<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

/**

 * CodeIgniter

 *

 * An open source application development framework for PHP 5.1.6 or newer

 *

 * @package		CodeIgniter

 * @author		ExpressionEngine Dev Team

 * @copyright	Copyright (c) 2008 - 2011, EllisLab, Inc.

 * @license		http://codeigniter.com/user_guide/license.html

 * @link		http://codeigniter.com

 * @since		Version 1.0

 * @filesource

 */



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



/**

 * Database Driver Class

 *

 * This is the platform-independent base DB implementation class.

 * This class will not be called directly. Rather, the adapter

 * class for the specific database will extend and instantiate it.

 *

 * @package		CodeIgniter

 * @subpackage	Drivers

 * @category	Database

 * @author		ExpressionEngine Dev Team

 * @link		http://codeigniter.com/user_guide/database/

 */

class CI_DB_driver {



	var $username;

	var $password;

	var $hostname;

	var $database;

	var $dbdriver		= 'mysql';

	var $dbprefix		= '';

	var $char_set		= 'utf8';

	var $dbcollat		= 'utf8_general_ci';

	var $autoinit		= TRUE; // Whether to automatically initialize the DB

	var $swap_pre		= '';

	var $port			= '';

	var $pconnect		= FALSE;

	var $conn_id		= FALSE;

	var $result_id		= FALSE;

	var $db_debug		= FALSE;

	var $benchmark		= 0;

	var $query_count	= 0;

	var $bind_marker	= '?';

	var $save_queries	= TRUE;

	var $queries		= array();

	var $query_times	= array();

	var $data_cache		= array();

	var $trans_enabled	= TRUE;

	var $trans_strict	= TRUE;

	var $_trans_depth	= 0;

	var $_trans_status	= TRUE; // Used with transactions to determine if a rollback should occur

	var $cache_on		= FALSE;

	var $cachedir		= '';

	var $cache_autodel	= FALSE;

	var $CACHE; // The cache class object



	// Private variables

	var $_protect_identifiers	= TRUE;

	var $_reserved_identifiers	= array('*'); // Identifiers that should NOT be escaped



	// These are use with Oracle

	var $stmt_id;

	var $curs_id;

	var $limit_used;







	/**

	 * Constructor.  Accepts one parameter containing the database

	 * connection settings.

	 *

	 * @param array

	 */

	function __construct($params)

	{

		if (is_array($params))

		{

			foreach ($params as $key => $val)

			{

				$this->$key = $val;

			}

		}



		log_message('debug', 'Database Driver Class Initialized');

	}



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



	/**

	 * Initialize Database Settings

	 *

	 * @access	private Called by the constructor

	 * @param	mixed

	 * @return	void

	 */

	function initialize()

	{

		// If an existing connection resource is available

		// there is no need to connect and select the database

		if (is_resource($this->conn_id) OR is_object($this->conn_id))

		{

			return TRUE;

		}



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



		// Connect to the database and set the connection ID

		$this->conn_id = ($this->pconnect == FALSE) ? $this->db_connect() : $this->db_pconnect();



		// No connection resource?  Throw an error

		if ( ! $this->conn_id)

		{

			log_message('error', 'Unable to connect to the database');



			if ($this->db_debug)

			{

				$this->display_error('db_unable_to_connect');

			}

			return FALSE;

		}



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



		// Select the DB... assuming a database name is specified in the config file

		if ($this->database != '')

		{

			if ( ! $this->db_select())

			{

				log_message('error', 'Unable to select database: '.$this->database);



				if ($this->db_debug)

				{

					$this->display_error('db_unable_to_select', $this->database);

				}

				return FALSE;

			}

			else

			{

				// We've selected the DB. Now we set the character set

				if ( ! $this->db_set_charset($this->char_set, $this->dbcollat))

				{

					return FALSE;

				}



				return TRUE;

			}

		}



		return TRUE;

	}



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



	/**

	 * Set client character set

	 *

	 * @access	public

	 * @param	string

	 * @param	string

	 * @return	resource

	 */

	function db_set_charset($charset, $collation)

	{

		if ( ! $this->_db_set_charset($this->char_set, $this->dbcollat))

		{

			log_message('error', 'Unable to set database connection charset: '.$this->char_set);



			if ($this->db_debug)

			{

				$this->display_error('db_unable_to_set_charset', $this->char_set);

			}



			return FALSE;

		}



		return TRUE;

	}



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



	/**

	 * The name of the platform in use (mysql, mssql, etc...)

