Source for file Manager.php

<?php
// +----------------------------------------------------------------------+
// | PHP Version 4                                                        |
// +----------------------------------------------------------------------+
// | Copyright (c) 1998-2004 Manuel Lemos, Tomas V.V.Cox,                 |
// | Stig. S. Bakken, Lukas Smith                                         |
// | All rights reserved.                                                 |
// +----------------------------------------------------------------------+
// | MDB2 is a merge of PEAR DB and Metabases that provides a unified DB  |
// | API as well as database abstraction for PHP applications.            |
// | This LICENSE is in the BSD license style.                            |
// |                                                                      |
// | Redistribution and use in source and binary forms, with or without   |
// | modification, are permitted provided that the following conditions   |
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// |                                                                      |
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// | notice, this list of conditions and the following disclaimer.        |
// |                                                                      |
// | Redistributions in binary form must reproduce the above copyright    |
// | notice, this list of conditions and the following disclaimer in the  |
// | documentation and/or other materials provided with the distribution. |
// |                                                                      |
// | Neither the name of Manuel Lemos, Tomas V.V.Cox, Stig. S. Bakken,    |
// | Lukas Smith nor the names of his contributors may be used to endorse |
// | or promote products derived from this software without specific prior|
// | written permission.                                                  |
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// | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS    |
// | FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE      |
// | REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,          |
// | INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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// |  OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED  |
// | AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT          |
// | LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY|
// | WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE          |
// | POSSIBILITY OF SUCH DAMAGE.                                          |
// +----------------------------------------------------------------------+
// | Author: Lukas Smith <smith@backendmedia.com>                         |
// +----------------------------------------------------------------------+
//
// $Id: Manager.php,v 1.10 2004/04/09 10:39:08 lsmith Exp $
//
 
require_once 'MDB2/Tools/Parser.php';
 
define('MDB2_MANAGER_DUMP_ALL',          0);
define('MDB2_MANAGER_DUMP_STRUCTURE',    1);
define('MDB2_MANAGER_DUMP_CONTENT',      2);
 
/**
 * The database manager is a class that provides a set of database
 * management services like installing, altering and dumping the data
 * structures of databases.
 *
 * @package MDB2
 * @category Database
 * @author  Lukas Smith <smith@backendmedia.com>
 */
class MDB2_Tools_Manager extends PEAR
{
    // {{{ properties
 
    var $db;
 
    var $warnings = array();
 
    var $options = array(
        'fail_on_invalid_names' => 1,
    );
 
    var $invalid_names = array(
        'user' => array(),
        'is' => array(),
        'file' => array(
            'oci' => array(),
            'oracle' => array()
        ),
        'notify' => array(
            'pgsql' => array()
        ),
        'restrict' => array(
            'mysql' => array()
        ),
        'password' => array(
            'ibase' => array()
        )
    );
 
    var $default_values = array(
        'integer' => 0,
        'float' => 0,
        'decimal' => 0,
        'text' => '',
        'timestamp' => '0001-01-01 00:00:00',
        'date' => '0001-01-01',
        'time' => '00:00:00'
    );
 
    var $database_definition = array(
        'name' => '',
        'create' => 0,
        'tables' => array()
    );
 
    // }}}
    // {{{ raiseError()
 
    /**
     * This method is used to communicate an error and invoke error
     * callbacks etc.  Basically a wrapper for PEAR::raiseError
     * without the message string.
     *
     * @param mixed $code integer error code, or a PEAR error object (all
     *       other parameters are ignored if this parameter is an object
     * @param int $mode error mode, see PEAR_Error docs
     * @param mixed $options If error mode is PEAR_ERROR_TRIGGER, this is the
     *       error level (E_USER_NOTICE etc).  If error mode is
     *       PEAR_ERROR_CALLBACK, this is the callback function, either as a
     *       function name, or as an array of an object and method name. For
     *       other error modes this parameter is ignored.
     * @param string $userinfo Extra debug information.  Defaults to the last
     *       query and native error code.
     * @param mixed $nativecode Native error code, integer or string depending
     *       the backend.
     * @return object a PEAR error object
     * @access public
     * @see PEAR_Error
     */
    function &raiseError($code = null, $mode = null, $options = null,
                         $userinfo = null)
    {
        $error =& MDB2_Driver_Common::raiseError($code, $mode, $options, $userinfo);
        return $error;
    }
 
    // }}}
    // {{{ debugOutput()
 
    /**
     * output debug info
     *
     * @return string content of the debug_output class variable
     * @access public
     */
    function debugOutput()
    {
        return $this->db->debugOutput();
    }
 
    // }}}
    // {{{ resetWarnings()
 
    /**
     * reset the warning array
     *
     * @access public
     */
    function resetWarnings()
    {
        $this->warnings = array();
    }
 
    // }}}
    // {{{ getWarnings()
 
    /**
     * get all warnings in reverse order.
     * This means that the last warning is the first element in the array
     *
     * @return array with warnings
     * @access public
     * @see resetWarnings()
     */
    function getWarnings()
    {
        return array_reverse($this->warnings);
    }
 
    // }}}
    // {{{ setOption()
 
    /**
     * set the option for the db class
     *
     * @param string $option option name
     * @param mixed $value value for the option
     * @return mixed MDB2_OK or MDB2 Error Object
     * @access public
     */
    function setOption($option, $value)
    {
        if (isset($this->options[$option])) {
            if (is_null($value)) {
                return $this->raiseError(MDB2_ERROR, null, null,
                    'may not set an option to value null');
            }
            $this->options[$option] = $value;
            return MDB2_OK;
        }
        return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
            "unknown option $option");
    }
 
    // }}}
    // {{{ getOption()
 
    /**
     * returns the value of an option
     *
     * @param string $option option name
     * @return mixed the option value or error object
     * @access public
     */
    function getOption($option)
    {
        if (isset($this->options[$option])) {
            return $this->options[$option];
        }
        return $this->raiseError(MDB2_ERROR_UNSUPPORTED,
            null, null, "unknown option $option");
    }
 
    // }}}
    // {{{ connect()
 
    /**
     * Create a new MDB2 connection object and connect to the specified
     * database
     *
     * @param   mixed   $dbinfo   'data source name', see the MDB2::parseDSN
     *                             method for a description of the dsn format.
     *                             Can also be specified as an array of the
     *                             format returned by MDB2::parseDSN.
     *                             Finally you can also pass an existing db
     *                             object to be used.
     * @param   mixed   $options  An associative array of option names and
     *                             their values.
     * @return  mixed MDB2_OK on success, or a MDB2 error object
     * @access  public
     * @see     MDB2::parseDSN
     */
    function connect(&$dbinfo, $options = false)
    {
        if (is_object($this->db) && !MDB2::isError($this->db)) {
            $this->disconnect();
        }
        if (is_object($dbinfo)) {
             $this->db =& $dbinfo;
        } else {
            $this->db =& MDB2::connect($dbinfo, $options);
            if (MDB2::isError($this->db)) {
                return $this->db;
            }
        }
        if (is_array($options)) {
            $this->options = array_merge($options, $this->options);
        }
        $this->db->loadModule('manager');
        return MDB2_OK;
    }
 
    // }}}
    // {{{ disconnect()
 
    /**
     * Log out and disconnect from the database.
     *
     * @access public
     */
    function disconnect()
    {
        if (MDB2::isConnection($this->db) && !MDB2::isError($this->db)) {
            $this->db->disconnect();
            unset($this->db);
        }
    }
 
    // }}}
    // {{{ setDatabase()
 
    /**
     * Select a different database
     *
     * @param string $name name of the database that should be selected
     * @return string name of the database previously connected to
     * @access public
     */
    function setDatabase($name)
    {
        return $this->db->setDatabase($name);
    }
 
    // }}}
    // {{{ _createTable()
 
