From 8289b4b235682748dbc908228ed78145cfe1ab01 Mon Sep 17 00:00:00 2001
From: bergmann <info@bergmann89.de>
Date: Sun, 24 Nov 2019 23:57:32 +0100
Subject: [PATCH] * refactored/simplified 'future' class

---
 include/asyncpp/core/future.h                 |  81 ++++---
 include/asyncpp/core/future.inl               | 215 ++++++++++--------
 include/asyncpp/core/future.pre.h             |  42 +---
 include/asyncpp/core/future/and_then.h        |  44 ++--
 include/asyncpp/core/future/and_then.inl      |  24 +-
 include/asyncpp/core/future/map.h             |  46 ++--
 include/asyncpp/core/future/map.inl           |  20 +-
 include/asyncpp/core/stream.inl               |   4 +-
 include/asyncpp/core/stream/for_each.h        |  44 ++--
 include/asyncpp/core/stream/for_each.inl      |  20 +-
 include/asyncpp/timing/delay.h                |  31 +--
 include/asyncpp/timing/delay.inl              |  21 +-
 include/asyncpp/timing/interval.h             |   7 +-
 include/asyncpp/timing/interval.inl           |  10 +-
 include/asyncpp/timing/timeout.h              |  47 ++--
 include/asyncpp/timing/timeout.inl            |  58 ++---
 test/asyncpp/core/future_tests.cpp            |  51 +----
 test/asyncpp/core/task_tests.cpp              |  34 +--
 .../asyncpp/executor/current_thread_tests.cpp |  47 ++--
 test/asyncpp/timing/delay_tests.cpp           |   3 +-
 test/asyncpp/timing/timeout_tests.cpp         |  42 ++--
 test/asyncpp/timing/timer_tests.cpp           |  12 +-
 test/helper/test_delay.h                      |  33 +++
 23 files changed, 433 insertions(+), 503 deletions(-)
 create mode 100644 test/helper/test_delay.h

diff --git a/include/asyncpp/core/future.h b/include/asyncpp/core/future.h
index ca5d0ef..b2f6357 100644
--- a/include/asyncpp/core/future.h
+++ b/include/asyncpp/core/future.h
@@ -12,61 +12,84 @@ namespace asyncpp
 {
 
     template<
-        typename T_object,
-        typename T_impl>
-    struct future
+        typename T_value,
+        typename T_derived>
+    struct base_future
+        : public tag_future
     {
-        using object_type       = T_object;
-        using clean_object_type = std::decay_t<object_type>;
-        using trait_type        = future_trait<clean_object_type>;
-        using value_type        = typename trait_type::value_type;
-        using result_type       = future_result<value_type>;
-        using reference         = clean_object_type&;
-        using pointer           = clean_object_type*;
-        using const_reference   = const clean_object_type&;
-        using const_pointer     = const clean_object_type*;
-
-        object_type ref;
+    public:
+        using value_type    = T_value;
+        using result_type   = future_result<value_type>;
+        using derived_type  = T_derived;
+        using this_type     = base_future<value_type, derived_type>;
 
+    public:
         /**
-         * @brief Value constructor.
+         * @brief Transform the result of this future.
          */
-        template<typename X_object>
-        inline future(X_object&& p_ref);
+        template<typename X_lambda>
+        inline auto map(X_lambda&& p_lambda) const &;
 
         /**
-         * @brief Function that will be called repeatedly to check if the future is ready.
+         * @brief Transform the result of this future.
          */
-        inline result_type poll();
+        template<typename X_lambda>
+        inline auto map(X_lambda&& p_lambda) &;
 
         /**
          * @brief Transform the result of this future.
          */
         template<typename X_lambda>
-        inline auto map(X_lambda&& p_lambda);
+        inline auto map(X_lambda&& p_lambda) &&;
+
+    public:
+        /**
+         * @brief Execute the given lambda after the future is finished and
+         *        wait for the future returned by the lambda.
+         */
+        template<typename X_lambda>
+        inline auto and_then(X_lambda&& p_lambda) const &;
 
         /**
          * @brief Execute the given lambda after the future is finished and
          *        wait for the future returned by the lambda.
          */
         template<typename X_lambda>
-        inline auto and_then(X_lambda&& p_lambda);
+        inline auto and_then(X_lambda&& p_lambda) &;
 
-        #ifdef asyncpp_timing
+        /**
+         * @brief Execute the given lambda after the future is finished and
+         *        wait for the future returned by the lambda.
+         */
+        template<typename X_lambda>
+        inline auto and_then(X_lambda&& p_lambda) &&;
+
+    #ifdef asyncpp_timing
+    public:
         /**
          * @brief Throw an execption if the timeout has passed.
          *
          * This method is only enabled if timer.h is included before.
          */
         template<typename X_base, typename X_ratio>
-        inline auto timeout(const duration<X_base, X_ratio>& p_timeout);
-        #endif
+        inline auto timeout(const duration<X_base, X_ratio>& p_timeout) const &;
 
-    public:
-        inline pointer operator->();
-        inline reference operator*();
-        inline const_pointer operator->() const;
-        inline const_reference operator*() const;
+        /**
+         * @brief Throw an execption if the timeout has passed.
+         *
+         * This method is only enabled if timer.h is included before.
+         */
+        template<typename X_base, typename X_ratio>
+        inline auto timeout(const duration<X_base, X_ratio>& p_timeout) &;
+
+        /**
+         * @brief Throw an execption if the timeout has passed.
+         *
+         * This method is only enabled if timer.h is included before.
+         */
+        template<typename X_base, typename X_ratio>
+        inline auto timeout(const duration<X_base, X_ratio>& p_timeout) &&;
+    #endif
     };
 
 }
diff --git a/include/asyncpp/core/future.inl b/include/asyncpp/core/future.inl
index 1659aa5..274a3d9 100644
--- a/include/asyncpp/core/future.inl
+++ b/include/asyncpp/core/future.inl
@@ -12,143 +12,174 @@
 namespace asyncpp
 {
 
