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<?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.doctrine-project.org>.

 */

/**

 * Doctrine_Expression_Driver

 *

 * @package     Doctrine

 * @subpackage  Expression

 * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL

 * @link        www.doctrine-project.org

 * @since       1.0

 * @version     $Revision$

 * @author      Konsta Vesterinen <kvesteri@cc.hut.fi>

 */

class Doctrine_Expression_Driver extends Doctrine_Connection_Module

{

    public function getIdentifier($column)

    {

        return $column;

    }

    public function getIdentifiers($columns)

    {

        return $columns;

    }

    /**

     * regexp

     * returns the regular expression operator

     *

     * @return string

     */

    public function regexp()

    {

        throw new Doctrine_Expression_Exception('Regular expression operator is not supported by this database driver.');

    }

    /**

     * Returns the average value of a column

     *

     * @param string $column    the column to use

     * @return string           generated sql including an AVG aggregate function

     */

    public function avg($column)

    {

        $column = $this->getIdentifier($column);

        return 'AVG(' .  $column . ')';

    }

    /**

     * Returns the number of rows (without a NULL value) of a column

     *

     * If a '*' is used instead of a column the number of selected rows

     * is returned.

     *

     * @param string|integer $column    the column to use

     * @return string                   generated sql including a COUNT aggregate function

     */

    public function count($column)

    {

        $column = $this->getIdentifier($column);

        return 'COUNT(' . $column . ')';

    }

    /**

     * Returns the highest value of a column

     *

     * @param string $column    the column to use

     * @return string           generated sql including a MAX aggregate function

     */

    public function max($column)

    {

        $column = $this->getIdentifier($column);

        return 'MAX(' . $column . ')';

    }

    /**

     * Returns the lowest value of a column

     *

     * @param string $column the column to use

     * @return string

     */

    public function min($column)

    {

        $column = $this->getIdentifier($column);

        return 'MIN(' . $column . ')';

    }

    /**

     * Returns the total sum of a column

     *

     * @param string $column the column to use

     * @return string

     */

    public function sum($column)

    {

        $column = $this->getIdentifier($column);

        return 'SUM(' . $column . ')';

    }

    // scalar functions

    /**

     * Returns the md5 sum of a field.

     *

     * Note: Not SQL92, but common functionality

     *

     * @return string

     */

    public function md5($column)

    {

        $column = $this->getIdentifier($column);

        return 'MD5(' . $column . ')';

    }

    /**

     * Returns the length of a text field.

     *

     * @param string $expression1

     * @param string $expression2

     * @return string

     */

    public function length($column)

    {

        $column = $this->getIdentifier($column);

        return 'LENGTH(' . $column . ')';

    }

    /**

     * Rounds a numeric field to the number of decimals specified.

     *

     * @param string $expression1

     * @param string $expression2

     * @return string

     */

    public function round($column, $decimals = 0)

    {

        $column = $this->getIdentifier($column);

        return 'ROUND(' . $column . ', ' . $decimals . ')';

    }

    /**

     * Returns the remainder of the division operation

     * $expression1 / $expression2.

     *

     * @param string $expression1

     * @param string $expression2

     * @return string

     */

    public function mod($expression1, $expression2)

    {

        $expression1 = $this->getIdentifier($expression1);

        $expression2 = $this->getIdentifier($expression2);

        return 'MOD(' . $expression1 . ', ' . $expression2 . ')';

    }

    /**

     * trim

     * returns the string $str with leading and proceeding space characters removed

     *

     * @param string $str       literal string or column name

     * @return string

     */

    public function trim($str)

    {

        return 'TRIM(' . $str . ')';

    }

    /**

     * rtrim

     * returns the string $str with proceeding space characters removed

     *

     * @param string $str       literal string or column name

     * @return string

     */

    public function rtrim($str)

    {

        return 'RTRIM(' . $str . ')';

    }

    /**

     * ltrim

     * returns the string $str with leading space characters removed

     *

     * @param string $str       literal string or column name

     * @return string

     */

    public function ltrim($str)

    {

        return 'LTRIM(' . $str . ')';

    }

    /**

     * upper

     * Returns the string $str with all characters changed to

     * uppercase according to the current character set mapping.

     *

     * @param string $str       literal string or column name

     * @return string

     */

    public function upper($str)

    {

        return 'UPPER(' . $str . ')';

    }

    /**

     * lower

     * Returns the string $str with all characters changed to

     * lowercase according to the current character set mapping.

     *

     * @param string $str       literal string or column name

     * @return string

     */

    public function lower($str)

    {

        return 'LOWER(' . $str . ')';

    }

    /**

     * locate

     * returns the position of the first occurrence of substring $substr in string $str

     *

     * @param string $substr    literal string to find

     * @param string $str       literal string

     * @return integer

     */

    public function locate($str, $substr)

    {

        return 'LOCATE(' . $str . ', ' . $substr . ')';

    }

    /**

     * Returns the current system date.

