<?php
 /**
  * @link http://www.yiiframework.com/
  * @copyright Copyright (c) 2008 Yii Software LLC
  * @license http://www.yiiframework.com/license/
  */

 namespace yii\base;

 use Yii;
 use yii\di\ServiceLocator;

 /**
  * Module is the base class for module and application classes.
  * Module是模块和应用类的基类
  *
  * A module represents a sub-application which contains MVC elements by itself, such as
  * models, views, controllers, etc.
  * 模块代表一个由模型、视图、控制器等组成的子应用
  *
  * A module may consist of [[modules|sub-modules]].
  * 模块内也可以包含模块或子模块
  *
  * [[components|Components]] may be registered with the module so that they are globally
  * accessible within the module.
  * 组件可以注册到模块，以便在模块内全局访问
  *
  * @property array $aliases List of path aliases to be defined. The array keys are alias names (must start
  * with '@') and the array values are the corresponding paths or aliases. See [[setAliases()]] for an example.
  * This property is write-only.
  * @property array $aliases 别名数组  只读
  * @property string $basePath The root directory of the module.
  * @property string $basePath  模块的根路径
  * @property string $controllerPath The directory that contains the controller classes. This property is
  * read-only.
  * @property string $controllerPath 控制的路径数组 只读
  * @property string $layoutPath The root directory of layout files. Defaults to "[[viewPath]]/layouts".
  * @property string $layoutPath 模板路径数组 只读
  * @property array $modules The modules (indexed by their IDs).
  * @property array $modules 模块数组
  * @property string $uniqueId The unique ID of the module. This property is read-only.
  * @property string $uniqueId 模块的唯一ID 只读
  * @property string $viewPath The root directory of view files. Defaults to "[[basePath]]/views".
  * @property string $viewPath 模块下的视图文件路径
  *
  * @author Qiang Xue <qiang.xue@gmail.com>
  * @since 2.0
  */
 class Module extends ServiceLocator
 {
     /**
      * @event ActionEvent an event raised before executing a controller action.
      * @event ActionEvent Action事件，在执行控制的的action方法时触发
      * You may set [[ActionEvent::isValid]] to be false to cancel the action execution.
      */
     const EVENT_BEFORE_ACTION = 'beforeAction';
     /**
      * @event ActionEvent an event raised after executing a controller action.
      * @event ActionEvent Action事件，在执行控制的的action方法后触发
      */
     const EVENT_AFTER_ACTION = 'afterAction';

     /**
      * @var array custom module parameters (name => value).
      * @var array 自定义模块参数
      */
     public $params = [];
     /**
      * @var string an ID that uniquely identifies this module among other modules which have the same [[module|parent]].
      * @var string 模块的唯一ID，用于区分同一父模块下的模块
      */
     public $id;
     /**
      * @var Module the parent module of this module. Null if this module does not have a parent.
      * @var 当前模块的父模块
      */
     public $module;
     /**
      * @var string|boolean the layout that should be applied for views within this module. This refers to a view name
      * relative to [[layoutPath]]. If this is not set, it means the layout value of the [[module|parent module]]
      * will be taken. If this is false, layout will be disabled within this module.
      * @var string|boolean 布局文件
      */
     public $layout;
     /**
      * @var array mapping from controller ID to controller configurations.
      * @var array 控制器ID到控制器配置的映射
      * Each name-value pair specifies the configuration of a single controller.
      * A controller configuration can be either a string or an array.
      * If the former, the string should be the fully qualified class name of the controller.
      * If the latter, the array must contain a 'class' element which specifies
      * the controller's fully qualified class name, and the rest of the name-value pairs
      * in the array are used to initialize the corresponding controller properties. For example,
      * 每一个键值对指定一个单独的控制器，控制器配置可以是一个字符串或者数组，如果是前者，该字符串是指定控制的的全路径（即带命名空间的）
      * 如果是后者，则数组中包含一个‘class’元素，该元素指定控制器的全路径，其余的参数用于初始化对应的属性，例子如下：
      *
      * ```php
      * [
      *   'account' => 'app\controllers\UserController',//字符串形式，指定了accout控制器的路径
      *   'article' => [
      *      'class' => 'app\controllers\PostController',//指定article控制器的路径
      *      'pageTitle' => 'something new',//提供了pageTitle参数
      *   ],
      * ]
      * ```
      */
     public $controllerMap = [];
     /**
      * @var string the namespace that controller classes are in.
      * @var string 控制器的命名空间
      * This namespace will be used to load controller classes by prepending it to the controller
      * class name.
      * 该命名空间用于加在控制器类的前面加载控制器类
      *
      * If not set, it will use the `controllers` sub-namespace under the namespace of this module.
      * For example, if the namespace of this module is "foo\bar", then the default
      * controller namespace would be "foo\bar\controllers".
      * 如果没有给定，默认为当前模块的命名空间加上 `controllers`构成的子命名空间
      * 如当前模块的命名空间为"foo\bar"，那么控制器的默认命名空间为"foo\bar\controllers"
      *
      * See also the [guide section on autoloading](guide:concept-autoloading) to learn more about
      * defining namespaces and how classes are loaded.
      */
     public $controllerNamespace;
     /**
      * @var string the default route of this module. Defaults to 'default'.
      * @var string 当前模块的默认路由 默认为'default'
      * The route may consist of child module ID, controller ID, and/or action ID.
      * route 可能包含子模块ID，控制器ID，和/或 action ID，如果action ID未给定，则会调用[Controller::defaultAction]指定的action
      * For example, `help`, `post/create`, `admin/post/create`.
      * If action ID is not given, it will take the default value as specified in
      * [[Controller::defaultAction]].
      */
     public $defaultRoute = 'default';