    /**
     * create a table and inititialize the table if data is available
     *
     * @param string $table_name  name of the table to be created
     * @param array  $table       multi dimensional array that containts the
     *                             structure and optional data of the table
     * @param boolean $overwrite  determine if the table/index should be
                                  overwritten if it already exists
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access private
     */
    function _createTable($table_name, $table, $overwrite = false)
    {
        $this->expectError(MDB2_ERROR_ALREADY_EXISTS);
        $result = $this->db->manager->createTable($table_name, $table['fields']);
        $this->popExpect();
        if (MDB2::isError($result)) {
            if ($result->getCode() === MDB2_ERROR_ALREADY_EXISTS) {
                $this->warnings[] = 'Table already exists: '.$table_name;
                if ($overwrite) {
                    $this->db->debug('Overwritting Table');
                    $result = $this->db->manager->dropTable($table_name);
                    if (MDB2::isError($result)) {
                        return $result;
                    }
                    $result = $this->db->manager->createTable($table_name, $table['fields']);
                    if (MDB2::isError($result)) {
                        return $result;
                    }
                } else {
                    $result = MDB2_OK;
                }
            } else {
                $this->db->debug('Create table error: '.$table_name);
                return $result;
            }
        }
        if (isset($table['initialization']) && is_array($table['initialization'])) {
            foreach ($table['initialization'] as $instruction) {
                switch ($instruction['type']) {
                    case 'insert':
                        $query_fields = $query_values = array();
                        if (isset($instruction['fields']) && is_array($instruction['fields'])) {
                            foreach ($instruction['fields'] as $field_name => $field) {
                                $query_fields[] = $field_name;
                                $query_values[] = '?';
                                $query_types[] = $table['fields'][$field_name]['type'];
                            }
                            $query_fields = implode(',',$query_fields);
                            $query_values = implode(',',$query_values);
                            $result = $prepared_query = $this->db->prepare(
                                "INSERT INTO $table_name ($query_fields) VALUES ($query_values)", $query_types);
                        }
                        if (!MDB2::isError($prepared_query)) {
                            if (isset($instruction['fields']) && is_array($instruction['fields'])) {
                                $lobs = array();
                                $field_number = 0;
                                foreach ($instruction['fields'] as $field_name => $field) {
                                    $field_number++;
                                    $query = $field_name;
                                    switch ($table['fields'][$field_name]['type']) {
                                        case 'integer':
                                        case 'text':
                                        case 'boolean':
                                        case 'date':
                                        case 'timestamp':
                                        case 'time':
                                        case 'float':
                                        case 'decimal':
                                            $result = $this->db->setParam($prepared_query,
                                                $field_number, $field);
                                            break;
                                        case 'clob':
                                            $lob_definition = array(
                                                'database' => $this->db,
                                                'error' => '',
                                                'data' => $field,
                                                'field_name' => $field_name
                                            );
                                            $result = $this->db->setParam($prepared_query,
                                                $field_number, $lob_definition, 'clob');
                                            break;
                                        case 'blob':
                                            $lob_definition = array(
                                                'database' => $this->db,
                                                'error' => '',
                                                'data' => $field,
                                                'field_name' => $field_name
                                            );
                                            $result = $this->db->setParam($prepared_query,
                                                $field_number, $lob_definition, 'blob');
                                            break;
                                        default:
                                            $result = $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                                                'type "'.$field['type'].'" is not yet supported');
                                            break;
                                    }
                                    if (MDB2::isError($result)) {
                                        break;
                                    }
                                }
                            }
                            if (!MDB2::isError($result)) {
                                $result = $this->db->execute($prepared_query);
                            }
                            for ($lob = 0; $lob < count($lobs); $lob++) {
                                $this->db->destroyLOB($lobs[$lob]);
                            }
                            $this->db->freePrepared($prepared_query);
                        }
                        break;
                }
            }
        };
        if (!MDB2::isError($result) && isset($table['indexes']) && is_array($table['indexes'])) {
            if (!$this->db->supports('indexes')) {
                return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                    'indexes are not supported');
            }
            foreach ($table['indexes'] as $index_name => $index) {
                $this->expectError(MDB2_ERROR_ALREADY_EXISTS);
                $result = $this->db->manager->createIndex($table_name, $index_name, $index);
                $this->popExpect();
                if (MDB2::isError($result)) {
                    if ($result->getCode() === MDB2_ERROR_ALREADY_EXISTS) {
                        $this->warnings[] = 'Index already exists: '.$index_name;
                        if ($overwrite) {
                            $this->db->debug('Overwritting Index');
                            $result = $this->db->manager->dropIndex($table_name, $index_name);
                            if (MDB2::isError($result)) {
                                break;
                            }
                            $result = $this->db->manager->createIndex($table_name, $index_name, $index);
                            if (MDB2::isError($result)) {
                                break;
                            }
                        } else {
                            $result = MDB2_OK;
                        }
                    } else {
                        $this->db->debug('Create index error: '.$table_name);
                        break;
                    }
                }
            }
        }
        if (MDB2::isError($result)) {
            $result = $this->db->manager->dropTable($table_name);
            if (MDB2::isError($result)) {
                $result = $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                    'could not drop the table ('.$result->getMessage().
                    ' ('.$result->getUserinfo().'))');
            }
            return $result;
        }
        return MDB2_OK;
    }
 
    // }}}
    // {{{ _dropTable()
 
    /**
     * drop a table
     *
     * @param string $table_name    name of the table to be dropped
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access private
     */
    function _dropTable($table_name)
    {
        return $this->db->manager->dropTable($table_name);
    }
 
    // }}}
    // {{{ _createSequence()
 
    /**
     * create a sequence
     *
     * @param string $sequence_name  name of the sequence to be created
     * @param array  $sequence       multi dimensional array that containts the
     *                                structure and optional data of the table
     * @param string $created_on_table 
     * @param boolean $overwrite    determine if the sequence should be overwritten
                                    if it already exists
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access private
     */
    function _createSequence($sequence_name, $sequence, $created_on_table, $overwrite = false)
    {
        if (!$this->db->supports('sequences')) {
            return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                'sequences are not supported');
        }
        if (!isset($sequence_name) || !strcmp($sequence_name, '')) {
            return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                'no valid sequence name specified');
        }
        $this->db->debug('Create sequence: '.$sequence_name);
        if (isset($sequence['start']) && is_int($sequence['start'])) {
            $start = $sequence['start'];
        } else if (isset($sequence['on']) && !$created_on_table) {
            $table = $sequence['on']['table'];
            $field = $sequence['on']['field'];
            if ($this->db->supports('summary_functions')) {
                $field = "MAX($field)";
            }
            $start = $this->db->queryOne("SELECT $field FROM $table", 'integer');
            if (MDB2::isError($start)) {
                return $start;
            }
            if (!is_int($start)) {
                $start = 1;
            }
        } else {
            $start = 1;
        }
 
        $this->expectError(MDB2_ERROR_ALREADY_EXISTS);
        $result = $this->db->manager->createSequence($sequence_name, $start);
        $this->popExpect();
        if (MDB2::isError($result)) {
            if ($result->getCode() === MDB2_ERROR_ALREADY_EXISTS) {
                $this->warnings[] = 'Sequence already exists: '.$sequence_name;
                if ($overwrite) {
                    $this->db->debug('Overwritting Sequence');
                    $result = $this->db->manager->dropSequence($sequence_name);
                    if (MDB2::isError($result)) {
                        return $result;
                    }
                    $result = $this->db->manager->createSequence($sequence_name, $start);
                    if (MDB2::isError($result)) {
                        return $result;
                    }
                } else {
                    return MDB2_OK;
                }
            } else {
                $this->db->debug('Create sequence error: '.$sequence_name);
                return $result;
            }
        }
    }
 
    // }}}
    // {{{ _dropSequence()
 
    /**
     * drop a table
     *
     * @param string $sequence_name    name of the sequence to be dropped
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access private
     */
    function _dropSequence($sequence_name)
    {
        if (!$this->db->supports('sequences')) {
            return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                'sequences are not supported');
        }
        $this->db->debug('Dropping sequence: '.$sequence_name);
        if (!isset($sequence_name) || !strcmp($sequence_name, '')) {
            return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                'no valid sequence name specified');
        }
        return $this->db->manager->dropSequence($sequence_name);
    }
 
    // }}}
    // {{{ _createDatabase()
 
    /**
     * Create a database space within which may be created database objects
     * like tables, indexes and sequences. The implementation of this function
     * is highly DBMS specific and may require special permissions to run
     * successfully. Consult the documentation or the DBMS drivers that you
     * use to be aware of eventual configuration requirements.
     *
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access private
     */
    function _createDatabase()
    {
        if (!isset($this->database_definition['name'])
            || !strcmp($this->database_definition['name'], '')
        ) {
            return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                'no valid database name specified');
        }
        $create = (isset($this->database_definition['create']) && $this->database_definition['create']);
        $overwrite = (isset($this->database_definition['overwrite']) && $this->database_definition['overwrite']);
        if ($create) {
            $this->db->debug('Create database: '.$this->database_definition['name']);
            $this->expectError(MDB2_ERROR_ALREADY_EXISTS);
            $result = $this->db->manager->createDatabase($this->database_definition['name']);
            $this->popExpect();
            if (MDB2::isError($result)) {
                if ($result->getCode() === MDB2_ERROR_ALREADY_EXISTS) {
                    $this->warnings[] = 'Database already exists: '.$this->database_definition['name'];
                    if ($overwrite) {
                        $this->db->debug('Overwritting Database');
                        $result = $this->db->manager->dropDatabase($this->database_definition['name']);
                        if (MDB2::isError($result)) {
                            return $result;
                        }
                        $result = $this->db->manager->createDatabase($this->database_definition['name']);
                        if (MDB2::isError($result)) {
                            return $result;
                        }
                    } else {
                        $result = MDB2_OK;
                    }
                } else {
                    $this->db->debug('Create database error.');
                    return $result;
                }
            }
        }
        $previous_database_name = $this->db->setDatabase($this->database_definition['name']);
        if (($support_transactions = $this->db->supports('transactions'))
            && MDB2::isError($result = $this->db->autoCommit(false))
        ) {
            return $result;
        }
 
