Method delete

structure/zset.go:299–328

SkipList is a data structure that allows fast search, insertion, and removal operations. Here we define a method delete on it. The delete method in the skip list will remove nodes that have a given score and key from the skip list. If no such nodes are found, the function does nothing. Parameters:

(score int, member string)

//	score: the score of the node to delete.
//	key: the key of the node to delete.
func (sl *SkipList) delete(score int, member string) {

	// update: an array of pointers to SkipListNodes; holds the nodes that will have their next pointers updated.
	update := make([]*SkipListNode, SKIPLIST_MAX_LEVEL)

	// node: start from the head of our SkipList sl
	node := sl.head

	// The code block of "for" loop populates the "update" variable with nodes which reference will change
	// due to the removal of the target node.
	for i := sl.level; i >= 0; i-- {
		// This loop is traversing the SkipList horizontally until it finds a node with a score greater
		// than or equal to our target score or if the scores are equal it also checks the member.
		for node.level[i].next != nil &&
			(node.level[i].next.value.score < score ||
				(node.level[i].next.value.score == score &&
					node.level[i].next.value.member < member)) {
			node = node.level[i].next
		}
		update[i] = node
	}

	// After the traversal, we set the node to point to the possibly (to be) deleted node.
	node = node.level[0].next

	// If the possibly deleted node is the target node (it has the same score and member), then remove it.
	if node != nil && node.value.score == score && node.value.member == member {
		sl.deleteNode(node, update)
	}
}
func (sl *SkipList) getRange(start int, end int, reverse bool) (nv []ZSetValue) {
	if end > sl.size {
		end = sl.size - 1