	 *

	 * @access	public

	 * @return	string

	 */

	function platform()

	{

		return $this->dbdriver;

	}



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



	/**

	 * Database Version Number.  Returns a string containing the

	 * version of the database being used

	 *

	 * @access	public

	 * @return	string

	 */

	function version()

	{

		if (FALSE === ($sql = $this->_version()))

		{

			if ($this->db_debug)

			{

				return $this->display_error('db_unsupported_function');

			}

			return FALSE;

		}



		// Some DBs have functions that return the version, and don't run special

		// SQL queries per se. In these instances, just return the result.

		$driver_version_exceptions = array('oci8', 'sqlite', 'cubrid');



		if (in_array($this->dbdriver, $driver_version_exceptions))

		{

			return $sql;

		}

		else

		{

			$query = $this->query($sql);

			return $query->row('ver');

		}

	}



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



	/**

	 * Execute the query

	 *

	 * Accepts an SQL string as input and returns a result object upon

	 * successful execution of a "read" type query.  Returns boolean TRUE

	 * upon successful execution of a "write" type query. Returns boolean

	 * FALSE upon failure, and if the $db_debug variable is set to TRUE

	 * will raise an error.

	 *

	 * @access	public

	 * @param	string	An SQL query string

	 * @param	array	An array of binding data

	 * @return	mixed

	 */

	function query($sql, $binds = FALSE, $return_object = TRUE)

	{

		if ($sql == '')

		{

			if ($this->db_debug)

			{

				log_message('error', 'Invalid query: '.$sql);

				return $this->display_error('db_invalid_query');

			}

			return FALSE;

		}



		// Verify table prefix and replace if necessary

		if ( ($this->dbprefix != '' AND $this->swap_pre != '') AND ($this->dbprefix != $this->swap_pre) )

		{

			$sql = preg_replace("/(\W)".$this->swap_pre."(\S+?)/", "\\1".$this->dbprefix."\\2", $sql);

		}



		// Compile binds if needed

		if ($binds !== FALSE)

		{

			$sql = $this->compile_binds($sql, $binds);

		}



		// Is query caching enabled?  If the query is a "read type"

		// we will load the caching class and return the previously

		// cached query if it exists

		if ($this->cache_on == TRUE AND stristr($sql, 'SELECT'))

		{

			if ($this->_cache_init())

			{

				$this->load_rdriver();

				if (FALSE !== ($cache = $this->CACHE->read($sql)))

				{

					return $cache;

				}

			}

		}



		// Save the  query for debugging

		if ($this->save_queries == TRUE)

		{

			$this->queries[] = $sql;

		}



		// Start the Query Timer

		$time_start = list($sm, $ss) = explode(' ', microtime());



		// Run the Query

		if (FALSE === ($this->result_id = $this->simple_query($sql)))

		{

			if ($this->save_queries == TRUE)

			{

				$this->query_times[] = 0;

			}



			// This will trigger a rollback if transactions are being used

			$this->_trans_status = FALSE;



			if ($this->db_debug)

			{

				// grab the error number and message now, as we might run some

				// additional queries before displaying the error

				$error_no = $this->_error_number();

				$error_msg = $this->_error_message();



				// We call this function in order to roll-back queries

				// if transactions are enabled.  If we don't call this here

				// the error message will trigger an exit, causing the

				// transactions to remain in limbo.

