###Redis SortedSet for C++
Redis's SortedSet is POWERFUL tool, an awesome Data-Structure to organizing data for sorting, hashing and ranking. See Redis SortedSet.
With the C++ client of redis, C++ programers can use its power easily.
Can we achieve these ranking features without Redis?
The answer is YES! One easiest way is combining STL's <map> and <unordered_map>, then creates your "Sorted Set", which can get values by O(1) complexity, and get ranks by O(log(N)).
However, redis use skiplist, which has a better performance than STL's red-black tree. So I have ported the redis sortedset source code into a stand alone C++ template, for any feature use.
####HOW TO USE: The score type is always DOUBLE, so you only need to indicate a key type. All APIs has a very similar interfaces with origin Redis commands, you can refer to the C++ header and the Redis command documents for quick startup. Refer Redis SortedSet Commands.
Examples:
SortedSet<int> sortedSet;
sortedSet.zadd(1, 300);
sortedSet.zadd(2, 299.9);
sortedSet.zadd(3, 100000);
std::vector< std::pair<int, double> > result;
sortedSet.zrange_withscores(0, -1, result);
std::for_each(result.begin(), result.end(), echo_ranking);
sortedSet.zrem(3);
sortedSet.zincrby(3, 100);
sortedSet.zrank(3);
####NOTE:
I implement it with STL's <unordered_map>, which is included in "std::tr1" namespace in older compilers. If you use gcc/g++ compilers, there is no worry for you, otherwise you may have to fix the namespace problem and define your one to "HASHSCOPE". Like this:
#define HASHSCOPE std or #define HASHSCOPE std::tr1