xlayout.hpp

/***************************************************************************
 * Copyright (c) Johan Mabille, Sylvain Corlay and Wolf Vollprecht          *
 * Copyright (c) QuantStack                                                 *
 *                                                                          *
 * Distributed under the terms of the BSD 3-Clause License.                 *
 *                                                                          *
 * The full license is in the file LICENSE, distributed with this software. *
 ****************************************************************************/
 
#ifndef XTENSOR_LAYOUT_HPP
#define XTENSOR_LAYOUT_HPP
 
#include <type_traits>
 
// Do not include anything else here.
// xlayout.hpp is included in xtensor_forward.hpp
// and we don't want to bring other headers to it.
#include "../core/xtensor_config.hpp"
 
namespace xt
{
    enum class layout_type
    {
        dynamic = 0x00,
        any = 0xFF,
        row_major = 0x01,
        column_major = 0x02
    };

    template <class... Args>
    constexpr layout_type compute_layout(Args... args) noexcept;
 
    constexpr layout_type default_assignable_layout(layout_type l) noexcept;
 
    constexpr layout_type layout_remove_any(const layout_type layout) noexcept;
 
    /******************
     * Implementation *
     ******************/
 
    namespace detail
    {
        constexpr layout_type compute_layout_impl() noexcept
        {
            return layout_type::any;
        }
 
        constexpr layout_type compute_layout_impl(layout_type l) noexcept
        {
            return l;
        }
 
        constexpr layout_type compute_layout_impl(layout_type lhs, layout_type rhs) noexcept
        {
            using type = std::underlying_type_t<layout_type>;
            return layout_type(static_cast<type>(lhs) & static_cast<type>(rhs));
        }
 
        template <class... Args>
        constexpr layout_type compute_layout_impl(layout_type lhs, Args... args) noexcept
        {
            return compute_layout_impl(lhs, compute_layout_impl(args...));
        }
    }
 
    template <class... Args>
    constexpr layout_type compute_layout(Args... args) noexcept
    {
        return detail::compute_layout_impl(args...);
    }
 
    constexpr layout_type default_assignable_layout(layout_type l) noexcept
    {
        return (l == layout_type::row_major || l == layout_type::column_major) ? l : XTENSOR_DEFAULT_LAYOUT;
    }
 
    constexpr layout_type layout_remove_any(const layout_type layout) noexcept
    {
        return layout == layout_type::any ? XTENSOR_DEFAULT_LAYOUT : layout;
    }
}
 
#endif