Add a C++17 std::disjunction polyfill

include/continuable/continuable-traverse-async.hpp

@@ -31,24 +31,24 @@
 #ifndef CONTINUABLE_TRAVERSE_ASYNC_HPP_INCLUDED
 #define CONTINUABLE_TRAVERSE_ASYNC_HPP_INCLUDED
 
-#include <continuable/detail/traverse-async.hpp>
-
 #include <utility>
 
+#include <continuable/detail/traverse-async.hpp>
+
 namespace cti {
 /// A tag which is passed to the `operator()` of the visitor
 /// if an element is visited synchronously.
-using detail::async_traverse_visit_tag;
+using detail::traversal::async_traverse_visit_tag;
 /// A tag which is passed to the `operator()` of the visitor
 /// if an element is visited after the traversal was detached.
-using detail::async_traverse_detach_tag;
+using detail::traversal::async_traverse_detach_tag;
 /// A tag which is passed to the `operator()` of the visitor
 /// if the asynchronous pack traversal was finished.
-using detail::async_traverse_complete_tag;
+using detail::traversal::async_traverse_complete_tag;
 
 /// A tag to identify that a mapper shall be constructed in-place
 /// from the first argument passed.
-using detail::async_traverse_in_place_tag;
+using detail::traversal::async_traverse_in_place_tag;
 
 /// Traverses the pack with the given visitor in an asynchronous way.
 ///
@@ -58,36 +58,32 @@ using detail::async_traverse_in_place_tag;
 /// Thus we require a visitor callable object which provides three
 /// `operator()` overloads as depicted by the code sample below:
 ///    ```cpp
-///    struct my_async_visitor
+///    struct my_async_visitor {
-///    {
+///      /// The synchronous overload is called for each object,
-///        /// The synchronous overload is called for each object,
+///      /// it may return false to suspend the current control.
-///        /// it may return false to suspend the current control.
+///      /// In that case the overload below is called.
-///        /// In that case the overload below is called.
+///      template <typename T>
-///        template <typename T>
+///      bool operator()(async_traverse_visit_tag, T&& element) {
-///        bool operator()(async_traverse_visit_tag, T&& element)
+///        return true;
-///        {
+///      }
-///            return true;
-///        }
 ///
-///        /// The asynchronous overload this is called when the
+///      /// The asynchronous overload this is called when the
-///        /// synchronous overload returned false.
+///      /// synchronous overload returned false.
-///        /// In addition to the current visited element the overload is
+///      /// In addition to the current visited element the overload is
-///        /// called with a contnuation callable object which resumes the
+///      /// called with a contnuation callable object which resumes the
-///        /// traversal when it's called later.
+///      /// traversal when it's called later.
-///        /// The continuation next may be stored and called later or
+///      /// The continuation next may be stored and called later or
-///        /// dropped completely to abort the traversal early.
+///      /// dropped completely to abort the traversal early.
-///        template <typename T, typename N>
+///      template <typename T, typename N>
-///        void operator()(async_traverse_detach_tag, T&& element, N&& next)
+///      void operator()(async_traverse_detach_tag, T&& element, N&& next) {
-///        {
+///      }
-///        }
 ///
-///        /// The overload is called when the traversal was finished.
+///      /// The overload is called when the traversal was finished.
-///        /// As argument the whole pack is passed over which we
+///      /// As argument the whole pack is passed over which we
-///        /// traversed asynchrnously.
+///      /// traversed asynchrnously.
-///        template <typename T>
+///      template <typename T>
-///        void operator()(async_traverse_complete_tag, T&& pack)
+///      void operator()(async_traverse_complete_tag, T&& pack) {
-///        {
+///      }
-///        }
 ///    };
 ///    ```
 ///
@@ -108,11 +104,9 @@ using detail::async_traverse_in_place_tag;
 /// traversal behaviour and capabilities.
 ///
 template <typename Visitor, typename... T>
-auto traverse_pack_async(Visitor&& visitor, T&&... pack)
+auto traverse_pack_async(Visitor&& visitor, T&&... pack) {
-    -> decltype(detail::apply_pack_transform_async(
+  return detail::traversal::apply_pack_transform_async(
-        std::forward<Visitor>(visitor), std::forward<T>(pack)...)) {
+      std::forward<Visitor>(visitor), std::forward<T>(pack)...);
-  return detail::apply_pack_transform_async(std::forward<Visitor>(visitor),
-                                            std::forward<T>(pack)...);
 }
 } // namespace cti
 

