ServiceLocator.hxx

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#ifndef _UTILS_SERVICELOCATOR_HXX_
#define _UTILS_SERVICELOCATOR_HXX_
 
#include <map>
#include <memory>
#include <string>
#include "utils/Atomic.hxx"
 
using std::shared_ptr;
using std::string;
 
template <typename ServiceType>
class RegisterableService
{
private:
    static string get_type_name(const char *alias)
    {
        string name(__PRETTY_FUNCTION__);
        if (alias != nullptr)
        {
            name += "_";
            name += alias;
        }
 
        return name;
    }
 
    template<typename LocatorType> friend class ServiceLocator;
};
 
class ServiceLocatorImpl
{
public:
    static void clear()
    {
        ServiceLocatorImpl::services.clear();
    }
 
private:
    static std::map<string, shared_ptr<void>> services;
    static Atomic lock_;
 
    static void register_service(string name, shared_ptr<void> &service)
    {
        AtomicHolder l(&ServiceLocatorImpl::lock_);
        ServiceLocatorImpl::services[name] = service;
    }
 
    static shared_ptr<void> get_service(string name)
    {
        AtomicHolder l(&ServiceLocatorImpl::lock_);
        auto it = ServiceLocatorImpl::services.find(name);
        if (it == ServiceLocatorImpl::services.end())
        {
            return nullptr;
        }
 
        return it->second;
    }
 
    template<typename ServiceType> friend class ServiceLocator;
};
 
template <typename ServiceType>
class ServiceLocator
{
public:
    static shared_ptr<ServiceType> get_service(const char *alias = nullptr)
    {
        string name = RegisterableService<ServiceType>::get_type_name(alias);
        shared_ptr<void> service = ServiceLocatorImpl::get_service(name);
        return std::static_pointer_cast<ServiceType>(service);
    }
 
    static void register_service(
        shared_ptr<ServiceType> &service, const char *alias = nullptr)
    {
        string name = RegisterableService<ServiceType>::get_type_name(alias);
        shared_ptr<void> temp(service);
        ServiceLocatorImpl::register_service(name, temp);
    }
};
 
#endif // _UTILS_SERVICELOCATOR_HXX_