Sprout/sprout/index_tuple/integer_range.hpp

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2013-03-31 04:39:26 +00:00
#ifndef SPROUT_INDEX_TUPLE_INTEGER_RANGE_HPP
#define SPROUT_INDEX_TUPLE_INTEGER_RANGE_HPP
#include <cstddef>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/index_tuple/integer_seq.hpp>
#include <sprout/index_tuple/detail/make_indexes_helper.hpp>
namespace sprout {
//
// integer_range
//
namespace detail {
template<typename T, typename Seq, T Next>
struct integer_range_next_even;
template<typename T, T... Is, T Next>
struct integer_range_next_even<T, sprout::integer_seq<T, Is...>, Next>
: public sprout::integer_seq<T, Is..., (Is + Next)...>
{};
template<typename T, typename Seq, T Next, T Tail>
struct integer_range_next_odd;
template<typename T, T... Is, T Next, T Tail>
struct integer_range_next_odd<T, sprout::integer_seq<T, Is...>, Next, Tail>
: public sprout::integer_seq<T, Is..., (Is + Next)..., Tail>
{};
template<typename T, T First, std::ptrdiff_t Step, std::size_t N, typename Enable = void>
struct integer_range_impl;
template<typename T, T First, std::ptrdiff_t Step, std::size_t N>
struct integer_range_impl<
T, First, Step, N,
typename std::enable_if<(N == 0)>::type
>
: public sprout::integer_seq<T>
{};
template<typename T, T First, std::ptrdiff_t Step, std::size_t N>
struct integer_range_impl<
T, First, Step, N,
typename std::enable_if<(N == 1)>::type
>
: public sprout::integer_seq<T, First>
{};
template<typename T, T First, std::ptrdiff_t Step, std::size_t N>
struct integer_range_impl<
T, First, Step, N,
typename std::enable_if<(N > 1 && N % 2 == 0)>::type
>
: public sprout::detail::integer_range_next_even<
T, typename sprout::detail::integer_range_impl<T, First, Step, N / 2>::type,
First + N / 2 * Step
>
{};
template<typename T, T First, std::ptrdiff_t Step, std::size_t N>
struct integer_range_impl<
T, First, Step, N,
typename std::enable_if<(N > 1 && N % 2 == 1)>::type
>
: public sprout::detail::integer_range_next_odd<
T, typename sprout::detail::integer_range_impl<T, First, Step, N / 2>::type,
First + N / 2 * Step, First + (N - 1) * Step
>
{};
} // namespace detail
template<typename T, T First, T Last, std::ptrdiff_t Step = 1>
struct integer_range
: public sprout::detail::make_indexes_helper<
sprout::detail::integer_range_impl<
T, First, Step, ((Last - First) + (Step - 1)) / Step
>
>
{};
} // namespace sprout
#endif // #ifndef SPROUT_INDEX_TUPLE_INTEGER_RANGE_HPP