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<?php
/*
 *  $Id: DBAdapter.php 1262 2009-10-26 20:54:39Z francois $
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 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.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the LGPL. For more information please see
 * <http://propel.phpdb.org>.
 */

/**
 * DBAdapter</code> defines the interface for a Propel database adapter.
 *
 * <p>Support for new databases is added by subclassing
 * <code>DBAdapter</code> and implementing its abstract interface, and by
 * registering the new database adapter and corresponding Creole
 * driver in the private adapters map (array) in this class.</p>
 *
 * <p>The Propel database adapters exist to present a uniform
 * interface to database access across all available databases.  Once
 * the necessary adapters have been written and configured,
 * transparent swapping of databases is theoretically supported with
 * <i>zero code change</i> and minimal configuration file
 * modifications.</p>
 *
 * @author     Hans Lellelid <hans@xmpl.org> (Propel)
 * @author     Jon S. Stevens <jon@latchkey.com> (Torque)
 * @author     Brett McLaughlin <bmclaugh@algx.net> (Torque)
 * @author     Daniel Rall <dlr@finemaltcoding.com> (Torque)
 * @version    $Revision: 1262 $
 * @package    propel.adapter
 */
abstract class DBAdapter {

        const ID_METHOD_NONE = 0;
        const ID_METHOD_AUTOINCREMENT = 1;
        const ID_METHOD_SEQUENCE = 2;

        /**
         * Creole driver to Propel adapter map.
         * @var        array
         */
        private static $adapters = array(
                'mysql' => 'DBMySQL',
                'mysqli' => 'DBMySQLi',
                'mssql' => 'DBMSSQL',
    'dblib' => 'DBMSSQL',
                'sybase' => 'DBSybase',
                'oracle' => 'DBOracle',
                'pgsql' => 'DBPostgres',
                'sqlite' => 'DBSQLite',
                '' => 'DBNone',
        );

        /**
         * Creates a new instance of the database adapter associated
         * with the specified Creole driver.
         *
         * @param      string $driver The name of the Propel/Creole driver to
         * create a new adapter instance for or a shorter form adapter key.
         * @return     DBAdapter An instance of a Propel database adapter.
         * @throws     PropelException if the adapter could not be instantiated.
         */
        public static function factory($driver) {
                $adapterClass = isset(self::$adapters[$driver]) ? self::$adapters[$driver] : null;
                if ($adapterClass !== null) {
                        $a = new $adapterClass();
                        return $a;
                } else {
                        throw new PropelException("Unsupported Propel driver: " . $driver . ": Check your configuration file");
                }
        }

        /**
         * This method is called after a connection was created to run necessary
         * post-initialization queries or code.
         *
         * If a charset was specified, this will be set before any other queries
         * are executed.
         *
         * This base method runs queries specified using the "query" setting.
         *
         * @param      PDO   A PDO connection instance.
         * @param      array An array of settings.
         * @see        setCharset()
         */
        public function initConnection(PDO $con, array $settings)
        {
                if (isset($settings['charset']['value'])) {
                        $this->setCharset($con, $settings['charset']['value']);
                }
                if (isset($settings['queries']) && is_array($settings['queries'])) {
                        foreach ($settings['queries'] as $queries) {
                                foreach ((array)$queries as $query) {
                                        $con->exec($query);
                                }
                        }
                }
        }

        /**
         * Sets the character encoding using SQL standard SET NAMES statement.
         *
         * This method is invoked from the default initConnection() method and must
         * be overridden for an RDMBS which does _not_ support this SQL standard.
         *
         * @param      PDO   A PDO connection instance.
         * @param      string The charset encoding.
         * @see        initConnection()
         */
        public function setCharset(PDO $con, $charset)
        {
                $con->exec("SET NAMES '" . $charset . "'");
        }

        /**
         * This method is used to ignore case.
         *
         * @param      string The string to transform to upper case.
         * @return     string The upper case string.
         */
        public abstract function toUpperCase($in);

        /**
         * Returns the character used to indicate the beginning and end of
         * a piece of text used in a SQL statement (generally a single
         * quote).
         *
         * @return     string The text delimeter.
         */
        public function getStringDelimiter()
        {
                return '\'';
        }

