PHP面向对象中的标识对象

/*
标识对象模式
这个模式主要功能就是创建sql语句中的wehre条件字符串的，下面直接看代码和注释:

*/
namespace woomapper;


//字段对象
class Field {
    protected $name = null;          //字段名称
    protected $operator = null;         //操作符    
    protected $comps = array();         //存放条件的数组    
    protected $incomplete = false;     //检查条件数组是否有值
    
    function __construct ($name){
        $this->name= $name;
    }
    
    //添加where 条件
    function addTest($operator,$value){
        $this->comps[] = array('name'=>$this->name,'operator'=>$operator,'value'=>$value);
    }
    
    //获取存放条件的数组
    function getComps(){
        return $this->comps;
    }
    
    function isIncomplete(){
        return empty($this->comps);
    }
}


//标识对象
class IdentityObject {
    protected $currentfield = null;        //当前操作的字段对象
    protected $fields = array();        //字段集合
    private $and = null;
    private $enforce = array();            //限定的合法字段        
    
    function __construct($field = null, array $enforce = null){
        if(!is_null($enforce)){
            $this->enforce = $enforce;
        }
        if(!is_null($field)){
            $this->field($field);
        }
    }
    
    //获取限定的合法字段
    function getObjectFields(){
        return $this->enforce;
    }
    
    //主要功能为设置当前需要操作的对象
    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;                    //采用连贯语法
    }
    
    //字段集合是否为空
    function isVoid(){
        return empty($this->fields);
    }
    
    //检查字段是否合法
    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}");
        }
    }
    
    
    //向字段对象添加where条件
    function eq($value){
        return $this->operator("=",$value);
    }
    
    function lt($value){
        return $this->operator("<",$value);
    }
    
    function gt($value){
        return $this->operator(">",$value);
    }
    
    //向字段对象添加where条件
    private function operator($symbol,$value){
        if($this->isVoid){
            throw new Exception("no object field defined");
        }
        $this->currentfield->addTest($symbol,$value);
        return $this;                                     //采用连贯语法
    }
    
    //获取此类中所有字段对象集合的where条件数组
    function getComps(){
        $ret = array();
        foreach($this->fields as $key => $field){
            $ret = array_merge($ret,$field->getComps());
        }
        return $ret;
    }
}

//客户端代码
$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);

//输出类似下面的内容

/*
array{
    array('name'=>'name','operator'=>'=','value'=>'The Good Show'),
    array('name'=>'start','operator'=>'>','value'=>'123456'),   //123456表示time()函数输出的时间戳
    array('name'=>'start','operator'=>'<','value'=>'123456')
}

*/

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