Fix bug in FindCommonParent

did not work when one of the states was parent itself

Author: dziegel

include/cpp_event_framework/Statemachine.hxx

@@ -659,6 +659,30 @@ public:
         return os << sm.Name();
     }
 
+    static StatePtr FindCommonParent(StatePtr state1, StatePtr state2)
+    {
+        auto* state = state1;
+
+        while (state != nullptr)
+        {
+            auto* parent = state2;
+
+            while (parent != nullptr)
+            {
+                if (parent == state)
+                {
+                    return parent;
+                }
+
+                parent = parent->parent_;
+            }
+
+            state = state->parent_;
+        }
+
+        return nullptr;
+    }
+
 private:
     StatePtr current_state_ = nullptr;
     bool working_ = false;
@@ -749,6 +773,7 @@ private:
             EnterState(*target);
         }
     }
+
     void EnterStatesFromDownTo(StatePtr top, StatePtr target)
     {
         EnterStatesFromDownToRecursive(top, target->parent_);
@@ -773,29 +798,6 @@ private:
             current_state_ = target;
         }
     }
-    static StatePtr FindCommonParent(StatePtr state1, StatePtr state2)
-    {
-        auto* state = state1->parent_;
-
-        while (state != nullptr)
-        {
-            auto* parent = state2->parent_;
-
-            while (parent != nullptr)
-            {
-                if (parent == state)
-                {
-                    return parent;
-                }
-
-                parent = parent->parent_;
-            }
-
-            state = state->parent_;
-        }
-
-        return nullptr;
-    }
 };
 
 template <typename Impl, typename Event, PolymorphicAllocatorProvider Allocator>

test/Statemachine_unittest.cxx

@@ -163,6 +163,13 @@ class StatemachineImpl
 public:
     void Main()
     {
+        assert(Fsm::FindCommonParent(&Fsm::kGreen, &Fsm::kOn) == &Fsm::kOn);
+        assert(Fsm::FindCommonParent(&Fsm::kOn, &Fsm::kGreen) == &Fsm::kOn);
+        assert(Fsm::FindCommonParent(&Fsm::kOn, &Fsm::kOff) == nullptr);
+        assert(Fsm::FindCommonParent(&Fsm::kOff, &Fsm::kOn) == nullptr);
+        assert(Fsm::FindCommonParent(&Fsm::kGreen, &Fsm::kRed) == &Fsm::kOn);
+        assert(Fsm::FindCommonParent(&Fsm::kRed, &Fsm::kGreen) == &Fsm::kOn);
+
         CheckAllFalse();
         fsm_.Start(&Fsm::kOff);
         assert(fsm_.CurrentState() == &Fsm::kOff);