From 3df06820ef4859b2d12ca4e99554a83544e8b185 Mon Sep 17 00:00:00 2001
From: Denis Blank <denis.blank@outlook.com>
Date: Mon, 12 Mar 2018 08:02:43 +0100
Subject: [PATCH] Make the seq dependency only dependent from the aggregate
 header

---
 doc/installation.dox                          |  3 +
 ...mapping.hpp => composition-aggregated.hpp} | 53 ++++++++++++++++-
 .../continuable/detail/composition-all.hpp    | 59 ++-----------------
 .../continuable/detail/composition-seq.hpp    | 15 ++---
 4 files changed, 65 insertions(+), 65 deletions(-)
 rename include/continuable/detail/{composition-remapping.hpp => composition-aggregated.hpp} (81%)

diff --git a/doc/installation.dox b/doc/installation.dox
index 1e546d3..e0dff0a 100644
--- a/doc/installation.dox
+++ b/doc/installation.dox
@@ -38,6 +38,9 @@ following compilers:
 Although the build is observed with the listed compilers earlier
 versions might work.
 
+\warning GCC is proven to be slower than Clang in template compilation and
+         thus it is suggested to use Clang instead.
+
 \section installation-dependencies Dependencies
 
 Continuable is a header-only library with one required header-only dependency:
diff --git a/include/continuable/detail/composition-remapping.hpp b/include/continuable/detail/composition-aggregated.hpp
similarity index 81%
rename from include/continuable/detail/composition-remapping.hpp
rename to include/continuable/detail/composition-aggregated.hpp
index afd68cb..dc24ddc 100644
--- a/include/continuable/detail/composition-remapping.hpp
+++ b/include/continuable/detail/composition-aggregated.hpp
@@ -54,7 +54,7 @@ namespace composition {
 ///   - value -> value
 ///   - single async value -> single value
 ///   - multiple async value -> tuple of async values.
-namespace remapping {
+namespace aggregated {
 /// Guards a type to be default constructible,
 /// and wraps it into an optional type if it isn't default constructible.
 template <typename T>
@@ -220,7 +220,56 @@ void finalize_data(Callback&& callback, Data&& data) {
                                std::forward<Callback>(callback),
                                std::forward<Data>(data));
 }
-} // namespace remapping
+
+struct all_hint_deducer {
+  static constexpr auto deduce(hints::signature_hint_tag<>) noexcept {
+    return spread_this();
+  }
+
+  template <typename First>
+  static constexpr auto deduce(hints::signature_hint_tag<First>) {
+    return unpack_lazy(lazy_value_t<First>{});
+  }
+
+  template <typename First, typename Second, typename... Args>
+  static constexpr auto
+  deduce(hints::signature_hint_tag<First, Second, Args...>) {
+    return spread_this(unpack_lazy(lazy_value_t<First>{}),
+                       unpack_lazy(lazy_value_t<Second>{}),
+                       unpack_lazy(lazy_value_t<Args>{})...);
+  }
+
+  template <
+      typename T,
+      std::enable_if_t<base::is_continuable<std::decay_t<T>>::value>* = nullptr>
+  auto operator()(T&& /*continuable*/) const {
+    return deduce(hints::hint_of(traits::identify<T>{}));
+  }
+};
+
+constexpr auto deduce_from_pack(traits::identity<void>)
+    -> hints::signature_hint_tag<>;
+template <typename... T>
+constexpr auto deduce_from_pack(traits::identity<std::tuple<T...>>)
+    -> hints::signature_hint_tag<T...>;
+template <typename T>
+constexpr auto deduce_from_pack(traits::identity<T>)
+    -> hints::signature_hint_tag<T>;
+
+// We must guard the mapped type against to be void since this represents an
+// empty signature hint.
+template <typename Composition>
+constexpr auto deduce_hint(Composition&& /*composition*/) {
+  // Don't change this way since it addresses a GCC compiler bug:
+  // error: extra ';' [-Werror=pedantic]
+  //  std::declval<Composition>()))>{})){};
+  using mapped_t =
+      decltype(map_pack(all_hint_deducer{}, std::declval<Composition>()));
+  using deduced_t = decltype(deduce_from_pack(traits::identity<mapped_t>{}));
+  return deduced_t{};
+}
+
+} // namespace aggregated
 } // namespace composition
 } // namespace detail
 } // namespace cti
diff --git a/include/continuable/detail/composition-all.hpp b/include/continuable/detail/composition-all.hpp
index d7cdb5c..91e466c 100644
--- a/include/continuable/detail/composition-all.hpp
+++ b/include/continuable/detail/composition-all.hpp
@@ -39,7 +39,7 @@
 #include <utility>
 
