tuples.h

/**
 * Unpack-able variadic tuples in C++. You can use these classes to conviniently unpack
 * tuple contents as an lvalue using the `unpack` function.
 * 
 * Example:
 *   tuple<int, double, int> t(1, 5.0, 3);
 *   int x_1; double x_2; int x_3;
 *   unpack(x_1, x_2, x_3) = t;
 */

namespace tuples {

	template<typename... Types>
	class tuple;

	template<>
	class tuple < > {
	};

	template<typename First, typename... Rest>
	class tuple < First, Rest... > {
	public:
		tuple(const First& first, const Rest&... rest)
			: _item(first)
			, _rest(rest...) { }

		const First _item;
		const tuple<Rest...> _rest;
	};

	template<typename... Types>
	class tuple_lvalue;

	template<>
	class tuple_lvalue < > {
	public:
		tuple_lvalue& operator=(const tuple<>& assign) {
			return *this;
		}
	};

	template < typename First, typename... Rest >
	class tuple_lvalue < First, Rest... > {
	public:
		tuple_lvalue<First, Rest...>(First& first, Rest&... rest)
			: _item(first)
			, _rest(rest...) { }

		tuple_lvalue& operator=(const tuple<First, Rest...>& assign) {
			_item = assign._item;
			_rest = assign._rest;
			return *this;
		}

		First& _item;
		tuple_lvalue<Rest...> _rest;
	};

	template<typename... Some>
	tuple_lvalue<Some...> unpack(Some&... x) {
		return tuple_lvalue<Some...>(x...);
	}

}