auto: add allowed transitions check

Signed-off-by: Alexandre Bernard <[email protected]>
multun · Jul 9, 2018 · 295c20a · 295c20a
1 parent df5f6e6
commit 295c20a
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Showing 3 changed files with 14 additions and 3 deletions.
diff --git a/auto.hh b/auto.hh
@@ -12,9 +12,10 @@
 #include "type_utils.hxx"
 
 template<template<class> class PInterface,
+         class AllowedTransitions,
          template<class> class ...States>
 class Auto {
-    using self_t = Auto<PInterface, States...>;
+    using self_t = Auto<PInterface, AllowedTransitions, States...>;
     using intf_t = PInterface<self_t>;
     using ttlist = TTList<States...>;
 
@@ -90,11 +91,14 @@ public:
              template<class> class OldState,
              class ...Args>
     void free_transit(Args&& ...args) {
-        // TODO: validate former state
+        static_assert(
+            AllowedTransitions::template contains<TPair<OldState, NewState>>());
+
 #ifdef AUTO_LOGGING
         std::cout << "transition from " << typeid(OldState<self_t>).name() << " to "
                   << typeid(NewState<self_t>).name() << std::endl;
 #endif
+
         enter<NewState, Args...>(std::forward<Args>(args)...);
     }
 

diff --git a/test.cc b/test.cc
@@ -44,7 +44,8 @@ struct StateB : ExInterface<Auto> {
 };
 
 
-using MyAuto = Auto<ExInterface, StateA, StateB>;
+using trans = TList<TPair<StateB, StateA>>;
+using MyAuto = Auto<ExInterface, trans, StateA, StateB>;
 
 int main() {
     MyAuto a;

diff --git a/type_utils.hxx b/type_utils.hxx
@@ -125,3 +125,9 @@ struct AlignofReducer {
             return AlignofReducer<T>{};
     }
 };
+
+template<template<class> class OldState, template<class> class NewState>
+struct TPair {
+    template<class T> using old_t = OldState<T>;
+    template<class T> using new_t = NewState<T>;
+};