From 9955f9e469c52958cf2469e89934f9418c17633e Mon Sep 17 00:00:00 2001
From: Denis Blank <denis.blank@outlook.com>
Date: Mon, 26 Nov 2018 02:19:16 +0100
Subject: [PATCH] Add the invoker for result<...>

---
 include/continuable/continuable-result.hpp    |  1 +
 include/continuable/detail/core/base.hpp      | 27 +++++++++----------
 .../detail/utility/flat-variant.hpp           |  3 +++
 .../detail/utility/result-trait.hpp           | 17 ++++++++++++
 4 files changed, 34 insertions(+), 14 deletions(-)

diff --git a/include/continuable/continuable-result.hpp b/include/continuable/continuable-result.hpp
index 0324b88..7c62dc0 100644
--- a/include/continuable/continuable-result.hpp
+++ b/include/continuable/continuable-result.hpp
@@ -37,6 +37,7 @@
 #include <continuable/detail/utility/flat-variant.hpp>
 #include <continuable/detail/utility/result-trait.hpp>
 #include <continuable/detail/utility/traits.hpp>
+#include <continuable/detail/utility/util.hpp>
 
 namespace cti {
 /// \defgroup Result Result
diff --git a/include/continuable/detail/core/base.hpp b/include/continuable/detail/core/base.hpp
index 8faba9f..b427716 100644
--- a/include/continuable/detail/core/base.hpp
+++ b/include/continuable/detail/core/base.hpp
@@ -39,6 +39,7 @@
 #include <continuable/detail/core/hints.hpp>
 #include <continuable/detail/core/types.hpp>
 #include <continuable/detail/features.hpp>
+#include <continuable/detail/utility/result-trait.hpp>
 #include <continuable/detail/utility/traits.hpp>
 #include <continuable/detail/utility/util.hpp>
 
@@ -260,23 +261,23 @@ auto invoker_of(traits::identity<result<Args...>>) {
           result<Args...> result =
               util::partial_invoke(std::forward<decltype(callback)>(callback),
                                    std::forward<decltype(args)>(args)...);
-          // 
           if (result.is_value()) {
             // Workaround for MSVC not capturing the reference
             // correctly inside the lambda.
             using Next = decltype(next_callback);
 
-            traits::unpack(
-              [&](auto&&... types) {
-              /// TODO Add inplace resolution here
-
-              invoke_no_except(std::forward<Next>(next_callback),
-                std::forward<decltype(types)>(types)...);
-            },
-              std::move(result));
+            result_trait<Args...>::visit(
+                std::move(result), //
+                [&](auto&&... values) {
+                  invoke_no_except(std::forward<Next>(next_callback),
+                                   std::forward<decltype(values)>(values)...);
+                });
 
           } else if (result.is_exception()) {
-
+            // Forward the exception to the next available handler
+            invoke_no_except(
+                std::forward<decltype(next_callback)>(next_callback),
+                exception_arg_t{}, std::move(result).get_exception());
           }
 
           // Otherwise the result is empty and we are cancelling our
@@ -300,11 +301,9 @@ inline auto sequenced_unpack_invoker() {
       using Next = decltype(next_callback);
 
       traits::unpack(
-          [&](auto&&... types) {
-            /// TODO Add inplace resolution here
-
+          [&](auto&&... values) {
             invoke_no_except(std::forward<Next>(next_callback),
-                             std::forward<decltype(types)>(types)...);
+                             std::forward<decltype(values)>(values)...);
           },
           std::move(result));
     CONTINUABLE_BLOCK_TRY_END
diff --git a/include/continuable/detail/utility/flat-variant.hpp b/include/continuable/detail/utility/flat-variant.hpp
index 25f42d6..38a1ec4 100644
--- a/include/continuable/detail/utility/flat-variant.hpp
+++ b/include/continuable/detail/utility/flat-variant.hpp
@@ -359,6 +359,9 @@ private:
 #endif
   }
   detail::slot_t get_slot() const noexcept {
+    // Check for invalid values especially for memory corruption,
+    // the empty element is included.
+    assert(this->slot_ <= sizeof...(T));
     return this->slot_;
   }
   bool is_slot(detail::slot_t const slot) const noexcept {
diff --git a/include/continuable/detail/utility/result-trait.hpp b/include/continuable/detail/utility/result-trait.hpp
index cd18296..9d7012b 100644
--- a/include/continuable/detail/utility/result-trait.hpp
+++ b/include/continuable/detail/utility/result-trait.hpp
@@ -36,6 +36,7 @@
 #include <utility>
 #include <continuable/detail/core/hints.hpp>
 #include <continuable/detail/utility/traits.hpp>
+#include <continuable/detail/utility/util.hpp>
 
 namespace cti {
 namespace detail {
@@ -52,6 +53,10 @@ struct result_trait<> {
 
   static constexpr void unwrap(surrogate_t) {
   }
+
+  template <typename Result, typename Mapper>
+  static void visit(Result&& /*result*/, Mapper&& /*mapper*/) {
+  }
 };
 template <typename T>
 struct result_trait<T> {
@@ -66,6 +71,12 @@ struct result_trait<T> {
   static decltype(auto) unwrap(R&& unwrap) {
     return std::forward<R>(unwrap);
   }
+
+  template <typename Result, typename Mapper>
+  static auto visit(Result&& result, Mapper&& mapper) {
+    return util::invoke(std::forward<Mapper>(mapper),
+                        std::forward<Result>(result).get_value());
+  }
 };
 template <typename First, typename Second, typename... Rest>
 struct result_trait<First, Second, Rest...> {
@@ -81,6 +92,12 @@ struct result_trait<First, Second, Rest...> {
   static decltype(auto) unwrap(R&& unwrap) {
     return std::forward<R>(unwrap);
   }
+
+  template <typename Result, typename Mapper>
+  static auto visit(Result&& result, Mapper&& mapper) {
+    return traits::unpack(std::forward<Mapper>(mapper),
+                          std::forward<Result>(result).get_value());
+  }
 };
 } // namespace detail
 } // namespace cti