Initial implementation

include/etl/not_null.h

@@ -0,0 +1,188 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2025 John Wellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef ETL_NOT_NULL_INCLUDED
+#define ETL_NOT_NULL_INCLUDED
+
+#include "platform.h"
+#include "error_handler.h"
+#include "exception.h"
+#include "ETL_STATIC_ASSERT.h"
+#include "unique_ptr.h"
+#include "type_traits.h"
+
+namespace etl 
+{
+  //***************************************************************************
+  /// The base class for not_null exceptions.
+  //***************************************************************************
+  class not_null_exception : public exception
+  {
+  public:
+
+    not_null_exception(string_type reason_, string_type file_name_, numeric_type line_number_)
+      : exception(reason_, file_name_, line_number_)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// The exception when the not_null contains a null.
+  //***************************************************************************
+  class not_null_contains_null : public not_null_exception
+  {
+  public:
+
+    not_null_contains_null(string_type file_name_, numeric_type line_number_)
+      : delegate_exception(ETL_ERROR_TEXT("not_null:contains null", ETL_NOT_NULL_FILE_ID"A"), file_name_, line_number_)
+    {
+    }
+  };
+
+  // Primary template
+  template <typename T>
+  class not_null;
+
+  // Specialisation for T*
+  template <typename T>
+  class not_null<T*> 
+  {
+  public:
+
+    explicit not_null(T* ptr_)
+      : ptr(ptr_) 
+    {
+      ETL_ASSERT(ptr != ETL_NULLPTR, ETL_ERROR(not_null_contains_null));
+    }
+
+    not_null(const etl::not_null& other)
+      : ptr(other.get()) 
+    {
+    }
+
+    not_null& operator =(const etl::not_null& other) 
+    {
+      ptr = other.get();
+
+      return *this;
+    }
+
+    not_null& operator =(T* ptr_) 
+    {
+      ETL_ASSERT(ptr_ != ETL_NULLPTR, ETL_ERROR(not_null_contains_null));
+      
+      ptr = ptr_;
+
+      return *this;
+    }
+
+    T* get() const 
+    { 
+      return ptr; 
+    }
+
+    operator T*() const 
+    { 
+      return ptr; 
+    }
+
+    typename etl::remove_pointer<T*>::type& operator*() const
+    { 
+      return *ptr; 
+    }
+  
+    T operator->() const 
+    { 
+      return ptr; 
+    }
+
+  private:
+
+    T* ptr;
+  };
+
+  // Partial specialisation for etl::unique_ptr
+  template <typename T, typename TDeleter>
+  class not_null<etl::unique_ptr<T, TDeleter>> 
+  {
+  public:
+
+    explicit not_null(etl::unique_ptr<T, TDeleter>&& ptr_)
+      : ptr(etl::move(ptr_)) 
+    {
+      ETL_ASSERT(ptr != ETL_NULLPTR, ETL_ERROR(not_null_contains_null));
+    }
+
+#if ETL_USING_CPP11
+    not_null& operator =(etl::unique_ptr<T, TDeleter>&& ptr_) 
+    {
+      ETL_ASSERT(ptr_ != ETL_NULLPTR, ETL_ERROR(not_null_contains_null));
+
+      ptr = etl::move(ptr_);
+
+      return *this;
+    }
+#endif
+
+    T* get() const 
+    { 
+      return ptr.get(); 
+    }
+
+    operator T*() const 
+    { 
+      return ptr.get(); 
+    }
+  
+    T& operator*() const
+    { 
+      return *ptr; 
+    }
+  
+    T* operator->() const 
+    { 
+      return ptr.get(); 
+    }
+
+    etl::unique_ptr<T, TDeleter>& unique() 
+    { 
+      return ptr; 
+    }
+  
+    const etl::unique_ptr<T, TDeleter>& unique() const 
+    { 
+      return ptr; 
+    }
+
+  private:
+  
+    etl::unique_ptr<T, TDeleter> ptr;
+  };
+}