-    /* future_base */
+    /* future::map */
 
-    template<typename T_impl>
-    template<typename X_future, typename X_lambda>
-    auto future_base<T_impl>
-        ::map(X_future&& self, X_lambda&& p_lambda)
+    template<
+        typename T_value,
+        typename T_derived>
+    template<
+        typename X_lambda>
+    auto base_future<T_value, T_derived>
+        ::map(X_lambda&& p_lambda) const &
     {
-        using future_type   = X_future;
-        using lambda_type   = X_lambda;
-        using map_type      = __future::map_impl<future_type, lambda_type>;
+        using lambda_type = X_lambda;
+        using map_type    = __future::map_impl<derived_type, lambda_type>;
+
+        auto& self = static_cast<derived_type const &>(*this);
 
-        return as_future(map_type(
-            std::forward<X_future>(self),
-            std::forward<X_lambda>(p_lambda)));
+        return map_type(
+            std::forward<derived_type const>(self),
+            std::forward<X_lambda>(p_lambda));
     }
 
-    template<typename T_impl>
-    template<typename X_future, typename X_lambda>
-    auto future_base<T_impl>
-        ::and_then(X_future&& self, X_lambda&& p_lambda)
+    template<
+        typename T_value,
+        typename T_derived>
+    template<
+        typename X_lambda>
+    auto base_future<T_value, T_derived>
+        ::map(X_lambda&& p_lambda) &
     {
-        using future_type   = X_future;
-        using lambda_type   = X_lambda;
-        using and_then_type = __future::and_then_impl<future_type, lambda_type>;
+        using lambda_type = X_lambda;
+        using map_type    = __future::map_impl<derived_type&, lambda_type>;
+
+        auto& self = static_cast<derived_type &>(*this);
 
-        return as_future(and_then_type(
-            std::forward<X_future>(self),
-            std::forward<X_lambda>(p_lambda)));
+        return map_type(
+            std::forward<derived_type &>(self),
+            std::forward<X_lambda>(p_lambda));
     }
 
-    #ifdef asyncpp_timing
-    template<typename T_impl>
-    template<typename X_future, typename X_base, typename X_ratio>
-    auto future_base<T_impl>
-        ::timeout(X_future&& self, const duration<X_base, X_ratio>& p_timeout)
+    template<
+        typename T_value,
+        typename T_derived>
+    template<
+        typename X_lambda>
+    auto base_future<T_value, T_derived>
+        ::map(X_lambda&& p_lambda) &&
     {
-        using future_type   = X_future;
-        using timeout_type  = timing::timeout<future_type>;
+        using lambda_type = X_lambda;
+        using map_type    = __future::map_impl<derived_type, lambda_type>;
 
-        return as_future(timeout_type(
-            std::forward<X_future>(self),
-            p_timeout));
+        auto& self = static_cast<derived_type &>(*this);
+
+        return map_type(
+            std::forward<derived_type &&>(self),
+            std::forward<X_lambda>(p_lambda));
     }
-    #endif
 
-    /* future */
+    /* future::and_then */
 
     template<
         typename T_value,
-        typename T_impl>
+        typename T_derived>
     template<
-        typename X_object>
-    future<T_value, T_impl>
-        ::future(X_object&& p_ref)
-            : ref(std::forward<X_object>(p_ref))
-        { }
+        typename X_lambda>
+    auto base_future<T_value, T_derived>
+        ::and_then(X_lambda&& p_lambda) const &
+    {
+        using lambda_type   = X_lambda;
+        using and_then_type = __future::and_then_impl<derived_type, lambda_type>;
 
-    template<
-        typename T_value,
-        typename T_impl>
-    typename future<T_value, T_impl>::result_type
-    future<T_value, T_impl>
-        ::poll()
-        { return trait_type::poll(*this); }
+        auto& self = static_cast<derived_type const &>(*this);
+
+        return and_then_type(
+            std::forward<derived_type const>(self),
+            std::forward<X_lambda>(p_lambda));
+    }
 
     template<
         typename T_value,
-        typename T_impl>
+        typename T_derived>
     template<
         typename X_lambda>
-    auto future<T_value, T_impl>
-        ::map(X_lambda&& p_lambda)
-        { return trait_type::map(std::move(*this), std::forward<X_lambda>(p_lambda)); }
+    auto base_future<T_value, T_derived>
+        ::and_then(X_lambda&& p_lambda) &
+    {
+        using lambda_type   = X_lambda;
+        using and_then_type = __future::and_then_impl<derived_type&, lambda_type>;
+
+        auto& self = static_cast<derived_type &>(*this);
+
+        return and_then_type(
+            std::forward<derived_type &>(self),
+            std::forward<X_lambda>(p_lambda));
+    }
 
     template<
         typename T_value,
-        typename T_impl>
+        typename T_derived>
     template<
         typename X_lambda>
-    auto future<T_value, T_impl>
-        ::and_then(X_lambda&& p_lambda)
-        { return trait_type::and_then(std::move(*this), std::forward<X_lambda>(p_lambda)); }
+    auto base_future<T_value, T_derived>
+        ::and_then(X_lambda&& p_lambda) &&
+    {
+        using lambda_type   = X_lambda;
+        using and_then_type = __future::and_then_impl<derived_type, lambda_type>;
+
+        auto& self = static_cast<derived_type &>(*this);
+
+        return and_then_type(
+            std::forward<derived_type &&>(self),
+            std::forward<X_lambda>(p_lambda));
+    }
+
+    /* future::timeout */
 
     #ifdef asyncpp_timing
     template<
         typename T_value,
-        typename T_impl>
+        typename T_derived>
     template<
         typename X_base,
         typename X_ratio>
-    auto future<T_value, T_impl>
-        ::timeout(const duration<X_base, X_ratio>& p_timeout)
-        { return trait_type::timeout(std::move(*this), p_timeout); }
-    #endif
+    auto base_future<T_value, T_derived>
+        ::timeout(const duration<X_base, X_ratio>& p_timeout) const &
+    {
+        using timeout_type = timing::timeout<derived_type>;
 
-    template<
-        typename T_value,
-        typename T_impl>
-    typename future<T_value, T_impl>::pointer
-    future<T_value, T_impl>::operator->()
-        { return &ref; }
+        auto& self = static_cast<derived_type const &>(*this);
 
