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<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package     CodeIgniter
 * @author      EllisLab Dev Team
 * @copyright   Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright   Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
 * @license     http://opensource.org/licenses/MIT      MIT License
 * @link        https://codeigniter.com
 * @since       Version 1.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * Loader Class
 *
 * Loads framework components.
 *
 * @package             CodeIgniter
 * @subpackage  Libraries
 * @category    Loader
 * @author              EllisLab Dev Team
 * @link                https://codeigniter.com/user_guide/libraries/loader.html
 */
class CI_Loader {

        // All these are set automatically. Don't mess with them.
        /**
         * Nesting level of the output buffering mechanism
         *
         * @var int
         */
        protected $_ci_ob_level;

        /**
         * List of paths to load views from
         *
         * @var array
         */
        protected $_ci_view_paths =     array(VIEWPATH  => TRUE);

        /**
         * List of paths to load libraries from
         *
         * @var array
         */
        protected $_ci_library_paths =  array(APPPATH, BASEPATH);

        /**
         * List of paths to load models from
         *
         * @var array
         */
        protected $_ci_model_paths =    array(APPPATH);

        /**
         * List of paths to load helpers from
         *
         * @var array
         */
        protected $_ci_helper_paths =   array(APPPATH, BASEPATH);

        /**
         * List of cached variables
         *
         * @var array
         */
        protected $_ci_cached_vars =    array();

        /**
         * List of loaded classes
         *
         * @var array
         */
        protected $_ci_classes =        array();

        /**
         * List of loaded models
         *
         * @var array
         */
        protected $_ci_models = array();

        /**
         * List of loaded helpers
         *
         * @var array
         */
        protected $_ci_helpers =        array();

        /**
         * List of class name mappings
         *
         * @var array
         */
        protected $_ci_varmap = array(
                'unit_test' => 'unit',
                'user_agent' => 'agent'
        );

        // --------------------------------------------------------------------

        /**
         * Class constructor
         *
         * Sets component load paths, gets the initial output buffering level.
         *
         * @return      void
         */
        public function __construct()
        {
                $this->_ci_ob_level = ob_get_level();
                $this->_ci_classes =& is_loaded();

                log_message('info', 'Loader Class Initialized');
        }

        // --------------------------------------------------------------------

        /**
         * Initializer
         *
         * @todo        Figure out a way to move this to the constructor
         *              without breaking *package_path*() methods.
         * @uses        CI_Loader::_ci_autoloader()
         * @used-by     CI_Controller::__construct()
         * @return      void
         */
        public function initialize()
        {
                $this->_ci_autoloader();
        }

        // --------------------------------------------------------------------

        /**
         * Is Loaded
         *
         * A utility method to test if a class is in the self::$_ci_classes array.
         *
         * @used-by     Mainly used by Form Helper function _get_validation_object().
         *
         * @param       string          $class  Class name to check for
         * @return      string|bool     Class object name if loaded or FALSE
         */
        public function is_loaded($class)
        {
                return array_search(ucfirst($class), $this->_ci_classes, TRUE);
        }

        // --------------------------------------------------------------------

        /**
         * Library Loader
         *
         * Loads and instantiates libraries.
         * Designed to be called from application controllers.
         *
         * @param       string  $library        Library name
         * @param       array   $params         Optional parameters to pass to the library class constructor
         * @param       string  $object_name    An optional object name to assign to
         * @return      object
         */
        public function library($library, $params = NULL, $object_name = NULL)
        {
                if (empty($library))
                {
                        return $this;
                }
                elseif (is_array($library))
                {
                        foreach ($library as $key => $value)
                        {
                                if (is_int($key))
                                {
                                        $this->library($value, $params);
                                }
                                else
                                {
                                        $this->library($key, $params, $value);
                                }
                        }

                        return $this;
                }

                if ($params !== NULL && ! is_array($params))
                {
                        $params = NULL;
                }

                $this->_ci_load_library($library, $params, $object_name);
                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Model Loader
         *
         * Loads and instantiates models.
         *
         * @param       string  $model          Model name
         * @param       string  $name           An optional object name to assign to
         * @param       bool    $db_conn        An optional database connection configuration to initialize
         * @return      object
         */
        public function model($model, $name = '', $db_conn = FALSE)
        {
                if (empty($model))
                {
                        return $this;
                }
                elseif (is_array($model))
                {
                        foreach ($model as $key => $value)
                        {
                                is_int($key) ? $this->model($value, '', $db_conn) : $this->model($key, $value, $db_conn);
                        }

                        return $this;
                }

                $path = '';

