IDFactory.h

#ifndef NTA_IDFACTORY_H_INCLUDED
#define NTA_IDFACTORY_H_INCLUDED
 
#define NTA_INVALID_ID 0
 
#include <vector>
 
#include "nta/MyEngine.h"
 
namespace nta {
    namespace utils {
        template<typename T>
        class IDFactory {
        private:
            std::vector<T> m_free;
            T m_last_id;
        public:
            IDFactory() : m_last_id(NTA_INVALID_ID) {}
            void clear() { m_free.clear(); m_last_id = NTA_INVALID_ID; }
            void reset() { clear(); }
 
            T gen_id();
            void free_id(T id);
            void free(T id) { free_id(id); }
            bool is_free(T id) const;
            bool is_in_use(T id) const { return id != NTA_INVALID_ID && !is_free(id); }
 
            std::size_t get_count() const { return (std::size_t)m_last_id - m_free.size() - NTA_INVALID_ID; }
            T get_last_id() const { return m_last_id; }
 
            T operator()() { return gen_id(); }
        };
        template<typename T>
        T IDFactory<T>::gen_id() {
            if (m_free.empty()) {
                return ++m_last_id;
            } else {
                T ret = m_free.back();
                m_free.pop_back();
                return ret;
            }
        }
        template<typename T>
        void IDFactory<T>::free_id(T id) {
            m_free.push_back(id);
        }
        template<typename T>
        bool IDFactory<T>::is_free(T id) const {
            if (id > m_last_id) return true;
            for (const auto& id2 : m_free) {
                if (id == id2) return true;
            }
            return false;
        }
    }
}
 
#endif // NTA_IDFACTORY_H_INCLUDED