uidDispenser.h

#pragma once
 
#include <utility>
 
namespace TuringSim::Utils {
    template<typename UID>
    class UidDispenser {
    public:
        typedef UID UIDType;
        static_assert(std::is_default_constructible_v<UID>);
 
        UidDispenser() {}
 
        UidDispenser(const UidDispenser& other) : uid(other.uid) {}
 
        UidDispenser(UidDispenser&& other) : uid(std::move(other.uid)) {}
 
        UidDispenser& operator=(const UidDispenser& other) {
            if(this != &other) {
                uid = other.uid;
            }
            return *this;
        }
        UidDispenser& operator=(UidDispenser&& other) {
            if(this != &other) {
                uid = std::move(other.uid);
            }
            return *this;
        }
 
        UID operator()() {
            return uid++;
        }
 
    private:
        UID uid {};
    };
 
    template<typename Tag, typename UID>
    class UidDispenser<std::pair<Tag, UID>> {
    public:
        typedef std::pair<Tag, UID> UIDType;
        static_assert(std::is_default_constructible_v<UID>);
 
        UidDispenser(const Tag& tag) : tag(tag) {}
 
        UidDispenser(const UidDispenser& other) : tag(other.tag), uid(other.uid) {}
 
        UidDispenser(UidDispenser&& other) : tag(std::move(other.tag)), uid(std::move(other.uid)) {}
 
        UidDispenser& operator=(const UidDispenser& other) {
            if(this != &other) {
                tag = other.tag;
                uid = other.uid;
            }
            return *this;
        }
 
        UidDispenser& operator=(UidDispenser&& other) {
            if(this != &other) {
                tag = std::move(other.tag);
                uid = std::move(other.uid);
            }
            return *this;
        }
 
        UIDType operator()() {
            return std::make_pair(tag, uid++);
        }
 
    private:
        Tag tag;
        UID uid {};
    };
 
    template<typename Tag, typename UID>
    class TaggedUidDispenserFactory {
    public:
        typedef std::pair<Tag, UID> UIDType;
        static_assert(std::is_default_constructible_v<UID>);
 
        UidDispenser<UIDType> operator()() {
            return UidDispenser<UIDType>{tag++};
        }
    private:
        Tag tag {};
    };
}