自个儿默写smarty模板引擎,不解析php呢(求高手帮忙)

自己默写smarty模板引擎,不解析php呢(求高手帮忙)
$realcontent =$this->filecontent;


$mode = '/\{\$([\w]+)\}/';
if(preg_match($mode,$realcontent)){

var_dump($assign_vars);

$realcontent=preg_replace($mode,"assign_vars['$1'] ?>",$realcontent); ;//替换成index.php文件中注入的变量


}
return $realcontent;


}

运行后代码为
assign_vars['content'] ?>

作者:assign_vars['name'] ?>assign_vars['var'] ?>

------解决思路----------------------

$realcontent = file_get_contents("template_test.html");
$tpl_string = <<< TEMPLEATE

    
        
        
    
    
        作者:{\$name}
        国家:{\$china}
        省份:{\$provice}
        城市:{\$city}
    

TEMPLEATE;
$mode = '/\{\$(\w+)\}/';
$assign_arr = array();
function assign($name, $value) {    
    global $assign_arr;
    $assign_arr[$name] = empty($value) ? '' : $value;    
    return $assign_arr;
}
function replace_content($match) {
    global $assign_arr;
    if (!empty($match)) {        
        return array_key_exists($match[1], $assign_arr) ? $assign_arr[$match[1]] : '';
    }
}
assign("title", "I love you");
assign("name", "iseagold");
assign("china", "中国");
assign("provice", "广东省");
assign("city", "深圳市");
assign("no", "页面不存在,未取出的变量");
echo preg_replace_callback($mode, "replace_content", $tpl_string);


//===================================简单的类版本==========================================================
class Template {
    public $assign_items = array();
    public $content;
    
    function __construct($file) {
        $this->content = file_get_contents($file);
    }
    function assign($name, $value) {
        $this->assign_items[$name] = empty($value) ? "" : $value;
    }
    function replace() {
        $arr_assign_items = array();
        $content = '';
        $content = $this->content;
        $arr_assign_items = $this->assign_items;        
        $pattern = '/\{\$(\w+)\}/';
        $this->content = preg_replace_callback($pattern, function($match) use($arr_assign_items) {
            if (!empty($match)) {                      
                
                if (array_key_exists($match[1], $arr_assign_items)) {
                    echo $arr_assign_items[$match[1]];
                    return $arr_assign_items[$match[1]];
                }
            }
        }, $content);
    }
    function display() {
        echo $this->content;
    }
}
$template = new Template("template_test.html");
$template->assign("title", "I love you");
$template->assign("name", "iseagold");
$template->assign("china", "中国");
$template->assign("provice", "广东省");
$template->assign("city", "深圳市");
$template->assign("no", "页面不存在,未取出的变量");
$template->replace();
$template->display();
?>

------解决思路----------------------
你只产生了 php 代码，并没有执行他