                // Is the model in a sub-folder? If so, parse out the filename and path.
                if (($last_slash = strrpos($model, '/')) !== FALSE)
                {
                        // The path is in front of the last slash
                        $path = substr($model, 0, ++$last_slash);

                        // And the model name behind it
                        $model = substr($model, $last_slash);
                }

                if (empty($name))
                {
                        $name = $model;
                }

                if (in_array($name, $this->_ci_models, TRUE))
                {
                        return $this;
                }

                $CI =& get_instance();
                if (isset($CI->$name))
                {
                        throw new RuntimeException('The model name you are loading is the name of a resource that is already being used: '.$name);
                }

                if ($db_conn !== FALSE && ! class_exists('CI_DB', FALSE))
                {
                        if ($db_conn === TRUE)
                        {
                                $db_conn = '';
                        }

                        $this->database($db_conn, FALSE, TRUE);
                }

                // Note: All of the code under this condition used to be just:
                //
                //       load_class('Model', 'core');
                //
                //       However, load_class() instantiates classes
                //       to cache them for later use and that prevents
                //       MY_Model from being an abstract class and is
                //       sub-optimal otherwise anyway.
                if ( ! class_exists('CI_Model', FALSE))
                {
                        $app_path = APPPATH.'core'.DIRECTORY_SEPARATOR;
                        if (file_exists($app_path.'Model.php'))
                        {
                                require_once($app_path.'Model.php');
                                if ( ! class_exists('CI_Model', FALSE))
                                {
                                        throw new RuntimeException($app_path."Model.php exists, but doesn't declare class CI_Model");
                                }
                        }
                        elseif ( ! class_exists('CI_Model', FALSE))
                        {
                                require_once(BASEPATH.'core'.DIRECTORY_SEPARATOR.'Model.php');
                        }

                        $class = config_item('subclass_prefix').'Model';
                        if (file_exists($app_path.$class.'.php'))
                        {
                                require_once($app_path.$class.'.php');
                                if ( ! class_exists($class, FALSE))
                                {
                                        throw new RuntimeException($app_path.$class.".php exists, but doesn't declare class ".$class);
                                }
                        }
                }

                $model = ucfirst($model);
                if ( ! class_exists($model, FALSE))
                {
                        foreach ($this->_ci_model_paths as $mod_path)
                        {
                                if ( ! file_exists($mod_path.'models/'.$path.$model.'.php'))
                                {
                                        continue;
                                }

                                require_once($mod_path.'models/'.$path.$model.'.php');
                                if ( ! class_exists($model, FALSE))
                                {
                                        throw new RuntimeException($mod_path."models/".$path.$model.".php exists, but doesn't declare class ".$model);
                                }

                                break;
                        }

                        if ( ! class_exists($model, FALSE))
                        {
                                throw new RuntimeException('Unable to locate the model you have specified: '.$model);
                        }
                }
                elseif ( ! is_subclass_of($model, 'CI_Model'))
                {
                        throw new RuntimeException("Class ".$model." already exists and doesn't extend CI_Model");
                }

                $this->_ci_models[] = $name;
                $CI->$name = new $model();
                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Database Loader
         *
         * @param       mixed   $params         Database configuration options
         * @param       bool    $return         Whether to return the database object
         * @param       bool    $query_builder  Whether to enable Query Builder
         *                                      (overrides the configuration setting)
         *
         * @return      object|bool     Database object if $return is set to TRUE,
         *                                      FALSE on failure, CI_Loader instance in any other case
         */
        public function database($params = '', $return = FALSE, $query_builder = NULL)
        {
                // Grab the super object
                $CI =& get_instance();

                // Do we even need to load the database class?
                if ($return === FALSE && $query_builder === NULL && isset($CI->db) && is_object($CI->db) && ! empty($CI->db->conn_id))
                {
                        return FALSE;
                }

                require_once(BASEPATH.'database/DB.php');

                if ($return === TRUE)
                {
                        return DB($params, $query_builder);
                }

                // Initialize the db variable. Needed to prevent
                // reference errors with some configurations
                $CI->db = '';

                // Load the DB class
                $CI->db =& DB($params, $query_builder);
                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Load the Database Utilities Class
         *
         * @param       object  $db     Database object
         * @param       bool    $return Whether to return the DB Utilities class object or not
         * @return      object
         */
        public function dbutil($db = NULL, $return = FALSE)
        {
                $CI =& get_instance();

                if ( ! is_object($db) OR ! ($db instanceof CI_DB))
                {
                        class_exists('CI_DB', FALSE) OR $this->database();
                        $db =& $CI->db;
                }

                require_once(BASEPATH.'database/DB_utility.php');
                require_once(BASEPATH.'database/drivers/'.$db->dbdriver.'/'.$db->dbdriver.'_utility.php');
                $class = 'CI_DB_'.$db->dbdriver.'_utility';

                if ($return === TRUE)
                {
                        return new $class($db);
                }

