin.dev/user/profile
url('user/profile')

# File: src/Illuminate/Foundation/helpers.php

/**
 * Generate a url for the application.
 *
 * @param string $path
 * @param mixed $parameters
 * @param bool $secure
 * @return Illuminate\Contracts\Routing\UrlGenerator|string
 */
function url($path = null, $parameters = [], $secure = null)
{
 if (is_null($path)) {
  return app(UrlGenerator::class);
 }

 return app(UrlGenerator::class)->to($path, $parameters, $secure);
}

/**
 * Register the URL generator service.
 *
 * @return void
 */
protected function registerUrlGenerator()
{
 $this->app['url'] = $this->app->share(function ($app) {
  // 略

  $url = new UrlGenerator(
   $routes, $app->rebinding(
    'request', $this->requestRebinder()
   )
  );

  return $url;
 });
}

// 用它提供的方法检测 URL 是否有效
if (app('url')->isValidUrl($rootUrl)) {
 app('url')->forceRootUrl($rootUrl);
}

// 强制生成使用 HTTPS 协议的 URL
app('url')->forceSchema('https');