设计模式专题（二十四） ——访问者模式

<?php
//访问者模式
//1.抽象element
abstract class Element{
         protected$isDelete;
         protected$isUpdate;
         protected$isInsert;
         protected$sql;
         protected$data;
         publicfunction __construct(){
                   $this->isDelete= false;
                   $this->isUpdate= false;
                   $this->isInsert= false;
                   $this->sql= '';
                   $this->data= array();
         }
         protectedfunction delete(){
                   $this->isDelete= true;
         }
         protectedfunction isUpdate(){
                   $this->isUpdate= true;
         }
         protectedfunction isInsert(){
                   $this->isInsert= true;
         }
         publicfunction getSql(){
                   return$this->sql;
         }
         publicfunction setData($type, $data){
                   switch($type) {
                            case'insert':
                                     $this->isInsert();
                                     $this->insert($data);
                                     break;
                            case'update':
                                     $this->isUpdate();
                                     $this->update($data);
                            case'delete':
                                     $this->isDelete();
                                     $this->delete($data);
                            default:
                                     $this->select($data);
                                     break;
                   }
                   $this->data= $data;
         }
         publicfunction insert($data){}
         publicfunction update($data){}
         publicfunction delete($data){}
         publicfunction select($data){}
}
//2.具体element--delete
class ElementTableA{
         publicfunction __construct(){
                   parent::__construct();
         }
         publicfunction insert($data){
                   $this->sql= 'insert tableA的sql';
         }
         publicfunction update($data){
                   $this->sql= 'update tableA的sql';
         }
         publicfunction delete($data){
                   $this->sql= 'delete tableA的sql';
         }
}
//table B 同 table A
//3.执行类
class UnitWork{
         public$sqls;
         public$elements;
         privatefunction setElements(array $elements){
                   foreach($elements as $index => $ele) {
                            if(!($eleinstanceof Element)){
                                     unset($elements[$index]);
                            }
                   }
                   if(empty($elements)){
                            returnfalse;
                   }
                   $this->elements= $elements;
                   returntrue;
         }
         privatefunction setSqls(){
                   foreach($this->elements as $element) {
                            if(empty($element->getSql())){
                                     continue;
                            }
                            $this->sqls[]= $element->sql;
                   }
                   if(empty($this->sqls)){
                            returnfalse;
                   }
                   returntrue;
         }
         privatefunction run(){
                   //1.连接数据库
                   foreach($this->sqls as $sql) {
                            //2.执行sql
                   }
                   //3.断开数据库连接
         }
         publicfunction commit(array $elements){
                   if(empty($elements)){
                            returnfalse;
                   }
                   $res= $this->setElements($elements);
                   if(!$res){
                            returnfalse;
                   }
                   $res= $this->setSqls();
                   if(!$res){
                            returnfalse;
                   }                
                   $this->run();
         }
}
//4.客户端
$ea = new ElementTableA();
$ea->insert(array('col1'=>'a','col2'=>'b'));
$eb = new ElementTableA();
$eb->update(array('id'=>'xx','col1'=>'a', 'col2'=>'b'));
$uw = new UnitWork();
$uw->commit(array($ea, $eb));