DataAccess/DataMapper/LazyLoadedEntities.php

   1 <?php
   2
   3 namespace DataAccess\DataMapper;
   4
   5 use DataAccess\DataMapper\Helpers\AbstractPopulationHelper;
   6 use ReflectionClass;
   7 use Iterator;
   8
   9 class LazyLoadedEntities implements Iterator
  10 {
  11     private $_maps;
  12     private $_entityName;
  13     private $_rows;
  14     private $_rowIndex = 0;
  15     private $_loadedEntitiesIndex = 0;
  16     private $_loadedEntities = array();
  17     private $_db;
  18
  19     public function __construct(array $rows, $entityName, $maps, $db)
  20     {
  21         $this->_rows = $rows;
  22         $this->_entityName = $entityName;
  23         $this->_maps = $maps;
  24         $this->_db = $db;
  25     }
  26
  27     public function current()
  28     {
  29         return $this->_loadedEntities[$this->_loadedEntitiesIndex];
  30     }
  31
  32     public function key()
  33     {
  34         return $this->_loadedEntitiesIndex;
  35     }
  36
  37     public function next()
  38     {
  39         $keys = array_keys($this->_loadedEntities);
  40         $pos = array_search($this->_loadedEntitiesIndex, $keys);
  41         if(isset($keys[$pos + 1]))
  42         {
  43             $this->_loadedEntitiesIndex = $keys[$pos+1];
  44         } else {
  45             $this->mapEntities(); //sets the loaded entites index
  46         }
  47     }
  48
  49     public function rewind()
  50     {
  51         $this->_rowIndex = 0;
  52         $this->mapEntities();
  53     }
  54
  55     public function valid()
  56     {
  57         //next will always load more entities when it runs out, therefore if
  58         //we have an empty loadEntities array, it means there were no more and we are done.
  59         if($this->_loadedEntities)
  60         {
  61             return true;
  62         }
  63
  64         return false;
  65     }
  66
  67     //unsets the current entities array, and maps in the next 10
  68     private function mapEntities()
  69     {
  70         $numToMap = 50;
  71         $tick = 0;
  72
  73         unset($this->_loadedEentities);
  74         $this->_loadedEntities = array();
  75
  76         $entityName = $this->_entityName;
  77         for($i = $this->_rowIndex; $i<$this->_rowIndex+$numToMap; $i++)
  78         {
  79             if(isset($this->_rows[$i]))
  80             {
  81                 $row = $this->_rows[$i];
  82                 $className = $this->_maps[$entityName]['class']; //the entity to instantiate and return
  83                 $constructors = AbstractPopulationHelper::getConstrutorArray($this->_maps, $entityName, $row, $this->_db);
  84
  85                 if(count($constructors) == 0)
  86                 {
  87                     $class = new $className;
  88                 } else {
  89                     $r = new ReflectionClass($className);
  90                     $class = $r->newInstanceArgs($constructors);
  91                 }
  92
  93                 $class->setId($row['id']);
  94                 $this->_loadedEntities[$row['id']] = $class;
  95
  96                 if($tick == 0) $this->_loadedEntitiesIndex = $row['id'];
  97                 $tick++;
  98             }
  99         }
 100
 101         $this->_rowIndex += $numToMap;
 102     }
 103 }