-    template<
-        typename T_value,
-        typename T_impl>
-    typename future<T_value, T_impl>::reference
-    future<T_value, T_impl>::operator*()
-        { return ref; }
+        return timeout_type(
+            std::forward<derived_type const>(self),
+            p_timeout);
+    }
 
     template<
         typename T_value,
-        typename T_impl>
-    typename future<T_value, T_impl>::const_pointer
-    future<T_value, T_impl>::operator->() const
-        { return &ref; }
-
+        typename T_derived>
     template<
-        typename T_value,
-        typename T_impl>
-    typename future<T_value, T_impl>::const_reference
-    future<T_value, T_impl>::operator*() const
-        { return ref; }
+        typename X_base,
+        typename X_ratio>
+    auto base_future<T_value, T_derived>
+        ::timeout(const duration<X_base, X_ratio>& p_timeout) &
+    {
+        using timeout_type = timing::timeout<derived_type&>;
 
-    /* misc */
+        auto& self = static_cast<derived_type &>(*this);
 
-    template<typename X_value>
-    constexpr future<X_value> as_future(X_value&& value)
+        return timeout_type(
+            std::forward<derived_type &>(self),
+            p_timeout);
+    }
+
+    template<
+        typename T_value,
+        typename T_derived>
+    template<
+        typename X_base,
+        typename X_ratio>
+    auto base_future<T_value, T_derived>
+        ::timeout(const duration<X_base, X_ratio>& p_timeout) &&
     {
-        using value_type  = X_value;
-        using future_type = future<value_type>;
+        using timeout_type = timing::timeout<derived_type>;
 
-        return future_type(std::forward<X_value>(value));
-    }
+        auto& self = static_cast<derived_type &>(*this);
 
-    template<typename T>
-    struct is_future<future<T>, void>
-        : public std::true_type
-        { };
+        return timeout_type(
+            std::forward<derived_type &&>(self),
+            p_timeout);
+    }
+    #endif
 
 }
diff --git a/include/asyncpp/core/future.pre.h b/include/asyncpp/core/future.pre.h
index c61db97..8902d35 100644
--- a/include/asyncpp/core/future.pre.h
+++ b/include/asyncpp/core/future.pre.h
@@ -5,48 +5,20 @@
 namespace asyncpp
 {
 
-    template<typename T_impl>
-    struct future_base
-    {
-    public:
-        using impl_type = T_impl;
-
-    public:
-        template<typename X_future>
-        static inline auto poll(X_future& self) = delete;
-
-        template<typename X_future, typename X_lambda>
-        static inline auto map(X_future&& self, X_lambda&& p_lambda);
-
-        template<typename X_future, typename X_lambda>
-        static inline auto and_then(X_future&& self, X_lambda&& p_lambda);
-
-        #ifdef asyncpp_timing
-        template<typename X_future, typename X_base, typename X_ratio>
-        static inline auto timeout(X_future&& self, const duration<X_base, X_ratio>& p_timeout);
-        #endif
-    };
-
-    template<typename T, typename = void>
-    struct future_trait;
+    struct tag_future
+        { };
 
     template<
-        typename T_object,
-        typename T_impl = future_trait<std::decay_t<T_object>>>
-    struct future;
+        typename T_value,
+        typename T_derived>
+    struct base_future;
 
-    template<typename T, typename = void>
+    template<typename T>
     struct is_future
-        : public std::false_type
+        : public std::is_base_of<tag_future, T>
         { };
 
     template<typename T>
     constexpr decltype(auto) is_future_v = is_future<T>::value;
 
-    /**
-     * @brief Construct a future from the given value.
-     */
-    template<typename X_value>
-    constexpr future<X_value> as_future(X_value&& value);
-
 }
diff --git a/include/asyncpp/core/future/and_then.h b/include/asyncpp/core/future/and_then.h
index fd31566..8cf2ce2 100644
--- a/include/asyncpp/core/future/and_then.h
+++ b/include/asyncpp/core/future/and_then.h
@@ -2,7 +2,7 @@
 
 #include <memory>
 
-#include <asyncpp/core/future.pre.h>
+#include "../future.pre.h"
 
 namespace asyncpp {
 namespace __future {
@@ -10,14 +10,22 @@ namespace __future {
     template<
         typename T_future,
         typename T_lambda>
-    struct and_then_impl
+    struct and_then_impl final :
+        public base_future<
+            decltype(std::declval<T_lambda>()(std::declval<typename std::decay_t<T_future>::value_type>())),
+            and_then_impl<T_future, T_lambda>
+        >
     {
     public:
         using lambda_type               = T_lambda;
         using first_future_type         = T_future;
-        using first_value_type          = typename first_future_type::value_type;
-        using second_future_type        = decltype(as_future(std::declval<lambda_type>()(std::declval<first_value_type>())));
+        using first_value_type          = typename std::decay_t<first_future_type>::value_type;
+        using second_future_type        = decltype(std::declval<lambda_type>()(std::declval<first_value_type>()));
         using second_future_type_ptr    = std::unique_ptr<second_future_type>;
+        using value_type                = typename second_future_type::value_type;
+        using this_type                 = and_then_impl<value_type, lambda_type>;
+        using base_future_type          = base_future<value_type, this_type>;
+        using result_type               = typename base_future_type::result_type;
 
     public:
         lambda_type             lambda;
@@ -34,28 +42,12 @@ namespace __future {
         inline and_then_impl(
             X_future&& p_outer,
             X_lambda&& p_lambda);
-    };
-
-} }
-
-namespace asyncpp
-{
 
-    /* future_trait for and_then_impl */
-
-    template<
-        typename T_future,
-        typename T_lambda>
-    struct future_trait<__future::and_then_impl<T_future, T_lambda>, void>
-        : public future_base<future<__future::and_then_impl<T_future, T_lambda>, void>>
-    {
-        using and_then_type      = __future::and_then_impl<T_future, T_lambda>;
-        using second_future_type = typename and_then_type::second_future_type;
-        using value_type         = typename second_future_type::value_type;
-        using result_type        = typename second_future_type::result_type;
-
-        template<typename X_future>
-        static inline auto poll(X_future& self);
+    public: /* future */
+        /**
+         * @brief Poll the result from the future.
+         */
+        inline result_type poll();
     };
 
