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https://github.com/bolero-MURAKAMI/Sprout.git
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100 lines
3.7 KiB
C++
100 lines
3.7 KiB
C++
#ifndef SPROUT_INDEX_TUPLE_INTEGER_RANGE_HPP
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#define SPROUT_INDEX_TUPLE_INTEGER_RANGE_HPP
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/index_tuple/integer_seq.hpp>
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#include <sprout/index_tuple/detail/make_indexes_helper.hpp>
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namespace sprout {
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namespace detail {
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template<typename T, T First, T Last>
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struct integer_range_default_step
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: public std::integral_constant<typename std::make_signed<T>::type, (First <= Last ? 1 : -1)>
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{};
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} // namespace detail
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namespace detail {
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template<typename T, typename Seq, T Next>
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struct integer_range_next_even;
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template<typename T, T... Is, T Next>
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struct integer_range_next_even<T, sprout::integer_seq<T, Is...>, Next>
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: public sprout::integer_seq<T, Is..., (Is + Next)...>
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{};
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template<typename T, typename Seq, T Next, T Tail>
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struct integer_range_next_odd;
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template<typename T, T... Is, T Next, T Tail>
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struct integer_range_next_odd<T, sprout::integer_seq<T, Is...>, Next, Tail>
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: public sprout::integer_seq<T, Is..., (Is + Next)..., Tail>
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{};
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template<typename T, T First, typename std::make_signed<T>::type Step, typename std::make_unsigned<T>::type N, typename Enable = void>
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struct integer_range_impl;
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template<typename T, T First, typename std::make_signed<T>::type Step, typename std::make_unsigned<T>::type N>
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struct integer_range_impl<
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T, First, Step, N,
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typename std::enable_if<(N == 0)>::type
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>
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: public sprout::integer_seq<T>
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{};
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template<typename T, T First, typename std::make_signed<T>::type Step, typename std::make_unsigned<T>::type N>
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struct integer_range_impl<
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T, First, Step, N,
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typename std::enable_if<(N == 1)>::type
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>
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: public sprout::integer_seq<T, First>
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{};
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template<typename T, T First, typename std::make_signed<T>::type Step, typename std::make_unsigned<T>::type N>
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struct integer_range_impl<
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T, First, Step, N,
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typename std::enable_if<(N > 1 && N % 2 == 0)>::type
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>
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: public sprout::detail::integer_range_next_even<
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T, typename sprout::detail::integer_range_impl<T, First, Step, N / 2>::type,
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N / 2 * Step
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>
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{};
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template<typename T, T First, typename std::make_signed<T>::type Step, typename std::make_unsigned<T>::type N>
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struct integer_range_impl<
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T, First, Step, N,
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typename std::enable_if<(N > 1 && N % 2 == 1)>::type
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>
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: public sprout::detail::integer_range_next_odd<
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T, typename sprout::detail::integer_range_impl<T, First, Step, N / 2>::type,
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N / 2 * Step, First + (N - 1) * Step
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>
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{};
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template<typename T, T First, T Last, typename std::make_signed<T>::type Step, typename Enable = void>
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struct integer_range {};
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template<typename T, T First, T Last, typename std::make_signed<T>::type Step>
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struct integer_range<
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T, First, Last, Step,
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typename std::enable_if<((First < Last && Step > 0) || (First > Last && Step < 0) || (First == Last))>::type
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>
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: public sprout::detail::integer_range_impl<
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T, First, Step,
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(static_cast<typename std::make_signed<T>::type>(Last - First) + (Step > 0 ? Step - 1 : Step + 1)) / Step
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>
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{};
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} // namespace detail
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//
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// integer_range
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//
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template<
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typename T, T First, T Last,
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typename std::make_signed<T>::type Step = sprout::detail::integer_range_default_step<T, First, Last>::value
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>
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struct integer_range
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: public sprout::detail::make_indexes_helper<
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sprout::detail::integer_range<T, First, Last, Step>
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>
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{
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static_assert(
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(First < Last && Step > 0) || (First > Last && Step < 0) || (First == Last),
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"(First < Last && Step > 0) || (First > Last && Step < 0) || (First == Last)"
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);
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};
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} // namespace sprout
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#endif // #ifndef SPROUT_INDEX_TUPLE_INTEGER_RANGE_HPP
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