From f4924871e2459714680e25fc3de268d80d6f3778 Mon Sep 17 00:00:00 2001
From: Stanislaw Halik <sthalik@misaki.pl>
Date: Sun, 22 Jul 2018 11:52:33 +0200
Subject: main-window: further work

---
 main-window/CMakeLists.txt   |  2 +-
 main-window/mixin-traits.cpp | 41 ++++++++++++++++++++++++++++++++---------
 main-window/mixin-traits.hpp | 41 ++++++++++++++++++++---------------------
 3 files changed, 53 insertions(+), 31 deletions(-)

diff --git a/main-window/CMakeLists.txt b/main-window/CMakeLists.txt
index 3edd241b..f69080f1 100644
--- a/main-window/CMakeLists.txt
+++ b/main-window/CMakeLists.txt
@@ -1,4 +1,4 @@
-otr_module(main-window BIN)
+otr_module(main-window BIN NO-INSTALL)
 foreach(k user-interface logic pose-widget migration spline)
     target_link_libraries(${self} opentrack-${k})
 endforeach()
diff --git a/main-window/mixin-traits.cpp b/main-window/mixin-traits.cpp
index ea8e9bc8..5dc2efd8 100644
--- a/main-window/mixin-traits.cpp
+++ b/main-window/mixin-traits.cpp
@@ -1,22 +1,27 @@
-//#define MIXIN_TRAIT_TESTS
+#define MIXIN_TRAIT_TESTS
 
 #ifdef MIXIN_TRAIT_TESTS
 #   include "mixin-traits.hpp"
 
+// the `impl' class provides a cast template through the CRTP pattern.
+// mixins don't do direct inheritance on themselves,
+// that's what mixin_traits::depends is for.
+
 namespace mixins::traits_detail {
 
 struct A {};
-struct B : A {};
+struct B {};
 struct C {};
+struct D {};
 
-template<> struct mixin_traits<B>
+template<> struct mixin_traits<A>
 {
-    using depends = tuple<A>;
+    using depends = tuple<>;
 };
 
-template<> struct mixin_traits<A>
+template<> struct mixin_traits<B>
 {
-    using depends = tuple<>;
+    using depends = tuple<A>;
 };
 
 template<> struct mixin_traits<C>
@@ -24,13 +29,31 @@ template<> struct mixin_traits<C>
     using depends = tuple<A>;
 };
 
+template<> struct mixin_traits<D>
+{
+    using depends = tuple<C>;
+};
+
 extern void test1();
 
 void test1()
 {
-    //impl<C> fail1;
-    impl<B> ok1;
-    impl<A> ok2;
+    struct U : B, A {};
+    struct V : D {};
+    struct W : C, A {};
+    struct Q : virtual W, virtual D {};
+
+#if 0
+    (void)impl<Q, W>();     // W not a mixin
+    (void)impl<V, A>();     // A
+    (void)impl<V, D>();     // D => C => A
+    (void)impl<V, D>();     // D => C => A
+    (void)impl<W, C, B>();  // B
+#else
+    (void)impl<U, B>();
+    (void)impl<W, C>();
+    (void)impl<Q, D, A>();
+#endif
 }
 
 } // ns mixins::traits_detail
diff --git a/main-window/mixin-traits.hpp b/main-window/mixin-traits.hpp
index 84a64d08..6a0206fc 100644
--- a/main-window/mixin-traits.hpp
+++ b/main-window/mixin-traits.hpp
@@ -1,7 +1,5 @@
 #pragma once
 
-#include "compat/linkage-macros.hpp"
-#include "compat/macros.hpp"
 #include "compat/meta.hpp"
 
 #include <type_traits>
@@ -9,40 +7,41 @@
 namespace mixins::traits_detail {
 
     using namespace meta;
-    template<typename... xs>
-    using tuple = meta::detail::tuple<xs...>;
+
+    template<typename... xs> using tuple = tuple_<xs...>;
 
     template<typename t>
     struct mixin_traits {
-        //using depends = tuple<>;
+        // implement this!
+        using depends = tuple<>;
+
+        // unconditional but at instantiation time
+        static_assert(sizeof(t) < sizeof(char),
+                      "must specialize mixin_traits");
     };
 
     template<typename klass, typename...> struct check_depends_;
 
     template<typename klass>
-    struct check_depends_<klass>
+    struct check_depends_<klass> : std::true_type
     {
-        using type = std::bool_constant<true>;
     };
 
     template<typename klass, typename x, typename... xs>
-    struct check_depends_<klass, x, xs...>
+    struct check_depends_<klass, x, xs...> :
+            std::bool_constant<
+                std::is_base_of_v<x, klass> &&
+                lift<check_depends_, cons<klass, typename mixin_traits<x>::depends>>::value &&
+                check_depends_<klass, xs...>::value
+            >
     {
-        using b1 = std::is_base_of<x, klass>;
-        using b2 = typename check_depends_<klass, xs...>::type;
-
-        using depends = typename mixin_traits<x>::depends;
-        using t1 = cons<klass, depends>;
-        using t2 = lift<check_depends_, t1>;
-        using b3 = typename t2::type;
-
-        using type = std::bool_constant<b1::value && b2::value && b3::value>;
     };
 
-    template<typename t>
-    class impl
+    template<typename klass, typename... xs>
+    struct impl
     {
-        using t1 = typename lift<check_depends_, cons<t, typename mixin_traits<t>::depends>>::type;
-        static_assert(t1::value);
+        static constexpr bool class_must_inherit_dependent_mixins =
+                lift<check_depends_, tuple<klass, xs...>>::value;
+        static_assert(class_must_inherit_dependent_mixins);
     };
 } // ns mixins::traits_detail
-- 
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