        $created_objects = 0;
        if (isset($this->database_definition['tables'])
            && is_array($this->database_definition['tables'])
        ) {
            foreach ($this->database_definition['tables'] as $table_name => $table) {
                $result = $this->_createTable($table_name, $table, $overwrite);
                if (MDB2::isError($result)) {
                    break;
                }
                $created_objects++;
            }
        }
        if (!MDB2::isError($result)
            && isset($this->database_definition['sequences'])
            && is_array($this->database_definition['sequences'])
        ) {
            foreach ($this->database_definition['sequences'] as $sequence_name => $sequence) {
                $result = $this->_createSequence($sequence_name, $sequence, 0, $overwrite);
 
                if (MDB2::isError($result)) {
                    break;
                }
                $created_objects++;
            }
        }
 
        if (MDB2::isError($result)) {
            if ($created_objects) {
                if ($support_transactions) {
                    $res = $this->db->rollback();
                    if (MDB2::isError($res))
                        $result = $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                            'Could not rollback the partially created database alterations ('.
                            $result->getMessage().' ('.$result->getUserinfo().'))');
                } else {
                    $result = $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                        'the database was only partially created ('.
                        $result->getMessage().' ('.$result->getUserinfo().'))');
                }
            }
        } else {
            if ($support_transactions) {
                $res = $this->db->autoCommit(true);
                if (MDB2::isError($res))
                    $result = $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                        'Could not end transaction after successfully created the database ('.
                        $res->getMessage().' ('.$res->getUserinfo().'))');
            }
        }
 
        $this->db->setDatabase($previous_database_name);
 
        if (MDB2::isError($result) && $create
            && MDB2::isError($res = $this->db->manager->dropDatabase($this->database_definition['name']))
        ) {
            return $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                'Could not drop the created database after unsuccessful creation attempt ('.
                $res->getMessage().' ('.$res->getUserinfo().'))');
        }
 
        if (MDB2::isError($result)) {
            return $result;
        }
 
        return MDB2_OK;
    }
 
    // }}}
    // {{{ _addDefinitionChange()
 
    /**
     * add change to an array of multiple changes
     *
     * @param array  &$changes 
     * @param string $definition 
     * @param string $item 
     * @param array  $change 
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access private
     */
    function _addDefinitionChange(&$changes, $definition, $item, $change)
    {
        if (!isset($changes[$definition][$item])) {
            $changes[$definition][$item] = array();
        }
        foreach ($change as $change_data_name => $change_data) {
            if (isset($change_data) && is_array($change_data)) {
                if (!isset($changes[$definition][$item][$change_data_name])) {
                    $changes[$definition][$item][$change_data_name] = array();
                }
                foreach ($change_data as $change_part_name => $change_part) {
                    $changes[$definition][$item][$change_data_name][$change_part_name] = $change_part;
                }
            } else {
                $changes[$definition][$item][$change_data_name] = $change_data;
            }
        }
        return MDB2_OK;
    }
 
    // }}}
    // {{{ _compareDefinitions()
 
    /**
     * compare a previous definition with the currenlty parsed definition
     *
     * @param array multi dimensional array that contains the previous definition
     * @return mixed array of changes on success, or a MDB2 error object
     * @access private
     */
    function _compareDefinitions($previous_definition)
    {
        $defined_tables = $changes = array();
        if (isset($this->database_definition['tables']) && is_array($this->database_definition['tables'])) {
            foreach ($this->database_definition['tables'] as $table_name => $table) {
                $was_table_name = $table['was'];
                if (isset($previous_definition['tables'][$table_name])
                    && isset($previous_definition['tables'][$table_name]['was'])
                    && !strcmp($previous_definition['tables'][$table_name]['was'], $was_table_name)
                ) {
                    $was_table_name = $table_name;
                }
                if (isset($previous_definition['tables'][$was_table_name])) {
                    if (strcmp($was_table_name, $table_name)) {
                        $this->_addDefinitionChange($changes, 'tables', $was_table_name, array('name' => $table_name));
                        $this->db->debug("Renamed table '$was_table_name' to '$table_name'");
                    }
                    if (isset($defined_tables[$was_table_name])) {
                        return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                            'the table "'.$was_table_name.
                            '" was specified as base of more than of table of the database');
                    }
                    $defined_tables[$was_table_name] = true;
 
                    $previous_fields = $previous_definition['tables'][$was_table_name]['fields'];
                    $defined_fields = array();
                    if (isset($table['fields']) && is_array($table['fields'])) {
                        foreach ($table['fields'] as $field_name => $field) {
                            $was_field_name = $field['was'];
                            if (isset($previous_fields[$field_name])
                                && isset($previous_fields[$field_name]['was'])
                                && !strcmp($previous_fields[$field_name]['was'], $was_field_name)
                            ) {
                                $was_field_name = $field_name;
                            }
                            if (isset($previous_fields[$was_field_name])) {
                                if (strcmp($was_field_name, $field_name)) {
                                    $query = $this->db->getDeclaration($field['type'], $field_name, $field);
                                    if (MDB2::isError($query)) {
                                        return $query;
                                    }
                                    $this->_addDefinitionChange($changes, 'tables',
                                        $was_table_name,
                                        array(
                                            'renamed_fields' => array(
                                                $was_field_name => array(
                                                    'name' => $field_name,
                                                    'declaration' => $query
                                                )
                                            )
                                        )
                                    );
                                    $this->db->debug("Renamed field '$was_field_name' to '$field_name' in table '$table_name'");
                                }
                                if (isset($defined_fields[$was_field_name])) {
                                    return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                                        'the field "'.$was_table_name.
                                        '" was specified as base of more than one field of table');
                                }
                                $defined_fields[$was_field_name] = true;
                                $change = array();
                                if ($field['type'] == $previous_fields[$was_field_name]['type']) {
                                    switch ($field['type']) {
                                        case 'integer':
                                            $previous_unsigned = isset($previous_fields[$was_field_name]['unsigned']);
                                            $unsigned = isset($fields[$field_name]['unsigned']);
                                            if (strcmp($previous_unsigned, $unsigned)) {
                                                $change['unsigned'] = $unsigned;
                                                $this->db->debug("Changed field '$field_name' type from '".($previous_unsigned ? 'unsigned ' : '').$previous_fields[$was_field_name]['type']."' to '".($unsigned ? 'unsigned ' : '').$field['type']."' in table '$table_name'");
                                            }
                                            break;
                                        case 'text':
                                        case 'clob':
                                        case 'blob':
                                            $previous_length = (isset($previous_fields[$was_field_name]['length']) ? $previous_fields[$was_field_name]['length'] : 0);
                                            $length = (isset($field['length']) ? $field['length'] : 0);
                                            if (strcmp($previous_length, $length)) {
                                                $change['length'] = $length;
                                                $this->db->debug("Changed field '$field_name' length from '".$previous_fields[$was_field_name]['type'].($previous_length == 0 ? ' no length' : "($previous_length)")."' to '".$field['type'].($length == 0 ? ' no length' : "($length)")."' in table '$table_name'");
                                            }
                                            break;
                                        case 'date':
                                        case 'timestamp':
                                        case 'time':
                                        case 'boolean':
                                        case 'float':
                                        case 'decimal':
                                            break;
                                        default:
                                            return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                                                'type "'.$field['type'].'" is not yet supported');
                                    }
 
                                    $previous_notnull = isset($previous_fields[$was_field_name]['notnull']);
                                    $notnull = isset($field['notnull']);
                                    if ($previous_notnull != $notnull) {
                                        $change['changed_not_null'] = true;
                                        if ($notnull) {
                                            $change['notnull'] = isset($field['notnull']);
                                        }
                                        $this->db->debug("Changed field '$field_name' notnull from $previous_notnull to $notnull in table '$table_name'");
                                    }
 
