PHP面向對象之標識對象

/*
標識對象模式
這個模式主要功能就是創建sql語句中的wehre條件字元串的，下麵直接看代碼和註釋:

*/
namespace woo\mapper;


//欄位對象
class Field {
    protected $name = null;          //欄位名稱
    protected $operator = null;         //操作符    
    protected $comps = array();         //存放條件的數組    
    protected $incomplete = false;     //檢查條件數組是否有值
    
    function __construct ($name){
        $this->name= $name;
    }
    
    //添加where 條件
    function addTest($operator,$value){
        $this->comps[] = array('name'=>$this->name,'operator'=>$operator,'value'=>$value);
    }
    
    //獲取存放條件的數組
    function getComps(){
        return $this->comps;
    }
    
    function isIncomplete(){
        return empty($this->comps);
    }
}


//標識對象
class IdentityObject {
    protected $currentfield = null;        //當前操作的欄位對象
    protected $fields = array();        //欄位集合
    private $and = null;
    private $enforce = array();            //限定的合法欄位        
    
    function __construct($field = null, array $enforce = null){
        if(!is_null($enforce)){
            $this->enforce = $enforce;
        }
        if(!is_null($field)){
            $this->field($field);
        }
    }
    
    //獲取限定的合法欄位
    function getObjectFields(){
        return $this->enforce;
    }
    
    //主要功能為設置當前需要操作的對象
    function field($fieldname){
        if(!$this->isVoid()&& $this->currentfield->isIncomplete()){
            throw new \Exception("Incomplete field");
        }
        $this->enforceField($fieldname);
        if(isset($this->fields[$fieldname]){
            $this->currentfield = $this->fields[$fieldname];
        } else {
            $this->currentfield = new Field($fieldname);
            $this->fields[$fieldname] = $this->currentfield;
        }
        return $this;                    //採用連貫語法
    }
    
    //欄位集合是否為空
    function isVoid(){
        return empty($this->fields);
    }
    
    //檢查欄位是否合法
    function enforceField ($fieldname){
        if(!in_array($fieldname,$this->enforce) && !empty($this->enforce)){
            $forcelist = implode(',',$this->enforce);
            throw new \Exception("{$fieldname} not a legal field {$forcelist}");
        }
    }
    
    
    //向欄位對象添加where條件
    function eq($value){
        return $this->operator("=",$value);
    }
    
    function lt($value){
        return $this->operator("<",$value);
    }
    
    function gt($value){
        return $this->operator(">",$value);
    }
    
    //向欄位對象添加where條件
    private function operator($symbol,$value){
        if($this->isVoid){
            throw new \Exception("no object field defined");
        }
        $this->currentfield->addTest($symbol,$value);
        return $this;                                     //採用連貫語法
    }
    
    //獲取此類中所有欄位對象集合的where條件數組
    function getComps(){
        $ret = array();
        foreach($this->fields as $key => $field){
            $ret = array_merge($ret,$field->getComps());
        }
        return $ret;
    }
}

//客戶端代碼
$idobj = new IdentityObject ();
$idobj->field("name")->eq("The Good Show")->field("start")->gt(time())->lt(time()+(24*60*60));
$test = $idobj->getComps();
var_dump($test);

//輸出類似下麵的內容

/*
array{
    array('name'=>'name','operator'=>'=','value'=>'The Good Show'),
    array('name'=>'start','operator'=>'>','value'=>'123456'),   //123456表示time()函數輸出的時間戳
    array('name'=>'start','operator'=>'<','value'=>'123456')
}

*/