TRUST_Ref.h

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#ifndef TRUST_Ref_included
#define TRUST_Ref_included
 
#include <type_traits>
#include <assert.h>
 
class Objet_U;
class Nom;
 
/*! @brief Template reference class for any class _CLASSE_ deriving from Objet_U.
 *
 *   TRUST_Ref<_CLASSE_> is a small template class containing a pointer to an instance of _CLASSE_.
 *
 *   Definition of the REF:
 *
 *   #include <TRUST_Ref.h>
 *   #include <_CLASSE_.h>
 *
 *   Creating an object of type OBS_PTR(_CLASSE_):
 *
 *    OBS_PTR(_CLASSE_) la_ref_;
 *
 *    or equivalently
 *
 *    TRUST_Ref<_CLASSE_>
 *
 */
 
// MACRO to replace OBS_PTR(_TYPE_) by TRUST_Ref<_TYPE_*> & keep previous syntax for some developers
#define REF(_TYPE_) \
  static_assert(false, "The old REF MACRO is now deprecated. Please use OBS_PTR instead.")
 
#define OBS_PTR(_TYPE_) TRUST_Ref<_TYPE_*>
 
template<typename _CLASSE_>
class TRUST_Ref final
{
  /*
   * Elie & Adrien :
   * Define the underlying (non-pointer) type
   * For example if _CLASSE_ = 'Probleme_base*', value_type is 'Probleme_base' : https://en.cppreference.com/w/cpp/types/remove_pointer
   */
  using value_type = typename std::remove_pointer<_CLASSE_>::type;
 
private:
  value_type * p_ = nullptr;
 
public:
  static constexpr bool HAS_POINTER = true;
 
  ~TRUST_Ref() = default;
  TRUST_Ref() = default;
  TRUST_Ref(const value_type& t) :  p_((value_type*)&t) { }
  TRUST_Ref(const TRUST_Ref& t) : p_(t.p_) { }
 
  const TRUST_Ref& operator=(const value_type& t)
  {
    p_ = const_cast<value_type *>(&t);
    return *this;
  }
 
  const TRUST_Ref& operator=(const TRUST_Ref& t)
  {
    p_ = t.p_;
    return *this;
  }
 
  // not deleted because of issues in TRUST_List iterators, e.g. LIST(REF ...)
  operator const value_type& () const { return valeur(); }
  operator value_type& () { return valeur(); }
 
  inline const value_type& valeur() const { assert(p_ != nullptr); return *p_; }
  inline value_type& valeur() { assert(p_ != nullptr); return *p_; }
  inline const value_type* operator ->() const { assert(p_ != nullptr); return p_; }
  inline value_type* operator ->() { assert(p_ != nullptr); return p_; }
 
  explicit operator bool() const noexcept { return p_ != nullptr; }
 
  const Nom& le_nom() const = delete;
  void reset() {  p_ = nullptr; }
};
 
// The result of == is true if r1 and r2 point to the same object (same key), or if both references are null.
template<typename _CLASSE_>
inline int operator ==(const TRUST_Ref<_CLASSE_>& r1, const TRUST_Ref<_CLASSE_>& r2)
{
  if (!r1 && !r2) return 1;
  if (r1->numero() == r2->numero()) return 1;
  return 0;
}
 
/* ======================================================= *
 * ======================================================= *
 * ======================================================= */
 
/*! @brief Class TRUST_Ref_Objet_U.
 *
 * This class is almost identical to TRUST_Ref<>, except that it does not contain implicit conversion operators.
 *
 */
class TRUST_Ref_Objet_U
{
private:
  Objet_U * p_ = nullptr;
 
public:
  static constexpr bool HAS_POINTER = true;
 
  ~TRUST_Ref_Objet_U();
  TRUST_Ref_Objet_U();
  TRUST_Ref_Objet_U(const Objet_U& t);
  TRUST_Ref_Objet_U(const TRUST_Ref_Objet_U& t);
 
  const TRUST_Ref_Objet_U& operator=(const Objet_U& t);
  const TRUST_Ref_Objet_U& operator=(const TRUST_Ref_Objet_U& t);
 
  explicit operator bool() const noexcept { return p_ != nullptr; }
 
  inline const Objet_U& valeur() const { assert(p_ != nullptr); return *p_; }
  inline Objet_U& valeur() { assert(p_ != nullptr); return *p_; }
  inline const Objet_U* operator ->() const { assert(p_ != nullptr); return p_; }
  inline Objet_U* operator ->() { assert(p_ != nullptr); return p_; }
};
 
int operator ==(const TRUST_Ref_Objet_U& r1, const TRUST_Ref_Objet_U& r2);
 
using RefObjU = TRUST_Ref_Objet_U;
 
#endif /* TRUST_Ref_included */