Method RPop

structure/list.go:195–222

RPop returns and removes the rightmost value of a list associated with a key. If the key does not exist, an error is returned. If the list is empty, an error is returned.

(key string)

// If the key does not exist, an error is returned.
// If the list is empty, an error is returned.
func (l *ListStructure) RPop(key string) (interface{}, error) {
	// Get the list
	lst, _, err := l.getListFromDB(key, false)
	if err != nil {
		return nil, err
	}
	// Return error if the list is empty
	if lst.Length == 0 {
		return nil, ErrListEmpty
	} else if lst.Length == 1 {
		popValue := lst.Head.Value
		lst.Head = nil
		lst.Length = 0
		return popValue, l.setListToDB(key, lst, 0)
	}

	// Find the new tail
	newTail := lst.Head
	for i := 0; i < lst.Length-2; i++ {
		newTail = newTail.Next
	}
	popValue := newTail.Next.Value
	newTail.Next = nil
	lst.Length--

	// Store in the database
	return popValue, l.setListToDB(key, lst, 0)
}

// LRange returns a range of elements from a list associated with a key.
// The range is inclusive, including both the start and stop indices.