CopiedPtr.hpp

//
// TGUI - Texus' Graphical User Interface
// Copyright (C) 2012-2025 Bruno Van de Velde (vdv_b@tgui.eu)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
//    you must not claim that you wrote the original software.
//    If you use this software in a product, an acknowledgment
//    in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
//    and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
 
#ifndef TGUI_COPIED_PTR_HPP
#define TGUI_COPIED_PTR_HPP

 
#include <TGUI/Config.hpp>
 
#include <memory>

 
namespace tgui
{
    struct CopiedPtrEmplaceTag { explicit CopiedPtrEmplaceTag() = default; };

    template <typename T>
    class CopiedPtr
    {
    public:

        CopiedPtr()
        {
        }

        CopiedPtr(std::nullptr_t)
        {
        }

        template <typename... Args>
        CopiedPtr(CopiedPtrEmplaceTag, Args&&... args) :
            m_ptr(std::make_unique<T>(args...)),
            m_cloner([](const void* val) -> void* { return new T(*static_cast<const T*>(val)); })
        {
        }

        CopiedPtr(const CopiedPtr& other) :
            m_ptr(other.m_ptr ? static_cast<T*>(other.m_cloner(other.m_ptr.get())) : nullptr),
            m_cloner(other.m_cloner)
        {
        }

        template <typename U>
        CopiedPtr(const CopiedPtr<U>& other) :
            m_ptr(other.m_ptr ? static_cast<T*>(other.m_cloner(other.m_ptr.get())) : nullptr),
            m_cloner(other.m_cloner)
        {
        }

        CopiedPtr(CopiedPtr&& other) :
            m_ptr(std::move(other.m_ptr)),
            m_cloner(std::move(other.m_cloner))
        {
        }

        template <typename U>
        CopiedPtr(CopiedPtr&& other) :
            m_ptr(std::move(other.m_ptr)),
            m_cloner(std::move(other.m_cloner))
        {
        }

        void swap(CopiedPtr& other)
        {
            std::swap(m_ptr, other.m_ptr);
            std::swap(m_cloner, other.m_cloner);
        }

        CopiedPtr& operator=(const CopiedPtr& other)
        {
            if (this != &other)
                CopiedPtr(other).swap(*this);
            return *this;
        }

        template <typename U>
        CopiedPtr& operator=(const CopiedPtr<U>& other)
        {
            CopiedPtr(other).swap(*this);
            return *this;
        }

        CopiedPtr& operator=(CopiedPtr&& other)
        {
            if (this != &other)
                CopiedPtr(std::move(other)).swap(*this);
            return *this;
        }

        template <typename U>
        CopiedPtr& operator=(CopiedPtr<U>&& other)
        {
            CopiedPtr(std::move(other)).swap(*this);
            return *this;
        }

        T& operator*()
        {
            return *m_ptr;
        }

        T* operator->() const
        {
            return m_ptr.get();
        }

        operator bool() const
        {
            return m_ptr != nullptr;
        }

        T* get() const
        {
            return m_ptr.get();
        }

        void reset()
        {
            m_ptr.reset();
            m_cloner = nullptr;
        }
 
    private:
        std::unique_ptr<T> m_ptr;
 
        // When m_ptr contains a pointer to a base class, we still need some way to copy the derived class
        void*(*m_cloner)(const void*) = nullptr;
 
        // The copy constructor needs access to classes with a different template parameter
        template <typename U>
        friend class CopiedPtr;
    };

    template <typename T, typename... Args>
    CopiedPtr<T> makeCopied(Args&&... args)
    {
        return CopiedPtr<T>(CopiedPtrEmplaceTag{}, std::forward<Args>(args)...);
    }

}

 
#endif // TGUI_COPIED_PTR_HPP