                $CI->dbutil = new $class($db);
                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Load the Database Forge Class
         *
         * @param       object  $db     Database object
         * @param       bool    $return Whether to return the DB Forge class object or not
         * @return      object
         */
        public function dbforge($db = NULL, $return = FALSE)
        {
                $CI =& get_instance();
                if ( ! is_object($db) OR ! ($db instanceof CI_DB))
                {
                        class_exists('CI_DB', FALSE) OR $this->database();
                        $db =& $CI->db;
                }

                require_once(BASEPATH.'database/DB_forge.php');
                require_once(BASEPATH.'database/drivers/'.$db->dbdriver.'/'.$db->dbdriver.'_forge.php');

                if ( ! empty($db->subdriver))
                {
                        $driver_path = BASEPATH.'database/drivers/'.$db->dbdriver.'/subdrivers/'.$db->dbdriver.'_'.$db->subdriver.'_forge.php';
                        if (file_exists($driver_path))
                        {
                                require_once($driver_path);
                                $class = 'CI_DB_'.$db->dbdriver.'_'.$db->subdriver.'_forge';
                        }
                }
                else
                {
                        $class = 'CI_DB_'.$db->dbdriver.'_forge';
                }

                if ($return === TRUE)
                {
                        return new $class($db);
                }

                $CI->dbforge = new $class($db);
                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * View Loader
         *
         * Loads "view" files.
         *
         * @param       string  $view   View name
         * @param       array   $vars   An associative array of data
         *                              to be extracted for use in the view
         * @param       bool    $return Whether to return the view output
         *                              or leave it to the Output class
         * @return      object|string
         */
        public function view($view, $vars = array(), $return = FALSE)
        {
                return $this->_ci_load(array('_ci_view' => $view, '_ci_vars' => $this->_ci_prepare_view_vars($vars), '_ci_return' => $return));
        }

        // --------------------------------------------------------------------

        /**
         * Generic File Loader
         *
         * @param       string  $path   File path
         * @param       bool    $return Whether to return the file output
         * @return      object|string
         */
        public function file($path, $return = FALSE)
        {
                return $this->_ci_load(array('_ci_path' => $path, '_ci_return' => $return));
        }

        // --------------------------------------------------------------------

        /**
         * Set Variables
         *
         * Once variables are set they become available within
         * the controller class and its "view" files.
         *
         * @param       array|object|string     $vars
         *                                      An associative array or object containing values
         *                                      to be set, or a value's name if string
         * @param       string  $val    Value to set, only used if $vars is a string
         * @return      object
         */
        public function vars($vars, $val = '')
        {
                $vars = is_string($vars)
                        ? array($vars => $val)
                        : $this->_ci_prepare_view_vars($vars);

                foreach ($vars as $key => $val)
                {
                        $this->_ci_cached_vars[$key] = $val;
                }

                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Clear Cached Variables
         *
         * Clears the cached variables.
         *
         * @return      CI_Loader
         */
        public function clear_vars()
        {
                $this->_ci_cached_vars = array();
                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Get Variable
         *
         * Check if a variable is set and retrieve it.
         *
         * @param       string  $key    Variable name
         * @return      mixed   The variable or NULL if not found
         */
        public function get_var($key)
        {
                return isset($this->_ci_cached_vars[$key]) ? $this->_ci_cached_vars[$key] : NULL;
        }

        // --------------------------------------------------------------------

        /**
         * Get Variables
         *
         * Retrieves all loaded variables.
         *
         * @return      array
         */
        public function get_vars()
        {
                return $this->_ci_cached_vars;
        }

        // --------------------------------------------------------------------

        /**
         * Helper Loader
         *
         * @param       string|string[] $helpers        Helper name(s)
         * @return      object
         */
        public function helper($helpers = array())
        {
                is_array($helpers) OR $helpers = array($helpers);
                foreach ($helpers as &$helper)
                {
                        $filename = basename($helper);
                        $filepath = ($filename === $helper) ? '' : substr($helper, 0, strlen($helper) - strlen($filename));
                        $filename = strtolower(preg_replace('#(_helper)?(.php)?$#i', '', $filename)).'_helper';
                        $helper   = $filepath.$filename;

                        if (isset($this->_ci_helpers[$helper]))
                        {
                                continue;
                        }

