xn65/inc/helpers.hpp

#ifndef XNA_HELPERS_HPP
#define XNA_HELPERS_HPP

#include <string>
#include <utility>
#include <stdexcept>

namespace xna {
	struct XnaHelper {
		template<typename T> struct is_shared_ptr : std::false_type {};
		template<typename T> struct is_shared_ptr<std::shared_ptr<T>> : std::true_type {};

		static inline std::wstring ToWString(const std::string& str)
		{
			std::wstring wstr;
			size_t size;
			wstr.resize(str.length());
			mbstowcs_s(&size, &wstr[0], wstr.size() + 1, str.c_str(), str.size());
			return wstr;
		}

		static inline std::string ToString(const std::wstring& wstr)
		{
			std::string str;
			size_t size;
			str.resize(wstr.length());
			wcstombs_s(&size, &str[0], str.size() + 1, wstr.c_str(), wstr.size());
			return str;
		}

		template <class T>
		static constexpr void HashCombine(std::size_t& seed, const T& v) {
			std::hash<T> hasher;
			seed ^= hasher(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
		}		

		template<typename T>
		static inline auto ReturnDefaultOrNull() {
			if constexpr (is_shared_ptr<T>::value)
				return (T)nullptr;
			else if (std::is_default_constructible<T>::value)
				return T();
			else
				throw std::runtime_error("Unable to build object");
		}
	};		
}

#endif