设计模式专题（二十三） ——解释器模式

<?php
//解释器模式——模拟where语句
//1.文本类
class Context{
         private$rawContents;//翻译前
         private$arrMid;//翻译中的临时变量
         private$interContents;//翻译后，失败时为##error：msg##
         publicfunction __construct($rawStr){
                   $this->rawContents= $rawStr;
                   $this->interContents= '';
                   $this->arrMid= array();
         }
         publicfunction getRaw(){
                   return$this->rawContents;
         }
         publicfunction getInter(){
                   return$this->interContents;
         }
         publicfunction getArrMid(){
                   return$this->arrMid;
         }
         publicfunction setRaw($rawStr){
                   $this->rawContents= $rawStr;
         }
         publicfunction setInter($interStr){
                   $this->interContents= $interStr;
         }
         publicfunction setArrMid(array $arr){
                   $this->arrMid= $arr;
         }
}
//2.解释器抽象类
abstract class Interpreter{
         protected$result = '';
         protected$context;
         publicfunction __construct(Context $context){
                   $this->context= $context;
         }
         publicfunction setContext(Context $context){
                   $this->context= $context;
         }
         publicfunction explain(){}
         publicfunction getResult(){
                   return$this->result;
         }
         protectedfunction setContextInter($interStr){
                   $this->context->setInter($interStr);
                   return$this->context;
         }       
}
//3.具体解释器1--where的比较解释器
class InterpreterCompare extendsInterpreter{
         publicfunction __construct(Context $context){
                   praent::__construct(Context$context);
         }
         publicfunction explain(){
                   $arrMid= $this->context->getArrMid();
                   if(5!= count($arrMid)){
                            $this->setContextInter('##error：wrongcompare type##');
                   }
                   switch($arrMid[3]) {
                            case'equal':
                                     $this->result= $arrMid[2] . '=' . $arrMid[4];
                                     $this->setContextInter($this->result);
                                     break;
                            case'large':
                                     $this->result= $arrMid[2] . '>' . $arrMid[4];
                                     $this->setContextInter($this->result);
                            default:
                                     $this->setContextInter('##error：wrongcompare node##');
                                     break;
                   }
                   return$this->context;
         }
}
//4.具体解释器2--where的like解释器
class InterpreterLike extends Interpreter{
         publicfunction __construct(Context $context){
                   praent::__construct(Context$context);
         }
         publicfunction explain(){
                   $arrMid= $this->context->getArrMid();
                   if(6!= count($arrMid)){
                            $this->setFalse('##error：wrongcompare type##');
                   }
                   $this->result= $arrMid[2];
                   $this->result.= '%' == $arrMid[3] ? '%' : '';
                   $this->result.= $arrMid[4];
                   $this->result.= '%' == $arrMid[5] ? '%' : '';
                   return$this->context;
         }
}
//5.工厂类
class InterpreterFactory{
         private$arrInters;
         private$context;
         privatestatic $ins;
         privatefunction __construct(){}
         privatefunction __clone(){}
         publicstatic function getInstance(){
                   if(null== self::$ins){
                            self::$ins= new self;
                            $this->arrInters= array();
                            $this->context= null;
                   }
                   returnself::$ins;
         }
         publicfunction setContext(Context $context){
                   $this->context= $context;
                   return$this;
         }
         publicfunction doInterpreter(){
                   $rawStr= $this->context->getRaw();
                   //原生的是where|and|compare|a|equal|b形式
                   $rawArr= explode('|', $rawStr);
                   if('where'!= $rawArr[0] || 6 != count($rawArr)){
                            return$this->setFalse('##error：wrong raw string##');
                   }
                   $this->context->setArrMid($rawArr);//设置中间变量
                   $interpreterType= $rawArr[2];//compare like
                   switch($interpreterType) {
                            case'compare':
                                     if(!isset($this->arrInters['compare'])){
                                               $this->arrInters['compare']= new InterpreterCompare($this->context);
                                     }
                                     $this->context= $this->arrInters['compare']->explain();
                                     break;
                            case'like':
                                     if(!isset($this->arrInters['like'])){
                                               $this->arrInters['like']= new InterpreterLike($this->context);
                                     }
                                     $this->context= $this->arrInters['like']->explain();                           
                                     break;
                            default:
                                     $this->setFalse('##error：wronginterpreter type##');
                                     break;
                   }
                   return$this->context;
         }
         privatefunction setFalse($interStr){
                   $this->context->setInter($interStr);
                   return$this->context;
         }
}
//6.客户端
$rawStr = 'where|and|compare|a|equal|b';
$rawContext = new Context($rawStr);
$interContext =InterpreterFactory::getInstance()
                ->setContext($rawContext)
                ->doInterpreter();