				$this->trans_complete();



				// Log and display errors

				log_message('error', 'Query error: '.$error_msg);

				return $this->display_error(

										array(

												'Error Number: '.$error_no,

												$error_msg,

												$sql

											)

										);

			}



			return FALSE;

		}



		// Stop and aggregate the query time results

		$time_end = list($em, $es) = explode(' ', microtime());

		$this->benchmark += ($em + $es) - ($sm + $ss);



		if ($this->save_queries == TRUE)

		{

			$this->query_times[] = ($em + $es) - ($sm + $ss);

		}



		// Increment the query counter

		$this->query_count++;



		// Was the query a "write" type?

		// If so we'll simply return true

		if ($this->is_write_type($sql) === TRUE)

		{

			// If caching is enabled we'll auto-cleanup any

			// existing files related to this particular URI

			if ($this->cache_on == TRUE AND $this->cache_autodel == TRUE AND $this->_cache_init())

			{

				$this->CACHE->delete();

			}



			return TRUE;

		}



		// Return TRUE if we don't need to create a result object

		// Currently only the Oracle driver uses this when stored

		// procedures are used

		if ($return_object !== TRUE)

		{

			return TRUE;

		}



		// Load and instantiate the result driver



		$driver			= $this->load_rdriver();

		$RES			= new $driver();

		$RES->conn_id	= $this->conn_id;

		$RES->result_id	= $this->result_id;



		if ($this->dbdriver == 'oci8')

		{

			$RES->stmt_id		= $this->stmt_id;

			$RES->curs_id		= NULL;

			$RES->limit_used	= $this->limit_used;

			$this->stmt_id		= FALSE;

		}



		// oci8 vars must be set before calling this

		$RES->num_rows	= $RES->num_rows();



		// Is query caching enabled?  If so, we'll serialize the

		// result object and save it to a cache file.

		if ($this->cache_on == TRUE AND $this->_cache_init())

		{

			// We'll create a new instance of the result object

			// only without the platform specific driver since

			// we can't use it with cached data (the query result

			// resource ID won't be any good once we've cached the

			// result object, so we'll have to compile the data

			// and save it)

			$CR = new CI_DB_result();

			$CR->num_rows		= $RES->num_rows();

			$CR->result_object	= $RES->result_object();

			$CR->result_array	= $RES->result_array();



			// Reset these since cached objects can not utilize resource IDs.

			$CR->conn_id		= NULL;

			$CR->result_id		= NULL;



			$this->CACHE->write($sql, $CR);

		}



		return $RES;

	}



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



	/**

	 * Load the result drivers

	 *

	 * @access	public

	 * @return	string	the name of the result class

	 */

	function load_rdriver()

	{

		$driver = 'CI_DB_'.$this->dbdriver.'_result';



		if ( ! class_exists($driver))

		{

			include_once(BASEPATH.'database/DB_result.php');

			include_once(BASEPATH.'database/drivers/'.$this->dbdriver.'/'.$this->dbdriver.'_result.php');

		}



		return $driver;

	}



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



	/**

	 * Simple Query

	 * This is a simplified version of the query() function.  Internally

	 * we only use it when running transaction commands since they do

	 * not require all the features of the main query() function.

	 *

	 * @access	public

	 * @param	string	the sql query

	 * @return	mixed

	 */

	function simple_query($sql)

	{

		if ( ! $this->conn_id)

		{

			$this->initialize();

		}



		return $this->_execute($sql);

	}



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



	/**

	 * Disable Transactions

	 * This permits transactions to be disabled at run-time.

	 *

	 * @access	public

	 * @return	void

	 */

	function trans_off()

	{

		$this->trans_enabled = FALSE;

	}



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



	/**

	 * Enable/disable Transaction Strict Mode

	 * When strict mode is enabled, if you are running multiple groups of

	 * transactions, if one group fails all groups will be rolled back.

