From 74d94888d1434ae87d7687604ca262f723bbb828 Mon Sep 17 00:00:00 2001
From: Vladislav Oleshko <vladislav.oleshko@gmail.com>
Date: Wed, 13 Apr 2022 20:49:22 +0300
Subject: [PATCH 1/2] Generic app constructor

---
 include/crow/app.h     | 17 +++++++++++++++++
 include/crow/utility.h | 40 ++++++++++++++++++++++++++++++++++++++++
 tests/unittest.cpp     | 13 +++++++++++++
 3 files changed, 70 insertions(+)

diff --git a/include/crow/app.h b/include/crow/app.h
index 7eb327983..564a00bde 100644
--- a/include/crow/app.h
+++ b/include/crow/app.h
@@ -58,6 +58,12 @@ namespace crow
         Crow()
         {}
 
+        /// Construct Crow with a subset of middleware
+        template<typename... Ts>
+        Crow(Ts&&... ts):
+          middlewares_(make_middleware_tuple(std::forward<Ts>(ts)...))
+        {}
+
         /// Process an Upgrade request
 
         ///
@@ -431,6 +437,17 @@ namespace crow
             cv_started_.wait(lock);
         }
 
+    private:
+        template<typename... Ts>
+        std::tuple<Middlewares...> make_middleware_tuple(Ts&&... ts)
+        {
+            auto fwd = std::forward_as_tuple((ts)...);
+            return std::make_tuple(
+              std::forward<Middlewares>(
+                black_magic::tuple_extract<Middlewares, decltype(fwd)>(fwd))...);
+        }
+
+
     private:
         std::uint8_t timeout_{5};
         uint16_t port_ = 80;
diff --git a/include/crow/utility.h b/include/crow/utility.h
index 8597950b6..27713e547 100644
--- a/include/crow/utility.h
+++ b/include/crow/utility.h
@@ -263,6 +263,46 @@ namespace crow
         struct has_type<T, std::tuple<T, Ts...>> : std::true_type
         {};
 
+        // Find index of type in tuple
+        template<class T, class Tuple>
+        struct tuple_index;
+
+        template<class T, class... Types>
+        struct tuple_index<T, std::tuple<T, Types...>>
+        {
+            static const int value = 0;
+        };
+
+        template<class T, class U, class... Types>
+        struct tuple_index<T, std::tuple<U, Types...>>
+        {
+            static const int value = 1 + tuple_index<T, std::tuple<Types...>>::value;
+        };
+
+        // Extract element from forward tuple or get default
+#ifdef CROW_CAN_USE_CPP14
+        template<typename T, typename Tup>
+        typename std::enable_if<has_type<T&, Tup>::value, typename std::decay<T>::type&&>::type
+          tuple_extract(Tup& tup)
+        {
+            return std::move(std::get<T&>(tup));
+        }
+#else
+        template<typename T, typename Tup>
+        typename std::enable_if<has_type<T&, Tup>::value, T&&>::type
+          tuple_extract(Tup& tup)
+        {
+            return std::move(std::get<tuple_index<T&, Tup>::value>(tup));
+        }
+#endif
+
+        template<typename T, typename Tup>
+        typename std::enable_if<!has_type<T&, Tup>::value, T>::type
+          tuple_extract(Tup&)
+        {
+            return T{};
+        }
+
         // Check F is callable with Args
         template<typename F, typename... Args>
         struct is_callable
diff --git a/tests/unittest.cpp b/tests/unittest.cpp
index 4c980993f..6ab9cbf9f 100644
--- a/tests/unittest.cpp
+++ b/tests/unittest.cpp
@@ -1452,6 +1452,19 @@ TEST_CASE("local_middleware")
     app.stop();
 } // local_middleware
 
+struct OnlyMoveConstructor
+{
+    OnlyMoveConstructor(int) {}
+    OnlyMoveConstructor(const OnlyMoveConstructor&) = delete;
+    OnlyMoveConstructor(OnlyMoveConstructor&&) = default;
+};
+
+TEST_CASE("app_constructor")
+{
+    App<NullMiddleware, OnlyMoveConstructor, FirstMW, SecondMW>
+      app(OnlyMoveConstructor(1), SecondMW{});
+} // app_constructor
+
 TEST_CASE("middleware_cookieparser")
 {
     static char buf[2048];

From 946292747e867ffcac6eda301529a4e49b67a9c9 Mon Sep 17 00:00:00 2001
From: Vladislav Oleshko <vladislav.oleshko@gmail.com>
Date: Mon, 23 May 2022 20:17:49 +0300
Subject: [PATCH 2/2] Small fixes

---
 include/crow/utility.h | 32 ++++++++++++++++----------------
 tests/unittest.cpp     |  6 ++++--
 2 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/include/crow/utility.h b/include/crow/utility.h
index a20990a55..98206384e 100644
--- a/include/crow/utility.h
+++ b/include/crow/utility.h
@@ -265,6 +265,22 @@ namespace crow
         struct has_type<T, std::tuple<T, Ts...>> : std::true_type
         {};
 
+        // Find index of type in tuple
+        template<class T, class Tuple>
+        struct tuple_index;
+
+        template<class T, class... Types>
+        struct tuple_index<T, std::tuple<T, Types...>>
+        {
+            static const int value = 0;
+        };
+
+        template<class T, class U, class... Types>
+        struct tuple_index<T, std::tuple<U, Types...>>
+        {
+            static const int value = 1 + tuple_index<T, std::tuple<Types...>>::value;
+        };
+
         // Extract element from forward tuple or get default
 #ifdef CROW_CAN_USE_CPP14
         template<typename T, typename Tup>
@@ -288,22 +304,6 @@ namespace crow
         {
             return T{};
         }
-      
-        // Find index of type in tuple
-        template<class T, class Tuple>
-        struct tuple_index;
-
-        template<class T, class... Types>
-        struct tuple_index<T, std::tuple<T, Types...>>
-        {
-            static const int value = 0;
-        };
-
-        template<class T, class U, class... Types>
-        struct tuple_index<T, std::tuple<U, Types...>>
-        {
-            static const int value = 1 + tuple_index<T, std::tuple<Types...>>::value;
-        };
 
         // Kind of fold expressions in C++11
         template<bool...>
diff --git a/tests/unittest.cpp b/tests/unittest.cpp
index c4b916304..568a30e1a 100644
--- a/tests/unittest.cpp
+++ b/tests/unittest.cpp
@@ -1523,8 +1523,10 @@ struct OnlyMoveConstructor
 
 TEST_CASE("app_constructor")
 {
-    App<NullMiddleware, OnlyMoveConstructor, FirstMW, SecondMW>
-      app(OnlyMoveConstructor(1), SecondMW{});
+    App<NullMiddleware, OnlyMoveConstructor, FirstMW<false>, SecondMW<false>>
+      app1(OnlyMoveConstructor(1), SecondMW<false>{});
+    App<NullMiddleware, OnlyMoveConstructor, FirstMW<false>, SecondMW<false>>
+      app2(FirstMW<false>{}, OnlyMoveConstructor(1));
 } // app_constructor
 
 TEST_CASE("middleware_blueprint")