[PHP] CachedArray class

CachedArray.php

<?php

class CachedArray implements ArrayAccess {
  private $cache,
          $read,
          $exists,
          $update,
          $delete;

  public function __construct($callbacks){
    if (is_callable($callbacks)){
      $this->read    = $callbacks;
    } else {
      $this->read    = ($_=&$callbacks['get'])    ?: false;;
      $this->exists  = ($_=&$callbacks['exists']) ?: false;
      $this->update  = ($_=&$callbacks['set'])    ?: false;;
      $this->delete  = ($_=&$callbacks['unset'])  ?: false;;
    }
  }

  public function offsetGet($id){
    return isset($this->cache[$id]) 
           ? $this->cache[$id] 
           : $this->cache[$id] = call_user_func($this->read, $id);
  }

  public function offsetSet($id, $value){
    if ($this->update) call_user_func($this->update, $id, $value);
  }

  public function offsetUnset($id){
    if ($this->delete) {
      unset($this->cache[$id]);
      call_user_func($this->delete, $id);
    }
  }

  public function offsetExists($id){
    return isset($this->cache[$id]) 
           ? true 
           : ($this->exists 
              ? call_user_func($this->exists, $id) 
              : true
           );
  }

}


/*


$users = new CachedArray([
  'get' => function($id){
      return SQL::single("SELECT * FROM users WHERE id=?",[$id]);
  },
  'set' => function($id, $value){
      $value = (array)$value;
      if ($id) {
        $value['id'] = $id;
        SQL::insertOrUpdate("users",$value);
      } else {
        // Append
        SQL::insert("users",$value);
      }
      return $value;
  },
  'unset' => function($id){
      return SQL::exec("DELETE FROM users WHERE id=?",[$id]);
  },
  'exists' => function($id){
      return !!SQL::value("SELECT 1 FROM users WHERE id=?",[$id]);
  },
]);



// Fetch an User

$me = $users["root"];

// Create a new User

$users["mario.ross"] = [
  'age' => 25,
  'level' => 50,
  'class' => 'paladine'
];


// Delete an User

unset($users["root"]);

// Check if an user exists

if (isset($users["lord.voldemort"])) ...

*/