a8/a8/commonrank.h

#ifndef A8_COMMONRANK_H
#define A8_COMONRANK_H

#include <algorithm>

namespace a8
{

    template <class T>
    class CommonRank
    {
    private:
        std::vector<T*> list_;
        std::set<T*> set_;
        std::function<bool (const T*, const T*)> cmp_func_;
        size_t max_num_ = 0;

    public:

        CommonRank() {}
        CommonRank(std::function<bool (const T*, const T*)> cmp_func, size_t max_num)
        {
            cmp_func_ = cmp_func;
            max_num_ = max_num;
        }

        size_t Size()
        {
            return list_.size();
        }

        const std::vector<T*>& GetList()
        {
            return list_;
        }

        void Sort()
        {
            std::sort(list_.begin(), list_.end(), cmp_func_);
        }

        void Update(T* val)
        {
            if (Size() < max_num_) {
                if (!Exists(val)) {
                    list_.push_back(val);
                    set_.insert(val);
                    Sort();
                }
            } else {
                if (cmp_func_(val, list_[list_.size() - 1])) {
                    if (!Exists(val)) {
                        set_.erase(list_[list_.size() - 1]);
                        list_[list_.size() - 1] = val;
                        set_.insert(val);
                        Sort();
                    }
                }
            }
        }

        bool Exists(T* val)
        {
            return set_.find(val) != set_.end();
        }

        void Remove(T* val)
        {
            if (!Exists(val)) {
                return;
            }
            {
                auto itr = std::find(list_.begin(), list_.end(), val);
                if (itr != list_.end()) {
                    list_.erase(itr);
                }
            }
            set_.erase(val);
        }

    };

    template <typename T>
    a8::CommonRank<T>& ForceCreateCommonRankList(std::map<long long, a8::CommonRank<T>>& rank_list,
                                                 long long key,
                                                 std::function<bool (const T*, const T*)> cmp_func,
                                                 size_t max_num)
    {
        auto itr = rank_list.find(key);
        if (itr != rank_list.end()) {
            return itr->second;
        }
        rank_list[key] = a8::CommonRank<T>(cmp_func, max_num);
        return rank_list[key];
    }

    template <typename T>
    static a8::CommonRank<T>& ForceCreateCommonRankList(std::map<std::string, a8::CommonRank<T>>& rank_list,
                                                        const std::string& key,
                                                        std::function<bool (const T*, const T*)> cmp_func,
                                                        size_t max_num)
    {
        auto itr = rank_list.find(key);
        if (itr != rank_list.end()) {
            return itr->second;
        }
        rank_list[key] = a8::CommonRank<T>(cmp_func, max_num);
        return rank_list[key];
    }

}

#endif