File indexing completed on 2024-06-23 05:27:09

 /*
     SPDX-FileCopyrightText: 2018 Ivan Čukić <ivan.cukic(at)kde.org>
 
     SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
 */
 
 #ifndef VOY_NODE_TRAITS_H
 #define VOY_NODE_TRAITS_H
 
 // STL
 #include <utility>
 
 #include "node_tags.h"
 
 #include "../traits.h"
 #include "../utils.h"
 #include "../basic/sink.h"
 
 namespace voy::dsl::node_traits {
 
 using namespace voy::traits;
 
 // Returns the category of the node. It can also be used to detect whether
 // a class contains the node category specification
 template <typename Node>
 using node_category = typename remove_cvref_t<Node>::node_category;
 
 
 // Used to detect whther the class contains a with_continuation function
 // for rvalues
 template <typename Node>
 using with_continuation_memfn = decltype(
         std::declval<Node&&>().with_continuation(voy::sink<void>{}));
 
 template <typename Node>
 voy_concept has_with_continuation = is_detected_v<with_continuation_memfn, Node>;
 
 
 // Returns whether the node has the specified tag or not
 template <typename Tag, typename Node>
 voy_concept is_tagged_with = std::is_same_v<Tag, node_category<Node>>;
 
 
 // The meta-function to check whether a class is a node is easier to implement
 // using the constexpr-if because of the branching.
 namespace detail {
     template < typename Node
              , typename DetectedCategory = detected_t<node_category, Node>
              >
     voy_concept is_node()
     {
         if constexpr (!is_detected_v<node_category, Node>) {
             // voy_fail(Node, "No category specified for the node");
             return false;
 
         } else if constexpr (std::is_same_v<void, DetectedCategory>) {
             // voy_fail(Node, "Category is void, which means we already have a complete graph path");
             return false;
 
         } else {
             return true;
         }
     }
 }
 
 // Wrapper for detail::is_node to make it look like a normal meta-function
 template <typename Node>
 voy_concept is_node = detail::is_node<Node>();
 
 
 // Checks whether the node is a source node
 template <typename Node>
 voy_concept is_source = is_tagged_with<source_node_tag, Node>;
 
 
 // Checks whether the node is a source node
 template <typename Node>
 voy_concept is_sink = is_tagged_with<sink_node_tag, Node>;
 
 
 // To be used with the detection idiom to check whether a type is
 // a connection_expr or a normal node
 template <typename Graph>
 using connection_expr_tag_definition = typename Graph::connection_expr_tag;
 
 template <typename Node>
 voy_concept is_connection_expr =
     is_detected_v<connection_expr_tag_definition, Node>;
 
 
 
 } // namespace voy::dsl::node_traits
 
 #endif // include guard