                        // Is this a helper extension request?
                        $ext_helper = config_item('subclass_prefix').$filename;
                        $ext_loaded = FALSE;
                        foreach ($this->_ci_helper_paths as $path)
                        {
                                if (file_exists($path.'helpers/'.$ext_helper.'.php'))
                                {
                                        include_once($path.'helpers/'.$ext_helper.'.php');
                                        $ext_loaded = TRUE;
                                }
                        }

                        // If we have loaded extensions - check if the base one is here
                        if ($ext_loaded === TRUE)
                        {
                                $base_helper = BASEPATH.'helpers/'.$helper.'.php';
                                if ( ! file_exists($base_helper))
                                {
                                        show_error('Unable to load the requested file: helpers/'.$helper.'.php');
                                }

                                include_once($base_helper);
                                $this->_ci_helpers[$helper] = TRUE;
                                log_message('info', 'Helper loaded: '.$helper);
                                continue;
                        }

                        // No extensions found ... try loading regular helpers and/or overrides
                        foreach ($this->_ci_helper_paths as $path)
                        {
                                if (file_exists($path.'helpers/'.$helper.'.php'))
                                {
                                        include_once($path.'helpers/'.$helper.'.php');

                                        $this->_ci_helpers[$helper] = TRUE;
                                        log_message('info', 'Helper loaded: '.$helper);
                                        break;
                                }
                        }

                        // unable to load the helper
                        if ( ! isset($this->_ci_helpers[$helper]))
                        {
                                show_error('Unable to load the requested file: helpers/'.$helper.'.php');
                        }
                }

                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Load Helpers
         *
         * An alias for the helper() method in case the developer has
         * written the plural form of it.
         *
         * @uses        CI_Loader::helper()
         * @param       string|string[] $helpers        Helper name(s)
         * @return      object
         */
        public function helpers($helpers = array())
        {
                return $this->helper($helpers);
        }

        // --------------------------------------------------------------------

        /**
         * Language Loader
         *
         * Loads language files.
         *
         * @param       string|string[] $files  List of language file names to load
         * @param       string          Language name
         * @return      object
         */
        public function language($files, $lang = '')
        {
                get_instance()->lang->load($files, $lang);
                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Config Loader
         *
         * Loads a config file (an alias for CI_Config::load()).
         *
         * @uses        CI_Config::load()
         * @param       string  $file                   Configuration file name
         * @param       bool    $use_sections           Whether configuration values should be loaded into their own section
         * @param       bool    $fail_gracefully        Whether to just return FALSE or display an error message
         * @return      bool    TRUE if the file was loaded correctly or FALSE on failure
         */
        public function config($file, $use_sections = FALSE, $fail_gracefully = FALSE)
        {
                return get_instance()->config->load($file, $use_sections, $fail_gracefully);
        }

        // --------------------------------------------------------------------

        /**
         * Driver Loader
         *
         * Loads a driver library.
         *
         * @param       string|string[] $library        Driver name(s)
         * @param       array           $params         Optional parameters to pass to the driver
         * @param       string          $object_name    An optional object name to assign to
         *
         * @return      object|bool     Object or FALSE on failure if $library is a string
         *                              and $object_name is set. CI_Loader instance otherwise.
         */
        public function driver($library, $params = NULL, $object_name = NULL)
        {
                if (is_array($library))
                {
                        foreach ($library as $key => $value)
                        {
                                if (is_int($key))
                                {
                                        $this->driver($value, $params);
                                }
                                else
                                {
                                        $this->driver($key, $params, $value);
                                }
                        }

                        return $this;
                }
                elseif (empty($library))
                {
                        return FALSE;
                }

                if ( ! class_exists('CI_Driver_Library', FALSE))
                {
                        // We aren't instantiating an object here, just making the base class available
                        require BASEPATH.'libraries/Driver.php';
                }

                // We can save the loader some time since Drivers will *always* be in a subfolder,
                // and typically identically named to the library
                if ( ! strpos($library, '/'))
                {
                        $library = ucfirst($library).'/'.$library;
                }

                return $this->library($library, $params, $object_name);
        }

        // --------------------------------------------------------------------

        /**
         * Add Package Path
         *
         * Prepends a parent path to the library, model, helper and config
         * path arrays.
         *
         * @see CI_Loader::$_ci_library_paths
         * @see CI_Loader::$_ci_model_paths
         * @see CI_Loader::$_ci_helper_paths
         * @see CI_Config::$_config_paths
         *
         * @param       string  $path           Path to add
         * @param       bool    $view_cascade   (default: TRUE)
         * @return      object
         */
        public function add_package_path($path, $view_cascade = TRUE)
        {
                $path = rtrim($path, '/').'/';

                array_unshift($this->_ci_library_paths, $path);
                array_unshift($this->_ci_model_paths, $path);
                array_unshift($this->_ci_helper_paths, $path);

