text: <?php
  /**
   * CodeIgniter
   *
   * An open source application development framework for PHP
   *
   * This content is released under the MIT License (MIT)
   *
   * Copyright (c) 2014 - 2019, 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 - 2019, British Columbia Institute of Technology (https://bcit.ca/)
   * @license	https://opensource.org/licenses/MIT	MIT License
   * @link	https://codeigniter.com
   * @since	Version 3.0.0
   * @filesource
   */
  defined('BASEPATH') OR exit('No direct script access allowed');
  
  /**
   * PDO 4D Forge Class
   *
   * @category	Database
   * @author		EllisLab Dev Team
   * @link		https://codeigniter.com/user_guide/database/
   */
  class CI_DB_pdo_4d_forge extends CI_DB_pdo_forge {
  
  	/**
  	 * CREATE DATABASE statement
  	 *
  	 * @var	string
  	 */
  	protected $_create_database	= 'CREATE SCHEMA %s';
  
  	/**
  	 * DROP DATABASE statement
  	 *
  	 * @var	string
  	 */
  	protected $_drop_database	= 'DROP SCHEMA %s';
  
  	/**
  	 * CREATE TABLE IF statement
  	 *
  	 * @var	string
  	 */
  	protected $_create_table_if	= 'CREATE TABLE IF NOT EXISTS';
  
  	/**
  	 * RENAME TABLE statement
  	 *
  	 * @var	string
  	 */
  	protected $_rename_table	= FALSE;
  
  	/**
  	 * DROP TABLE IF statement
  	 *
  	 * @var	string
  	 */
  	protected $_drop_table_if	= 'DROP TABLE IF EXISTS';
  
  	/**
  	 * UNSIGNED support
  	 *
  	 * @var	array
  	 */
  	protected $_unsigned		= array(
  		'INT16'		=> 'INT',
  		'SMALLINT'	=> 'INT',
  		'INT'		=> 'INT64',
  		'INT32'		=> 'INT64'
  	);
  
  	/**
  	 * DEFAULT value representation in CREATE/ALTER TABLE statements
  	 *
  	 * @var	string
  	 */
  	protected $_default		= FALSE;
  
  	// --------------------------------------------------------------------
  
  	/**
  	 * ALTER TABLE
  	 *
  	 * @param	string	$alter_type	ALTER type
  	 * @param	string	$table		Table name
  	 * @param	mixed	$field		Column definition
  	 * @return	string|string[]
  	 */
  	protected function _alter_table($alter_type, $table, $field)
  	{
  		if (in_array($alter_type, array('ADD', 'DROP'), TRUE))
  		{
  			return parent::_alter_table($alter_type, $table, $field);
  		}
  
  		// No method of modifying columns is supported
  		return FALSE;
  	}
  
  	// --------------------------------------------------------------------
  
  	/**
  	 * Process column
  	 *
  	 * @param	array	$field
  	 * @return	string
  	 */
  	protected function _process_column($field)
  	{
  		return $this->db->escape_identifiers($field['name'])
  			.' '.$field['type'].$field['length']
  			.$field['null']
  			.$field['unique']
  			.$field['auto_increment'];
  	}
  
  	// --------------------------------------------------------------------
  
  	/**
  	 * Field attribute TYPE
  	 *
  	 * Performs a data type mapping between different databases.
  	 *
  	 * @param	array	&$attributes
  	 * @return	void
  	 */
  	protected function _attr_type(&$attributes)
  	{
  		switch (strtoupper($attributes['TYPE']))
  		{
  			case 'TINYINT':
  				$attributes['TYPE'] = 'SMALLINT';
  				$attributes['UNSIGNED'] = FALSE;
  				return;
  			case 'MEDIUMINT':
  				$attributes['TYPE'] = 'INTEGER';
  				$attributes['UNSIGNED'] = FALSE;
  				return;
  			case 'INTEGER':
  				$attributes['TYPE'] = 'INT';
  				return;
  			case 'BIGINT':
  				$attributes['TYPE'] = 'INT64';
  				return;
  			default: return;
  		}
  	}
  
  	// --------------------------------------------------------------------
  
  	/**
  	 * Field attribute UNIQUE
  	 *
  	 * @param	array	&$attributes
  	 * @param	array	&$field
  	 * @return	void
  	 */
  	protected function _attr_unique(&$attributes, &$field)
  	{
  		if ( ! empty($attributes['UNIQUE']) && $attributes['UNIQUE'] === TRUE)
  		{
  			$field['unique'] = ' UNIQUE';
  
  			// UNIQUE must be used with NOT NULL
  			$field['null'] = ' NOT NULL';
  		}
  	}
  
  	// --------------------------------------------------------------------
  
  	/**
  	 * Field attribute AUTO_INCREMENT
  	 *
  	 * @param	array	&$attributes
  	 * @param	array	&$field
  	 * @return	void
  	 */
  	protected function _attr_auto_increment(&$attributes, &$field)
  	{
  		if ( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE)
  		{
  			if (stripos($field['type'], 'int') !== FALSE)
  			{
  				$field['auto_increment'] = ' AUTO_INCREMENT';
  			}
  			elseif (strcasecmp($field['type'], 'UUID') === 0)
  			{
  				$field['auto_increment'] = ' AUTO_GENERATE';
  			}
  		}
  	}
  
  }
  