                                    $previous_default = isset($previous_fields[$was_field_name]['default']);
                                    $default = isset($field['default']);
                                    if (strcmp($previous_default, $default)) {
                                        $change['changed_default'] = true;
                                        if ($default) {
                                            $change['default'] = $field['default'];
                                        }
                                        $this->db->debug("Changed field '$field_name' default from ".($previous_default ? "'".$previous_fields[$was_field_name]['default']."'" : 'NULL').' TO '.($default ? "'".$fields[$field_name]['default']."'" : 'NULL')." IN TABLE '$table_name'");
                                    } else {
                                        if ($default
                                            && strcmp($previous_fields[$was_field_name]['default'], $field['default'])
                                        ) {
                                            $change['changed_default'] = true;
                                            $change['default'] = $field['default'];
                                            $this->db->debug("Changed field '$field_name' default from '".$previous_fields[$was_field_name]['default']."' to '".$fields[$field_name]['default']."' in table '$table_name'");
                                        }
                                    }
                                } else {
                                    $change['type'] = $field['type'];
                                    $this->db->debug("Changed field '$field_name' type from '".$previous_fields[$was_field_name]['type']."' to '".$fields[$field_name]['type']."' in table '$table_name'");
                                }
                                if (count($change)) {
                                    $query = $this->db->getDeclaration($field['type'], $field_name, $field);
                                    if (MDB2::isError($query)) {
                                        return $query;
                                    }
                                    $change['declaration'] = $query;
                                    $change['definition'] = $field;
                                    $this->_addDefinitionChange($changes, 'tables', $was_table_name, array('changed_fields' => array($field_name => $change)));
                                }
                            } else {
                                if (strcmp($field_name, $was_field_name)) {
                                    return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                                        'it was specified a previous field name ("'.
                                        $was_field_name.'") for field "'.$field_name.'" of table "'.
                                        $table_name.'" that does not exist');
                                }
                                $query = $this->db->getDeclaration($field['type'], $field_name, $field);
                                if (MDB2::isError($query)) {
                                    return $query;
                                }
                                $change['declaration'] = $query;
                                $this->_addDefinitionChange($changes, 'tables', $table_name, array('added_fields' => array($field_name => $change)));
                                $this->db->debug("Added field '$field_name' to table '$table_name'");
                            }
                        }
                    }
                    if (isset($previous_fields) && is_array($previous_fields)) {
                        foreach ($previous_fields as $field_previous_name => $field_previous) {
                            if (!isset($defined_fields[$field_previous_name])) {
                                $this->_addDefinitionChange($changes, 'tables', $table_name, array('removed_fields' => array($field_previous_name => array())));
                                $this->db->debug("Removed field '$field_name' from table '$table_name'");
                            }
                        }
                    }
                    $indexes = array();
                    if (isset($this->database_definition['tables'][$table_name]['indexes'])
                        && is_array($this->database_definition['tables'][$table_name]['indexes'])
                    ) {
                        $indexes = $this->database_definition['tables'][$table_name]['indexes'];
                    }
                    $previous_indexes = array();
                    if (isset($previous_definition['tables'][$was_table_name]['indexes'])
                        && is_array($previous_definition['tables'][$was_table_name]['indexes'])
                    ) {
                        $previous_indexes = $previous_definition['tables'][$was_table_name]['indexes'];
                    }
                    $defined_indexes = array();
                    foreach ($indexes as $index_name => $index) {
                        $was_index_name = $index['was'];
                        if (isset($previous_indexes[$index_name])
                            && isset($previous_indexes[$index_name]['was'])
                            && !strcmp($previous_indexes[$index_name]['was'], $was_index_name)
                        ) {
                            $was_index_name = $index_name;
                        }
                        if (isset($previous_indexes[$was_index_name])) {
                            $change = array();
 
                            if (strcmp($was_index_name, $index_name)) {
                                $change['name'] = $was_index_name;
                                $this->db->debug("Changed index '$was_index_name' name to '$index_name' in table '$table_name'");
                            }
                            if (isset($defined_indexes[$was_index_name])) {
                                return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                                    'the index "'.$was_index_name.'" was specified as base of'.
                                    ' more than one index of table "'.$table_name.'"');
                            }
                            $defined_indexes[$was_index_name] = true;
 
                            $previous_unique = isset($previous_indexes[$was_index_name]['unique']);
                            $unique = isset($index['unique']);
                            if ($previous_unique != $unique) {
                                $change['changed_unique'] = true;
                                if ($unique) {
                                    $change['unique'] = $unique;
                                }
                                $this->db->debug("Changed index '$index_name' unique from $previous_unique to $unique in table '$table_name'");
                            }
                            $defined_fields = array();
                            $previous_fields = $previous_indexes[$was_index_name]['fields'];
                            if (isset($index['fields']) && is_array($index['fields'])) {
                                foreach ($index['fields'] as $field_name => $field) {
                                    if (isset($previous_fields[$field_name])) {
                                        $defined_fields[$field_name] = true;
                                        $sorting = (isset($field['sorting']) ? $field['sorting'] : '');
                                        $previous_sorting = (isset($previous_fields[$field_name]['sorting']) ? $previous_fields[$field_name]['sorting'] : '');
                                        if (strcmp($sorting, $previous_sorting)) {
                                            $this->db->debug("Changed index field '$field_name' sorting default from '$previous_sorting' to '$sorting' in table '$table_name'");
                                            $change['changed_fields'] = true;
                                        }
                                    } else {
                                        $change['changed_fields'] = true;
                                        $this->db->debug("Added field '$field_name' to index '$index_name' of table '$table_name'");
                                    }
                                }
                            }
                            if (isset($previous_fields) && is_array($previous_fields)) {
                                foreach ($previous_fields as $field_name => $field) {
                                    if (!isset($defined_fields[$field_name])) {
                                        $change['changed_fields'] = true;
                                        $this->db->debug("Removed field '$field_name' from index '$index_name' of table '$table_name'");
                                    }
                                }
                            }
 
                            if (count($change)) {
                                $this->_addDefinitionChange($changes, 'indexes', $table_name,array('changed_indexes' => array($index_name => $change)));
                            }
                        } else {
                            if (strcmp($index_name, $was_index_name)) {
                                return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                                    'it was specified a previous index name ("'.$was_index_name.
                                    ') for index "'.$index_name.'" of table "'.$table_name.'" that does not exist');
                            }
                            $this->_addDefinitionChange($changes, 'indexes', $table_name,array('added_indexes' => array($index_name => $indexes[$index_name])));
                            $this->db->debug("Added index '$index_name' to table '$table_name'");
                        }
                    }
                    foreach ($previous_indexes as $index_previous_name => $index_previous) {
                        if (!isset($defined_indexes[$index_previous_name])) {
                            $this->_addDefinitionChange($changes, 'indexes', $table_name, array('removed_indexes' => array($index_previous_name => $was_table_name)));
                            $this->db->debug("Removed index '$index_name' from table '$table_name'");
                        }
                    }
                } else {
                    if (strcmp($table_name, $was_table_name)) {
                        return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                            'it was specified a previous table name ("'.
                            $was_table_name.'") for table "'.$table_name.
                            '" that does not exist');
                    }
                    $this->_addDefinitionChange($changes, 'tables', $table_name,array('add' => 1));
                    $this->db->debug("Added table '$table_name'");
                }
            }
            if (isset($previous_definition['tables']) && is_array($previous_definition['tables'])) {
                foreach ($previous_definition['tables'] as $table_name => $table) {
                    if (!isset($defined_tables[$table_name])) {
                        $this->_addDefinitionChange($changes, 'tables', $table_name, array('remove' => 1));
                        $this->db->debug("Removed table '$table_name'");
                    }
                }
            }
            if (isset($this->database_definition['sequences']) && is_array($this->database_definition['sequences'])) {
                foreach ($this->database_definition['sequences'] as $sequence_name => $sequence) {
                    $was_sequence_name = $sequence['was'];
                    if (isset($previous_definition['sequences'][$sequence_name])
                        && isset($previous_definition['sequences'][$sequence_name]['was'])
                        && !strcmp($previous_definition['sequences'][$sequence_name]['was'], $was_sequence_name)
                    ) {
                        $was_sequence_name = $sequence_name;
                    }
                    if (isset($previous_definition['sequences'][$was_sequence_name])) {
                        if (strcmp($was_sequence_name, $sequence_name)) {
                            $this->_addDefinitionChange($changes, 'sequences', $was_sequence_name,array('name' => $sequence_name));
                            $this->db->debug("Renamed sequence '$was_sequence_name' to '$sequence_name'");
                        }
                        if (isset($defined_sequences[$was_sequence_name])) {
                            return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                                'the sequence "'.$was_sequence_name.'" was specified as base'.
                                ' of more than of sequence of the database');
                        }
                        $defined_sequences[$was_sequence_name] = true;
                        $change = array();
                        if (strcmp($sequence['start'], $previous_definition['sequences'][$was_sequence_name]['start'])) {
                            $change['start'] = $this->database_definition['sequences'][$sequence_name]['start'];
                            $this->db->debug("Changed sequence '$sequence_name' start from '".$previous_definition['sequences'][$was_sequence_name]['start']."' to '".$this->database_definition['sequences'][$sequence_name]['start']."'");
                        }
                        if (strcmp($sequence['on']['table'], $previous_definition['sequences'][$was_sequence_name]['on']['table'])
                            || strcmp($sequence['on']['field'], $previous_definition['sequences'][$was_sequence_name]['on']['field'])
                        ) {
                            $change['on'] = $sequence['on'];
                            $this->db->debug("Changed sequence '$sequence_name' on table field from '".$previous_definition['sequences'][$was_sequence_name]['on']['table'].'.'.$previous_definition['sequences'][$was_sequence_name]['on']['field']."' to '".$this->database_definition['sequences'][$sequence_name]['on']['table'].'.'.$this->database_definition['sequences'][$sequence_name]['on']['field']."'");
                        }
                        if (count($change)) {
                            $this->_addDefinitionChange($changes, 'sequences', $was_sequence_name,array('change' => array($sequence_name => array($change))));
                        }
                    } else {
                        if (strcmp($sequence_name, $was_sequence_name)) {
                            return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                                'it was specified a previous sequence name ("'.$was_sequence_name.
                                '") for sequence "'.$sequence_name.'" that does not exist');
                        }
                        $this->_addDefinitionChange($changes, 'sequences', $sequence_name, array('add' => 1));
                        $this->db->debug("Added sequence '$sequence_name'");
                    }
                }
            }
            if (isset($previous_definition['sequences']) && is_array($previous_definition['sequences'])) {
                foreach ($previous_definition['sequences'] as $sequence_name => $sequence) {
                    if (!isset($defined_sequences[$sequence_name])) {
                        $this->_addDefinitionChange($changes, 'sequences', $sequence_name, array('remove' => 1));
                        $this->db->debug("Removed sequence '$sequence_name'");
                    }
                }
            }
        }
        return $changes;
    }
 
    // }}}
    // {{{ _alterDatabase()
 
