Subversion-Projekte lars-tiefland.php_share

<?php

/*

 *  $Id: Expression.php 7490 2010-03-29 19:53:27Z jwage $

 *

 * 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 memorizes a dql expression that use a db function.

 *

 * This class manages abstractions of dql expressions like query parts

 * that use CONCAT(), MIN(), SUM().

 *

 * @package     Doctrine

 * @subpackage  Expression

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

 * @link        www.doctrine-project.org

 * @since       1.0

 * @version     $Revision: 7490 $

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

 */

class Doctrine_Expression

{

    protected $_expression;

    protected $_conn;

    protected $_tokenizer;

    /**

     * Creates an expression.

     *

     * The constructor needs the dql fragment that contains one or more dbms

     * functions.

     * <code>

     * $e = new Doctrine_Expression("CONCAT('some', 'one')");

     * </code>

     *

     * @param string $expr                  sql fragment

     * @param Doctrine_Connection $conn     the connection (optional)

     */

    public function __construct($expr, $conn = null)

    {

        if ($conn !== null) {

            $this->_conn = $conn;

        }

        $this->_tokenizer = new Doctrine_Query_Tokenizer();

        $this->setExpression($expr);

    }

    /**

     * Retrieves the connection associated to this expression at creation,

     * or the current connection used if it was not specified.

     *

     * @return Doctrine_Connection The connection

     */

    public function getConnection()

    {

        if ( ! isset($this->_conn)) {

            return Doctrine_Manager::connection();

        }

        return $this->_conn;

    }

    /**

     * Sets the contained expression assuring that it is parsed.

     * <code>

     * $e->setExpression("CONCAT('some', 'one')");

     * </code>

     *

     * @param string $clause The expression to set

     * @return void

     */

    public function setExpression($clause)

    {

        $this->_expression = $this->parseClause($clause);

    }

    /**

     * Parses a single expressions and substitutes dql abstract functions

     * with their concrete sql counterparts for the given connection.

     *

     * @param string $expr The expression to parse

     * @return string

     */

    public function parseExpression($expr)

    {

        $pos  = strpos($expr, '(');

        $quoted = (substr($expr, 0, 1) === "'" && substr($expr, -1) === "'");

        if ($pos === false || $quoted) {

            return $expr;

        }

        // get the name of the function

        $name   = substr($expr, 0, $pos);

        $argStr = substr($expr, ($pos + 1), -1);

        // parse args

        foreach ($this->_tokenizer->bracketExplode($argStr, ',') as $arg) {

           $args[] = $this->parseClause($arg);

        }

        return call_user_func_array(array($this->getConnection()->expression, $name), $args);

    }

    /**

     * Parses a set of expressions at once.

     * @see parseExpression()

     *

     * @param string $clause    The clause. Can be complex and parenthesised.

     * @return string           The parsed clause.

     */

    public function parseClause($clause)

    {

        $e = $this->_tokenizer->bracketExplode($clause, ' ');

        foreach ($e as $k => $expr) {

            $e[$k] = $this->parseExpression($expr);

        }

        return implode(' ', $e);

    }

    /**

     * Gets the sql fragment represented.

     *

     * @return string

     */

    public function getSql()

    {

        return $this->_expression;

    }

    /**

     * Magic method.

     *

     * Returns a string representation of this object. Proxies to @see getSql().

     *

     * @return string

     */

    public function __toString()

    {

        return $this->getSql();

    }

}