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<?php |
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/** |
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* @link http://www.newicon.net/neon |
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* @copyright Copyright (c) 2019 Newicon Ltd |
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* @license http://www.newicon.net/neon/license/ |
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* @package neon |
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*/ |
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namespace neon\core\helpers; |
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use yii\base\Component; |
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/** |
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* Defines a basic iterator for use in paginated database requests. |
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* |
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* To use it you can simply create one which will have a start value of 0 |
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* and a length of 100. You can request up to 1000 items back at once. If you |
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* need more than 1000, then you should be seriously considering why. |
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* |
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* To request the total during a call, set returnTotal() on the Iterator. |
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* This will, for efficiency reasons, only set this if you are at the |
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* beginning of the iteration, i.e. start=0. Counts are costly so should be |
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* avoided. This way you can set the request at the beginning and use the |
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* total value from then on. |
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* |
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* @package neon\core\helpers |
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*/ |
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class Iterator extends Component |
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{ |
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/** |
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* The maximum number that can be returned in any one request |
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* @const integer |
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*/ |
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const MAX_LENGTH = 1000; |
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/** |
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* Return the total number found |
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* @var integer |
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*/ |
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public $total = 0; |
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/** |
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* The starting position |
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* @var integer |
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*/ |
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private $_start = 0; |
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/** |
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* The number to return |
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* @var integer |
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*/ |
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private $_length = 100; |
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/** |
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* Whether or not to get the total |
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* @var boolean |
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*/ |
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private $_returnTotal = false; |
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/** |
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* Set the starting position |
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* @param integer $start |
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*/ |
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public function setStart($start) |
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{ |
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$this->_start = max(0, $start); |
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} |
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/** |
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* Set the number to return |
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* @param integer $length |
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*/ |
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public function setLength($length) |
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{ |
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$this->_length = min($length, self::MAX_LENGTH); |
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} |
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/** |
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* Get the starting position |
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* @return integer |
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*/ |
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public function getStart() |
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{ |
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return $this->_start; |
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} |
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/** |
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* Get the number to return |
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* @return integer |
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*/ |
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public function getLength() |
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{ |
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return $this->_length; |
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} |
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/** |
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* Use to request a total is calculated. This will only |
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* work if the starting position is 0 for efficiency reasons |
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* or if you force it to return a total (this should be |
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* avoided if possible as counts are very expensive operations) |
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*/ |
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public function returnTotal(bool $force=false) |
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{ |
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$this->_returnTotal=($force? true : ($this->_start == 0)); |
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} |
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/** |
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* Whether or not to calculate and return a total |
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* @return boolean |
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*/ |
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public function shouldReturnTotal() |
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{ |
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return $this->_returnTotal; |
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} |
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/** |
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* Convert to an array |
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* @return |
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* start => the start value |
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* length => the length value |
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* total => truthy if should return total, otherwise the total |
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*/ |
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public function toArray() |
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{ |
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return [ |
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'start' => $this->start, |
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'length' => $this->length, |
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'total' => $this->_returnTotal ? true : $this->total |
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]; |
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} |
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} |
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