dylib.hpp

#pragma once

#if defined(_MSC_VER)
#define WIN32_LEAN_AND_MEAN
#define NOMINMAX
#include <windows.h>
#else
#include <dlfcn.h>
#endif

class DynamicLibrary
{
  public:
	DynamicLibrary() : handle(nullptr)
	{
	}

	~DynamicLibrary()
	{
		if (handle != nullptr)
		{
#if defined(_MSC_VER)
			FreeLibrary(static_cast<HINSTANCE>(handle));
#else
			dlclose(handle);
#endif
		}
	}

	bool try_load(const char *library)
	{
#if defined(_MSC_VER)
		handle = static_cast<void *>(LoadLibraryA(library));

		if (handle == nullptr)
		{
			handle = static_cast<void *>(LoadLibraryExA(library, NULL,
			                                            LOAD_LIBRARY_SEARCH_DEFAULT_DIRS |
			                                                LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR));
		}

#else
		handle = dlopen(library, RTLD_NOW);
#endif
		return handle != nullptr;
	}

	bool LibraryIsLoaded() const
	{
		return handle != nullptr;
	}

	void *get_symbol(const char *name)
	{
#if defined(_MSC_VER)
		FARPROC function_address = GetProcAddress(static_cast<HINSTANCE>(handle), name);
#else
		void *function_address = dlsym(handle, name);
#endif

		return reinterpret_cast<void *>(function_address);
	}

  private:
	void *handle = nullptr;
};

// Next we will introduce some magic macros to declare function pointers and load them from dynamic
// library robustly

#define DYLIB_EXTERN_DECLARE(f) extern decltype(&::f) f
#define DYLIB_DECLARE(f) decltype(&::f) f = nullptr

#define DYLIB_LOAD_INIT                                                   \
	ankerl::unordered_dense::map<std::string, void *> _function_pointers; \
	bool _load_success = true

#define DYLIB_LOAD_FUNCTION(f)                                        \
	{                                                                 \
		auto ptr = reinterpret_cast<decltype(f)>(lib.get_symbol(#f)); \
		if (ptr == nullptr)                                           \
		{                                                             \
			fmt::print("function {} is not loaded correctly\n", #f);  \
			_load_success = false;                                    \
		}                                                             \
		_function_pointers[#f] = reinterpret_cast<void *>(ptr);       \
	}

#define IS_DYLIB_LOAD_SUCCESS _load_success

#define DYLIB_SAVE_FUNCTION(f) f = reinterpret_cast<decltype(f)>(_function_pointers[#f])