	 * If strict mode is disabled, each group is treated autonomously, meaning

	 * a failure of one group will not affect any others

	 *

	 * @access	public

	 * @return	void

	 */

	function trans_strict($mode = TRUE)

	{

		$this->trans_strict = is_bool($mode) ? $mode : TRUE;

	}



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



	/**

	 * Start Transaction

	 *

	 * @access	public

	 * @return	void

	 */

	function trans_start($test_mode = FALSE)

	{

		if ( ! $this->trans_enabled)

		{

			return FALSE;

		}



		// When transactions are nested we only begin/commit/rollback the outermost ones

		if ($this->_trans_depth > 0)

		{

			$this->_trans_depth += 1;

			return;

		}



		$this->trans_begin($test_mode);

	}



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



	/**

	 * Complete Transaction

	 *

	 * @access	public

	 * @return	bool

	 */

	function trans_complete()

	{

		if ( ! $this->trans_enabled)

		{

			return FALSE;

		}



		// When transactions are nested we only begin/commit/rollback the outermost ones

		if ($this->_trans_depth > 1)

		{

			$this->_trans_depth -= 1;

			return TRUE;

		}



		// The query() function will set this flag to FALSE in the event that a query failed

		if ($this->_trans_status === FALSE)

		{

			$this->trans_rollback();



			// If we are NOT running in strict mode, we will reset

			// the _trans_status flag so that subsequent groups of transactions

			// will be permitted.

			if ($this->trans_strict === FALSE)

			{

				$this->_trans_status = TRUE;

			}



			log_message('debug', 'DB Transaction Failure');

			return FALSE;

		}



		$this->trans_commit();

		return TRUE;

	}



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



	/**

	 * Lets you retrieve the transaction flag to determine if it has failed

	 *

	 * @access	public

	 * @return	bool

	 */

	function trans_status()

	{

		return $this->_trans_status;

	}



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



	/**

	 * Compile Bindings

	 *

	 * @access	public

	 * @param	string	the sql statement

	 * @param	array	an array of bind data

	 * @return	string

	 */

	function compile_binds($sql, $binds)

	{

		if (strpos($sql, $this->bind_marker) === FALSE)

		{

			return $sql;

		}



		if ( ! is_array($binds))

		{

			$binds = array($binds);

		}



		// Get the sql segments around the bind markers

		$segments = explode($this->bind_marker, $sql);



		// The count of bind should be 1 less then the count of segments

		// If there are more bind arguments trim it down

		if (count($binds) >= count($segments)) {

			$binds = array_slice($binds, 0, count($segments)-1);

		}



		// Construct the binded query

		$result = $segments[0];

		$i = 0;

		foreach ($binds as $bind)

		{

			$result .= $this->escape($bind);

			$result .= $segments[++$i];

		}



		return $result;

	}



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



	/**

	 * Determines if a query is a "write" type.

	 *

	 * @access	public

	 * @param	string	An SQL query string

	 * @return	boolean

	 */

	function is_write_type($sql)

	{

		if ( ! preg_match('/^\s*"?(SET|INSERT|UPDATE|DELETE|REPLACE|CREATE|DROP|TRUNCATE|LOAD DATA|COPY|ALTER|GRANT|REVOKE|LOCK|UNLOCK)\s+/i', $sql))

		{

			return FALSE;

		}

		return TRUE;

	}



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



	/**

	 * Calculate the aggregate query elapsed time

	 *

	 * @access	public

	 * @param	integer	The number of decimal places

	 * @return	integer

	 */

	function elapsed_time($decimals = 6)

	{

		return number_format($this->benchmark, $decimals);

	}



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



	/**

	 * Returns the total number of queries

	 *

	 * @access	public

	 * @return	integer

	 */

	function total_queries()

	{

		return $this->query_count;

	}



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



	/**

	 * Returns the last query that was executed

	 *

	 * @access	public

	 * @return	void

	 */

	function last_query()

	{

		return end($this->queries);

	}



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



	/**

	 * "Smart" Escape String

	 *

	 * Escapes data based on type

	 * Sets boolean and null types

	 *

	 * @access	public

	 * @param	string

	 * @return	mixed

	 */

	function escape($str)

	{

		if (is_string($str))

		{

			$str = "'".$this->escape_str($str)."'";

		}

		elseif (is_bool($str))

		{

			$str = ($str === FALSE) ? 0 : 1;

		}

		elseif (is_null($str))

		{

			$str = 'NULL';

		}



		return $str;

