smart_pointer.hpp

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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2025 Denis Corbin
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// to contact the author, see the AUTHOR file
/*********************************************************************/
 
 
#ifndef SMART_POINTER_HPP
#define SMART_POINTER_HPP
 
#include "../my_config.h"
 
#include "infinint.hpp"
#include "erreurs.hpp"
 
namespace libdar
{
 
 
 
 
    template <class T> class smart_node
    {
    public:
    smart_node(T *arg): ptr(arg), count_ref(0) { if(arg == nullptr) throw SRC_BUG; };
    smart_node(const smart_node & ref) = delete;
    smart_node(smart_node && ref) noexcept = delete;
    smart_node & operator = (const smart_node & ref) = delete;
    smart_node & operator = (smart_node && ref) = delete;
        ~smart_node() noexcept(false) { if(ptr != nullptr) delete ptr; if(!count_ref.is_zero()) throw SRC_BUG; };
 
    void add_ref() { ++count_ref; };
    void del_ref() { if(count_ref.is_zero()) throw SRC_BUG; --count_ref; if(count_ref.is_zero()) delete this; };
    T & get_val() { return *ptr; };
 
    private:
    T *ptr;
    infinint count_ref;
 
    };
 
 
 
    template <class T> class smart_pointer
    {
    public:
    smart_pointer() { ptr = nullptr; };
 
 
    smart_pointer(T *arg)
    {
        if(arg != nullptr)
        {
        ptr = new (std::nothrow) smart_node<T>(arg);
        if(ptr == nullptr)
            throw Ememory("smart_pointer::smart_pointer");
        ptr->add_ref();
        }
        else
        ptr = nullptr;
    };
 
    smart_pointer(const smart_pointer & ref) { ptr = ref.ptr; if(ptr != nullptr) ptr->add_ref(); };
 
    smart_pointer(smart_pointer && ref) noexcept { ptr = ref.ptr; ref.ptr = nullptr; };
 
    ~smart_pointer() { if(ptr != nullptr) ptr->del_ref(); };
 
    smart_pointer & operator = (const smart_pointer & ref)
    {
        if(ref.ptr != ptr)
        {
        if(ref.ptr != nullptr)
        {
            if(ptr != nullptr)
            ptr->del_ref();
            ptr = ref.ptr;
            ptr->add_ref();
        }
        else
        {
            ptr->del_ref(); // ptr is no nullptr because ref.ptr != ptr
            ptr = nullptr;
        }
        }
        return *this;
    };
 
    smart_pointer & operator = (smart_pointer && ref)
    {
        if(ptr != ref.ptr)
        {
        if(ptr != nullptr)
            ptr->del_ref();
        ptr = ref.ptr;
        ref.ptr = nullptr;
        }
 
        return *this;
    };
 
 
    const smart_pointer & assign(T *arg)
    {
        smart_pointer<T> tmp(arg);
        *this = tmp;
        return *this;
    }
 
    T & operator *() const { if(ptr == nullptr) throw SRC_BUG; return ptr->get_val(); };
 
    T* operator ->() const { if(ptr == nullptr) throw SRC_BUG; return &(ptr->get_val()); };
 
    bool is_null() const { return ptr == nullptr; };
 
    private:
    smart_node<T> *ptr;
    };
 
 
} // end of namespace
 
#endif