makeContainer.h

/*  This file is part of the Vc library. {{{
Copyright © 2013-2015 Matthias Kretz <kretz@kde.org>

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      documentation and/or other materials provided with the distribution.
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      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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}}}*/

#ifndef VC_COMMON_MAKECONTAINER_H_
#define VC_COMMON_MAKECONTAINER_H_

#include "../vector.h"
#include <initializer_list>

namespace Vc_VERSIONED_NAMESPACE
{

    namespace
    {
        template<typename Container, typename T> struct make_container_helper
        {
            static constexpr Container help(std::initializer_list<T> list) { return { list }; }
        };

        template <typename T_, typename Abi, typename Alloc,
                  template <class, class> class Container>
        struct make_container_helper<Container<Vector<T_, Abi>, Alloc>,
                                     typename Vector<T_, Abi>::EntryType> {
            typedef Vector<T_, Abi> V;
            typedef typename V::EntryType T;
            typedef Container<V, Alloc> C;
            static inline C help(std::initializer_list<T> list) {
                const std::size_t size = (list.size() + (V::Size - 1)) / V::Size;
                C v(size);
                auto containerIt = v.begin();
                auto init = std::begin(list);
                const auto initEnd = std::end(list);
                for (std::size_t i = 0; i < size - 1; ++i) {
                    *containerIt++ = V(init, Vc::Unaligned);
                    init += V::Size;
                }
                Vc_ASSERT(all_of(*containerIt == V::Zero()));
                int j = 0;
                while (init != initEnd) {
                    (*containerIt)[j++] = *init++;
                }
                return v;
            }
        };

        template <typename T_, typename Abi, std::size_t N,
                  template <class, std::size_t> class Container>
        struct make_container_helper<Container<Vector<T_, Abi>, N>,
                                     typename Vector<T_, Abi>::EntryType> {
            typedef Vector<T_, Abi> V;
            typedef typename V::EntryType T;
            static constexpr std::size_t size = (N + (V::Size - 1)) / V::Size;
            typedef Container<
                V,
#if defined Vc_CLANG && Vc_CLANG < 0x30700 // TODO: when did Vc_APPLECLANG fix it?
                // clang before 3.7.0 has a bug when returning std::array<__m256x, 1>. So
                // increase it to std::array<__m256x, 2> and fill it with zeros. Better
                // than returning garbage.
                (size == 1 && std::is_same<Abi, VectorAbi::Avx>::value) ? 2 :
#endif
                                                                        size> C;
            static inline C help(std::initializer_list<T> list) {
                Vc_ASSERT(N == list.size())
                Vc_ASSERT(size == (list.size() + (V::Size - 1)) / V::Size)
                C v;
                auto containerIt = v.begin();
                auto init = std::begin(list);
                const auto initEnd = std::end(list);
                for (std::size_t i = 0; i < size - 1; ++i) {
                    *containerIt++ = V(init, Vc::Unaligned);
                    init += V::Size;
                }
                Vc_ASSERT(all_of(*containerIt == V::Zero()));
                int j = 0;
                while (init != initEnd) {
                    (*containerIt)[j++] = *init++;
                }
                return v;
            }
        };
    } // anonymous namespace

    template<typename Container, typename T>
    constexpr auto makeContainer(std::initializer_list<T> list) -> decltype(make_container_helper<Container, T>::help(list))
    {
        return make_container_helper<Container, T>::help(list);
    }

    template<typename Container, typename T>
    constexpr auto make_container(std::initializer_list<T> list) -> decltype(makeContainer<Container, T>(list))
    {
        return makeContainer<Container, T>(list);
    }

}  // namespace Vc

#endif // VC_COMMON_MAKECONTAINER_H_