	}



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



	/**

	 * Escape LIKE String

	 *

	 * Calls the individual driver for platform

	 * specific escaping for LIKE conditions

	 *

	 * @access	public

	 * @param	string

	 * @return	mixed

	 */

	function escape_like_str($str)

	{

		return $this->escape_str($str, TRUE);

	}



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



	/**

	 * Primary

	 *

	 * Retrieves the primary key.  It assumes that the row in the first

	 * position is the primary key

	 *

	 * @access	public

	 * @param	string	the table name

	 * @return	string

	 */

	function primary($table = '')

	{

		$fields = $this->list_fields($table);



		if ( ! is_array($fields))

		{

			return FALSE;

		}



		return current($fields);

	}



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



	/**

	 * Returns an array of table names

	 *

	 * @access	public

	 * @return	array

	 */

	function list_tables($constrain_by_prefix = FALSE)

	{

		// Is there a cached result?

		if (isset($this->data_cache['table_names']))

		{

			return $this->data_cache['table_names'];

		}



		if (FALSE === ($sql = $this->_list_tables($constrain_by_prefix)))

		{

			if ($this->db_debug)

			{

				return $this->display_error('db_unsupported_function');

			}

			return FALSE;

		}



		$retval = array();

		$query = $this->query($sql);



		if ($query->num_rows() > 0)

		{

			foreach ($query->result_array() as $row)

			{

				if (isset($row['TABLE_NAME']))

				{

					$retval[] = $row['TABLE_NAME'];

				}

				else

				{

					$retval[] = array_shift($row);

				}

			}

		}



		$this->data_cache['table_names'] = $retval;

		return $this->data_cache['table_names'];

	}



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



	/**

	 * Determine if a particular table exists

	 * @access	public

	 * @return	boolean

	 */

	function table_exists($table_name)

	{

		return ( ! in_array($this->_protect_identifiers($table_name, TRUE, FALSE, FALSE), $this->list_tables())) ? FALSE : TRUE;

	}



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



	/**

	 * Fetch MySQL Field Names

	 *

	 * @access	public

	 * @param	string	the table name

	 * @return	array

	 */

	function list_fields($table = '')

	{

		// Is there a cached result?

		if (isset($this->data_cache['field_names'][$table]))

		{

			return $this->data_cache['field_names'][$table];

		}



		if ($table == '')

		{

			if ($this->db_debug)

			{

				return $this->display_error('db_field_param_missing');

			}

			return FALSE;

		}



		if (FALSE === ($sql = $this->_list_columns($table)))

		{

			if ($this->db_debug)

			{

				return $this->display_error('db_unsupported_function');

			}

			return FALSE;

		}



		$query = $this->query($sql);



		$retval = array();

		foreach ($query->result_array() as $row)

		{

			if (isset($row['COLUMN_NAME']))

			{

				$retval[] = $row['COLUMN_NAME'];

			}

			else

			{

				$retval[] = current($row);

			}

		}



		$this->data_cache['field_names'][$table] = $retval;

		return $this->data_cache['field_names'][$table];

	}



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



	/**

	 * Determine if a particular field exists

	 * @access	public

	 * @param	string

	 * @param	string

	 * @return	boolean

	 */

	function field_exists($field_name, $table_name)

	{

		return ( ! in_array($field_name, $this->list_fields($table_name))) ? FALSE : TRUE;

	}



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



	/**

	 * Returns an object with field data

	 *

	 * @access	public

	 * @param	string	the table name

	 * @return	object

	 */

	function field_data($table = '')

	{

		if ($table == '')

		{

			if ($this->db_debug)

			{

				return $this->display_error('db_field_param_missing');

			}

			return FALSE;

		}



		$query = $this->query($this->_field_data($this->_protect_identifiers($table, TRUE, NULL, FALSE)));



		return $query->field_data();

	}



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



	/**

	 * Generate an insert string

	 *

	 * @access	public

	 * @param	string	the table upon which the query will be performed

	 * @param	array	an associative array data of key/values

	 * @return	string

	 */

	function insert_string($table, $data)

