selected_expr.hpp

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//=======================================================================
// Copyright (c) 2014-2023 Baptiste Wicht
// Distributed under the terms of the MIT License.
// (See accompanying file LICENSE or copy at
//  http://opensource.org/licenses/MIT)
//=======================================================================

#pragma once

#ifdef ETL_MANUAL_SELECT

#include "etl/wrapper_traits.hpp"

namespace etl {

template <typename Selector, Selector V, typename Expr>
struct selected_expr final {
    using expr_t     = Expr;          
    using value_type = value_t<Expr>; 

    using selector_t = Selector; 

    static constexpr selector_t selector_value = V; 

private:
    Expr value;

    friend struct wrapper_traits<selected_expr>;

public:
    //Cannot be constructed with no args
    selected_expr() = delete;

    explicit selected_expr(Expr l) : value(std::forward<Expr>(l)) {
        //Nothing else to init
    }

    //Expresison can be copied and moved
    selected_expr(const selected_expr& e)     = default;
    selected_expr(selected_expr&& e) noexcept = default;

    //Expressions are invariant
    selected_expr& operator=(const selected_expr& e) = delete;
    selected_expr& operator=(selected_expr&& e) = delete;

    template <typename E>
    bool alias(const E& other) const noexcept {
        return value.alias(other);
    }

    // Assignment functions

    template <typename L>
    void assign_to(L&& lhs) const {
        decltype(auto) forced = detail::get_forced_impl<selector_t>();

        auto old_forced = forced;

        forced.impl   = selector_value;
        forced.forced = true;

        value.assign_to(lhs);

        forced = old_forced;
    }

    template <typename L>
    void assign_add_to(L&& lhs) const {
        decltype(auto) forced = detail::get_forced_impl<selector_t>();

        auto old_forced = forced;

        forced.impl   = selector_value;
        forced.forced = true;

        value.assign_add_to(lhs);

        forced = old_forced;
    }

    template <typename L>
    void assign_sub_to(L&& lhs) const {
        decltype(auto) forced = detail::get_forced_impl<selector_t>();

        auto old_forced = forced;

        forced.impl   = selector_value;
        forced.forced = true;

        value.assign_sub_to(lhs);

        forced = old_forced;
    }

    template <typename L>
    void assign_mul_to(L&& lhs) const {
        decltype(auto) forced = detail::get_forced_impl<selector_t>();

        auto old_forced = forced;

        forced.impl   = selector_value;
        forced.forced = true;

        value.assign_mul_to(lhs);

        forced = old_forced;
    }

    template <typename L>
    void assign_div_to(L&& lhs) const {
        decltype(auto) forced = detail::get_forced_impl<selector_t>();

        auto old_forced = forced;

        forced.impl   = selector_value;
        forced.forced = true;

        value.assign_div_to(lhs);

        forced = old_forced;
    }

    template <typename L>
    void assign_mod_to(L&& lhs) const {
        decltype(auto) forced = detail::get_forced_impl<selector_t>();

        auto old_forced = forced;

        forced.impl   = selector_value;
        forced.forced = true;

        value.assign_mod_to(lhs);

        forced = old_forced;
    }

    friend std::ostream& operator<<(std::ostream& os, const selected_expr& expr) {
        return os << "selected(" << expr.value << ")";
    }
};

template <typename Selector, Selector V, typename Expr>
struct etl_traits<etl::selected_expr<Selector, V, Expr>> : wrapper_traits<etl::selected_expr<Selector, V, Expr>> {};

} //end of namespace etl

#endif