include/continuable/continuable-traverse.hpp

@@ -42,7 +42,7 @@ namespace cti {
 ///
 /// This function tries to visit all plain elements which may be wrapped in:
 /// - homogeneous containers (`std::vector`, `std::list`)
-/// - heterogenous containers `(hpx::tuple`, `std::pair`, `std::array`)
+/// - heterogenous containers `(std::tuple`, `std::pair`, `std::array`)
 /// and re-assembles the pack with the result of the mapper.
 /// Mapping from one type to a different one is supported.
 ///
@@ -52,9 +52,9 @@ namespace cti {
 ///    ```cpp
 ///    // Maps all integers to floats
 ///    map_pack([](int value) {
-///        return float(value);
+///      return float(value);
 ///    },
-///    1, hpx::util::make_tuple(2, std::vector<int>{3, 4}), 5);
+///    1, std::make_tuple(2, std::vector<int>{3, 4}), 5);
 ///    ```
 ///
 /// \throws       std::exception like objects which are thrown by an
@@ -67,26 +67,23 @@ namespace cti {
 ///
 /// \returns      The mapped element or in case the pack contains
 ///               multiple elements, the pack is wrapped into
-///               a `hpx::tuple`.
+///               a `std::tuple`.
 ///
 template <typename Mapper, typename... T>
-auto map_pack(Mapper&& mapper, T&&... pack)
+auto map_pack(Mapper&& mapper, T&&... pack) {
-    -> decltype(detail::apply_pack_transform(detail::strategy_remap_tag{},
+  return detail::traversal::apply_pack_transform(
-                                             std::forward<Mapper>(mapper),
+      detail::traversal::strategy_remap_tag{}, std::forward<Mapper>(mapper),
-                                             std::forward<T>(pack)...)) {
+      std::forward<T>(pack)...);
-  return detail::apply_pack_transform(detail::strategy_remap_tag{},
-                                      std::forward<Mapper>(mapper),
-                                      std::forward<T>(pack)...);
 }
 
 /// Indicate that the result shall be spread across the parent container
 /// if possible. This can be used to create a mapper function used
 /// in map_pack that maps one element to an arbitrary count (1:n).
 template <typename... T>
-constexpr detail::spreading::spread_box<typename std::decay<T>::type...>
+constexpr auto spread_this(T&&... args) {
-spread_this(T&&... args) {
+  return detail::traversal::spreading::spread_box<
-  return detail::spreading::spread_box<typename std::decay<T>::type...>(
+      typename std::decay<T>::type...>(
-      util::make_tuple(std::forward<T>(args)...));
+      std::make_tuple(std::forward<T>(args)...));
 }
 
 /// Traverses the pack with the given visitor.
@@ -97,9 +94,9 @@ spread_this(T&&... args) {
 /// See `map_pack` for a detailed description.
 template <typename Mapper, typename... T>
 void traverse_pack(Mapper&& mapper, T&&... pack) {
-  detail::apply_pack_transform(detail::strategy_traverse_tag{},
+  detail::traversal::apply_pack_transform(
-                               std::forward<Mapper>(mapper),
+      detail::traversal::strategy_traverse_tag{}, std::forward<Mapper>(mapper),
-                               std::forward<T>(pack)...);
+      std::forward<T>(pack)...);
 }
 } // namespace cti
 

include/continuable/detail/features.hpp

@@ -67,6 +67,9 @@
 #endif
 #endif
 
+// TODO
+// #define CONTINUABLE_HAS_CXX17_DISJUNCTION
+
 /// This is enabled by the CMake project
 // #undef CONTINUABLE_HAS_EXPERIMENTAL_COROUTINE
 

include/continuable/detail/traits.hpp

@@ -411,6 +411,21 @@ constexpr auto merge(identity<LeftArgs...> /*left*/,
 /// Deduces to a std::false_type
 template <typename T>
 using fail = std::integral_constant<bool, !std::is_same<T, T>::value>;
+
+#ifdef CONTINUABLE_HAS_CXX17_DISJUNCTION
+using std::disjunction;
+#else
+/// Declares a C++14 polyfill for C++17 std::disjunction.
+template <typename Args, typename = void_t<>>
+struct disjunction_impl : std::common_type<std::false_type> {};
+template <typename... Args>
+struct disjunction_impl<identity<Args...>,
+                        void_t<std::enable_if_t<bool(Args::value)>...>>
+    : std::common_type<std::true_type> {};
+template <typename... Args>
+using disjunction = disjunction_impl<identity<Args...>>;
+#endif // CONTINUABLE_HAS_CXX17_DISJUNCTION
+
 } // namespace traits
 } // namespace detail
 } // namespace cti

include/continuable/detail/traverse.hpp

@@ -39,6 +39,7 @@
 #include <utility>
 
 #include <continuable/detail/container-category.hpp>
+#include <continuable/detail/traits.hpp>
 
 namespace cti {
 namespace detail {
@@ -207,7 +208,7 @@ constexpr auto apply_spread_impl(std::false_type, C&& callable, T&&... args)
 /// Deduces to a true_type if any of the given types marks
 /// the underlying type to be spread into the current context.
 template <typename... T>
-using is_any_spread_t = any_of<is_spread<T>...>;
+using is_any_spread_t = traits::disjunction<is_spread<T>...>;
 
 template <typename C, typename... T>
 constexpr auto map_spread(C&& callable, T&&... args)