	{

		$fields = array();

		$values = array();



		foreach ($data as $key => $val)

		{

			$fields[] = $this->_escape_identifiers($key);

			$values[] = $this->escape($val);

		}



		return $this->_insert($this->_protect_identifiers($table, TRUE, NULL, FALSE), $fields, $values);

	}



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



	/**

	 * Generate an update string

	 *

	 * @access	public

	 * @param	string	the table upon which the query will be performed

	 * @param	array	an associative array data of key/values

	 * @param	mixed	the "where" statement

	 * @return	string

	 */

	function update_string($table, $data, $where)

	{

		if ($where == '')

		{

			return false;

		}



		$fields = array();

		foreach ($data as $key => $val)

		{

			$fields[$this->_protect_identifiers($key)] = $this->escape($val);

		}



		if ( ! is_array($where))

		{

			$dest = array($where);

		}

		else

		{

			$dest = array();

			foreach ($where as $key => $val)

			{

				$prefix = (count($dest) == 0) ? '' : ' AND ';



				if ($val !== '')

				{

					if ( ! $this->_has_operator($key))

					{

						$key .= ' =';

					}



					$val = ' '.$this->escape($val);

				}



				$dest[] = $prefix.$key.$val;

			}

		}



		return $this->_update($this->_protect_identifiers($table, TRUE, NULL, FALSE), $fields, $dest);

	}



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



	/**

	 * Tests whether the string has an SQL operator

	 *

	 * @access	private

	 * @param	string

	 * @return	bool

	 */

	function _has_operator($str)

	{

		$str = trim($str);

		if ( ! preg_match("/(\s|<|>|!|=|is null|is not null)/i", $str))

		{

			return FALSE;

		}



		return TRUE;

	}



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



	/**

	 * Enables a native PHP function to be run, using a platform agnostic wrapper.

	 *

	 * @access	public

	 * @param	string	the function name

	 * @param	mixed	any parameters needed by the function

	 * @return	mixed

	 */

	function call_function($function)

	{

		$driver = ($this->dbdriver == 'postgre') ? 'pg_' : $this->dbdriver.'_';



		if (FALSE === strpos($driver, $function))

		{

			$function = $driver.$function;

		}



		if ( ! function_exists($function))

		{

			if ($this->db_debug)

			{

				return $this->display_error('db_unsupported_function');

			}

			return FALSE;

		}

		else

		{

			$args = (func_num_args() > 1) ? array_splice(func_get_args(), 1) : null;

			if (is_null($args))

			{

				return call_user_func($function);

			}

			else

			{

				return call_user_func_array($function, $args);

			}

		}

	}



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



	/**

	 * Set Cache Directory Path

	 *

	 * @access	public

	 * @param	string	the path to the cache directory

	 * @return	void

	 */

	function cache_set_path($path = '')

	{

		$this->cachedir = $path;

	}



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



	/**

	 * Enable Query Caching

	 *

	 * @access	public

	 * @return	void

	 */

	function cache_on()

	{

		$this->cache_on = TRUE;

		return TRUE;

	}



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



	/**

	 * Disable Query Caching

	 *

	 * @access	public

	 * @return	void

	 */

	function cache_off()

	{

		$this->cache_on = FALSE;

		return FALSE;

	}





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



	/**

	 * Delete the cache files associated with a particular URI

	 *

	 * @access	public

	 * @return	void

	 */

	function cache_delete($segment_one = '', $segment_two = '')

	{

		if ( ! $this->_cache_init())

		{

			return FALSE;

		}

		return $this->CACHE->delete($segment_one, $segment_two);

	}



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



	/**

	 * Delete All cache files

	 *

	 * @access	public

	 * @return	void

	 */

	function cache_delete_all()

	{

		if ( ! $this->_cache_init())

		{

			return FALSE;

		}



		return $this->CACHE->delete_all();

	}



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



	/**

	 * Initialize the Cache Class

	 *

	 * @access	private

	 * @return	void

	 */

	function _cache_init()

	{

		if (is_object($this->CACHE) AND class_exists('CI_DB_Cache'))

