Checking for cycles in action attach

reading_machine/src/Action.cpp

@@ -358,7 +358,30 @@ Action Action::attach(Object governorObject, int governorIndex, Object dependent
       govLineIndex = config.getStack(governorIndex);
     }
 
-    return addHypothesisRelative(Config::headColName, dependentObject, dependentIndex, std::to_string(govLineIndex)).appliable(config, action);
+    int depLineIndex = 0;
+    if (dependentObject == Object::Buffer)
+    {
+      depLineIndex = config.getWordIndex() + dependentIndex;
+      if (!config.has(0, depLineIndex, 0))
+        return false;
+    }
+    else
+    {
+      if (!config.hasStack(dependentIndex))
+        return false;
+      depLineIndex = config.getStack(dependentIndex);
+    }
+
+    // Check for cycles
+    while (govLineIndex != depLineIndex)
+    {
+      try
+      {
+        govLineIndex = std::stoi(config.getLastNotEmptyHypConst(Config::headColName, govLineIndex));
+      } catch(std::exception &) {return true;}
+    }
+
+    return false;
   };
 
   return {Type::Write, apply, undo, appliable};