        /**
         * This method is used to ignore case.
         *
         * @param      string $in The string whose case to ignore.
         * @return     string The string in a case that can be ignored.
         */
        public abstract function ignoreCase($in);

        /**
         * This method is used to ignore case in an ORDER BY clause.
         * Usually it is the same as ignoreCase, but some databases
         * (Interbase for example) does not use the same SQL in ORDER BY
         * and other clauses.
         *
         * @param      string $in The string whose case to ignore.
         * @return     string The string in a case that can be ignored.
         */
        public function ignoreCaseInOrderBy($in)
        {
                return $this->ignoreCase($in);
        }

        /**
         * Returns SQL which concatenates the second string to the first.
         *
         * @param      string String to concatenate.
         * @param      string String to append.
         * @return     string
         */
        public abstract function concatString($s1, $s2);

        /**
         * Returns SQL which extracts a substring.
         *
         * @param      string String to extract from.
         * @param      int Offset to start from.
         * @param      int Number of characters to extract.
         * @return     string
         */
        public abstract function subString($s, $pos, $len);

        /**
         * Returns SQL which calculates the length (in chars) of a string.
         *
         * @param      string String to calculate length of.
         * @return     string
         */
        public abstract function strLength($s);


        /**
         * Quotes database objec identifiers (table names, col names, sequences, etc.).
         * @param      string $text The identifier to quote.
         * @return     string The quoted identifier.
         */
        public function quoteIdentifier($text)
        {
                return '"' . $text . '"';
        }

        /**
         * Quotes a database table which could have space seperating it from an alias, both should be identified seperately
         * @param      string $table The table name to quo
         * @return     string The quoted table name
         **/
        public function quoteIdentifierTable($table) {
                return implode(" ", array_map(array($this, "quoteIdentifier"), explode(" ", $table) ) );
        }

        /**
         * Returns the native ID method for this RDBMS.
         * @return     int one of DBAdapter:ID_METHOD_SEQUENCE, DBAdapter::ID_METHOD_AUTOINCREMENT.
         */
        protected function getIdMethod()
        {
                return DBAdapter::ID_METHOD_AUTOINCREMENT;
        }

        /**
         * Whether this adapter uses an ID generation system that requires getting ID _before_ performing INSERT.
         * @return     boolean
         */
        public function isGetIdBeforeInsert()
        {
                return ($this->getIdMethod() === DBAdapter::ID_METHOD_SEQUENCE);
        }

        /**
         * Whether this adapter uses an ID generation system that requires getting ID _before_ performing INSERT.
         * @return     boolean
         */
        public function isGetIdAfterInsert()
        {
                return ($this->getIdMethod() === DBAdapter::ID_METHOD_AUTOINCREMENT);
        }

        /**
         * Gets the generated ID (either last ID for autoincrement or next sequence ID).
         * @return     mixed
         */
        public function getId(PDO $con, $name = null)
        {
                return $con->lastInsertId($name);
        }

        /**
         * Returns timestamp formatter string for use in date() function.
         * @return     string
         */
        public function getTimestampFormatter()
        {
                return "Y-m-d H:i:s";
        }

        /**
         * Returns date formatter string for use in date() function.
         * @return     string
         */
        public function getDateFormatter()
        {
                return "Y-m-d";
        }

        /**
         * Returns time formatter string for use in date() function.
         * @return     string
         */
        public function getTimeFormatter()
        {
                return "H:i:s";
        }

        /**
         * Should Column-Names get identifiers for inserts or updates.
         * By default false is returned -> backwards compability.
         *
         * it`s a workaround...!!!
         *
         * @todo       should be abstract
         * @return     boolean
         * @deprecated
         */
        public function useQuoteIdentifier()
        {
                return false;
        }

        /**
         * Modifies the passed-in SQL to add LIMIT and/or OFFSET.
         */
        public abstract function applyLimit(&$sql, $offset, $limit);

        /**
         * Gets the SQL string that this adapter uses for getting a random number.
         *
         * @param      mixed $seed (optional) seed value for databases that support this
         */
        public abstract function random($seed = null);

}