    /**
     * Execute the necessary actions to implement the requested changes
     * in a database structure.
     *
     * @param array $previous_definition an associative array that contains
     *  the definition of the database structure before applying the requested
     *  changes. The definition of this array may be built separately, but
     *  usually it is built by the Parse method the Metabase parser class.
     * @param array $changes an associative array that contains the definition of
     *  the changes that are meant to be applied to the database structure.
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access private
     */
    function _alterDatabase($previous_definition, $changes)
    {
        $result = '';
        if (isset($changes['tables']) && is_array($changes['tables'])) {
            foreach ($changes['tables'] as $table_name => $table) {
                if (isset($table['add']) || isset($table['remove'])) {
                    continue;
                }
                $result = $this->db->manager->alterTable($table_name, $table, 1);
                if (MDB2::isError($result)) {
                    return $result;
                }
            }
        }
        if (isset($changes['sequences']) && is_array($changes['sequences'])) {
            if (!$this->db->supports('sequences')) {
                return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                    'sequences are not supported');
            }
            foreach ($changes['sequences'] as $sequence) {
                if (isset($sequence['add'])
                    || isset($sequence['remove'])
                    || isset($sequence['change'])
                ) {
                    continue;
                }
                return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                    'some sequences changes are not yet supported');
            }
        }
        if (isset($changes['indexes']) && is_array($changes['indexes'])) {
            if (!$this->db->supports('indexes')) {
                return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                    'indexes are not supported');
            }
            foreach ($changes['indexes'] as $index) {
                $table_changes = count($index);
                if (isset($index['added_indexes'])) {
                    $table_changes--;
                }
                if (isset($index['removed_indexes'])) {
                    $table_changes--;
                }
                if (isset($index['changed_indexes'])) {
                    $table_changes--;
                }
                if ($table_changes) {
                    return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                        'index alteration not yet supported');
                }
            }
        }
 
        $previous_database_name = $this->db->setDatabase($this->database_definition['name']);
        if (($support_transactions = $this->db->supports('transactions'))
            && MDB2::isError($result = $this->db->autoCommit(false))
        ) {
            return $result;
        }
        $error = '';
        $alterations = 0;
        if (isset($changes['indexes']) && is_array($changes['indexes'])) {
            foreach ($changes['indexes'] as $index_name => $index) {
                if (isset($index['removed_indexes']) && is_array($index['removed_indexes'])) {
                    foreach ($index['removed_indexes'] as $index_remove_name => $index_remove) {
                        $result = $this->db->manager->dropIndex($index_name,$index_remove_name);
                        if (MDB2::isError($result)) {
                            break;
                        }
                        $alterations++;
                    }
                }
                if (!MDB2::isError($result)
                    && is_array($index['changed_indexes'])
                ) {
                    foreach ($index['changed_indexes'] as $index_changed_name => $index_changed) {
                        $was_name = (isset($indexes[$name]['name']) ? $indexes[$index_changed_name]['name'] : $index_changed_name);
                        $result = $this->db->manager->dropIndex($index_name, $was_name);
                        if (MDB2::isError($result)) {
                            break;
                        }
                        $alterations++;
                    }
                }
                if (MDB2::isError($result)) {
                    break;
                }
            }
        }
        if (!MDB2::isError($result) && isset($changes['tables'])
            && is_array($changes['tables'])
        ) {
            foreach ($changes['tables'] as $table_name => $table) {
                if (isset($table['remove'])) {
                    $result = $this->_dropTable($table_name);
                    if (!MDB2::isError($result)) {
                        $alterations++;
                    }
                } else {
                    if (!isset($table['add'])) {
                        $result = $this->db->manager->alterTable($table_name, $changes['tables'][$table_name], 0);
                        if (!MDB2::isError($result)) {
                            $alterations++;
                        }
                    }
                }
                if (MDB2::isError($result)) {
                    break;
                }
            }
            foreach ($changes['tables'] as $table_name => $table) {
                if (isset($table['add'])) {
                    $result = $this->_createTable($table_name, $this->database_definition['tables'][$table_name]);
                    if (!MDB2::isError($result)) {
                        $alterations++;
                    }
                }
                if (MDB2::isError($result)) {
                    break;
                }
            }
        }
        if (!MDB2::isError($result) && isset($changes['sequences'])
            && is_array($changes['sequences'])
        ) {
            foreach ($changes['sequences'] as $sequence_name => $sequence) {
                if (isset($sequence['add'])) {
                    $created_on_table = false;
                    if (isset($this->database_definition['sequences'][$sequence_name]['on'])) {
                        $table = $this->database_definition['sequences'][$sequence_name]['on']['table'];
                        if (isset($changes['tables'])
                            && isset($changes['tables'][$table_name])
                            && isset($changes['tables'][$table_name]['add'])
                        ) {
                            $created_on_table = true;
                        }
                    }
 
                    $result = $this->_createSequence($sequence_name,
                        $this->database_definition['sequences'][$sequence_name], $created_on_table);
                    if (!MDB2::isError($result)) {
                        $alterations++;
                    }
                } else {
                    if (isset($sequence['remove'])) {
                        if (!strcmp($error = $this->_dropSequence($sequence_name), '')) {
                            $alterations++;
                        }
                    } else {
                        if (isset($sequence['change'])) {
                            $created_on_table = false;
                            if (isset($this->database_definition['sequences'][$sequence_name]['on'])) {
                                $table = $this->database_definition['sequences'][$sequence_name]['on']['table'];
                                if (isset($changes['tables'])
                                    && isset($changes['tables'][$table_name])
                                    && isset($changes['tables'][$table_name]['add'])
                                ) {
                                    $created_on_table = true;
                                }
                            }
                            if (!MDB2::isError($result = $this->_dropSequence(
                                    $this->database_definition['sequences'][$sequence_name]['was']), '')
                                && !MDB2::isError($result = $this->_createSequence(
                                    $sequence_name, $this->database_definition['sequences'][$sequence_name], $created_on_table), '')
                            ) {
                                $alterations++;
                            }
                        } else {
                            return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                                'changing sequences is not yet supported');
                        }
                    }
                }
                if (MDB2::isError($result)) {
                    break;
                }
            }
        }
        if (!MDB2::isError($result) && isset($changes['indexes'])
            && is_array($changes['indexes'])
        ) {
            foreach ($changes['indexes'] as $table_name => $indexes) {
                if (isset($indexes['changed_indexes'])) {
                    $changedindexes = $indexes['changed_indexes'];
                    foreach ($changedindexes as $index_name => $index) {
                        $result = $this->db->manager->createIndex($table_name, $index_name,
                            $this->database_definition['tables'][$table_name]['indexes'][$index_name]);
                        if (MDB2::isError($result)) {
                            break;
                        }
                        $alterations++;
                    }
                }
                if (!MDB2::isError($result)
                    && isset($indexes['added_indexes'])
                ) {
                    $addedindexes = $indexes['added_indexes'];
                    foreach ($addedindexes as $index_name => $index) {
                        $result = $this->db->manager->createIndex($table_name, $index_name,
                            $this->database_definition['tables'][$table_name]['indexes'][$index_name]);
                        if (MDB2::isError($result)) {
                            break;
                        }
                        $alterations++;
                    }
                }
                if (MDB2::isError($result)) {
                    break;
                }
            }
        }
        if ($alterations && MDB2::isError($result)) {
            if ($support_transactions) {
                $res = $this->db->rollback();
                if (MDB2::isError($res))
                    $result = $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                        'Could not rollback the partially created database alterations ('.
                        $result->getMessage().' ('.$result->getUserinfo().'))');
            } else {
                $result = $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                    'the requested database alterations were only partially implemented ('.
                    $result->getMessage().' ('.$result->getUserinfo().'))');
            }
        }
        if ($support_transactions) {
            $result = $this->db->autoCommit(true);
            if (MDB2::isError($result)) {
                $result = $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                    'Could not end transaction after successfully implemented the requested database alterations ('.
                    $result->getMessage().' ('.$result->getUserinfo().'))');
            }
        }
        $this->db->setDatabase($previous_database_name);
        return $result;
    }
 
    // }}}
    // {{{ _escapeSpecialCharacters()
 
    /**
     * add escapecharacters to all special characters in a string
     *
     * @param string $string string that should be escaped
     * @return string escaped string
     * @access private
     */
    function _escapeSpecialCharacters($string)
    {
        if (is_string($string)) {
            $string = strval($string);
        }
        for ($escaped = '', $character = 0;
            $character < strlen($string);
            $character++)
        {
            switch ($string[$character]) {
                case '\"':
                case '>':
                case '<':
                case '&':
                    $code = ord($string[$character]);
                    break;
                default:
                    $code = ord($string[$character]);
                    if ($code < 32 || $code>127) {
                        break;
                    }
                    $escaped .= $string[$character];
                    continue 2;
            }
            $escaped .= "&#$code;";
        }
        return $escaped;
    }
 
    // }}}
    // {{{ _dumpSequence()
 
