<?php
/*
 *  $Id$
 *
 * 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, see
 * <http://www.phpdoctrine.com>.
 */
Doctrine::autoload('Doctrine_Expression');
/**
 * Doctrine_Expression_Sqlite
 *
 * @package     Doctrine ORM
 * @url         www.phpdoctrine.com
 * @license     LGPL
 */
class Doctrine_Expression_Sqlite extends Doctrine_Expression {
    /**
     * Returns the md5 sum of the data that SQLite's md5() function receives.
     *
     * @return string
     */
    public static function md5Impl($data) {
        return md5($data);
    }
    /**
     * Returns the modules of the data that SQLite's mod() function receives.
     *
     * @return string
     */
    public static function modImpl($dividend, $divisor) {
        return $dividend % $divisor;
    }

    /**
     * Returns a concattenation of the data that SQLite's concat() function receives.
     *
     * @return string
     */
    public static function concatImpl() {
        $args = func_get_args();
        return join( '', $args );
    }
    /**
     * returns the regular expression operator 
     *
     * @return string
     */
    public function regexp() {
        return 'RLIKE';
    }
    /**
     * Return string to call a variable with the current timestamp inside an SQL statement
     * There are three special variables for current date and time.
     *
     * @return string       sqlite function as string
     */
    public function now($type = 'timestamp') {
        switch ($type) {
        case 'time':
            return 'time(\'now\')';
        case 'date':
            return 'date(\'now\')';
        case 'timestamp':
        default:
            return 'datetime(\'now\')';
        }
    }
    /**
     * return string to call a function to get random value inside an SQL statement
     *
     * @return string to generate float between 0 and 1
     */
    public function random() {
        return '((RANDOM() + 2147483648) / 4294967296)';
    }
    /**
     * return string to call a function to get a substring inside an SQL statement
     *
     * Note: Not SQL92, but common functionality. 
     * 
     * SQLite only supports the 2 parameter variant of this function
     *
     * @param string $value         an sql string literal or column name/alias
     * @param integer $position     where to start the substring portion
     * @param integer $length       the substring portion length
     * @return string               SQL substring function with given parameters
     */
    public function substring($value, $position = 1, $length = null) {
        if($length !== null)
            return 'SUBSTR(' . $value . ', ' . $position . ', ' . $length . ')';

        return 'SUBSTR(' . $value . ', ' . $position . ', LENGTH(' . $value . '))';
    }
}