视图(View) - TP5源代码阅读

public static function instance($engine = [], $replace = [])
    {
 if (is_null(self::$instance)) {
     self::$instance = new self($engine, $replace);
 }
 return self::$instance;
    }


### $view->__construct()
>>视图构造函数，创建视图对象

public function __construct($engine = [], $replace = [])
    {
 // 初始化模板引擎
 $this->engine((array) $engine);
 $this->replace = $replace;
    }


### $view->engine()
>>模板引擎创建，根据配置创建相应的模板引擎(默认为Think)

public function engine($options = [])
    {
 if (is_string($options)) {
     $type    = $options;
     $options = [];
 } else {
     $type = !empty($options['type']) ? $options['type'] : 'Think';
 }

 $class = false !== strpos($type, '\') ? $type : '\think\view\driver\' . ucfirst($type);
 if (isset($options['type'])) {
     unset($options['type']);
 }
 $this->engine = new $class($options);
 return $this;
    }

>>由上可知，默认的模板引擎(Think)实现为viewdriverThink.php文件。模板引擎具体的信息见 模板引擎 章节

### $view->config()
>>模板引擎配置，配置模板引擎参数

public function config($name, $value = null)
    {
 $this->engine->config($name, $value);
 return $this;
    }




# 2 视图操作

## 2-1 模板变量
### $view->assign()
>>存储数据到模板变量中。

public function assign($name, $value = '')
    {
 if (is_array($name)) {
     $this->data = array_merge($this->data, $name);
 } else {
     $this->data[$name] = $value;
 }
 return $this;
    }


### $view->__get()
>> 模板变量获取快捷操作

public function __get($name)
    {
 return $this->data[$name];
    }


### $view->__set()
>> 模板变量赋值快捷操作

public function __set($name, $value)
    {
 $this->data[$name] = $value;
    }


### $view->__isset()
>> 模板变量检测快捷操作

public function __isset($name)
    {
 return isset($this->data[$name]);
    }


## 2-2 模板文件
>>模板文件，作为界面组织的文件。模板引擎将模板变量填充到模板文件中生成输出的Web页面

### $view->replace()
>> 模板字符串替换内容配置

public function replace($content, $replace = '')
    {
 if (is_array($content)) {
     $this->replace = array_merge($this->replace, $content);
 } else {
     $this->replace[$content] = $replace;
 }
 return $this;
    }



### $view->fetch()
>> 获取模板文件解析结果


public function fetch($template = '', $vars = [], $replace = [], $config = [], $renderContent = false)
    {
 // 模板变量
 $vars = array_merge($this->data, $vars);

 // 页面缓存
 ob_start();
 ob_implicit_flush(0);

 // 渲染输出
 $method = $renderContent ? 'display' : 'fetch';
 $this->engine->$method($template, $vars, $config);

 // 获取并清空缓存
 $content = ob_get_clean();
 // 内容过滤标签
 Hook::listen('view_filter', $content);
 // 允许用户自定义模板的字符串替换
 $replace = array_merge($this->replace, $replace);
 if (!empty($replace)) {
     $content = strtr($content, $replace);
 }
 return $content;
    }


### $view->display()
>> 输出模板文件解析结果

public function display($content, $vars = [], $replace = [], $config = [])
    {
 return $this->fetch($content, $vars, $replace, $config, true);
    }