php重载数组操作符

php重载数组操作符

在php中提供了许多接口用于实现一些很特定的功能,比如你想把一个对象当作array使用时,只需要实现ArrayAccess接口,当你想要foreach中能够使用一个对象时,只需要实现Iterator接口,下面给一个例子出来

class BtstoreRoot

{

/**

* 根结点

* @var BtstoreElement

*/

static $root;

}

class BtstoreElement implements ArrayAccess, Iterator

{

/**

* 当前所代表的目录

* @var string

*/

private $dataDir;

/**

* 当前所代表的数据

* @var array

*/

private $arrData;

/**

* 构造函数

* @param string $dataDir

* @param array $arrData

*/

function __construct($dataDir, $arrData)

{

$this->dataDir = '';

$this->arrData = array ();

if (! empty ( $dataDir ) && is_dir ( $dataDir ))

{

$this->dataDir = $dataDir;

}

if (! empty ( $arrData ))

{

$this->arrData = $arrData;

}

}

function __get($key)

{

if (isset ( $this->arrData [$key] ))

{

$data = $this->arrData [$key];

if (is_array ( $data ) && ! is_object ( $data ))

{

$data = new BtstoreElement ( '', $data );

}

return $data;

}

if (! empty ( $this->dataDir ))

{

$path = $this->dataDir . '/' . $key;

if (is_dir ( $path ))

{

$data = new BtstoreElement ( $path, null );

$this->arrData [$key] = $data;

return $data;

}

if (is_file ( $path ))

{

$content = file_get_contents ( $path );

$arrData = unserialize ( $content );

$data = new BtstoreElement ( '', $arrData );

$this->arrData [$key] = $data;

return $data;

}

}

trigger_error ( "undefined index:$key" );

}

function __isset($key)

{

if (isset ( $this->arrData [$key] ))

{

return true;

}

if (file_exists ( $this->dataDir . '/' . $key ))

{

return true;

}

return false;

}

function toArray()

{

return $this->arrData;

}

/* (non-PHPdoc)

* @see ArrayAccess::offsetExists()

*/

public function offsetExists($offset)

{

return $this->__isset ( $offset );

}

/* (non-PHPdoc)

* @see ArrayAccess::offsetGet()

*/

public function offsetGet($offset)

{

return $this->__get ( $offset );

}

/* (non-PHPdoc)

* @see ArrayAccess::offsetSet()

*/

public function offsetSet($offset, $value)

{

trigger_error ( 'offsetSet not implemented by BtstoreElement' );

}

/* (non-PHPdoc)

* @see ArrayAccess::offsetUnset()

*/

public function offsetUnset($offset)

{

trigger_error ( 'offsetUnset not implemented by BtstoreElement' );

}

/* (non-PHPdoc)

* @see Iterator::current()

*/

public function current()

{

return current ( $this->arrData );

}

/* (non-PHPdoc)

* @see Iterator::next()

*/

public function next()

{

return next ( $this->arrData );

}

/* (non-PHPdoc)

* @see Iterator::key()

*/

public function key()

{

return key ( $this->arrData );

}

/* (non-PHPdoc)

* @see Iterator::valid()

*/

public function valid()

{

$data = current ( $this->arrData );

return ! empty ( $data );

}

/* (non-PHPdoc)

* @see Iterator::rewind()

*/

public function rewind()

{

reset ( $this->arrData );

}

}

/**

* 获取一个BtstoreElement对象

* @return BtstoreElement

*/

function btstore_get()

{

if (empty ( BtstoreRoot::$root ))

{

BtstoreRoot::$root = new BtstoreElement ( ScriptConf::BTSTORE_ROOT, null );

}

return BtstoreRoot::$root;

}