/**
* This method returns the collection as a linked list.
*
* @access public
* @static
* @param IString\Type $xs the operand
* @return ILinkedList\Type the collection as a linked list
*/
public static function toLinkedList(IString\Type $xs) : ILinkedList\Type
{
$length = $xs->length();
$zs = ILinkedList\Type::nil();
for ($i = IInt32\Module::decrement($length); IInt32\Module::ge($i, IInt32\Type::zero())->unbox(); $i = IInt32\Module::decrement($i)) {
$zs = ILinkedList\Type::cons($xs->item($i), $zs);
}
return $zs;
}
/**
* This method computes the nth fibonacci number.
*
* @access public
* @static
* @param IInt32\Type $n the operand
* @return IInt32\Type the result
*/
public static function fibonacci(IInt32\Type $n) : IInt32\Type
{
return IInt32\Module::le($n, IInt32\Type::one())->unbox() ? $n : IInt32\Module::add(IInt32\Module::fibonacci(IInt32\Module::decrement($n)), IInt32\Module::fibonacci(IInt32\Module::subtract($n, IInt32\Type::box(2))));
}
/**
* This method creates a list of "n" length with every item set to the given object.
*
* @access public
* @static
* @param Core\Type $x the object to be replicated
* @param IInt32\Type $n the number of times to replicate
* @return ILinkedList\Type the collection
*/
public static function replicate(Core\Type $x, IInt32\Type $n) : ILinkedList\Type
{
if ($n->unbox() <= 0) {
return ILinkedList\Type::nil();
}
return ILinkedList\Type::cons($x, ILinkedList\Type::replicate($x, IInt32\Module::decrement($n)));
}
/**
* This method tests the "decrement" method.
*
* @dataProvider data_decrement
*/
public function test_decrement(array $provided, array $expected)
{
$p0 = IInt32\Module::decrement(IInt32\Type::box($provided[0]));
$e0 = $expected[0];
$this->assertInstanceOf('\\Saber\\Data\\IInt32\\Type', $p0);
$this->assertEquals($e0, $p0->unbox());
}
/**
* This method returns the last item in this list.
*
* @access public
* @static
* @param IArrayList\Type $xs the left operand
* @return mixed the last item in this linked
* list
*/
public static function last(IArrayList\Type $xs)
{
return $xs->item(IInt32\Module::decrement($xs->length()));
}
/**
* This method returns the first "n" items in the list.
*
* @access public
* @static
* @param ILinkedList\Type $xs the left operand
* @param IInt32\Type $n the number of items to take
* @return ILinkedList\Type the list
*/
public static function take(ILinkedList\Type $xs, IInt32\Type $n) : ILinkedList\Type
{
if ($n->unbox() <= 0 || $xs->__isEmpty()) {
return ILinkedList\Type::nil();
}
return ILinkedList\Type::cons($xs->head(), ILinkedList\Module::take($xs->tail(), IInt32\Module::decrement($n)));
}