-}
+} }
diff --git a/include/asyncpp/core/future/and_then.inl b/include/asyncpp/core/future/and_then.inl
index 81f3c26..df34ba7 100644
--- a/include/asyncpp/core/future/and_then.inl
+++ b/include/asyncpp/core/future/and_then.inl
@@ -21,36 +21,28 @@ namespace __future {
         , lambda(std::forward<X_lambda>(p_lambda))
         { }
 
-} }
-
-namespace asyncpp
-{
-
-    /* future_trait for ant_then_impl */
-
     template<
         typename T_future,
         typename T_lambda>
-    template<
-        typename X_future>
-    auto future_trait<__future::and_then_impl<T_future, T_lambda>, void>
-        ::poll(X_future& self)
+    typename and_then_impl<T_future, T_lambda>::result_type
+    and_then_impl<T_future, T_lambda>
+        ::poll()
     {
         while (true)
         {
-            if (self->second)
+            if (second)
             {
-                return self->second->poll();
+                return second->poll();
             }
             else
             {
-                auto r = self->first.poll();
+                auto r = first.poll();
                 if (!r)
                     return result_type::not_ready();
 
-                self->second = std::make_unique<second_future_type>(as_future(r.call(self->lambda)));
+                second = std::make_unique<second_future_type>(r.call(lambda));
             }
         }
     }
 
-}
+} }
diff --git a/include/asyncpp/core/future/map.h b/include/asyncpp/core/future/map.h
index f3e026b..eed3ede 100644
--- a/include/asyncpp/core/future/map.h
+++ b/include/asyncpp/core/future/map.h
@@ -1,16 +1,27 @@
 #pragma once
 
+#include "../future.pre.h"
+
 namespace asyncpp {
 namespace __future {
 
     template<
         typename T_future,
         typename T_lambda>
-    struct map_impl
+    struct map_impl final :
+        public base_future<
+            typename std::decay_t<T_future>::value_type,
+            map_impl<T_future, T_lambda>
+        >
     {
     public:
-        using future_type = T_future;
-        using lambda_type = T_lambda;
+        using future_type       = T_future;
+        using lambda_type       = T_lambda;
+        using future_value_type = typename std::decay_t<future_type>::value_type;
+        using value_type        = decltype(std::declval<lambda_type>()(std::declval<future_value_type>()));
+        using this_type         = map_impl<future_type, lambda_type>;
+        using base_future_type  = base_future<value_type, this_type>;
+        using result_type       = typename base_future_type::result_type;
 
     public:
         future_type future;
@@ -26,29 +37,12 @@ namespace __future {
         inline map_impl(
             X_future&& p_future,
             X_lambda&& p_lambda);
-    };
-
-} }
-
-namespace asyncpp
-{
-
-    /* future_trait for map_impl */
-
-    template<
-        typename T_future,
-        typename T_lambda>
-    struct future_trait<__future::map_impl<T_future, T_lambda>, void>
-        : public future_base<future<__future::map_impl<T_future, T_lambda>, void>>
-    {
-        using future_type       = T_future;
-        using inner_value_type  = typename future_type::value_type;
-        using lambda_type       = T_lambda;
-        using value_type        = decltype(std::declval<lambda_type>()(std::declval<inner_value_type>()));
-        using result_type       = future_result<value_type>;
 
-        template<typename X_future>
-        static inline auto poll(X_future& self);
+    public: /* future */
+        /**
+         * @brief Poll the result from the future.
+         */
+        inline result_type poll();
     };
 
-}
+} }
diff --git a/include/asyncpp/core/future/map.inl b/include/asyncpp/core/future/map.inl
index 34074e8..bdc6c39 100644
--- a/include/asyncpp/core/future/map.inl
+++ b/include/asyncpp/core/future/map.inl
@@ -21,25 +21,17 @@ namespace __future {
         , lambda(std::forward<X_lambda>(p_lambda))
         { }
 
-} }
-
-namespace asyncpp
-{
-
-    /* future_trait for map_impl */
-
     template<
         typename T_future,
         typename T_lambda>
-    template<
-        typename X_future>
-    auto future_trait<__future::map_impl<T_future, T_lambda>, void>
-        ::poll(X_future& self)
+    typename map_impl<T_future, T_lambda>::result_type
+    map_impl<T_future, T_lambda>
+        ::poll()
     {
-        auto r = self->future.poll();
+        auto r = future.poll();
         return r
-            ? result_type::ready(r.call(self->lambda))
+            ? result_type::ready(r.call(lambda))
             : result_type::not_ready();
     }
 
-}
+} }
diff --git a/include/asyncpp/core/stream.inl b/include/asyncpp/core/stream.inl
index ed1c88f..1fce400 100644
--- a/include/asyncpp/core/stream.inl
+++ b/include/asyncpp/core/stream.inl
@@ -22,9 +22,9 @@ namespace asyncpp
         using lambda_type   = X_lambda;
         using for_each_type = __stream::for_each_impl<stream_type, lambda_type>;
 
-        return as_future(for_each_type(
+        return for_each_type(
             std::forward<X_stream>(self),
-            std::forward<X_lambda>(p_lambda)));
+            std::forward<X_lambda>(p_lambda));
     }
 
     #ifdef asyncpp_timing
diff --git a/include/asyncpp/core/stream/for_each.h b/include/asyncpp/core/stream/for_each.h
index a4e9050..491dfed 100644
--- a/include/asyncpp/core/stream/for_each.h
+++ b/include/asyncpp/core/stream/for_each.h
@@ -8,11 +8,19 @@ namespace __stream {
     template<
         typename T_stream,
         typename T_lambda>
-    struct for_each_impl
+    struct for_each_impl final :
+        public base_future<
+            void,
+            for_each_impl<T_stream, T_lambda>
+        >
     {
     public:
-        using stream_type = T_stream;
-        using lambda_type = T_lambda;
+        using stream_type       = T_stream;
+        using lambda_type       = T_lambda;
+        using value_type        = void;
+        using this_type         = for_each_impl<stream_type, lambda_type>;
+        using base_future_type  = base_future<value_type, this_type>;
+        using result_type       = typename base_future_type::result_type;
 
     public:
         stream_type stream;
@@ -28,30 +36,12 @@ namespace __stream {
         inline for_each_impl(
             X_stream&& p_stream,
             X_lambda&& p_lambda);
-    };
-
-} }
 