     /**
      * @var string the root directory of the module.
      * @var string 当前模块的根路径
      */
     private $_basePath;
     /**
      * @var string the root directory that contains view files for this module
      * @var string 当前模块下视图文件的路径数组
      */
     private $_viewPath;
     /**
      * @var string the root directory that contains layout view files for this module.
      * @var string 当前模块下的布局文件路径数组
      */
     private $_layoutPath;
     /**
      * @var array child modules of this module
      * @var array 当前模块的子模块数组
      */
     private $_modules = [];

     /**
      * Constructor.
      * 构造函数
      * @param string $id the ID of this module
      * @param string $id 当前模块的ID
      * @param Module $parent the parent module (if any)
      * @param Module $parent 当前模块的父模块（如果有的话）
      * @param array $config name-value pairs that will be used to initialize the object properties
      * @param array $config 配置文件|数组
      */
     public function __construct($id, $parent = null, $config = [])
     {
         $this->id = $id;//给当前模块赋值唯一ID
         $this->module = $parent;//给module属性（即当前模块的父模块）赋值
         parent::__construct($config);//将配置文件赋值到Object的属性中，因为Object是所有类的基类，理论可以整个项目中访问
     }

     /**
      * Returns the currently requested instance of this module class.
      * 从Yii::$app->loadedModules['yii\web\Application']数组中取得当前类的实例
      * If the module class is not currently requested, null will be returned.
      * This method is provided so that you access the module instance from anywhere within the module.
      * 该方法可以在模块内的任何地方访问类的实例
      * @return static|null the currently requested instance of this module class, or null if the module class is not requested.
      */
     public static function getInstance()
     {
         $class = get_called_class();
         return isset(Yii::$app->loadedModules[$class]) ? Yii::$app->loadedModules[$class] : null;
     }

     /**
      * Sets the currently requested instance of this module class.
      * 将当前类名和存储类的对象变量加入Yii::$app->loadedModules['yii\web\Application']数组中
      * 这样直接通过Yii::$app->loadedModules['yii\web\Application']就可以直接调用这个类
      * @param Module|null $instance the currently requested instance of this module class.
      * If it is null, the instance of the calling class will be removed, if any.
      */
     public static function setInstance($instance)//module模块里会用到，为getInstance提供数据
     {
         if ($instance === null) {
             unset(Yii::$app->loadedModules[get_called_class()]);//如果没有传入参数，说明是删除，直接unset
         } else {
             Yii::$app->loadedModules[get_class($instance)] = $instance;//否则将该类和类的实例存入loadedModules数组中
         }
     }

     /**
      * Initializes the module.
      * 初始化模块，取出控制器的命名空间，也可以理解为路径 注：第一次加载的时候才会执行
      * This method is called after the module is created and initialized with property values
      * given in configuration. The default implementation will initialize [[controllerNamespace]]
      * if it is not set.
      *
      * If you override this method, please make sure you call the parent implementation.
      */
     public function init()
     {
         if ($this->controllerNamespace === null) {//判断controllerNamespace属性是否被赋值，没有赋值才执行
             $class = get_class($this);//获取类名
             if (($pos = strrpos($class, '\\')) !== false) {
                 $this->controllerNamespace = substr($class, 0, $pos) . '\\controllers';//取得命名空间
             }
         }
     }