Support describing concepts in source-to-asciidoc transfomation

[akrzemi1]

My current documentation (which I create manually) provides the definition of the concept, and then, for every constraint, a description is provided:
https://github.com/akrzemi1/markable/blob/master/documentation/reference.adoc#concept-mark_policy

Does something like this works, or could be made to work, in mrdocs?

[alandefreitas]

Yes. We already extract the concepts (https://github.com/cppalliance/mrdocs/blob/develop/include/mrdocs/Metadata/Concept.hpp) and the XML generator already includes this information (https://github.com/cppalliance/mrdocs/blob/develop/test-files/golden-tests/concept.cpp / https://github.com/cppalliance/mrdocs/blob/develop/test-files/golden-tests/concept.xml). But that's recent work, so there's no asciidoc template yet.

[akrzemi1]

Will the following concept definition and annotations be documented?

/** Requirements on a mark policy

  @tparam MP mark policy 
 */
template <typename MP>
concept mark_policy =
  requires
  {
    /// type of the _logical value_
    typename MP::value_type;
    /// type of the value used for the actual storage
    typename MP::storage_type;
    /// type used for the return type of `markable::value()`
    typename MP::reference_type;
    /// type of the _representation value_
    typename MP::representation_type;
  } &&
  requires(const typename MP::representation_type &  cr,
                 typename MP::representation_type && rr,
           const typename MP::storage_type &         s,
           const typename MP::value_type &           cv,
                 typename MP::value_type &&          rv)
  {
    /// Returns the representation value representing a marked value
    { MP::marked_value() }
      -> ::std::convertible_to<typename MP::representation_type>;
    /// Checks if the representation value represents a marked value
    { MP::is_marked_value(cr) }
      -> ::std::convertible_to<bool>;

    /** Given a value of the storage type, provides access to the logical value
    
      @pre: `!MP::is_marked_value(MP::representation(s))` is `true`.
      */
    { MP::access_value(s) }
      -> ::std::same_as<typename MP::reference_type>;
    /// Given a value of the storage type, provides access to the representation value
    { MP::representation(s) }
      -> ::std::same_as<const typename MP::representation_type &>;
    /// Encodes the provided logical value in the storage type
    { MP::store_value(cv) }
      -> ::std::convertible_to<typename MP::storage_type>;
    /// Encodes the provided logical value in the storage type
    { MP::store_value(::std::move(rv)) }
      -> ::std::convertible_to<typename MP::storage_type>;
    /// Encodes the provided representation value in the storage type
    { MP::store_representation(cr) }
      -> ::std::convertible_to<typename MP::storage_type>;
    /// Encodes the provided representation value in the storage type
    { MP::store_representation(::std::move(rr)) }
      -> ::std::convertible_to<typename MP::storage_type>;
  };

[alandefreitas]

I believe it would extract the concepts but only include it in the XML output for now. @sdkrystian ?

[akrzemi1]

I mean, the above exmple requires parsing preconditons of a single constraint. It also has two requires-clauses.