-namespace asyncpp
-{
-
-    /* future_trait for map_impl */
-
-    template<
-        typename T_stream,
-        typename T_lambda>
-    struct future_trait<__stream::for_each_impl<T_stream, T_lambda>, void>
-        : public future_base<future<__stream::for_each_impl<T_stream, T_lambda>, void>>
-    {
-        using stream_type       = T_stream;
-        using inner_value_type  = typename stream_type::value_type;
-        using inner_result_type = future_result<inner_value_type>;
-        using lambda_type       = T_lambda;
-        using value_type        = decltype(std::declval<inner_result_type>().call(std::declval<lambda_type>()));
-        using result_type       = future_result<value_type>;
-
-        template<typename X_future>
-        static inline auto poll(X_future& self);
+    public: /* future */
+        /**
+         * @brief Poll the result from the future.
+         */
+        inline result_type poll();
     };
 
-}
+} }
diff --git a/include/asyncpp/core/stream/for_each.inl b/include/asyncpp/core/stream/for_each.inl
index 2d2dfc7..1ad6581 100644
--- a/include/asyncpp/core/stream/for_each.inl
+++ b/include/asyncpp/core/stream/for_each.inl
@@ -21,32 +21,24 @@ namespace __stream {
         , lambda(std::forward<X_lambda>(p_lambda))
         { }
 
-} }
-
-namespace asyncpp
-{
-
-    /* future_trait for for_each_impl */
-
     template<
         typename T_stream,
         typename T_lambda>
-    template<
-        typename X_stream>
-    auto future_trait<__stream::for_each_impl<T_stream, T_lambda>, void>
-        ::poll(X_stream& self)
+    typename for_each_impl<T_stream, T_lambda>::result_type
+    for_each_impl<T_stream, T_lambda>
+        ::poll()
     {
         while (true)
         {
-            auto r = self->stream.poll();
+            auto r = stream.poll();
             if (r.is_done())
                 return result_type::ready();
 
             if (r.is_not_ready())
                 return result_type::not_ready();
 
-            r.call(self->lambda);
+            r.call(lambda);
         }
     }
 
-}
+} }
diff --git a/include/asyncpp/timing/delay.h b/include/asyncpp/timing/delay.h
index 116f560..fda6241 100644
--- a/include/asyncpp/timing/delay.h
+++ b/include/asyncpp/timing/delay.h
@@ -9,10 +9,13 @@
 namespace asyncpp {
 namespace timing {
 
-    struct delay
+    struct delay final
+        : public base_future<void, delay>
     {
     public:
-        friend struct future_trait<delay, void>;
+        using value_type        = void;
+        using base_future_type  = base_future<void, delay>;
+        using result_type       = typename base_future_type::result_type;
 
     private:
         time_point                  _deadline;
@@ -50,24 +53,12 @@ namespace timing {
          */
         template<typename T_base, typename T_ratio>
         inline void reset(const duration<T_base, T_ratio>& p_duration);
-    };
-
-} }
-
-namespace asyncpp
-{
-
-    /* future_impl for timing::delay */
 
-    template<>
-    struct future_trait<timing::delay, void>
-        : public future_base<future<timing::delay, void>>
-    {
-        using value_type    = void;
-        using result_type   = future_result<value_type>;
-
-        template<typename X_future>
-        static inline auto poll(X_future& self);
+    public: /* future */
+        /**
+         * @brief Poll the result from the future.
+         */
+        inline result_type poll();
     };
 
-}
+} }
diff --git a/include/asyncpp/timing/delay.inl b/include/asyncpp/timing/delay.inl
index d3b7f4f..95d158e 100644
--- a/include/asyncpp/timing/delay.inl
+++ b/include/asyncpp/timing/delay.inl
@@ -43,26 +43,19 @@ namespace timing {
         _deadline = asyncpp::now() + p_duration;
     }
 
-} }
-
-namespace asyncpp
-{
-
-    /* future_impl for timing::delay */
-
-    template<typename X_future>
-    auto future_trait<timing::delay, void>
-        ::poll(X_future& self)
+    typename delay::result_type
+    delay
+        ::poll()
     {
         auto now = asyncpp::now();
 
-        if (self->_deadline <= now)
+        if (_deadline <= now)
             return result_type::ready();
 
-        if (self->_registration.expired())
-            self->_registration = timing::__impl::timer_base::register_resource(self->_deadline);
+        if (_registration.expired())
+            _registration = timing::__impl::timer_base::register_resource(_deadline);
 
         return result_type::not_ready();
     }
 
-}
+} }
diff --git a/include/asyncpp/timing/interval.h b/include/asyncpp/timing/interval.h
index 5ba811a..c8ac674 100644
--- a/include/asyncpp/timing/interval.h
+++ b/include/asyncpp/timing/interval.h
@@ -9,16 +9,13 @@
 namespace asyncpp {
 namespace timing {
 
-    struct interval
+    struct interval final
     {
-    public:
-        using delay_future_type = future<delay>;
-
     public:
         friend struct stream_trait<interval, void>;
 
     private:
-        delay_future_type   _delay;     //!< Delay future
+        delay               _delay;     //!< Delay future
         clock::duration     _duration;  //!< Interval duration.
         time_point          _deadline;  //!< Deadline after the interval should end.
 
