imstkFactory.h

/*
** This file is part of the Interactive Medical Simulation Toolkit (iMSTK)
** iMSTK is distributed under the Apache License, Version 2.0.
** See accompanying NOTICE for details.
*/

#pragma once

#include <functional>
#include <memory>
#include <string>
#include <unordered_map>
#include <vector>

namespace imstk
{
template<typename T, class ... Args>
class ObjectFactory
{
public:

    using BaseType = T;
    using Creator  = std::function<T(Args...)>; 

    static T create(const std::string& name, Args&& ... args)
    {
        // at will throw if name doesn't exist in the map
        return registry().at(name)(std::forward<Args>(args)...);
    }

    static void add(const std::string& name, Creator c)
    {
        registry()[name] = std::move(c);
    }

    static bool contains(const std::string& name)
    {
        return registry().find(name) != registry().cend();
    }

    static const std::vector<std::string> getNames()
    {
        std::vector<std::string> result;
        for (const auto& item : registry())
        {
            result.push_back(item.first);
        }
        return result;
    }

private:
    using Registry = std::unordered_map<std::string, Creator>;

    static Registry& registry()
    {
        static Registry registry = {};
        return registry;
    }
};

template<typename T, typename U, typename ... Args>
class SharedObjectRegistrar
{
public:
    SharedObjectRegistrar(std::string name)
    {
        static_assert(std::is_base_of<T, U>::value,
            "U must be a subclass of T");
        ObjectFactory<std::shared_ptr<T>, Args ...>::add(name, [](Args&& ... args) { return std::make_shared<U>(std::forward<Args>(args)...); });
    }
};
} // namespace imstk