/**
* This method returns the latter value should the former value evaluates
* to null.
*
* @access public
* @static
* @param IOption\Type $xs the value to be evaluated
* @param IOption\Type $ys the default value
* @return IOption\Type the result
*/
public static function nvl(IOption\Type $xs = null, IOption\Type $ys = null) : IOption\Type
{
return $xs ?? $ys ?? IOption\Type::none();
}
/**
* This method tests the "size" method.
*/
public function test_size()
{
$p0 = IOption\Type::some(IInt32\Type::zero())->size();
$e0 = 1;
$this->assertInstanceOf('\\Saber\\Data\\IInt32\\Type', $p0);
$this->assertSame($e0, $p0->unbox());
$p1 = IOption\Type::none()->size();
$e1 = 0;
$this->assertInstanceOf('\\Saber\\Data\\IInt32\\Type', $p1);
$this->assertSame($e1, $p1->unbox());
}
/**
* This method returns an option using the tail for the boxed object.
*
* @access public
* @static
* @param IString\Type $xs the left operand
* @return IOption\Type the option
*/
public static function tailOption(IString\Type $xs) : IOption\Type
{
return $xs->__isEmpty() ? IOption\Type::none() : IOption\Type::some($xs->tail());
}
/**
* This method returns the either as an option.
*
* @access public
* @final
* @return IOption\Type the either as an option
*/
public final function toOption() : IOption\Type
{
return $this->either->__isLeft() ? IOption\Type::some($this->either->item()) : IOption\Type::none();
}