		{

			return TRUE;

		}



		if ( ! class_exists('CI_DB_Cache'))

		{

			if ( ! @include(BASEPATH.'database/DB_cache.php'))

			{

				return $this->cache_off();

			}

		}



		$this->CACHE = new CI_DB_Cache($this); // pass db object to support multiple db connections and returned db objects

		return TRUE;

	}



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



	/**

	 * Close DB Connection

	 *

	 * @access	public

	 * @return	void

	 */

	function close()

	{

		if (is_resource($this->conn_id) OR is_object($this->conn_id))

		{

			$this->_close($this->conn_id);

		}

		$this->conn_id = FALSE;

	}



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



	/**

	 * Display an error message

	 *

	 * @access	public

	 * @param	string	the error message

	 * @param	string	any "swap" values

	 * @param	boolean	whether to localize the message

	 * @return	string	sends the application/error_db.php template

	 */

	function display_error($error = '', $swap = '', $native = FALSE)

	{

		$LANG =& load_class('Lang', 'core');

		$LANG->load('db');



		$heading = $LANG->line('db_error_heading');



		if ($native == TRUE)

		{

			$message = $error;

		}

		else

		{

			$message = ( ! is_array($error)) ? array(str_replace('%s', $swap, $LANG->line($error))) : $error;

		}



		// Find the most likely culprit of the error by going through

		// the backtrace until the source file is no longer in the

		// database folder.



		$trace = debug_backtrace();



		foreach ($trace as $call)

		{

			if (isset($call['file']) && strpos($call['file'], BASEPATH.'database') === FALSE)

			{

				// Found it - use a relative path for safety

				$message[] = 'Filename: '.str_replace(array(BASEPATH, APPPATH), '', $call['file']);

				$message[] = 'Line Number: '.$call['line'];



				break;

			}

		}



		$error =& load_class('Exceptions', 'core');

		echo $error->show_error($heading, $message, 'error_db');

		exit;

	}



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



	/**

	 * Protect Identifiers

	 *

	 * This function adds backticks if appropriate based on db type

	 *

	 * @access	private

	 * @param	mixed	the item to escape

	 * @return	mixed	the item with backticks

	 */

	function protect_identifiers($item, $prefix_single = FALSE)

	{

		return $this->_protect_identifiers($item, $prefix_single);

	}



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



	/**

	 * Protect Identifiers

	 *

	 * This function is used extensively by the Active Record class, and by

	 * a couple functions in this class.

	 * It takes a column or table name (optionally with an alias) and inserts

	 * the table prefix onto it.  Some logic is necessary in order to deal with

	 * column names that include the path.  Consider a query like this:

	 *

	 * SELECT * FROM hostname.database.table.column AS c FROM hostname.database.table

	 *

	 * Or a query with aliasing:

	 *

	 * SELECT m.member_id, m.member_name FROM members AS m

	 *

	 * Since the column name can include up to four segments (host, DB, table, column)

	 * or also have an alias prefix, we need to do a bit of work to figure this out and

	 * insert the table prefix (if it exists) in the proper position, and escape only

	 * the correct identifiers.

	 *

	 * @access	private

	 * @param	string

	 * @param	bool

	 * @param	mixed

	 * @param	bool

	 * @return	string

	 */

	function _protect_identifiers($item, $prefix_single = FALSE, $protect_identifiers = NULL, $field_exists = TRUE)

	{

		if ( ! is_bool($protect_identifiers))

		{

			$protect_identifiers = $this->_protect_identifiers;

		}



		if (is_array($item))

		{

			$escaped_array = array();



			foreach ($item as $k => $v)

			{

				$escaped_array[$this->_protect_identifiers($k)] = $this->_protect_identifiers($v);

			}



			return $escaped_array;

		}



		// Convert tabs or multiple spaces into single spaces

		$item = preg_replace('/[\t ]+/', ' ', $item);



		// If the item has an alias declaration we remove it and set it aside.

