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index_range のオーダーを N(logN) に再実装

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bolero-MURAKAMI 2012-02-28 14:40:02 +09:00
parent d5dcbaf4b2
commit 8ad87d104d
1 changed files with 97 additions and 31 deletions
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110
sprout/index_tuple.hpp
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@ -2,6 +2,7 @@
#define SPROUT_INDEX_TUPLE_HPP
#include <cstddef>
#include <type_traits>
#include <sprout/config.hpp>
namespace sprout {
@ -19,45 +20,110 @@ namespace sprout {
//
// index_range
//
template<
sprout::index_t First,
sprout::index_t Last,
sprout::index_t Step = 1,
typename Acc = sprout::index_tuple<>,
bool Break = (First >= Last)
>
struct index_range {
typedef Acc type;
namespace detail {
template<typename IndexTuple, sprout::index_t Next>
struct index_range_next;
template<sprout::index_t... Indexes, sprout::index_t Next>
struct index_range_next<sprout::index_tuple<Indexes...>, Next> {
public:
typedef sprout::index_tuple<Indexes..., (Indexes + Next)...> type;
};
template<
sprout::index_t First,
sprout::index_t Last,
sprout::index_t Step,
sprout::index_t... Indexes
template<typename IndexTuple, sprout::index_t Next, sprout::index_t Tail>
struct index_range_next2;
template<sprout::index_t... Indexes, sprout::index_t Next, sprout::index_t Tail>
struct index_range_next2<sprout::index_tuple<Indexes...>, Next, Tail> {
public:
typedef sprout::index_tuple<Indexes..., (Indexes + Next)..., Tail> type;
};
template<sprout::index_t First, sprout::index_t Step, std::size_t N, typename Enable = void>
struct index_range_impl;
template<sprout::index_t First, sprout::index_t Step, std::size_t N>
struct index_range_impl<
First,
Step,
N,
typename std::enable_if<(N == 0)>::type
> {
public:
typedef sprout::index_tuple<> type;
};
template<sprout::index_t First, sprout::index_t Step, std::size_t N>
struct index_range_impl<
First,
Step,
N,
typename std::enable_if<(N == 1)>::type
> {
public:
typedef sprout::index_tuple<First> type;
};
template<sprout::index_t First, sprout::index_t Step, std::size_t N>
struct index_range_impl<
First,
Step,
N,
typename std::enable_if<(N > 1 && N % 2 == 0)>::type
>
: public sprout::detail::index_range_next<
typename sprout::detail::index_range_impl<First, Step, N / 2>::type,
First + N / 2 * Step
>
{};
template<sprout::index_t First, sprout::index_t Step, std::size_t N>
struct index_range_impl<
First,
Step,
N,
typename std::enable_if<(N > 1 && N % 2 == 1)>::type
>
: public sprout::detail::index_range_next2<
typename sprout::detail::index_range_impl<First, Step, N / 2>::type,
First + N / 2 * Step,
First + (N - 1) * Step
>
{};
} // namespace detail
template<sprout::index_t First, sprout::index_t Last, sprout::index_t Step = 1>
struct index_range
: public sprout::detail::index_range_impl<
First,
Step,
((Last - First) + (Step - 1)) / Step
>
struct index_range<First, Last, Step, sprout::index_tuple<Indexes...>, false>
: public sprout::index_range<First + Step, Last, Step, sprout::index_tuple<Indexes..., First> >
{};
//
// index_n
//
namespace detail {
template<
sprout::index_t I,
sprout::index_t N,
typename Acc = sprout::index_tuple<>,
std::size_t N,
typename Acc,
bool Break = (N == 0)
>
struct index_n {
struct index_n_impl {
public:
typedef Acc type;
};
template<
sprout::index_t I,
sprout::index_t N,
std::size_t N,
sprout::index_t... Indexes
>
struct index_n<I, N, sprout::index_tuple<Indexes...>, false>
: public sprout::index_n<I, N - 1, sprout::index_tuple<Indexes..., I> >
struct index_n_impl<I, N, sprout::index_tuple<Indexes...>, false>
: public sprout::detail::index_n_impl<I, N - 1, sprout::index_tuple<Indexes..., I> >
{};
} // namespace detail
template<
sprout::index_t I,
std::size_t N,
typename Acc = sprout::index_tuple<>
>
struct index_n
: public sprout::detail::index_n_impl<I, N, Acc>
{};
} // namespace sprout