Method ZRank

structure/zset.go:669–685

* ZRank is a method belonging to the ZSetStructure type. This method retrieves the rank of an element within a sorted set identified by a key. The rank is an integer corresponding to the element's 0-based position in the sorted set when it is arranged in ascending order. Parameters: key (string): T

(key string, member string)

fmt.Printf("The rank of '%s' in the set '%s' is %d\n", "memberName", "myKey", rank)
*/
func (zs *ZSetStructure) ZRank(key string, member string) (int, error) {
	if err := checkKey(key); err != nil {
		return 0, err
	}
	keyBytes := stringToBytesWithKey(key)

	zSet, err := zs.getZSetFromDB(keyBytes)
	if err != nil {
		return 0, fmt.Errorf("failed to get or create ZSet from DB with key '%v': %w", key, err)
	}
	if v, ok := zSet.dict[member]; ok {
		return zSet.skipList.getRank(v.score, member), nil
	}

	// rank zero means no rank found
	return 0, _const.ErrKeyNotFound
}

// ZRevRank calculates the reverse rank of a member in a ZSet (Sorted Set) associated with a given key.
// ZSet exploits the Sorted Set data structure of Redis with O(log(N)) time complexity for Fetching the rank.