segmented (#30)

FrancoisChabot · Jun 18, 2019 · 1c71606 · 1c71606
1 parent 7af85c8
commit 1c71606
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Showing 5 changed files with 51 additions and 1 deletion.
diff --git a/include/var_future/future.h b/include/var_future/future.h
@@ -316,6 +316,10 @@ auto async(QueueT& q, CbT&& callback);
 template <typename Alloc, typename... Ts>
 Basic_future<Alloc, Ts...> flatten(Basic_future<Alloc, std::tuple<Ts...>>& rhs);
 
+template<typename... Ts>
+auto segmented(Ts&&... args);
+
+
 }  // namespace aom
 
 #include "var_future/impl/async.h"

diff --git a/include/var_future/impl/future.h b/include/var_future/impl/future.h
@@ -207,5 +207,17 @@ Basic_future<Alloc, Ts...> flatten(
   return Basic_future<Alloc, Ts...>(std::move(storage));
 }
 
+/**
+ * @brief Permits a callback to produce a higher-order future.
+ * 
+ * @tparam Ts 
+ * @param args 
+ * @return auto 
+ */
+template<typename... Ts>
+auto segmented(Ts&&... args) {
+  return detail::Segmented_callback_result<std::decay_t<Ts>...>{ std::make_tuple(std::forward<Ts>(args)...)};
+}
+
 }  // namespace aom
 #endif
diff --git a/include/var_future/impl/storage_decl.h b/include/var_future/impl/storage_decl.h
@@ -27,6 +27,12 @@ namespace aom {
 
 namespace detail {
 
+template<typename... Ts>
+struct Segmented_callback_result {
+  std::tuple<Ts...> values_;
+};
+
+
 template <typename... Ts>
 class Future_handler_iface {
  public:
@@ -99,6 +105,9 @@ class Future_storage : public Alloc {
   template <typename Arg_alloc>
   void fullfill(Basic_future<Arg_alloc, Ts...>&& f);
 
+  template <typename... Us>
+  void fullfill(Segmented_callback_result<Us...>&& f);
+
   void finish(finish_type&& f);
 
   template <typename Arg_alloc>
@@ -244,6 +253,11 @@ struct Storage_for_cb_result<Alloc, expected<T>> {
   using type = typename Storage_for_cb_result<Alloc, T>::type;
 };
 
+template <typename Alloc, typename... Us>
+struct Storage_for_cb_result<Alloc, Segmented_callback_result<Us...>> {
+  using type = Future_storage<Alloc, decay_future_t<Us>...>;
+};
+
 template <typename Alloc, typename T>
 using Storage_for_cb_result_t = typename Storage_for_cb_result<Alloc, T>::type;
 

diff --git a/include/var_future/impl/storage_impl.h b/include/var_future/impl/storage_impl.h
@@ -47,6 +47,12 @@ void Future_storage<Alloc, Ts...>::fullfill(fullfill_type&& v) {
   }
 }
 
+template <typename Alloc, typename... Ts>
+template <typename... Us>
+void Future_storage<Alloc, Ts...>::fullfill(Segmented_callback_result<Us...>&& f) {
+  fullfill(std::move(f.values_));
+}
+
 template <typename Alloc, typename... Ts>
 template <typename Arg_alloc>
 void Future_storage<Alloc, Ts...>::fullfill(

diff --git a/tests/misc.cpp b/tests/misc.cpp
@@ -303,7 +303,6 @@ TEST(Future, variadic_get) {
   static_assert(std::is_same_v<Future<int, void, int>::value_type, std::tuple<int, int>>);
 }
 
-
 TEST(Future, variadic_get_failure) {
   Promise<void, void> p;
   auto f = p.get_future();
@@ -312,3 +311,18 @@ TEST(Future, variadic_get_failure) {
 
   EXPECT_THROW(f.get(), std::runtime_error);
 }
+
+TEST(Future, segmented_callback) {
+  Promise<void> p;
+
+  auto f = p.get_future().then([](){
+    return segmented(12, 12);
+  })
+  .then([](int a, int b) {
+    return a + b;
+  });
+
+  p.set_value();
+
+  EXPECT_EQ(24, f.get());
+}