not_null.h

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/******************************************************************************
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Embedded Template Library.
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Copyright(c) 2025 John Wellbelove
 
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#ifndef ETL_NOT_NULL_INCLUDED
#define ETL_NOT_NULL_INCLUDED
 
#include "platform.h"
#include "error_handler.h"
#include "exception.h"
#include "memory.h"
#include "type_traits.h"
 
namespace etl
{
  //***************************************************************************
  //***************************************************************************
  class not_null_exception : public exception
  {
  public:
 
    not_null_exception(string_type reason_, string_type file_name_, numeric_type line_number_) ETL_NOEXCEPT_EXPR(ETL_NOT_USING_EXCEPTIONS)
      : exception(reason_, file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class not_null_contains_null : public not_null_exception
  {
  public:
 
    not_null_contains_null(string_type file_name_, numeric_type line_number_) ETL_NOEXCEPT_EXPR(ETL_NOT_USING_EXCEPTIONS)
      : not_null_exception(ETL_ERROR_TEXT("not_null:contains null", ETL_NOT_NULL_FILE_ID"A"), file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  // not_null
  // Primary template
  //***************************************************************************
  template <typename T>
  class not_null;
 
  //***************************************************************************
  // Specialisation for T*
  // A container for pointers that are not allowed to be null.
  //***************************************************************************
  template <typename T>
  class not_null<T*>
  {
  public:
 
    typedef T        value_type;
    typedef T*       pointer;
    typedef const T* const_pointer;
    typedef T&       reference;
    typedef const T& const_reference;
    typedef pointer  underlying_type;
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 explicit not_null(underlying_type ptr_) ETL_NOEXCEPT_EXPR(ETL_NOT_USING_EXCEPTIONS)
      : ptr(ptr_)
    {
      ETL_ASSERT(ptr_ != ETL_NULLPTR, ETL_ERROR(not_null_contains_null));
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 not_null(const etl::not_null<T*>& other) ETL_NOEXCEPT
      : ptr(other.get())
    {
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 not_null& operator=(underlying_type rhs) ETL_NOEXCEPT_EXPR(ETL_NOT_USING_EXCEPTIONS)
    {
      ETL_ASSERT_OR_RETURN_VALUE(rhs != ETL_NULLPTR, ETL_ERROR(not_null_contains_null), *this);
 
      ptr = rhs;
 
      return *this;
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 not_null& operator=(const etl::not_null<T*>& rhs) ETL_NOEXCEPT
    {
      ptr = rhs.get();
 
      return *this;
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 pointer get() const ETL_NOEXCEPT
    {
      return ptr;
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 operator pointer() const ETL_NOEXCEPT
    {
      return ptr;
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 reference operator*() const ETL_NOEXCEPT
    {
      return *ptr;
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 pointer operator->() const ETL_NOEXCEPT
    {
      return ptr;
    }
 
  private:

    pointer ptr;
  };
 
  //***************************************************************************
  // Partial specialisation for etl::unique_ptr
  // A container for unique_ptr that are not allowed to be null.
  //***************************************************************************
  template <typename T, typename TDeleter>
  class not_null<etl::unique_ptr<T, TDeleter> >
  {
  private:
 
    typedef etl::not_null<etl::unique_ptr<T, TDeleter> > this_type;
    typedef etl::unique_ptr<T, TDeleter>                 underlying_type;
 
  public:
 
    typedef T        value_type;
    typedef T*       pointer;
    typedef const T* const_pointer;
    typedef T&       reference;
    typedef const T& const_reference;
 
#if ETL_USING_CPP11
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 explicit not_null(underlying_type&& u_ptr_) ETL_NOEXCEPT_EXPR(ETL_NOT_USING_EXCEPTIONS)
      : u_ptr(etl::move(u_ptr_))
    {
      ETL_ASSERT(u_ptr.get() != ETL_NULLPTR, ETL_ERROR(not_null_contains_null));
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 not_null& operator=(underlying_type&& rhs) ETL_NOEXCEPT_EXPR(ETL_NOT_USING_EXCEPTIONS)
    {
      ETL_ASSERT_OR_RETURN_VALUE(rhs.get() != ETL_NULLPTR, ETL_ERROR(not_null_contains_null), *this);
 
      u_ptr = etl::move(rhs);
 
      return *this;
    }
#endif
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 pointer get() const ETL_NOEXCEPT
    {
      return u_ptr.get();
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 operator pointer() const ETL_NOEXCEPT
    {
      return u_ptr.get();
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 reference operator*() const ETL_NOEXCEPT
    {
      return *u_ptr;
    }
 
    //*********************************
    //*********************************
    ETL_CONSTEXPR14 pointer operator->() const ETL_NOEXCEPT
    {
      return u_ptr.get();
    }
 
  private:
 
    ETL_CONSTEXPR14 explicit not_null(const this_type& u_ptr_) ETL_NOEXCEPT ETL_DELETE;
    ETL_CONSTEXPR14 not_null& operator=(const this_type& rhs) ETL_NOEXCEPT ETL_DELETE;
 
#if ETL_USING_CPP11
    ETL_CONSTEXPR14 explicit not_null(this_type&& u_ptr_) ETL_NOEXCEPT = delete;
    ETL_CONSTEXPR14 not_null& operator=(this_type&& rhs) ETL_NOEXCEPT = delete;
#endif

    underlying_type u_ptr;
  };
} // namespace etl
 
#endif