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<?php
/*
* $Id: Expression.php 10831 2013-05-29 19:32:17Z btowles $
*
* 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();
}
}