Tuples.h

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/** @noop License Comment
 *  @file
 *  @copyright
 *  This Source Code is subject to the terms of the Mozilla Public License, v2.0.
 *  If a copy of the MPL was not distributed with this file You can obtain one at
 *  https://mozilla.org/MPL/2.0/
 *  
 *  @author David Mórász
 *  @date 2025
 */
 
#pragma once
 
#include "CoreMinimal.h"
 
/** Templating utilities for manipulating `TTuple`s */
namespace Mcro::Tuples
{
    /** Compose one tuple out of the elements of another tuple based on the input index parameter pack */
    template <typename Tuple, size_t... Indices>
    using TComposeFrom = TTuple<typename TTupleElement<Indices, Tuple>::Type...>;
 
    /** @copydoc TSkip */
    template <size_t Count, typename Tuple>
    requires (TTupleArity<Tuple>::Value >= Count)
    struct TSkip_Struct
    {
        template <size_t... Indices>
        static consteval TComposeFrom<Tuple, (Indices + Count)...> Compose(std::index_sequence<Indices...>&&);
 
        using Type = decltype(
            Compose(std::make_index_sequence<TTupleArity<Tuple>::Value - Count>{})
        );
    };
 
    /** Skip the first `Count` elements of the input tuple */
    template <size_t Count, typename Tuple>
    using TSkip = typename TSkip_Struct<Count, Tuple>::Type;
 
    /** @copydoc TTrimEnd */
    template <size_t Count, typename Tuple>
    requires (TTupleArity<Tuple>::Value >= Count)
    struct TTrimEnd_Struct
    {
        template <size_t... Indices>
        static consteval TComposeFrom<Tuple, Indices...> Compose(std::index_sequence<Indices...>&&);
 
        using Type = decltype(
            Compose(std::make_index_sequence<TTupleArity<Tuple>::Value - Count>{})
        );
    };
 
    /** Disregard the last `Count` elements of the input tuple */
    template <size_t Count, typename Tuple>
    using TTrimEnd = typename TTrimEnd_Struct<Count, Tuple>::Type;
 
    /** @copydoc TTake */
    template <size_t Count, typename Tuple>
    requires (TTupleArity<Tuple>::Value >= Count)
    struct TTake_Struct
    {
        template <size_t... Indices>
        static consteval TComposeFrom<Tuple, Indices...> Compose(std::index_sequence<Indices...>&&);
 
        using Type = decltype(
            Compose(std::make_index_sequence<Count>{})
        );
    };
 
    /** Take only the first `Count` elements of the input tuple */
    template <size_t Count, typename Tuple>
    using TTake = typename TTake_Struct<Count, Tuple>::Type;
}