diff --git a/include/asyncpp/timing/interval.inl b/include/asyncpp/timing/interval.inl
index 4f26dac..898ec88 100644
--- a/include/asyncpp/timing/interval.inl
+++ b/include/asyncpp/timing/interval.inl
@@ -22,7 +22,7 @@ namespace timing {
         const time_point&                           p_at,
         const asyncpp::duration<T_base, T_ratio>&   p_duration,
         time_point                                  p_deadline)
-            : _delay   (as_future(delay(p_at)))
+            : _delay   (p_at)
             , _duration(p_duration)
             , _deadline(p_deadline)
             { }
@@ -43,17 +43,17 @@ namespace asyncpp
         ::poll(X_stream& self)
     {
         if (    self->_deadline.time_since_epoch().count()
-            &&  self->_delay->deadline() >= self->_deadline
-            &&  asyncpp::now()           >= self->_delay->deadline())
+            &&  self->_delay.deadline() >= self->_deadline
+            &&  asyncpp::now()           >= self->_delay.deadline())
             return result_type::done();
 
         auto ret = self->_delay.poll();
         if (ret.is_not_ready())
             return result_type::not_ready();
 
-        auto now = self->_delay->deadline();
+        auto now = self->_delay.deadline();
         auto new_deadline = now + self->_duration;
-        self->_delay->reset(new_deadline);
+        self->_delay.reset(new_deadline);
 
         return result_type::ready();
     }
diff --git a/include/asyncpp/timing/timeout.h b/include/asyncpp/timing/timeout.h
index c4260d6..82cdcfd 100644
--- a/include/asyncpp/timing/timeout.h
+++ b/include/asyncpp/timing/timeout.h
@@ -21,21 +21,27 @@ namespace timing {
         inline timeout_exception();
     };
 
+    struct tag_timeout
+        { };
+
     template<typename T_inner>
-    struct timeout
+    struct timeout final
+        :   public std::conditional_t<
+                is_future_v<T_inner>,
+                base_future<typename std::decay_t<T_inner>::value_type, timeout<T_inner>>,
+                tag_timeout>
     {
     public:
-        using inner_type        = T_inner;
-        using delay_future_type = future<delay>;
+        using inner_type = T_inner;
+        using value_type = typename std::decay_t<inner_type>::value_type;
 
     public:
         friend struct stream_trait<timeout, void>;
-        friend struct future_trait<timeout, void>;
 
     private:
-        inner_type          _inner;     //!< Inner future / stream.
-        clock::duration     _timeout;   //!< Timeout.
-        delay_future_type   _delay;     //!< Delay future.
+        inner_type      _inner;     //!< Inner future / stream.
+        clock::duration _timeout;   //!< Timeout.
+        delay           _delay;     //!< Delay future.
 
     public:
         /**
@@ -52,6 +58,15 @@ namespace timing {
         template<typename X_base, typename X_ratio>
         inline void reset(
             const duration<X_base, X_ratio>& p_timeout);
+
+    public: /* future */
+        /**
+         * @brief Poll the result from the future.
+         */
+        template<
+            typename X = std::decay_t<inner_type>,
+            typename = std::enable_if_t<is_future_v<X>>>
+        inline auto poll();
     };
 
 } }
@@ -59,24 +74,6 @@ namespace timing {
 namespace asyncpp
 {
 
-    /* future_trait for timing::timeout */
-
-    template<typename T_inner>
-    struct future_trait<
-        timing::timeout<T_inner>,
-        std::enable_if_t<is_future_v<T_inner>>
-    >
-        : public future_base<future<timing::timeout<T_inner>, void>>
-    {
-        using inner_type    = T_inner;
-        using timeout_type  = timing::timeout<inner_type>;
-        using value_type    = typename inner_type::value_type;
-        using result_type   = typename inner_type::result_type;
-
-        template<typename X_future>
-        static inline result_type poll(X_future& self);
-    };
-
     /* stream_trait for timing::timeout */
 
     template<typename T_inner>
diff --git a/include/asyncpp/timing/timeout.inl b/include/asyncpp/timing/timeout.inl
index 9f99a47..14b6a4e 100644
--- a/include/asyncpp/timing/timeout.inl
+++ b/include/asyncpp/timing/timeout.inl
@@ -15,55 +15,59 @@ namespace timing {
 
     /* timer */
 
-    template<typename T_inner>
-    template<typename X_inner, typename X_base, typename X_ratio>
+    template<
+        typename T_inner>
+    template<
+        typename X_inner,
+        typename X_base,
+        typename X_ratio>
     timeout<T_inner>
         ::timeout(
             X_inner&&                           p_inner,
             const duration<X_base, X_ratio>&    p_duration)
             : _inner    (std::forward<X_inner>(p_inner))
             , _timeout  (p_duration)
-            , _delay    (as_future(delay(asyncpp::now() + p_duration)))
+            , _delay    (asyncpp::now() + p_duration)
         { }
 
-    template<typename T_inner>
-    template<typename X_base, typename X_ratio>
+    template<
+        typename T_inner>
+    template<
+        typename X_base,
+        typename X_ratio>
     void timeout<T_inner>
         ::reset(const duration<X_base, X_ratio>& p_duration)
     {
         _timeout = p_duration;
-        _delay->reset(asyncpp::now() + p_duration);
+        _delay.reset(asyncpp::now() + p_duration);
     }
 
-} }
-
-namespace asyncpp
-{
-
-    /* future_trait for timing::timeout */
-
-    template<typename T_inner>
-    template<typename X_future>
-    typename T_inner::result_type
-    future_trait<
-        timing::timeout<T_inner>,
-        std::enable_if_t<is_future_v<T_inner>>
-    >
-        ::poll(X_future& self)
+    template<
+        typename T_inner>
+    template<
+        typename X,
+        typename>
+    auto timeout<T_inner>
+        ::poll()
     {
-        auto r = self->_inner.poll();
+        auto r = _inner.poll();
 
         if (    r.is_not_ready()
-            &&  self->_delay.poll())
+            &&  _delay.poll())
         {
-            auto new_deadline = self->_delay->deadline() + self->_timeout;
-            self->_delay->reset(new_deadline);
+            auto new_deadline = _delay.deadline() + _timeout;
+            _delay.reset(new_deadline);
             throw timing::timeout_exception();
         }
 
         return r;
     }
 
+} }
+
+namespace asyncpp
+{
+
     /* stream_trait for timing::timeout */
 
     template<typename T_inner>
@@ -81,13 +85,13 @@ namespace asyncpp
         {
             if (self->_delay.poll())
             {
-                self->_delay->reset(self->_timeout);
+                self->_delay.reset(self->_timeout);
                 throw timing::timeout_exception();
             }
         }
         else
         {
-            self->_delay->reset(self->_timeout);
+            self->_delay.reset(self->_timeout);
         }
 
         return r;
diff --git a/test/asyncpp/core/future_tests.cpp b/test/asyncpp/core/future_tests.cpp
index 78c8b7f..3901406 100644
--- a/test/asyncpp/core/future_tests.cpp
+++ b/test/asyncpp/core/future_tests.cpp
@@ -2,43 +2,14 @@
 