                $this->_ci_view_paths = array($path.'views/' => $view_cascade) + $this->_ci_view_paths;

                // Add config file path
                $config =& $this->_ci_get_component('config');
                $config->_config_paths[] = $path;

                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Get Package Paths
         *
         * Return a list of all package paths.
         *
         * @param       bool    $include_base   Whether to include BASEPATH (default: FALSE)
         * @return      array
         */
        public function get_package_paths($include_base = FALSE)
        {
                return ($include_base === TRUE) ? $this->_ci_library_paths : $this->_ci_model_paths;
        }

        // --------------------------------------------------------------------

        /**
         * Remove Package Path
         *
         * Remove a path from the library, model, helper and/or config
         * path arrays if it exists. If no path is provided, the most recently
         * added path will be removed removed.
         *
         * @param       string  $path   Path to remove
         * @return      object
         */
        public function remove_package_path($path = '')
        {
                $config =& $this->_ci_get_component('config');

                if ($path === '')
                {
                        array_shift($this->_ci_library_paths);
                        array_shift($this->_ci_model_paths);
                        array_shift($this->_ci_helper_paths);
                        array_shift($this->_ci_view_paths);
                        array_pop($config->_config_paths);
                }
                else
                {
                        $path = rtrim($path, '/').'/';
                        foreach (array('_ci_library_paths', '_ci_model_paths', '_ci_helper_paths') as $var)
                        {
                                if (($key = array_search($path, $this->{$var})) !== FALSE)
                                {
                                        unset($this->{$var}[$key]);
                                }
                        }

                        if (isset($this->_ci_view_paths[$path.'views/']))
                        {
                                unset($this->_ci_view_paths[$path.'views/']);
                        }

                        if (($key = array_search($path, $config->_config_paths)) !== FALSE)
                        {
                                unset($config->_config_paths[$key]);
                        }
                }

                // make sure the application default paths are still in the array
                $this->_ci_library_paths = array_unique(array_merge($this->_ci_library_paths, array(APPPATH, BASEPATH)));
                $this->_ci_helper_paths = array_unique(array_merge($this->_ci_helper_paths, array(APPPATH, BASEPATH)));
                $this->_ci_model_paths = array_unique(array_merge($this->_ci_model_paths, array(APPPATH)));
                $this->_ci_view_paths = array_merge($this->_ci_view_paths, array(APPPATH.'views/' => TRUE));
                $config->_config_paths = array_unique(array_merge($config->_config_paths, array(APPPATH)));

                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Internal CI Data Loader
         *
         * Used to load views and files.
         *
         * Variables are prefixed with _ci_ to avoid symbol collision with
         * variables made available to view files.
         *
         * @used-by     CI_Loader::view()
         * @used-by     CI_Loader::file()
         * @param       array   $_ci_data       Data to load
         * @return      object
         */
        protected function _ci_load($_ci_data)
        {
                // Set the default data variables
                foreach (array('_ci_view', '_ci_vars', '_ci_path', '_ci_return') as $_ci_val)
                {
                        $$_ci_val = isset($_ci_data[$_ci_val]) ? $_ci_data[$_ci_val] : FALSE;
                }

                $file_exists = FALSE;

                // Set the path to the requested file
                if (is_string($_ci_path) && $_ci_path !== '')
                {
                        $_ci_x = explode('/', $_ci_path);
                        $_ci_file = end($_ci_x);
                }
                else
                {
                        $_ci_ext = pathinfo($_ci_view, PATHINFO_EXTENSION);
                        $_ci_file = ($_ci_ext === '') ? $_ci_view.'.php' : $_ci_view;

                        foreach ($this->_ci_view_paths as $_ci_view_file => $cascade)
                        {
                                if (file_exists($_ci_view_file.$_ci_file))
                                {
                                        $_ci_path = $_ci_view_file.$_ci_file;
                                        $file_exists = TRUE;
                                        break;
                                }

                                if ( ! $cascade)
                                {
                                        break;
                                }
                        }
                }

                if ( ! $file_exists && ! file_exists($_ci_path))
                {
                        show_error('Unable to load the requested file: '.$_ci_file);
                }

                // This allows anything loaded using $this->load (views, files, etc.)
                // to become accessible from within the Controller and Model functions.
                $_ci_CI =& get_instance();
                foreach (get_object_vars($_ci_CI) as $_ci_key => $_ci_var)
                {
                        if ( ! isset($this->$_ci_key))
                        {
                                $this->$_ci_key =& $_ci_CI->$_ci_key;
                        }
                }

