Line data    Source code

       1           0 : // Distributed under the MIT License.
       2             : // See LICENSE.txt for details.
       3             : 
       4             : #pragma once
       5             : 
       6             : #include <memory>
       7             : #include <type_traits>
       8             : 
       9             : #include "DataStructures/DataBox/TagTraits.hpp"
      10             : #include "Utilities/NoSuchType.hpp"
      11             : #include "Utilities/TMPL.hpp"
      12             : 
      13           0 : namespace Tags {
      14             : /*!
      15             :  * \ingroup DataBoxTagsGroup
      16             :  * \brief Tag used to retrieve the DataBox from the `db::get` function
      17             :  *
      18             :  * The main use of this tag is to allow fetching the DataBox from itself. The
      19             :  * primary use case is to allow an invokable to take a DataBox as an argument
      20             :  * when called through `db::apply`.
      21             :  *
      22             :  * \snippet Test_DataBox.cpp databox_self_tag_example
      23             :  */
      24           1 : struct DataBox {
      25             :   // Trick to get friend function declaration to compile but a const
      26             :   // NoSuchtype****& is rather useless
      27           0 :   using type = NoSuchType****;
      28             : };
      29             : }  // namespace Tags
      30             : 
      31             : namespace db {
      32             : 
      33             : namespace detail {
      34             : template <typename TagList, typename Tag>
      35             : using list_of_matching_tags = tmpl::conditional_t<
      36             :     std::is_same_v<Tag, ::Tags::DataBox>, tmpl::list<::Tags::DataBox>,
      37             :     tmpl::filter<TagList, std::is_base_of<tmpl::pin<Tag>, tmpl::_1>>>;
      38             : 
      39             : template <typename Tag, typename TagList,
      40             :           typename MatchingTagsList = list_of_matching_tags<TagList, Tag>>
      41             : struct first_matching_tag_impl {
      42             :   using type = tmpl::front<MatchingTagsList>;
      43             : };
      44             : 
      45             : template <typename Tag, typename TagList>
      46             : struct first_matching_tag_impl<Tag, TagList, tmpl::list<>> {
      47             :   static_assert(std::is_same<Tag, NoSuchType>::value,
      48             :                 "Could not find the DataBox tag in the list of DataBox tags. "
      49             :                 "The first template parameter of 'first_matching_tag_impl' is "
      50             :                 "the tag that cannot be found and the second is the list of "
      51             :                 "tags being searched.");
      52             :   using type = NoSuchType;
      53             : };
      54             : 
      55             : template <typename TagList, typename Tag>
      56             : using first_matching_tag = typename first_matching_tag_impl<Tag, TagList>::type;
      57             : 
      58             : template <typename TagList, typename Tag>
      59             : constexpr auto number_of_matching_tags =
      60             :     tmpl::size<list_of_matching_tags<TagList, Tag>>::value;
      61             : 
      62             : template <typename TagList, typename Tag>
      63             : struct has_unique_matching_tag
      64             :     : std::integral_constant<bool, number_of_matching_tags<TagList, Tag> == 1> {
      65             : };
      66             : 
      67             : template <typename TagList, typename Tag>
      68             : using has_unique_matching_tag_t =
      69             :     typename has_unique_matching_tag<TagList, Tag>::type;
      70             : 
      71             : template <typename TagList, typename Tag>
      72             : constexpr bool has_unique_matching_tag_v =
      73             :     has_unique_matching_tag<TagList, Tag>::value;
      74             : 
      75             : template <typename TagList, typename Tag>
      76             : struct has_no_matching_tag
      77             :     : std::integral_constant<bool, number_of_matching_tags<TagList, Tag> == 0> {
      78             : };
      79             : 
      80             : template <typename TagList, typename Tag>
      81             : using has_no_matching_tag_t = typename has_no_matching_tag<TagList, Tag>::type;
      82             : 
      83             : template <typename TagList, typename Tag>
      84             : constexpr bool has_no_matching_tag_v = has_no_matching_tag<TagList, Tag>::value;
      85             : 
      86             : template <typename T>
      87             : struct ConvertToConst {
      88             :   using type = const T&;
      89             : };
      90             : 
      91             : template <typename T>
      92             : struct ConvertToConst<std::unique_ptr<T>> {
      93             :   using type = const T&;
      94             : };
      95             : 
      96             : template <typename Tag, typename TagsList, bool = db::is_base_tag_v<Tag>>
      97             : struct const_item_type_impl {
      98             :   using type = typename db::detail::ConvertToConst<
      99             :       std::decay_t<typename Tag::type>>::type;
     100             : };
     101             : 
     102             : template <typename Tag, typename TagsList>
     103             : struct const_item_type_impl<Tag, TagsList, true> {
     104             :   using type = typename db::detail::ConvertToConst<std::decay_t<
     105             :       typename db::detail::first_matching_tag<TagsList, Tag>::type>>::type;
     106             : };
     107             : }  // namespace detail
     108             : 
     109             : template <typename Tag, typename TagsList>
     110           0 : using const_item_type =
     111             :     typename detail::const_item_type_impl<Tag, TagsList>::type;
     112             : }  // namespace db