xeval.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_EVAL_HPP
#define XTENSOR_EVAL_HPP
 
#include "xexpression_traits.hpp"
#include "xshape.hpp"
#include "xtensor_forward.hpp"
 
namespace xt
{
 
    namespace detail
    {
        template <class T>
        using is_container = std::is_base_of<xcontainer<std::remove_const_t<T>>, T>;
    }
 
    template <class T>
    inline auto eval(T&& t) -> std::enable_if_t<detail::is_container<std::decay_t<T>>::value, T&&>
    {
        return std::forward<T>(t);
    }
 
    template <class T>
    inline auto eval(T&& t)
        -> std::enable_if_t<!detail::is_container<std::decay_t<T>>::value, temporary_type_t<T>>
    {
        return std::forward<T>(t);
    }
 
 
    namespace detail
    {
        /**********************************
         * has_same_layout implementation *
         **********************************/
 
        template <layout_type L = layout_type::any, class E>
        constexpr bool has_same_layout()
        {
            return (std::decay_t<E>::static_layout == L) || (L == layout_type::any);
        }
 
        template <layout_type L = layout_type::any, class E>
        constexpr bool has_same_layout(E&&)
        {
            return has_same_layout<L, E>();
        }
 
        template <class E1, class E2>
        constexpr bool has_same_layout(E1&&, E2&&)
        {
            return has_same_layout<std::decay_t<E1>::static_layout, E2>();
        }
 
        /*********************************
         * has_fixed_dims implementation *
         *********************************/
 
        template <class E>
        constexpr bool has_fixed_dims()
        {
            return detail::is_array<typename std::decay_t<E>::shape_type>::value;
        }
 
        template <class E>
        constexpr bool has_fixed_dims(E&&)
        {
            return has_fixed_dims<E>();
        }
 
        /****************************************
         * as_xarray_container_t implementation *
         ****************************************/
 
        template <class E, layout_type L>
        using as_xarray_container_t = xarray<typename std::decay_t<E>::value_type, layout_remove_any(L)>;
 
        /*****************************************
         * as_xtensor_container_t implementation *
         *****************************************/
 
        template <class E, layout_type L>
        using as_xtensor_container_t = xtensor<
            typename std::decay_t<E>::value_type,
            std::tuple_size<typename std::decay_t<E>::shape_type>::value,
            layout_remove_any(L)>;
    }
 
    template <layout_type L = layout_type::any, class E>
    inline auto as_strided(E&& e)
        -> std::enable_if_t<has_data_interface<std::decay_t<E>>::value && detail::has_same_layout<L, E>(), E&&>
    {
        return std::forward<E>(e);
    }
 
    template <layout_type L = layout_type::any, class E>
    inline auto as_strided(E&& e) -> std::enable_if_t<
        (!(has_data_interface<std::decay_t<E>>::value && detail::has_same_layout<L, E>()))
            && detail::has_fixed_dims<E>(),
        detail::as_xtensor_container_t<E, L>>
    {
        return e;
    }
 
    template <layout_type L = layout_type::any, class E>
    inline auto as_strided(E&& e) -> std::enable_if_t<
        (!(has_data_interface<std::decay_t<E>>::value && detail::has_same_layout<L, E>()))
            && (!detail::has_fixed_dims<E>()),
        detail::as_xarray_container_t<E, L>>
    {
        return e;
    }
 
}
 
#endif