/**
* Construct expression
*
* @param string $expression Expression to create
* @param string $defaultName Default name in expression
* @param bool $descending Descending order?
* @param string $comparer Comparer function
*/
public function __construct($expression, $defaultName = '', $descending = false, $comparer = null)
{
// Default name
$this->_defaultName = $defaultName;
// Internal expression
$this->_expression = new PHPLinq_Expression($expression, $defaultName);
// Comparer function set?
if (is_null($comparer)) {
$comparer = 'strcmp';
}
// Descending?
if ($descending) {
$comparer = '-1 * ' . $comparer;
}
$this->_descending = $descending;
// Compile comparer function
// Check http://www.php.net/manual/nl/function.create-function.php#14322 for this chr(0).'$f' approach...
$f = substr($this->_expression->getFunctionReference(), 1);
$this->_functionReference = new PHPLinq_Function($defaultName . 'A, ' . $defaultName . 'B', "return {$comparer}(\n\t\t\t\t\tcall_user_func(chr(0).'{$f}', {$defaultName}A),\n\t\t\t\t\tcall_user_func(chr(0).'{$f}', {$defaultName}B)\n\t\t\t\t);");
}
