SqlExpression::compile

public function compile()
{
	$this->i = -1;

	if (strpos($this->expression, '\') === false)
	{
		// regular case
		return preg_replace_callback($this->pattern, array($this, 'execPlaceholders'), $this->expression);
	}
	else
	{
		// handle escaping  and \
		$parts = explode('\\', $this->expression);

		foreach ($parts as &$part)
		{
			if (!empty($part))
			{
				$part = preg_replace_callback($this->pattern, array($this, 'execPlaceholders'), $part);
			}
		}

		$parts = str_replace('\?', '?', $parts);

		return implode('\\', $parts);
	}
}