 #include <asyncpp.h>
 
+#include "../../helper/test_delay.h"
+
 using namespace ::testing;
 using namespace ::asyncpp;
 
-struct delay
-{
-    int const   delay   { 5 };
-    int         count   { 0 };
-};
-
-namespace asyncpp
-{
-
-    template<>
-    struct future_trait<delay, void>
-        : public future_base<future<delay, void>>
-    {
-        using value_type = int&;
-
-        template<typename T_future>
-        static inline auto poll(T_future& self)
-        {
-            using result_type = future_result<value_type>;
-
-            if (self->count >= self->delay)
-                return result_type::ready(self->count);
-
-            ++self->count;
-            return result_type::not_ready();
-        }
-    };
-
-}
-
 TEST(future_tests, poll)
 {
-    delay d { 5, 0 };
-    auto f = as_future(d);
+    test_delay f(5, 0);
 
     auto r0 = f.poll();
     ASSERT_FALSE(r0);
@@ -58,14 +29,14 @@ TEST(future_tests, poll)
     auto r = f.poll();
     ASSERT_TRUE (r);
     ASSERT_EQ   (5,   *r);
-    ASSERT_EQ   (5,    d.count);
-    ASSERT_EQ   (&*r, &d.count);
+    ASSERT_EQ   (5,    f._count);
+    ASSERT_EQ   (&*r, &f._count);
 }
 
 TEST(future_tests, map)
 {
-    delay d { 1, 1 };
-    auto f = as_future(d)
+    test_delay d(1, 1);
+    auto f = d
         .map([](int& i){
             return 10 + i;
         });
@@ -77,10 +48,10 @@ TEST(future_tests, map)
 
 TEST(future_tests, and_then)
 {
-    delay d { 2, 0 };
-    auto f = as_future(d)
+    test_delay d(2, 0);
+    auto f = d
         .and_then([](int& i){
-            return delay { 5, i };
+            return test_delay { 5, i };
         });
 
     auto r0 = f.poll();
@@ -101,5 +72,5 @@ TEST(future_tests, and_then)
     auto r = f.poll();
     ASSERT_TRUE(r);
     ASSERT_EQ  (5, *r);
-    ASSERT_EQ  (2, d.count);
+    ASSERT_EQ  (2, f.first._count);
 }
diff --git a/test/asyncpp/core/task_tests.cpp b/test/asyncpp/core/task_tests.cpp
index e1ead2e..90ae885 100644
--- a/test/asyncpp/core/task_tests.cpp
+++ b/test/asyncpp/core/task_tests.cpp
@@ -2,42 +2,14 @@
 
 #include <asyncpp.h>
 
+#include "../../helper/test_delay.h"
+
 using namespace ::testing;
 using namespace ::asyncpp;
 
-struct delay
-{
-    int const   delay   { 5 };
-    int         count   { 0 };
-};
-
-namespace asyncpp
-{
-
-    template<>
-    struct future_trait<delay, void>
-        : public future_base<future<delay, void>>
-    {
-        using value_type = int&;
-
-        template<typename T_future>
-        static inline auto poll(T_future& self)
-        {
-            using result_type = future_result<value_type>;
-
-            if (self->count >= self->delay)
-                return result_type::ready(self->count);
-
-            ++self->count;
-            return result_type::not_ready();
-        }
-    };
-
-}
-
 TEST(task_tests, poll)
 {
-    auto t = make_task(as_future(delay { 5, 0 }));
+    auto t = make_task(test_delay { 5, 0 });
 
     ASSERT_FALSE(t->poll());
     ASSERT_FALSE(t->poll());
diff --git a/test/asyncpp/executor/current_thread_tests.cpp b/test/asyncpp/executor/current_thread_tests.cpp
index 6d66761..c564d97 100644
--- a/test/asyncpp/executor/current_thread_tests.cpp
+++ b/test/asyncpp/executor/current_thread_tests.cpp
@@ -11,9 +11,29 @@ using namespace ::testing;
 using namespace ::asyncpp;
 
 struct test
+    : public base_future<void, test>
 {
+public:
+    using value_type        = void;
+    using this_type         = test;
+    using base_future_type  = base_future<void, this_type>;
+    using result_type       = typename base_future_type::result_type;
+
+public:
     bool        done    { false };
     task_ptr_w  task;
+
+public:
+    inline test() = default;
+
+public:
+    inline auto poll()
+    {
+        task = task::current();
+        return done
+            ? result_type::ready()
+            : result_type::not_ready();
+    }
 };
 
 struct mock
@@ -21,30 +41,8 @@ struct mock
     MOCK_METHOD0(call, void());
 };
 
-namespace asyncpp
-{
-
-    template<>
-    struct future_trait<test, void>
-        : public future_base<future<test, void>>
-    {
-        using value_type    = void;
-        using result_type   = future_result<value_type>;
-
-        template<typename X_future>
-        static inline auto poll(X_future& self)
-        {
-            self->task = task::current();
-            return self->done
-                ? result_type::ready()
-                : result_type::not_ready();
-        }
-    };
-
-}
-
 TEST(current_thread_tests, run)
-{/*
+{
     Sequence s;
     StrictMock<runtime_mock> m;
     executor::current_thread<StrictMock<runtime_mock>&> e(m);
@@ -52,7 +50,6 @@ TEST(current_thread_tests, run)
     EXPECT_CALL(m, init_thread());
 
     test t;
-    auto f = as_future(t);
 