 #include <continuable/detail/base.hpp>
-#include <continuable/detail/composition-remapping.hpp>
+#include <continuable/detail/composition-aggregated.hpp>
 #include <continuable/detail/composition.hpp>
 #include <continuable/detail/hints.hpp>
 #include <continuable/detail/traits.hpp>
@@ -49,55 +49,6 @@ namespace cti {
 namespace detail {
 namespace composition {
 namespace all {
-struct all_hint_deducer {
-  static constexpr auto deduce(hints::signature_hint_tag<>) noexcept {
-    return spread_this();
-  }
-
-  template <typename First>
-  static constexpr auto deduce(hints::signature_hint_tag<First>) {
-    return remapping::unpack_lazy(remapping::lazy_value_t<First>{});
-  }
-
-  template <typename First, typename Second, typename... Args>
-  static constexpr auto
-  deduce(hints::signature_hint_tag<First, Second, Args...>) {
-    return spread_this(
-        remapping::unpack_lazy(remapping::lazy_value_t<First>{}),
-        remapping::unpack_lazy(remapping::lazy_value_t<Second>{}),
-        remapping::unpack_lazy(remapping::lazy_value_t<Args>{})...);
-  }
-
-  template <
-      typename T,
-      std::enable_if_t<base::is_continuable<std::decay_t<T>>::value>* = nullptr>
-  auto operator()(T&& /*continuable*/) const {
-    return deduce(hints::hint_of(traits::identify<T>{}));
-  }
-};
-
-constexpr auto deduce_from_pack(traits::identity<void>)
-    -> hints::signature_hint_tag<>;
-template <typename... T>
-constexpr auto deduce_from_pack(traits::identity<std::tuple<T...>>)
-    -> hints::signature_hint_tag<T...>;
-template <typename T>
-constexpr auto deduce_from_pack(traits::identity<T>)
-    -> hints::signature_hint_tag<T>;
-
-// We must guard the mapped type against to be void since this represents an
-// empty signature hint.
-template <typename Composition>
-constexpr auto deduce_hint(Composition&& /*composition*/) {
-  // Don't change this way since it addresses a GCC compiler bug:
-  // error: extra ';' [-Werror=pedantic]
-  //  std::declval<Composition>()))>{})){};
-  using mapped_t =
-      decltype(map_pack(all_hint_deducer{}, std::declval<Composition>()));
-  using deduced_t = decltype(deduce_from_pack(traits::identity<mapped_t>{}));
-  return deduced_t{};
-}
-
 /// Caches the partial results and invokes the callback when all results
 /// are arrived. This class is thread safe.
 template <typename Callback, typename Result>
@@ -118,7 +69,7 @@ class result_submitter
 
     // Call the final callback with the cleaned result
     std::call_once(flag_, [&] {
-      remapping::finalize_data(std::move(callback_), std::move(result_));
+      aggregated::finalize_data(std::move(callback_), std::move(result_));
     });
   }
 
@@ -185,7 +136,7 @@ template <typename Submitter>
 struct continuable_dispatcher {
   std::shared_ptr<Submitter>& submitter;
 
-  template <typename Box, std::enable_if_t<remapping::is_continuable_box<
+  template <typename Box, std::enable_if_t<aggregated::is_continuable_box<
                               std::decay_t<Box>>::value>* = nullptr>
   void operator()(Box&& box) const {
     // Retrieve a callback from the submitter and attach it to the continuable
@@ -199,7 +150,7 @@ template <>
 struct composition_finalizer<composition_strategy_all_tag> {
   template <typename Composition>
   static constexpr auto hint() {
-    return decltype(all::deduce_hint(std::declval<Composition>())){};
+    return decltype(aggregated::deduce_hint(std::declval<Composition>())){};
   }
 
   /// Finalizes the all logic of a given composition
@@ -209,7 +160,7 @@ struct composition_finalizer<composition_strategy_all_tag> {
         (auto&& callback) mutable {
 
       // Create the target result from the composition
-      auto result = remapping::box_continuables(std::move(composition));
+      auto result = aggregated::box_continuables(std::move(composition));
 
       using submitter_t =
           all::result_submitter<std::decay_t<decltype(callback)>,
diff --git a/include/continuable/detail/composition-seq.hpp b/include/continuable/detail/composition-seq.hpp
index 522673d..adc4573 100644
--- a/include/continuable/detail/composition-seq.hpp
+++ b/include/continuable/detail/composition-seq.hpp
@@ -39,8 +39,7 @@
 
 #include <continuable/continuable-traverse-async.hpp>
 #include <continuable/detail/base.hpp>
-#include <continuable/detail/composition-all.hpp>
-#include <continuable/detail/composition-remapping.hpp>
+#include <continuable/detail/composition-aggregated.hpp>
 #include <continuable/detail/traits.hpp>
 #include <continuable/detail/util.hpp>
 
@@ -93,7 +92,7 @@ public:
     return data_.box;
   }
 
-  template <typename Box, std::enable_if_t<remapping::is_continuable_box<
+  template <typename Box, std::enable_if_t<aggregated::is_continuable_box<
                               std::decay_t<Box>>::value>* = nullptr>
   bool operator()(async_traverse_visit_tag, Box&& /*box*/) {
     return false;
@@ -121,8 +120,8 @@ public:
 
   template <typename T>
   void operator()(async_traverse_complete_tag, T&& /*pack*/) {
-    return remapping::finalize_data(std::move(data_.callback),
-                                    std::move(data_.box));
+    return aggregated::finalize_data(std::move(data_.callback),
+                                     std::move(data_.box));
   }
 };
 } // namespace seq
@@ -132,9 +131,7 @@ template <>
 struct composition_finalizer<composition_strategy_seq_tag> {
   template <typename Composition>
   static constexpr auto hint() {
-    // The result is the same as in the all composition
-    using all_finalizer = composition_finalizer<composition_strategy_all_tag>;
-    return all_finalizer::hint<Composition>();
+    return decltype(aggregated::deduce_hint(std::declval<Composition>())){};
   }
 
   /// Finalizes the all logic of a given composition
@@ -143,7 +140,7 @@ struct composition_finalizer<composition_strategy_seq_tag> {
     return [composition = std::forward<Composition>(composition)] // ...
         (auto&& callback) mutable {
 
-      auto boxed = remapping::box_continuables(std::move(composition));
+      auto boxed = aggregated::box_continuables(std::move(composition));
 
       // The data from which the visitor is constructed in-place
       using data_t =