		// Basically we remove everything to the right of the first space

		if (strpos($item, ' ') !== FALSE)

		{

			$alias = strstr($item, ' ');

			$item = substr($item, 0, - strlen($alias));

		}

		else

		{

			$alias = '';

		}



		// This is basically a bug fix for queries that use MAX, MIN, etc.

		// If a parenthesis is found we know that we do not need to

		// escape the data or add a prefix.  There's probably a more graceful

		// way to deal with this, but I'm not thinking of it -- Rick

		if (strpos($item, '(') !== FALSE)

		{

			return $item.$alias;

		}



		// Break the string apart if it contains periods, then insert the table prefix

		// in the correct location, assuming the period doesn't indicate that we're dealing

		// with an alias. While we're at it, we will escape the components

		if (strpos($item, '.') !== FALSE)

		{

			$parts	= explode('.', $item);



			// Does the first segment of the exploded item match

			// one of the aliases previously identified?  If so,

			// we have nothing more to do other than escape the item

			if (in_array($parts[0], $this->ar_aliased_tables))

			{

				if ($protect_identifiers === TRUE)

				{

					foreach ($parts as $key => $val)

					{

						if ( ! in_array($val, $this->_reserved_identifiers))

						{

							$parts[$key] = $this->_escape_identifiers($val);

						}

					}



					$item = implode('.', $parts);

				}

				return $item.$alias;

			}



			// Is there a table prefix defined in the config file?  If not, no need to do anything

			if ($this->dbprefix != '')

			{

				// We now add the table prefix based on some logic.

				// Do we have 4 segments (hostname.database.table.column)?

				// If so, we add the table prefix to the column name in the 3rd segment.

				if (isset($parts[3]))

				{

					$i = 2;

				}

				// Do we have 3 segments (database.table.column)?

				// If so, we add the table prefix to the column name in 2nd position

				elseif (isset($parts[2]))

				{

					$i = 1;

				}

				// Do we have 2 segments (table.column)?

				// If so, we add the table prefix to the column name in 1st segment

				else

				{

					$i = 0;

				}



				// This flag is set when the supplied $item does not contain a field name.

				// This can happen when this function is being called from a JOIN.

				if ($field_exists == FALSE)

				{

					$i++;

				}



				// Verify table prefix and replace if necessary

				if ($this->swap_pre != '' && strncmp($parts[$i], $this->swap_pre, strlen($this->swap_pre)) === 0)

				{

					$parts[$i] = preg_replace("/^".$this->swap_pre."(\S+?)/", $this->dbprefix."\\1", $parts[$i]);

				}



				// We only add the table prefix if it does not already exist

				if (substr($parts[$i], 0, strlen($this->dbprefix)) != $this->dbprefix)

				{

					$parts[$i] = $this->dbprefix.$parts[$i];

				}



				// Put the parts back together

				$item = implode('.', $parts);

			}



			if ($protect_identifiers === TRUE)

			{

				$item = $this->_escape_identifiers($item);

			}



			return $item.$alias;

		}



		// Is there a table prefix?  If not, no need to insert it

		if ($this->dbprefix != '')

		{

			// Verify table prefix and replace if necessary

			if ($this->swap_pre != '' && strncmp($item, $this->swap_pre, strlen($this->swap_pre)) === 0)

			{

				$item = preg_replace("/^".$this->swap_pre."(\S+?)/", $this->dbprefix."\\1", $item);

			}



			// Do we prefix an item with no segments?

			if ($prefix_single == TRUE AND substr($item, 0, strlen($this->dbprefix)) != $this->dbprefix)

			{

				$item = $this->dbprefix.$item;

			}

		}



		if ($protect_identifiers === TRUE AND ! in_array($item, $this->_reserved_identifiers))

		{

			$item = $this->_escape_identifiers($item);

		}



		return $item.$alias;

	}



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



	/**

	 * Dummy method that allows Active Record class to be disabled

	 *

	 * This function is used extensively by every db driver.

	 *

	 * @return	void

	 */

	protected function _reset_select()

	{

	}



}



/* End of file DB_driver.php */

/* Location: ./system/database/DB_driver.php */