理解Laravel中的pipeline

Route::get('/', function() {    return debug_backtrace();});

php artisan serve

public function handle($request, Closure $next) {    //do something for $request    return $next($request);}

/**  * Set the object being sent through the pipeline. *  * @param  mixed  $passable  * @return $this */public function send($passable) {        $this->passable = $passable;        return $this;}

(new Pipeline($this))    ->send($request)    ->through($this->app->shouldSkipMiddleware() ? [] : $this->middleware)    ->then($this->dispatchToRouter());

/**   * Set the array of pipes.   *   * @param  dynamic|array  $pipes   * @return $this */public function through($pipes){        $this->pipes = is_array($pipes) ? $pipes : func_get_args();        return $this;}

/** * Run the pipeline with a final destination callback.   *   * @param  \Closure  $destination   * @return mixed */public function then(Closure $destination){        $firstSlice = $this->getInitialSlice($destination);        $pipes = array_reverse($this->pipes);        return call_user_func(                array_reduce($pipes, $this->getSlice(), $firstSlice),         $this->passable);    );}

public function then(Closure $destination){        //把传进来的匿名函数包装成一个闭包，不太理解没关系，反正知道$firstSlice是一个函数就好了    $firstSlice = $this->getInitialSlice($destination);        //把through方法传进来的参数，也就是中间件数组反转，为什么要这么做？    //简单讲是利用栈的特性，继续往下看就知道了    $pipes = array_reverse($this->pipes);      //array_reduce(...)返回一个函数A，然后执行这个函数，把send进来的对象当参数传递函数A    return call_user_func(                array_reduce($pipes, $this->getSlice(), $firstSlice),         $this->passable);    );}

function fake_array_reduce($arr, $func, $initial=null)    $temp = $initial;    foreach($arr as $v) {        $temp = $func($temp, $v);    }    return $temp;}

/**   * Get a Closure that represents a slice of the application onion.   *   * @return \Closure   */protected function getSlice(){        return function ($stack, $pipe) {                return function ($passable) use ($stack, $pipe) {                      if ($pipe instanceof Closure) {                                return call_user_func($pipe, $passable, $stack);                        } else {                                list($name, $parameters) = $this->parsePipeString($pipe);                return call_user_func_array(                    [$this->container->make($name), $this->method],                        array_merge([$passable, $stack], $parameters)                );                        }                };        };}

function haha($stack, $middleware) {    return function($param) use ($stack, $middleware){        //do something     };}function fake_array_reduce($middlewares, $func, $inital=null) {    $temp = $initial;    //假设传递进来的函数$func = 'haha'    foreach($middlewares as $middleware) {        $temp = $func($temp, $middleware);    }    return $temp;}

 return function($stack, $pipe) {    return function($passable) use ($stack, $pipe) {        if($pipe instanceof Closure) {            return call_user_func($pipe, $passable, $stack);        } else {            //..        }    }}

return call_user_func($middleware[0]->handle, $this->passable, f2);

public function handle($request, Closure $next) {    //...    return $next($request);}