     *

     * @return string

     */

    public function now()

    {

        return 'NOW()';

    }

    /**

     * soundex

     * Returns a string to call a function to compute the

     * soundex encoding of a string

     *

     * The string "?000" is returned if the argument is NULL.

     *

     * @param string $value

     * @return string   SQL soundex function with given parameter

     */

    public function soundex($value)

    {

        throw new Doctrine_Expression_Exception('SQL soundex function not supported by this driver.');

    }

    /**

     * 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, $from, $len = null)

    {

        $value = $this->getIdentifier($value);

        if ($len === null)

            return 'SUBSTRING(' . $value . ' FROM ' . $from . ')';

        else {

            $len = $this->getIdentifier($len);

            return 'SUBSTRING(' . $value . ' FROM ' . $from . ' FOR ' . $len . ')';

        }

    }

    /**

     * Returns a series of strings concatinated

     *

     * concat() accepts an arbitrary number of parameters. Each parameter

     * must contain an expression or an array with expressions.

     *

     * @param string|array(string) strings that will be concatinated.

     */

    public function concat()

    {

        $args = func_get_args();

        return 'CONCAT(' . join(', ', (array) $args) . ')';

    }

    /**

     * Returns the SQL for a logical not.

     *

     * @return string a logical expression

     */

    public function not($expression)

    {

        $expression = $this->getIdentifier($expression);

        return 'NOT(' . $expression . ')';

    }

    /**

     * Returns the SQL to perform the same mathematical operation over an array

     * of values or expressions.

     *

     * basicMath() accepts an arbitrary number of parameters. Each parameter

     * must contain a value or an expression or an array with values or

     * expressions.

     *

     * @param string $type the type of operation, can be '+', '-', '*' or '/'.

     * @param string|array(string)

     * @return string an expression

     */

    private function basicMath($type, array $args)

    {

        $elements = $this->getIdentifiers($args);

        if (count($elements) < 1) {

            return '';

        }

        if (count($elements) == 1) {

            return $elements[0];

        } else {

            return '(' . implode(' ' . $type . ' ', $elements) . ')';

        }

    }

    /**

     * Returns the SQL to add values or expressions together.

     *

     * add() accepts an arbitrary number of parameters. Each parameter

     * must contain a value or an expression or an array with values or

     * expressions.

     *

     * @param string|array(string)

     * @return string an expression

     */

    public function add(array $args)

    {

        return $this->basicMath('+', $args);

    }

    /**

     * Returns the SQL to subtract values or expressions from eachother.

     *

     * subtract() accepts an arbitrary number of parameters. Each parameter

     * must contain a value or an expression or an array with values or

     * expressions.

     *

     * @param string|array(string)

     * @return string an expression

     */

    public function sub(array $args)

    {

        return $this->basicMath('-', $args );

    }

    /**

     * Returns the SQL to multiply values or expressions by eachother.

     *

     * multiply() accepts an arbitrary number of parameters. Each parameter

     * must contain a value or an expression or an array with values or

     * expressions.

     *

     * @param string|array(string)

     * @return string an expression

     */

    public function mul(array $args)

    {

        return $this->basicMath('*', $args);

    }

    /**

     * Returns the SQL to divide values or expressions by eachother.

     *

     * divide() accepts an arbitrary number of parameters. Each parameter

     * must contain a value or an expression or an array with values or

     * expressions.

     *

     * @param string|array(string)

     * @return string an expression

     */

    public function div(array $args)

    {

        return $this->basicMath('/', $args);

    }

    /**

     * Returns the SQL to check if two values are equal.

     *

     * @param string $value1 logical expression to compare

     * @param string $value2 logical expression to compare with

     * @return string logical expression

     */

    public function eq($value1, $value2)

    {

        $value1 = $this->getIdentifier($value1);

        $value2 = $this->getIdentifier($value2);

        return $value1 . ' = ' . $value2;

    }

    /**

     * Returns the SQL to check if two values are unequal.

     *

     * @param string $value1 logical expression to compare

     * @param string $value2 logical expression to compare with

     * @return string logical expression

     */

    public function neq($value1, $value2)

    {

        $value1 = $this->getIdentifier($value1);

        $value2 = $this->getIdentifier($value2);

        return $value1 . ' <> ' . $value2;

    }

    /**

     * Returns the SQL to check if one value is greater than another value.

     *

     * @param string $value1 logical expression to compare

     * @param string $value2 logical expression to compare with

     * @return string logical expression

     */

    public function gt($value1, $value2)

    {

        $value1 = $this->getIdentifier($value1);

        $value2 = $this->getIdentifier($value2);

        return $value1 . ' > ' . $value2;

    }

    /**

     * Returns the SQL to check if one value is greater than or equal to

     * another value.