                /*
                 * Extract and cache variables
                 *
                 * You can either set variables using the dedicated $this->load->vars()
                 * function or via the second parameter of this function. We'll merge
                 * the two types and cache them so that views that are embedded within
                 * other views can have access to these variables.
                 */
                empty($_ci_vars) OR $this->_ci_cached_vars = array_merge($this->_ci_cached_vars, $_ci_vars);
                extract($this->_ci_cached_vars);

                /*
                 * Buffer the output
                 *
                 * We buffer the output for two reasons:
                 * 1. Speed. You get a significant speed boost.
                 * 2. So that the final rendered template can be post-processed by
                 *      the output class. Why do we need post processing? For one thing,
                 *      in order to show the elapsed page load time. Unless we can
                 *      intercept the content right before it's sent to the browser and
                 *      then stop the timer it won't be accurate.
                 */
                ob_start();

                // If the PHP installation does not support short tags we'll
                // do a little string replacement, changing the short tags
                // to standard PHP echo statements.
                if ( ! is_php('5.4') && ! ini_get('short_open_tag') && config_item('rewrite_short_tags') === TRUE)
                {
                        echo eval('?>'.preg_replace('/;*\s*\?>/', '; ?>', str_replace('<?=', '<?php echo ', file_get_contents($_ci_path))));
                }
                else
                {
                        include($_ci_path); // include() vs include_once() allows for multiple views with the same name
                }

                log_message('info', 'File loaded: '.$_ci_path);

                // Return the file data if requested
                if ($_ci_return === TRUE)
                {
                        $buffer = ob_get_contents();
                        @ob_end_clean();
                        return $buffer;
                }

                /*
                 * Flush the buffer... or buff the flusher?
                 *
                 * In order to permit views to be nested within
                 * other views, we need to flush the content back out whenever
                 * we are beyond the first level of output buffering so that
                 * it can be seen and included properly by the first included
                 * template and any subsequent ones. Oy!
                 */
                if (ob_get_level() > $this->_ci_ob_level + 1)
                {
                        ob_end_flush();
                }
                else
                {
                        $_ci_CI->output->append_output(ob_get_contents());
                        @ob_end_clean();
                }

                return $this;
        }

        // --------------------------------------------------------------------

        /**
         * Internal CI Library Loader
         *
         * @used-by     CI_Loader::library()
         * @uses        CI_Loader::_ci_init_library()
         *
         * @param       string  $class          Class name to load
         * @param       mixed   $params         Optional parameters to pass to the class constructor
         * @param       string  $object_name    Optional object name to assign to
         * @return      void
         */
        protected function _ci_load_library($class, $params = NULL, $object_name = NULL)
        {
                // Get the class name, and while we're at it trim any slashes.
                // The directory path can be included as part of the class name,
                // but we don't want a leading slash
                $class = str_replace('.php', '', trim($class, '/'));

                // Was the path included with the class name?
                // We look for a slash to determine this
                if (($last_slash = strrpos($class, '/')) !== FALSE)
                {
                        // Extract the path
                        $subdir = substr($class, 0, ++$last_slash);

                        // Get the filename from the path
                        $class = substr($class, $last_slash);
                }
                else
                {
                        $subdir = '';
                }

                $class = ucfirst($class);

                // Is this a stock library? There are a few special conditions if so ...
                if (file_exists(BASEPATH.'libraries/'.$subdir.$class.'.php'))
                {
                        return $this->_ci_load_stock_library($class, $subdir, $params, $object_name);
                }

                // Let's search for the requested library file and load it.
                foreach ($this->_ci_library_paths as $path)
                {
                        // BASEPATH has already been checked for
                        if ($path === BASEPATH)
                        {
                                continue;
                        }

                        $filepath = $path.'libraries/'.$subdir.$class.'.php';

                        // Safety: Was the class already loaded by a previous call?
                        if (class_exists($class, FALSE))
                        {
                                // Before we deem this to be a duplicate request, let's see
                                // if a custom object name is being supplied. If so, we'll
                                // return a new instance of the object
                                if ($object_name !== NULL)
                                {
                                        $CI =& get_instance();
                                        if ( ! isset($CI->$object_name))
                                        {
                                                return $this->_ci_init_library($class, '', $params, $object_name);
                                        }
                                }

                                log_message('debug', $class.' class already loaded. Second attempt ignored.');
                                return;
                        }
                        // Does the file exist? No? Bummer...
                        elseif ( ! file_exists($filepath))
                        {
                                continue;
                        }

                        include_once($filepath);
                        return $this->_ci_init_library($class, '', $params, $object_name);
                }

                // One last attempt. Maybe the library is in a subdirectory, but it wasn't specified?
                if ($subdir === '')
                {
                        return $this->_ci_load_library($class.'/'.$class, $params, $object_name);
                }

