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<?php |
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namespace EventEspresso\core\services\orm\tree_traversal; |
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/** |
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* Class BaseNode |
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* |
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* Represents a task to be done when traversing a model object tree to identify all the dependent model objects. |
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* See the concrete classes for details, but the basic structure is you have a starter ModelObjNode that wraps the |
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* model object whose dependent related objects you want to identify, it has a list of RelationNodes (one for each of |
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* its model's relations); each of those builds a list of ModelObjNodes for each of the related model objects, |
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* recursively. |
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* Client code creates a ModelObjNode, provides it with a model object, and repeatedly `visit()` on it until all of its |
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* related model objects are identified. |
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* |
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* When traversing the tree of objects, the pseudo code is this: |
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* |
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* Start off with a model object, and a budget of how many model objects we want to discover |
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* For each of its relations: |
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* count the number of related model objects |
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* then fetch some of them from the DB (no more than what's in our budget) |
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* record how many we fetched, and compare it to our budget |
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* if we're at the budget's limit, stop. |
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* otherwise, for each of them: |
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* start again with it being the root model object. |
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* |
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* @package Event Espresso |
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* @author Mike Nelson |
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* @since $VID:$ |
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* |
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*/ |
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abstract class BaseNode |
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{ |
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/** |
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* @var boolean |
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*/ |
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protected $complete; |
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/** |
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* Whether this item has already been initialized |
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*/ |
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abstract protected function isDiscovered(); |
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/** |
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* Determines if the work is done yet or not. Requires you to have first discovered what work exists by calling |
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* discover(). |
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* @since $VID:$ |
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* @return boolean |
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*/ |
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abstract public function isComplete(); |
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/** |
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* Discovers what work needs to be done to complete traversing this node and its children. |
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* Note that this is separate from the constructor, so we can create child nodes without |
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* discovering them immediately. |
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* @since $VID:$ |
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* @return mixed |
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*/ |
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abstract protected function discover(); |
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/** |
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* Identifies model objects, up to the limit $model_objects_to_identify. |
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* @since $VID:$ |
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* @param int $model_objects_to_identify |
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* @return int units of work done |
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*/ |
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abstract protected function work($model_objects_to_identify); |
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/** |
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* Shows the entity/relation node as an array. |
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* @since $VID:$ |
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* @return array |
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*/ |
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abstract public function toArray(); |
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/** |
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* Discovers how much work there is to do, double-checks the work isn't already finished, and then does the work. |
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* Note: do not call when site is in maintenance mode level 2. |
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* |
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* @since $VID:$ |
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* @param $model_objects_to_identify |
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* @return int number of model objects we want to identify during this call. On subsequent calls we'll continue |
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* where we left off. |
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*/ |
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public function visit($model_objects_to_identify) |
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{ |
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if (! $this->isDiscovered()) { |
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$this->discover(); |
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} |
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if ($this->isComplete()) { |
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return 0; |
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} |
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return $this->work($model_objects_to_identify); |
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} |
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} |
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// End of file BaseNode.php |
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// Location: EventEspresso\core\services\orm\tree_traversal/BaseNode.php |
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eventespresso /
event-espresso-core
