InitializeOnCopy.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"
#include "Mcro/FunctionTraits.h"
 
namespace Mcro::InitializeOnCopy
{
    using namespace Mcro::FunctionTraits;
 
    /**
     *  @brief
     *  A type wrapper around a default initializeable object which may not be copyable but which needs to be a member
     *  of a copyable class. On each instance of such class the wrapped value may not need to be copied and default
     *  constructing it is enough. Useful for mutexes for example.
     */
    template <CDefaultInitializable T>
    requires (!CCopyable<T>)
    struct TInitializeOnCopy
    {
        TInitializeOnCopy() : Value() {}
        TInitializeOnCopy(TInitializeOnCopy const&) : Value() {}
        TInitializeOnCopy(TInitializeOnCopy&&) noexcept : Value() {}
        auto operator=(TInitializeOnCopy const&) -> TInitializeOnCopy& { return *this; }
        auto operator=(TInitializeOnCopy&& other) noexcept -> TInitializeOnCopy& { return *this; }
 
        TUniqueObj<T> Value;
 
              T* operator -> ()       { return &Value.Get(); }
        const T* operator -> () const { return &Value.Get(); }
        
              T& Get()       { return Value.Get(); }
        const T& Get() const { return Value.Get(); }
        
        template <typename Self>
        operator typename TCopyQualifiersFromTo<Self, T&>::Type (this Self&& self) { return self.Get(); }
    };
}