                // If we got this far we were unable to find the requested class.
                log_message('error', 'Unable to load the requested class: '.$class);
                show_error('Unable to load the requested class: '.$class);
        }

        // --------------------------------------------------------------------

        /**
         * Internal CI Stock Library Loader
         *
         * @used-by     CI_Loader::_ci_load_library()
         * @uses        CI_Loader::_ci_init_library()
         *
         * @param       string  $library_name   Library name to load
         * @param       string  $file_path      Path to the library filename, relative to libraries/
         * @param       mixed   $params         Optional parameters to pass to the class constructor
         * @param       string  $object_name    Optional object name to assign to
         * @return      void
         */
        protected function _ci_load_stock_library($library_name, $file_path, $params, $object_name)
        {
                $prefix = 'CI_';

                if (class_exists($prefix.$library_name, FALSE))
                {
                        if (class_exists(config_item('subclass_prefix').$library_name, FALSE))
                        {
                                $prefix = config_item('subclass_prefix');
                        }

                        // Before we deem this to be a duplicate request, let's see
                        // if a custom object name is being supplied. If so, we'll
                        // return a new instance of the object
                        if ($object_name !== NULL)
                        {
                                $CI =& get_instance();
                                if ( ! isset($CI->$object_name))
                                {
                                        return $this->_ci_init_library($library_name, $prefix, $params, $object_name);
                                }
                        }

                        log_message('debug', $library_name.' class already loaded. Second attempt ignored.');
                        return;
                }

                $paths = $this->_ci_library_paths;
                array_pop($paths); // BASEPATH
                array_pop($paths); // APPPATH (needs to be the first path checked)
                array_unshift($paths, APPPATH);

                foreach ($paths as $path)
                {
                        if (file_exists($path = $path.'libraries/'.$file_path.$library_name.'.php'))
                        {
                                // Override
                                include_once($path);
                                if (class_exists($prefix.$library_name, FALSE))
                                {
                                        return $this->_ci_init_library($library_name, $prefix, $params, $object_name);
                                }
                                else
                                {
                                        log_message('debug', $path.' exists, but does not declare '.$prefix.$library_name);
                                }
                        }
                }

                include_once(BASEPATH.'libraries/'.$file_path.$library_name.'.php');

                // Check for extensions
                $subclass = config_item('subclass_prefix').$library_name;
                foreach ($paths as $path)
                {
                        if (file_exists($path = $path.'libraries/'.$file_path.$subclass.'.php'))
                        {
                                include_once($path);
                                if (class_exists($subclass, FALSE))
                                {
                                        $prefix = config_item('subclass_prefix');
                                        break;
                                }
                                else
                                {
                                        log_message('debug', $path.' exists, but does not declare '.$subclass);
                                }
                        }
                }

                return $this->_ci_init_library($library_name, $prefix, $params, $object_name);
        }

        // --------------------------------------------------------------------

        /**
         * Internal CI Library Instantiator
         *
         * @used-by     CI_Loader::_ci_load_stock_library()
         * @used-by     CI_Loader::_ci_load_library()
         *
         * @param       string          $class          Class name
         * @param       string          $prefix         Class name prefix
         * @param       array|null|bool $config         Optional configuration to pass to the class constructor:
         *                                              FALSE to skip;
         *                                              NULL to search in config paths;
         *                                              array containing configuration data
         * @param       string          $object_name    Optional object name to assign to
         * @return      void
         */
        protected function _ci_init_library($class, $prefix, $config = FALSE, $object_name = NULL)
        {
                // Is there an associated config file for this class? Note: these should always be lowercase
                if ($config === NULL)
                {
                        // Fetch the config paths containing any package paths
                        $config_component = $this->_ci_get_component('config');

                        if (is_array($config_component->_config_paths))
                        {
                                $found = FALSE;
                                foreach ($config_component->_config_paths as $path)
                                {
                                        // We test for both uppercase and lowercase, for servers that
                                        // are case-sensitive with regard to file names. Load global first,
                                        // override with environment next
                                        if (file_exists($path.'config/'.strtolower($class).'.php'))
                                        {
                                                include($path.'config/'.strtolower($class).'.php');
                                                $found = TRUE;
                                        }
                                        elseif (file_exists($path.'config/'.ucfirst(strtolower($class)).'.php'))
                                        {
                                                include($path.'config/'.ucfirst(strtolower($class)).'.php');
                                                $found = TRUE;
                                        }