     *

     * @param string $value1 logical expression to compare

     * @param string $value2 logical expression to compare with

     * @return string logical expression

     */

    public function gte($value1, $value2)

    {

        $value1 = $this->getIdentifier($value1);

        $value2 = $this->getIdentifier($value2);

        return $value1 . ' >= ' . $value2;

    }

    /**

     * Returns the SQL to check if one value is less than another value.

     *

     * @param string $value1        logical expression to compare

     * @param string $value2        logical expression to compare with

     * @return string logical expression

     */

    public function lt($value1, $value2)

    {

        $value1 = $this->getIdentifier($value1);

        $value2 = $this->getIdentifier($value2);

        return $value1 . ' < ' . $value2;

    }

    /**

     * Returns the SQL to check if one value is less than or equal to

     * another value.

     *

     * @param string $value1        logical expression to compare

     * @param string $value2        logical expression to compare with

     * @return string logical expression

     */

    public function lte($value1, $value2)

    {

        $value1 = $this->getIdentifier($value1);

        $value2 = $this->getIdentifier($value2);

        return $value1 . ' <= ' . $value2;

    }

    /**

     * Returns the SQL to check if a value is one in a set of

     * given values..

     *

     * in() accepts an arbitrary number of parameters. The first parameter

     * must always specify the value that should be matched against. Successive

     * must contain a logical expression or an array with logical expressions.

     * These expressions will be matched against the first parameter.

     *

     * @param string $column        the value that should be matched against

     * @param string|array(string)  values that will be matched against $column

     * @return string logical expression

     */

    public function in($column, $values)

    {

        if ( ! is_array($values)) {

            $values = array($values);

        }

        $values = $this->getIdentifiers($values);

        $column = $this->getIdentifier($column);

        if (count($values) == 0) {

            throw new Doctrine_Expression_Exception('Values array for IN operator should not be empty.');

        }

        return $column . ' IN (' . implode(', ', $values) . ')';

    }

    /**

     * Returns SQL that checks if a expression is null.

     *

     * @param string $expression the expression that should be compared to null

     * @return string logical expression

     */

    public function isNull($expression)

    {

        $expression = $this->getIdentifier($expression);

        return $expression . ' IS NULL';

    }

    /**

     * Returns SQL that checks if a expression is not null.

     *

     * @param string $expression the expression that should be compared to null

     * @return string logical expression

     */

    public function isNotNull($expression)

    {

        $expression = $this->getIdentifier($expression);

        return $expression . ' IS NOT NULL';

    }

    /**

     * Returns SQL that checks if an expression evaluates to a value between

     * two values.

     *

     * The parameter $expression is checked if it is between $value1 and $value2.

     *

     * Note: There is a slight difference in the way BETWEEN works on some databases.

     * http://www.w3schools.com/sql/sql_between.asp. If you want complete database

     * independence you should avoid using between().

     *

     * @param string $expression the value to compare to

     * @param string $value1 the lower value to compare with

     * @param string $value2 the higher value to compare with

     * @return string logical expression

     */

    public function between($expression, $value1, $value2)

    {

        $expression = $this->getIdentifier($expression);

        $value1 = $this->getIdentifier($value1);

        $value2 = $this->getIdentifier($value2);

        return $expression . ' BETWEEN ' .$value1 . ' AND ' . $value2;

    }

    /**

     * Returns global unique identifier

     *

     * @return string to get global unique identifier

     */

    public function guid()

    {

        throw new Doctrine_Expression_Exception('method not implemented');

    }

    /**

     * returns arcus cosine SQL string

     *

     * @return string

     */

    public function acos($value)

    {

        return 'ACOS(' . $value . ')';

    }

    /**

     * sin

     *

     * @param string $value

     * @return void

     */

    public function sin($value)

    {

        return 'SIN(' . $value . ')';

    }

    /**

     * pi

     *

     * @return void

     */

    public function pi()

    {

        return 'PI()';

    }

    /**

     * cos

     *

     * @param string $value

     * @return void

     */

    public function cos($value)

    {

        return 'COS(' . $value . ')';

    }

    /**

     * coalesce

     *

     * @return string

     */

    public function coalesce()

    {

        $args = func_get_args();

	    return 'COALESCE(' . join(', ', (array) $args) . ')';

    }

    /**

     * __call

     *

     * for all native RDBMS functions the function name itself is returned

     */

    public function __call($m, $a)

    {

        if ($this->conn->getAttribute(Doctrine_Core::ATTR_PORTABILITY) & Doctrine_Core::PORTABILITY_EXPR) {

            throw new Doctrine_Expression_Exception('Unknown expression: ' . $m);

        }

        return $m . '(' . implode(', ', $a) . ')';

    }

}