function.hpp

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#ifndef __FUNCTION_H__
#define __FUNCTION_H__
 
#include <dlfcn.h>
#include <stdexcept>
 
namespace mxvm {
 
    template <typename Sig>
    class Function;
    template <typename R, typename... Args>
    class Function<R(Args...)> {
      public:
        using Fn = R (*)(Args...);

        Function(char const *lib, char const *name) {
            handle = dlopen(lib, RTLD_LAZY);
            if (!handle)
                throw std::runtime_error(dlerror());
            void *sym = dlsym(handle, name);
            if (!sym) {
                dlclose(handle);
                throw std::runtime_error(dlerror());
            }
            fn = reinterpret_cast<Fn>(sym);
        }

        Function(char const *name) {
            handle = dlopen(nullptr, RTLD_LAZY);
            if (!handle)
                throw std::runtime_error(dlerror());
            void *sym = dlsym(handle, name);
            if (!sym) {
                dlclose(handle);
                throw std::runtime_error(dlerror());
            }
            fn = reinterpret_cast<Fn>(sym);
        }
 
        ~Function() {
            if (handle)
                dlclose(handle);
        }
 
        Function(const Function &) = delete;
        Function &operator=(const Function &) = delete;
 
        Function(Function &&other) noexcept : handle(other.handle), fn(other.fn) {
            other.handle = nullptr;
            other.fn = nullptr;
        }
        Function &operator=(Function &&other) noexcept {
            if (this != &other) {
                if (handle)
                    dlclose(handle);
                handle = other.handle;
                fn = other.fn;
                other.handle = nullptr;
                other.fn = nullptr;
            }
            return *this;
        }

        R operator()(Args... args) const {
            if (!fn)
                throw std::runtime_error("Null function pointer");
            return fn(std::forward<Args>(args)...);
        }
 
      private:
        void *handle = nullptr;  
        Fn fn = nullptr;         
    };
 
} // namespace mxvm
 
#endif