smart_ptr_list.h

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/*
 * Copyright (C) 2018, 2022, 2024 Kernkonzept GmbH.
 * Author(s): Sarah Hoffmann <sarah.hoffmann@kernkonzept.com>
 *
 * License: see LICENSE.spdx (in this directory or the directories above)
 */
#pragma once
 
#include "../type_traits"
 
namespace cxx { namespace Bits {

template <typename T, typename STORE_T>
class Smart_ptr_list_item
{
  using Value_type = T;
  using Storage_type = STORE_T;
 
  template<typename U> friend class Smart_ptr_list;
  Storage_type _n;
};

template <typename ITEM>
class Smart_ptr_list
{
  using Value_type = typename ITEM::Value_type;
  using Next_type = typename ITEM::Storage_type;
 
public:
  class Iterator
  {
  public:
    Iterator() : _c(nullptr) {}
 
    Value_type *operator * () const { return _c; }
    Value_type *operator -> () const { return _c; }
 
    Iterator operator ++ ()
    {
      _c = _c->_n.get();
      return *this;
    }
 
    bool operator == (Iterator const &o) const { return _c == o._c; }
    bool operator != (Iterator const &o) const { return !operator == (o); }
 
  private:
    friend class Smart_ptr_list;
 
    explicit Iterator(Value_type *i) : _c(i) {}
 
    Value_type *_c;
  };
 
  class Const_iterator
  {
  public:
    Const_iterator() : _c(nullptr) {}
 
    Value_type const *operator * () const { return _c; }
    Value_type const *operator -> () const { return _c; }
 
    Const_iterator operator ++ ()
    {
      _c = _c->_n.get();
      return *this;
    }
 
    bool operator == (Const_iterator const &o) const { return _c == o._c; }
    bool operator != (Const_iterator const &o) const { return !operator == (o); }
 
  private:
    friend class Smart_ptr_list;
 
    explicit Const_iterator(Value_type const *i) : _c(i) {}
 
    Value_type const *_c;
  };
 
  Smart_ptr_list() : _b(&_f) {}

  void push_front(Next_type &&e)
  {
    e->_n = cxx::move(this->_f);
    this->_f = cxx::move(e);
 
    if (_b == &_f)
      _b = &(_f->_n);
  }

  void push_front(Next_type const &e)
  {
    e->_n = cxx::move(this->_f);
    this->_f = e;
 
    if (_b == &_f)
      _b = &(_f->_n);
  }

  void push_back(Next_type &&e)
  {
    *_b = cxx::move(e);
    _b = &((*_b)->_n);
  }

  void push_back(Next_type const &e)
  {
    *_b = e;
    _b = &((*_b)->_n);
  }

  Value_type *front() const
  { return _f.get(); }

  Next_type pop_front()
  {
    Next_type ret = cxx::move(_f);
 
    if (ret)
      _f = cxx::move(ret->_n);
 
    if (!_f)
      _b = &_f;
 
    return ret;
  }

  bool empty() const
  { return !_f; }
 
  Iterator begin() { return Iterator(_f.get()); }
  Iterator end() { return Iterator(); }
 
  Const_iterator begin() const { return Const_iterator(_f.get()); }
  Const_iterator end() const { return Const_iterator(); }
 
  Const_iterator cbegin() const { return const_iterator(_f.get()); }
  Const_iterator cend() const { return Const_iterator(); }
 
private:
  Next_type _f;
  Next_type *_b;
};
 
} }