Line data    Source code

       1           0 : // Distributed under the MIT License.
       2             : // See LICENSE.txt for details.
       3             : 
       4             : #pragma once
       5             : 
       6             : #include <cstddef>
       7             : 
       8             : #include "Utilities/TMPL.hpp"
       9             : 
      10             : namespace db {
      11             : /// \ingroup DataBoxGroup
      12             : /// Struct that can be specialized to allow DataBox items to have
      13             : /// subitems.  Specializations must define:
      14             : /// * `using type = tmpl::list<...>` listing the subtags of `Tag`
      15             : /// * A static member function to initialize a subitem of a simple
      16             : ///   item:
      17             : ///   ```
      18             : ///   template <typename Subtag>
      19             : ///   static void create_item(
      20             : ///       const gsl::not_null<typename Tag::type*> parent_value,
      21             : ///       const gsl::not_null<typename Subtag::type*> sub_value);
      22             : ///   ```
      23             : ///   Mutating the subitems must also modify the main item.
      24             : /// * A static member function evaluating a subitem of a compute
      25             : ///   item:
      26             : ///   ```
      27             : ///   template <typename Subtag>
      28             : ///   static typename Subtag::type create_compute_item(
      29             : ///       typename Tag::type& parent_value);
      30             : ///   ```
      31             : template <typename Tag, typename = std::nullptr_t>
      32           1 : struct Subitems {
      33           0 :   using type = tmpl::list<>;
      34             : };
      35             : }  // namespace db