    /**
     * dump the structure of a sequence
     *
     * @param string  $sequence_name 
     * @param string  $eol 
     * @return mixed string with xml seqeunce definition on success, or a MDB2 error object
     * @access private
     */
    function _dumpSequence($sequence_name, $eol, $dump = MDB2_MANAGER_DUMP_ALL)
    {
        $sequence_definition = $this->database_definition['sequences'][$sequence_name];
        $buffer = "$eol <sequence>$eol  <name>$sequence_name</name>$eol";
        if ($dump == MDB2_MANAGER_DUMP_ALL || $dump == MDB2_MANAGER_DUMP_CONTENT) {
            if (isset($sequence_definition['start'])) {
                $start = $sequence_definition['start'];
                $buffer .= "  <start>$start</start>$eol";
            }
        }
        if (isset($sequence_definition['on'])) {
            $buffer .= "  <on>$eol   <table>".$sequence_definition['on']['table'].
                "</table>$eol   <field>".$sequence_definition['on']['field'].
                "</field>$eol  </on>$eol";
        }
        $buffer .= " </sequence>$eol";
        return $buffer;
    }
 
    // }}}
    // {{{ parseDatabaseDefinitionFile()
 
    /**
     * Parse a database definition file by creating a Metabase schema format
     * parser object and passing the file contents as parser input data stream.
     *
     * @param string $input_file the path of the database schema file.
     * @param array $variables an associative array that the defines the text
     *  string values that are meant to be used to replace the variables that are
     *  used in the schema description.
     * @param bool $fail_on_invalid_names (optional) make function fail on invalid
     *  names
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access public
     */
    function parseDatabaseDefinitionFile($input_file, $variables, $fail_on_invalid_names = true)
    {
        $parser =& new MDB2_Tools_Parser($variables, $fail_on_invalid_names);
        $result = $parser->setInputFile($input_file);
        if (MDB2::isError($result)) {
            return $result;
        };
        $result = $parser->parse();
        if (MDB2::isError($result)) {
            return $result;
        };
        if (MDB2::isError($parser->error)) {
            return $parser->error;
        }
        return $parser->database_definition;
    }
 
    // }}}
    // {{{ _debugDatabaseChanges()
 
    /**
     * Dump the changes between two database definitions.
     *
     * @param array $changes an associative array that specifies the list
     *  of database definitions changes as returned by the _compareDefinitions
     *  manager class function.
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access private
     */
    function _debugDatabaseChanges($changes)
    {
        if (isset($changes['tables'])) {
            foreach ($changes['tables'] as $table_name => $table)
            {
                $this->db->debug("$table_name:");
                if (isset($table['add'])) {
                    $this->db->debug("\tAdded table '$table_name'");
                } elseif (isset($table['remove'])) {
                    $this->db->debug("\tRemoved table '$table_name'");
                } else {
                    if (isset($table['name'])) {
                        $this->db->debug("\tRenamed table '$table_name' to '".
                            $table['name']."'");
                    }
                    if (isset($table['added_fields'])) {
                        foreach ($table['added_fields'] as $field_name => $field) {
                            $this->db->debug("\tAdded field '".$field_name."'");
                        }
                    }
                    if (isset($table['removed_fields'])) {
                        foreach ($table['removed_fields'] as $field_name => $field) {
                            $this->db->debug("\tRemoved field '".$field_name."'");
                        }
                    }
                    if (isset($table['renamed_fields'])) {
                        foreach ($table['renamed_fields'] as $field_name => $field) {
                            $this->db->debug("\tRenamed field '".$field_name."' to '".
                                $field['name']."'");
                        }
                    }
                    if (isset($table['changed_fields'])) {
                        foreach ($table['changed_fields'] as $field_name => $field) {
                            if (isset($field['type'])) {
                                $this->db->debug(
                                    "\tChanged field '$field_name' type to '".
                                        $field['type']."'");
                            }
                            if (isset($field['unsigned'])) {
                                $this->db->debug(
                                    "\tChanged field '$field_name' type to '".
                                    ($field['unsigned'] ? '' : 'not ')."unsigned'");
                            }
                            if (isset($field['length'])) {
                                $this->db->debug(
                                    "\tChanged field '$field_name' length to '".
                                    ($field['length'] == 0 ? 'no length' : $field['length'])."'");
                            }
                            if (isset($field['changed_default'])) {
                                $this->db->debug(
                                    "\tChanged field '$field_name' default to ".
                                    (isset($field['default']) ? "'".$field['default']."'" : 'NULL'));
                            }
                            if (isset($field['changed_not_null'])) {
                                $this->db->debug(
                                   "\tChanged field '$field_name' notnull to ".(isset($field['notnull']) ? "'1'" : '0'));
                            }
                        }
                    }
                }
            }
        }
        if (isset($changes['sequences'])) {
            foreach ($changes['sequences'] as $sequence_name => $sequence)
            {
                $this->db->debug("$sequence_name:");
                if (isset($sequence['add'])) {
                    $this->db->debug("\tAdded sequence '$sequence_name'");
                } elseif (isset($sequence['remove'])) {
                    $this->db->debug("\tRemoved sequence '$sequence_name'");
                } else {
                    if (isset($sequence['name'])) {
                        $this->db->debug(
                            "\tRenamed sequence '$sequence_name' to '".
                            $sequence['name']."'");
                    }
                    if (isset($sequence['change'])) {
                        foreach ($sequence['change'] as $sequence_name => $sequence) {
                            if (isset($sequence['start'])) {
                                $this->db->debug(
                                    "\tChanged sequence '$sequence_name' start to '".
                                    $sequence['start']."'");
                            }
                        }
                    }
                }
            }
        }
        if (isset($changes['indexes'])) {
            foreach ($changes['indexes'] as $table_name => $table)
            {
                $this->db->debug("$table_name:");
                if (isset($table['added_indexes'])) {
                    foreach ($table['added_indexes'] as $index_name => $index) {
                        $this->db->debug("\tAdded index '".$index_name.
                            "' of table '$table_name'");
                    }
                }
                if (isset($table['removed_indexes'])) {
                    foreach ($table['removed_indexes'] as $index_name => $index) {
                        $this->db->debug("\tRemoved index '".$index_name.
                            "' of table '$table_name'");
                    }
                }
                if (isset($table['changed_indexes'])) {
                    foreach ($table['changed_indexes'] as $index_name => $index) {
                        if (isset($index['name'])) {
                            $this->db->debug(
                                "\tRenamed index '".$index_name."' to '".$index['name'].
                                "' on table '$table_name'");
                        }
                        if (isset($index['changed_unique'])) {
                            $this->db->debug(
                                "\tChanged index '".$index_name."' unique to '".
                                isset($index['unique'])."' on table '$table_name'");
                        }
                        if (isset($index['changed_fields'])) {
                            $this->db->debug("\tChanged index '".$index_name.
                                "' on table '$table_name'");
                        }
                    }
                }
            }
        }
        return MDB2_OK;
    }
 
    // }}}
    // {{{ _dumpDatabaseContents()
 
    /**
     * Parse a database schema definition file and dump the respective structure
     * and contents.
     *
     * @param string $schema_file path of the database schema file.
     * @param mixed $setup_arguments an associative array that takes pairs of tag names and values
     *  that define the setup arguments that are passed to the
     *  MDB2_Tools_Manager::connect function.
     * @param array $dump_arguments an associative array that takes pairs of tag names and values
     *  that define dump options as defined for the MDB2_Tools_Manager::DumpDatabase
     *  function.
     * @param array $variables an associative array that the defines the text string values
     *  that are meant to be used to replace the variables that are used in the
     *  schema description as defined for the
     *  MDB2_Tools_Manager::parseDatabaseDefinitionFile function.
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access private
     */
    function _dumpDatabaseContents($schema_file, $setup_arguments, $dump_arguments, $variables)
    {
        $database_definition = $this->parseDatabaseDefinitionFile($schema_file,
            $variables, $this->options['fail_on_invalid_names']);
        if (MDB2::isError($database_definition)) {
            return $database_definition;
        }
 
        $this->database_definition = $database_definition;
 
        $result = $this->connect($setup_arguments);
        if (MDB2::isError($result)) {
            return $result;
        }
 
        return $this->dumpDatabase($dump_arguments);
    }
 
    // }}}
    // {{{ getDefinitionFromDatabase()
 