     EXPECT_CALL(m, idle(nullptr))
         .InSequence(s)
@@ -68,7 +65,7 @@ TEST(current_thread_tests, run)
             s->notify();
         }));;
 
-    e.run(f); */
+    e.run(t);
 }
 
 TEST(current_thread_tests, interval)
diff --git a/test/asyncpp/timing/delay_tests.cpp b/test/asyncpp/timing/delay_tests.cpp
index 4f4bc5d..40cd8d3 100644
--- a/test/asyncpp/timing/delay_tests.cpp
+++ b/test/asyncpp/timing/delay_tests.cpp
@@ -22,8 +22,7 @@ TEST(delay_tests, poll)
     t.make_current();
 
     {
-    delay d(time_point(std::chrono::seconds(1000)));
-    auto f = as_future(d);
+    delay f(time_point(std::chrono::seconds(1000)));
 
     EXPECT_EQ(0, t.resource_count());
 
diff --git a/test/asyncpp/timing/timeout_tests.cpp b/test/asyncpp/timing/timeout_tests.cpp
index 1bae92c..439db09 100644
--- a/test/asyncpp/timing/timeout_tests.cpp
+++ b/test/asyncpp/timing/timeout_tests.cpp
@@ -10,28 +10,31 @@ using namespace ::asyncpp;
 using namespace ::asyncpp::timing;
 
 struct test
+    : public base_future<int, test>
 {
+public:
+    using value_type        = int;
+    using this_type         = test;
+    using base_future_type  = base_future<value_type, this_type>;
+
+public:
     int i;
-};
 
-namespace asyncpp
-{
+    inline test(int p_i)
+        : i(p_i)
+        { }
 
-    template<>
-    struct future_trait<test, void>
-        : public future_base<future<test, void>>
+public:
+    inline result_type poll()
     {
-        using value_type    = int;
-        using result_type   = future_result<value_type>;
+        return i
+            ? result_type::ready(i)
+            : result_type::not_ready();
+    }
+};
 
-        template<typename X_future>
-        static inline result_type poll(X_future& self)
-        {
-            return self->i
-                ? result_type::ready(self->i)
-                : result_type::not_ready();
-        }
-    };
+namespace asyncpp
+{
 
     template<>
     struct stream_trait<test, void>
@@ -62,8 +65,8 @@ TEST(timeout_tests, poll_future_no_timeout)
     EXPECT_CALL(m, now())
         .WillOnce(Return(time_point(std::chrono::seconds(0))));
 
-    auto t = test { 0 };
-    auto f = as_future(t)
+    test t(0);
+    auto f = t
         .timeout(std::chrono::seconds(5));
 
     EXPECT_CALL(m, now())
@@ -95,8 +98,7 @@ TEST(timeout_tests, poll_future_timeout)
     EXPECT_CALL(m, now())
         .WillOnce(Return(time_point(std::chrono::seconds(0))));
 
-    auto t = test { 0 };
-    auto f = as_future(t)
+    auto f = test(0)
         .timeout(std::chrono::seconds(5));
 
     EXPECT_CALL(m, now())
diff --git a/test/asyncpp/timing/timer_tests.cpp b/test/asyncpp/timing/timer_tests.cpp
index 87c2a11..9189641 100644
--- a/test/asyncpp/timing/timer_tests.cpp
+++ b/test/asyncpp/timing/timer_tests.cpp
@@ -38,14 +38,12 @@ TEST(timer_tests, resource_registration)
     EXPECT_CALL(m, now)
         .WillRepeatedly(Return(time_point(std::chrono::seconds(0))));
 
-    using delay_future_type = decltype(as_future(timing::delay(std::chrono::seconds(10))));
-
     timing::timer t;
     t.make_current();
 
-    auto f1 = std::make_unique<delay_future_type>(timing::delay(std::chrono::seconds(10)));
-    auto f2 = std::make_unique<delay_future_type>(timing::delay(std::chrono::seconds(20)));
-    auto f3 = std::make_unique<delay_future_type>(timing::delay(std::chrono::seconds(30)));
+    auto f1 = std::make_unique<timing::delay>(std::chrono::seconds(10));
+    auto f2 = std::make_unique<timing::delay>(std::chrono::seconds(20));
+    auto f3 = std::make_unique<timing::delay>(std::chrono::seconds(30));
 
     EXPECT_EQ(0, t.resource_count());
 
@@ -80,8 +78,6 @@ TEST(timer_tests, resource_registration)
 
 TEST(timer_tests, idle)
 {
-    using delay_future_type = decltype(as_future(std::declval<timing::delay>()));
-
     time_point x;
     InSequence seq;
     StrictMock<now_mock> nm;
@@ -102,7 +98,7 @@ TEST(timer_tests, idle)
 
     EXPECT_CALL(nm, now);
 
-    auto f = std::make_unique<delay_future_type>(timing::delay(time_point(std::chrono::seconds(10))));
+    auto f = std::make_unique<timing::delay>(time_point(std::chrono::seconds(10)));
     f->poll();
 
     EXPECT_CALL(nm, now);
diff --git a/test/helper/test_delay.h b/test/helper/test_delay.h
new file mode 100644
index 0000000..cd53c79
--- /dev/null
+++ b/test/helper/test_delay.h
@@ -0,0 +1,33 @@
+#pragma once
+
+#include <asyncpp.h>
+
+struct test_delay final
+    : public asyncpp::base_future<int&, test_delay>
+{
+public:
+    using value_type        = int&;
+    using this_type         = test_delay;
+    using base_future_type  = base_future<value_type, this_type>;
+    using result_type       = typename base_future_type::result_type;
+
+public:
+    int const   _delay  { 5 };
+    int         _count  { 0 };
+
+public:
+    test_delay(int p_delay, int p_count)
+        : _delay(p_delay)
+        , _count(p_count)
+        { }
+
+    inline result_type poll()
+    {
+        if (_count >= _delay)
+            return result_type::ready(_count);
+
+        ++_count;
+
+        return result_type::not_ready();
+    }
+};