                                        if (file_exists($path.'config/'.ENVIRONMENT.'/'.strtolower($class).'.php'))
                                        {
                                                include($path.'config/'.ENVIRONMENT.'/'.strtolower($class).'.php');
                                                $found = TRUE;
                                        }
                                        elseif (file_exists($path.'config/'.ENVIRONMENT.'/'.ucfirst(strtolower($class)).'.php'))
                                        {
                                                include($path.'config/'.ENVIRONMENT.'/'.ucfirst(strtolower($class)).'.php');
                                                $found = TRUE;
                                        }

                                        // Break on the first found configuration, thus package
                                        // files are not overridden by default paths
                                        if ($found === TRUE)
                                        {
                                                break;
                                        }
                                }
                        }
                }

                $class_name = $prefix.$class;

                // Is the class name valid?
                if ( ! class_exists($class_name, FALSE))
                {
                        log_message('error', 'Non-existent class: '.$class_name);
                        show_error('Non-existent class: '.$class_name);
                }

                // Set the variable name we will assign the class to
                // Was a custom class name supplied? If so we'll use it
                if (empty($object_name))
                {
                        $object_name = strtolower($class);
                        if (isset($this->_ci_varmap[$object_name]))
                        {
                                $object_name = $this->_ci_varmap[$object_name];
                        }
                }

                // Don't overwrite existing properties
                $CI =& get_instance();
                if (isset($CI->$object_name))
                {
                        if ($CI->$object_name instanceof $class_name)
                        {
                                log_message('debug', $class_name." has already been instantiated as '".$object_name."'. Second attempt aborted.");
                                return;
                        }

                        show_error("Resource '".$object_name."' already exists and is not a ".$class_name." instance.");
                }

                // Save the class name and object name
                $this->_ci_classes[$object_name] = $class;

                // Instantiate the class
                $CI->$object_name = isset($config)
                        ? new $class_name($config)
                        : new $class_name();
        }

        // --------------------------------------------------------------------

        /**
         * CI Autoloader
         *
         * Loads component listed in the config/autoload.php file.
         *
         * @used-by     CI_Loader::initialize()
         * @return      void
         */
        protected function _ci_autoloader()
        {
                if (file_exists(APPPATH.'config/autoload.php'))
                {
                        include(APPPATH.'config/autoload.php');
                }

                if (file_exists(APPPATH.'config/'.ENVIRONMENT.'/autoload.php'))
                {
                        include(APPPATH.'config/'.ENVIRONMENT.'/autoload.php');
                }

                if ( ! isset($autoload))
                {
                        return;
                }

                // Autoload packages
                if (isset($autoload['packages']))
                {
                        foreach ($autoload['packages'] as $package_path)
                        {
                                $this->add_package_path($package_path);
                        }
                }

                // Load any custom config file
                if (count($autoload['config']) > 0)
                {
                        foreach ($autoload['config'] as $val)
                        {
                                $this->config($val);
                        }
                }

                // Autoload helpers and languages
                foreach (array('helper', 'language') as $type)
                {
                        if (isset($autoload[$type]) && count($autoload[$type]) > 0)
                        {
                                $this->$type($autoload[$type]);
                        }
                }

                // Autoload drivers
                if (isset($autoload['drivers']))
                {
                        $this->driver($autoload['drivers']);
                }

                // Load libraries
                if (isset($autoload['libraries']) && count($autoload['libraries']) > 0)
                {
                        // Load the database driver.
                        if (in_array('database', $autoload['libraries']))
                        {
                                $this->database();
                                $autoload['libraries'] = array_diff($autoload['libraries'], array('database'));
                        }

                        // Load all other libraries
                        $this->library($autoload['libraries']);
                }

                // Autoload models
                if (isset($autoload['model']))
                {
                        $this->model($autoload['model']);
                }
        }

        // --------------------------------------------------------------------

        /**
         * Prepare variables for _ci_vars, to be later extract()-ed inside views
         *
         * Converts objects to associative arrays and filters-out internal
         * variable names (i.e. keys prexied with '_ci_').
         *
         * @param       mixed   $vars
         * @return      array
         */
        protected function _ci_prepare_view_vars($vars)
        {
                if ( ! is_array($vars))
                {
                        $vars = is_object($vars)
                                ? get_object_vars($object)
                                : array();
                }

                foreach (array_keys($vars) as $key)
                {
                        if (strncmp($key, '_ci_', 4) === 0)
                        {
                                unset($vars[$key]);
                        }
                }

                return $vars;
        }

        // --------------------------------------------------------------------

        /**
         * CI Component getter
         *
         * Get a reference to a specific library or model.
         *
         * @param       string  $component      Component name
         * @return      bool
         */
        protected function &_ci_get_component($component)
        {
                $CI =& get_instance();
                return $CI->$component;
        }
}