    /**
     * Attempt to reverse engineer a schema structure from an existing MDB2
     * This method can be used if no xml schema file exists yet.
     * The resulting xml schema file may need some manual adjustments.
     *
     * @return mixed MDB2_OK or array with all ambiguities on success, or a MDB2 error object
     * @access public
     */
    function getDefinitionFromDatabase()
    {
        $this->db->loadModule('reverse');
        $database = $this->db->database_name;
        if (strlen($database) == 0) {
            return $this->raiseError('it was not specified a valid database name');
        }
        $this->database_definition = array(
            'name' => $database,
            'create' => 1,
            'tables' => array()
        );
        $tables = $this->db->manager->listTables();
        if (MDB2::isError($tables)) {
            return $tables;
        }
 
        for ($table = 0; $table < count($tables); $table++) {
            $table_name = $tables[$table];
            $fields = $this->db->manager->listTableFields($table_name);
            if (MDB2::isError($fields)) {
                return $fields;
            }
            $this->database_definition['tables'][$table_name] = array('fields' => array());
            for ($field = 0; $field < count($fields); $field++) {
                $field_name = $fields[$field];
                $definition = $this->db->reverse->getTableFieldDefinition($table_name, $field_name);
                if (MDB2::isError($definition)) {
                    return $definition;
                }
                $this->database_definition['tables'][$table_name]['fields'][$field_name] = $definition[0][0];
                $field_choices = count($definition[0]);
                if ($field_choices > 1) {
                    $warning = "There are $field_choices type choices in the table $table_name field $field_name (#1 is the default): ";
                    $field_choice_cnt = 1;
                    $this->database_definition['tables'][$table_name]['fields'][$field_name]['choices'] = array();
                    foreach ($definition[0] as $field_choice) {
                        $this->database_definition['tables'][$table_name]['fields'][$field_name]['choices'][] = $field_choice;
                        $warning .= 'choice #'.($field_choice_cnt).': '.serialize($field_choice);
                        $field_choice_cnt++;
                    }
                    $this->warnings[] = $warning;
                }
                if (isset($definition[1])) {
                    $sequence = $definition[1]['definition'];
                    $sequence_name = $definition[1]['name'];
                    $this->db->debug('Implicitly defining sequence: '.$sequence_name);
                    if (!isset($this->database_definition['sequences'])) {
                        $this->database_definition['sequences'] = array();
                    }
                    $this->database_definition['sequences'][$sequence_name] = $sequence;
                }
                if (isset($definition[2])) {
                    $index = $definition[2]['definition'];
                    $index_name = $definition[2]['name'];
                    $this->db->debug('Implicitly defining index: '.$index_name);
                    if (!isset($this->database_definition['tables'][$table_name]['indexes'])) {
                        $this->database_definition['tables'][$table_name]['indexes'] = array();
                    }
                    $this->database_definition['tables'][$table_name]['indexes'][$index_name] = $index;
                }
            }
            $indexes = $this->db->manager->listTableIndexes($table_name);
            if (MDB2::isError($indexes)) {
                return $indexes;
            }
            if (is_array($indexes) && count($indexes) > 0 && !isset($this->database_definition['tables'][$table_name]['indexes'])) {
                $this->database_definition['tables'][$table_name]['indexes'] = array();
            }
            for ($index = 0, $index_cnt = count($indexes); $index < $index_cnt; $index++)
            {
                $index_name = $indexes[$index];
                $definition = $this->db->reverse->getTableIndexDefinition($table_name, $index_name);
                if (MDB2::isError($definition)) {
                    return $definition;
                }
               $this->database_definition['tables'][$table_name]['indexes'][$index_name] = $definition;
            }
            // ensure that all fields that have an index on them are set to NOT NULL
            if (isset($this->database_definition['tables'][$table_name]['indexes'])
                && is_array($this->database_definition['tables'][$table_name]['indexes'])
                && count($this->database_definition['tables'][$table_name]['indexes']) > 0
            ) {
                foreach ($this->database_definition['tables'][$table_name]['indexes'] as $index_check_null) {
                    foreach ($index_check_null['fields'] as $field_name_check_null => $field_check_null) {
                        $this->database_definition['tables'][$table_name]['fields'][$field_name_check_null]['notnull'] = true;
                    }
                }
            }
            // ensure that all fields that are set to NOT NULL also have a default value
            if (is_array($this->database_definition['tables'][$table_name]['fields'])
                && count($this->database_definition['tables'][$table_name]['fields']) > 0
            ) {
                foreach ($this->database_definition['tables'][$table_name]['fields'] as $field_set_default_name => $field_set_default) {
                    if (isset($field_set_default['notnull']) && $field_set_default['notnull']
                        && !isset($field_set_default['default'])
                    ) {
                        if (isset($this->default_values[$field_set_default['type']])) {
                            $this->database_definition['tables'][$table_name]['fields'][$field_set_default_name]['default'] = $this->default_values[$field_set_default['type']];
                        } else {
                            $this->database_definition['tables'][$table_name]['fields'][$field_set_default_name]['default'] = 0;
                        }
                    }
                    if (isset($field_set_default['choices']) && is_array($field_set_default['choices'])) {
                        foreach ($field_set_default['choices'] as $field_choices_set_default_name => $field_choices_set_default) {
                            if (isset($field_choices_set_default['notnull'])
                                && $field_choices_set_default['notnull']
                                && !isset($field_choices_set_default['default'])
                            ) {
                                if (isset($this->default_values[$field_choices_set_default['type']])) {
                                    $this->database_definition['tables'][$table_name]['fields'][$field_set_default_name]['choices'][$field_choices_set_default_name]['default'] = $this->default_values[$field_choices_set_default['type']];
                                } else {
                                    $this->database_definition['tables'][$table_name]['fields'][$field_set_default_name]['choices'][$field_choices_set_default_name]['default'] = 0;
                                }
                            }
                        }
                    }
                }
            }
        }
 
        $sequences = $this->db->manager->listSequences();
        if (MDB2::isError($sequences)) {
            return $sequences;
        }
        if (is_array($sequences) && count($sequences) > 0 && !isset($this->database_definition['sequences'])) {
            $this->database_definition['sequences'] = array();
        }
        for ($sequence = 0; $sequence < count($sequences); $sequence++) {
            $sequence_name = $sequences[$sequence];
            $definition = $this->db->reverse->getSequenceDefinition($sequence_name);
            if (MDB2::isError($definition)) {
                return $definition;
            }
            $this->database_definition['sequences'][$sequence_name] = $definition;
        }
        return MDB2_OK;
    }
 
    // }}}
    // {{{ dumpDatabase()
 
    /**
     * Dump a previously parsed database structure in the Metabase schema
     * XML based format suitable for the Metabase parser. This function
     * may optionally dump the database definition with initialization
     * commands that specify the data that is currently present in the tables.
     *
     * @param array $arguments an associative array that takes pairs of tag
     *  names and values that define dump options.
     *                  array (
     *                      'definition'    =>    Boolean
     *                          true   :  dump currently parsed definition
     *                          default:  dump currently connected database
     *                      'Output_Mode'    =>    String
     *                          'file' :   dump into a file
     *                          default:   dump using a function
     *                      'output'        =>    String
     *                          depending on the 'Output_Mode'
     *                                   name of the file
     *                                   name of the function
     *                      'EndOfLine'        =>    String
     *                          end of line delimiter that should be used
     *                          default: "\n"
     *                  );
     * @param integer $dump constant that determines what data to dump
     *                       MDB2_MANAGER_DUMP_ALL       : the entire db
     *                       MDB2_MANAGER_DUMP_STRUCTURE : only the structure of the db
     *                       MDB2_MANAGER_DUMP_CONTENT   : only the content of the db
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access public
     */
    function dumpDatabase($arguments, $dump = MDB2_MANAGER_DUMP_ALL)
    {
        if (isset($arguments['definition']) && $arguments['definition']) {
            $dump_definition = true;
        } else {
            if (!$this->db) {
                return $this->raiseError(MDB2_ERROR_NODBSELECTED,
                    null, null, 'please connect to a RDBMS first');
            }
            $error = $this->getDefinitionFromDatabase();
            if (MDB2::isError($error)) {
                return $error;
            }
            $dump_definition = false;
        }
 
        if (isset($arguments['output'])) {
            if (isset($arguments['output_mode']) && $arguments['output_mode'] == 'file') {
                $fp = fopen($arguments['output'], 'w');
                $output = false;
            } elseif (function_exists($arguments['output'])) {
                $output = $arguments['output'];
            } else {
                return $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                        'no valid output function specified');
            }
        } else {
            return $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                'no output method specified');
        }
        if (isset($arguments['end_of_line'])) {
            $eol = $arguments['end_of_line'];
        } else {
            $eol = "\n";
        }
 
        $sequences = array();
        if (isset($this->database_definition['sequences'])
            && is_array($this->database_definition['sequences'])
        ) {
            foreach ($this->database_definition['sequences'] as $sequence_name => $sequence) {
                if (isset($sequence['on'])) {
                    $table = $sequence['on']['table'];
                } else {
                    $table = '';
                }
                $sequences[$table][] = $sequence_name;
            }
        }
        $previous_database_name = (strcmp($this->database_definition['name'], '') ? $this->db->setDatabase($this->database_definition['name']) : '');
        $buffer = ('<?xml version="1.0" encoding="ISO-8859-1" ?>'.$eol);
        $buffer .= ("<database>$eol$eol <name>".$this->database_definition['name']."</name>$eol <create>".$this->database_definition['create']."</create>$eol");
 
