解释器模式

<?php
//解析类
class Parse {
    private $_vars = array();
    
    public function assign($_var, $_value) {
        $this->_vars[$_var] = $_value;
    }
    
    public function __get($_key) {
        return $this->$_key;
    } 
    
    public function display($_str) {
        /*变量处理*/
        $_variable = new Variable();
        $_str = $_variable->expression($this, $_str);
        /*if语句处理*/
        
        return $_str;
    }
}
?>

<?php
abstract class Compile {
    abstract public function expression($_parse, $_str);
}
?>
<?php
//变量操作
class Variable extends Compile {
    public function expression($_parse, $_str) {
        $_patten = '/\{\$([\w]+)\}/e';
        if (preg_match($_patten, $_str)) {
            $_str = preg_replace($_patten, "\$_parse->_vars['$1']", $_str);
        }
        return $_str;
    }
}
?>

<?php

require 'Parse.class.php';
require 'Compile.class.php';
require 'Variable.class.php';

$_parse = new Parse();

$_parse->assign('name', 'Lee');
$_parse->assign('age', 100);
$_parse->assign('price', 22.5);
$_parse->assign('pp', '联想');

$_str = '

This is a {$name}，{$age}岁。

这是一台{$pp}电脑，他的价格为：{$price}。

';


echo $_parse->display($_str);


?>