        if ($output) {
            $output($buffer);
        } else {
            fwrite($fp, $buffer);
        }
        $buffer = '';
        if (isset($this->database_definition['tables']) && is_array($this->database_definition['tables'])) {
            foreach ($this->database_definition['tables'] as $table_name => $table) {
                $buffer = ("$eol <table>$eol$eol  <name>$table_name</name>$eol");
                if ($dump == MDB2_MANAGER_DUMP_ALL || $dump == MDB2_MANAGER_DUMP_STRUCTURE) {
                    $buffer .= ("$eol  <declaration>$eol");
                    if (isset($table['fields']) && is_array($table['fields'])) {
                        foreach ($table['fields'] as $field_name => $field) {
                            if (!isset($field['type'])) {
                                return $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                                    'it was not specified the type of the field "'.
                                    $field_name.'" of the table "'.$table_name);
                            }
                            $buffer .=("$eol   <field>$eol    <name>$field_name</name>$eol    <type>".$field['type']."</type>$eol");
                            if (in_array($field_name, array_keys($this->invalid_names))) {
                                $this->warnings[] = "invalid field name: $field_name. You will need to set the class var \$fail_on_invalid_names to false or change the field name.";
                            }
                            switch ($field['type']) {
                                case 'integer':
                                    if (isset($field['unsigned'])) {
                                        $buffer .=("    <unsigned>1</unsigned>$eol");
                                    }
                                    break;
                                case 'text':
                                case 'clob':
                                case 'blob':
                                    if (isset($field['length'])) {
                                        $buffer .=('    <length>'.$field['length'].
                                            "</length>$eol");
                                    }
                                    break;
                                case 'boolean':
                                case 'date':
                                case 'timestamp':
                                case 'time':
                                case 'float':
                                case 'decimal':
                                    break;
                                default:
                                    return $this->raiseError('type "'.$field['type'].
                                        '" is not yet supported');
                            }
                            if (isset($field['notnull'])) {
                                $buffer .=("    <notnull>1</notnull>$eol");
                            }
                            if (isset($field['default'])) {
                                $buffer .=('    <default>'.$this->_escapeSpecialCharacters($field['default'])."</default>$eol");
                            }
                            $buffer .=("   </field>$eol");
                        }
                    }
                    if (isset($table['indexes']) && is_array($table['indexes'])) {
                        foreach ($table['indexes'] as $index_name => $index) {
                            $buffer .=("$eol   <index>$eol    <name>$index_name</name>$eol");
                            if (isset($index['unique'])) {
                                $buffer .=("    <unique>1</unique>$eol");
                            }
                            foreach ($index['fields'] as $field_name => $field) {
                                $buffer .=("    <field>$eol     <name>$field_name</name>$eol");
                                if (is_array($field) && isset($field['sorting'])) {
                                    $buffer .=('     <sorting>'.$field['sorting']."</sorting>$eol");
                                }
                                $buffer .=("    </field>$eol");
                            }
                            $buffer .=("   </index>$eol");
                        }
                    }
                    $buffer .= ("$eol  </declaration>$eol");
                }
                if ($output) {
                    $output($buffer);
                } else {
                    fwrite($fp, $buffer);
                }
                $buffer = '';
                if ($dump == MDB2_MANAGER_DUMP_ALL || $dump == MDB2_MANAGER_DUMP_CONTENT) {
                    if ($dump_definition) {
                        if (isset($table['initialization']) && is_array($table['initialization'])) {
                            $buffer = ("$eol  <initialization>$eol");
                            foreach ($table['initialization'] as $instruction_name => $instruction) {
                                switch ($instruction['type']) {
                                    case 'insert':
                                        $buffer .= ("$eol   <insert>$eol");
                                        foreach ($instruction['fields'] as $field_name => $field) {
                                            $buffer .= ("$eol    <field>$eol     <name>$field_name</name>$eol     <value>".$this->_escapeSpecialCharacters($field)."</value>$eol   </field>$eol");
                                        }
                                        $buffer .= ("$eol   </insert>$eol");
                                        break;
                                }
                            }
                            $buffer .= ("$eol  </initialization>$eol");
                        }
                    } else {
                        $types = array();
                        foreach ($table['fields'] as $field) {
                            $types[] = $field['type'];
                        }
                        $query = 'SELECT '.implode(',',array_keys($table['fields']))." FROM $table_name";
                        $data = $this->db->queryAll($query, $types, MDB2_FETCHMODE_ASSOC);
                        if (MDB2::isError($data)) {
                            return $data;
                        }
                        $rows = count($data);
                        if ($rows > 0) {
                            $buffer = ("$eol  <initialization>$eol");
                            if ($output) {
                                $output($buffer);
                            } else {
                                fwrite($fp, $buffer);
                            }
 
                            for ($row = 0; $row < $rows; $row++) {
                                $buffer = ("$eol   <insert>$eol");
                                $values = $data[$row];
                                if (!is_array($values)) {
                                    break;
                                } else {
                                    foreach ($values as $field_name => $field) {
                                            $buffer .= ("$eol   <field>$eol     <name>$field_name</name>$eol     <value>");
                                            $buffer .= $this->_escapeSpecialCharacters($values[$field_name]);
                                            $buffer .= ("</value>$eol   </field>$eol");
                                    }
                                }
                                $buffer .= ("$eol   </insert>$eol");
                                if ($output) {
                                    $output($buffer);
                                } else {
                                    fwrite($fp, $buffer);
                                }
                                $buffer = '';
                            }
                            $buffer = ("$eol  </initialization>$eol");
                            if ($output) {
                                $output($buffer);
                            } else {
                                fwrite($fp, $buffer);
                            }
                            $buffer = '';
                        }
                    }
                }
                $buffer .= ("$eol </table>$eol");
                if ($output) {
                    $output($buffer);
                } else {
                    fwrite($fp, $buffer);
                }
                if (isset($sequences[$table_name])) {
                    for ($sequence = 0, $j = count($sequences[$table_name]);
                        $sequence < $j;
                        $sequence++)
                    {
                        $result = $this->_dumpSequence($sequences[$table_name][$sequence], $eol, $dump);
                        if (MDB2::isError($result)) {
                            return $result;
                        }
                        if ($output) {
                            $output($result);
                        } else {
                            fwrite($fp, $result);
                        }
                    }
                }
            }
        }
        if (isset($sequences[''])) {
            for ($sequence = 0;
                $sequence < count($sequences['']);
                $sequence++)
            {
                $result = $this->_dumpSequence($sequences[''][$sequence], $eol, $dump);
                if (MDB2::isError($result)) {
                    return $result;
                }
                if ($output) {
                       $output($result);
                   } else {
                       fwrite($fp, $result);
                }
            }
        }
 
        $buffer = ("$eol</database>$eol");
        if ($output) {
            $output($buffer);
        } else {
            fwrite($fp, $buffer);
            fclose($fp);
        }
 
        if (strcmp($previous_database_name, '')) {
            $this->db->setDatabase($previous_database_name);
        }
        return MDB2_OK;
    }
 
    // }}}
    // {{{ updateDatabase()
 
    /**
     * Compare the correspondent files of two versions of a database schema
     * definition: the previously installed and the one that defines the schema
     * that is meant to update the database.
     * If the specified previous definition file does not exist, this function
     * will create the database from the definition specified in the current
     * schema file.
     * If both files exist, the function assumes that the database was previously
     * installed based on the previous schema file and will update it by just
     * applying the changes.
     * If this function succeeds, the contents of the current schema file are
     * copied to replace the previous schema file contents. Any subsequent schema
     * changes should only be done on the file specified by the $current_schema_file
     * to let this function make a consistent evaluation of the exact changes that
     * need to be applied.
     *
     * @param string $current_schema_file name of the updated database schema
     *  definition file.
     * @param string $previous_schema_file name the previously installed database
     *  schema definition file.
     * @param array $variables an associative array that is passed to the argument
     *  of the same name to the parseDatabaseDefinitionFile function. (there third
     *  param)
     * @return mixed MDB2_OK on success, or a MDB2 error object
     * @access public
     */
    function updateDatabase($current_schema_file, $previous_schema_file = false, $variables = array())
    {
        $database_definition = $this->parseDatabaseDefinitionFile($current_schema_file,
            $variables, $this->options['fail_on_invalid_names']);
        if (MDB2::isError($database_definition)) {
            return $database_definition;
        }
        $this->database_definition = $database_definition;
        $copy = false;
/*
        $this->expectError(MDB2_ERROR_UNSUPPORTED);
        $databases = $this->db->manager->listDatabases();
        $this->popExpect();
        if ((MDB2::isError($databases) || (is_array($databases) && in_array($this->database_definition['name'], $databases)))
            && $previous_schema_file && file_exists($previous_schema_file)
        ) {
*/
        if ($previous_schema_file && file_exists($previous_schema_file)) {
            $previous_definition = $this->parseDatabaseDefinitionFile($previous_schema_file, $variables, 0);
            if (MDB2::isError($previous_definition)) {
                return $previous_definition;
            }
            $changes = $this->_compareDefinitions($previous_definition);
            if (MDB2::isError($changes)) {
                return $changes;
            }
            if (isset($changes) && is_array($changes)) {
                $result = $this->_alterDatabase($previous_definition, $changes);
                if (MDB2::isError($result)) {
                    return $result;
                }
                $copy = true;
                if ($this->db->options['debug']) {
                    $result = $this->_debugDatabaseChanges($changes);
                    if (MDB2::isError($result)) {
                        return $result;
                    }
                }
            }
        } else {
            $result = $this->_createDatabase();
            if (MDB2::isError($result)) {
                return $result;
            }
            $copy = true;
        }
        if ($copy && $previous_schema_file && !copy($current_schema_file, $previous_schema_file)) {
            return $this->raiseError(MDB2_ERROR_MANAGER, null, null,
                'Could not copy the new database definition file to the current file');
        }
        return MDB2_OK;
    }
 
    // }}}
}
?>