Preserve default state values

Author: dcwhite

src/Dataflow/Network/Module.cc

@@ -347,7 +347,12 @@ const ModuleStateHandle Module::get_state() const
 
 void Module::set_state(ModuleStateHandle state)
 {
-  state_ = state;
+  if (!state_)
+    state_ = state;
+  else if (state) // merge/overwrite
+  {
+    state_->overwriteWith(*state);
+  }
   initStateObserver(state_.get());
   postStateChangeInternalSignalHookup();
 }

src/Dataflow/Network/ModuleStateInterface.cc

@@ -35,6 +35,14 @@ ModuleStateInterface::~ModuleStateInterface()
 {
 }
 
+void ModuleStateInterface::overwriteWith(const ModuleStateInterface& other)
+{
+  for (const auto& otherKey : other.getKeys())
+  {
+    setValue(otherKey, other.getValue(otherKey).value());
+  }
+}
+
 ModuleStateInterfaceFactory::~ModuleStateInterfaceFactory()
 {
 }

src/Dataflow/Network/ModuleStateInterface.h

@@ -61,6 +61,9 @@ namespace Networks {
     virtual bool containsKey(const Name& name) const = 0;
     virtual Keys getKeys() const = 0;
     virtual ModuleStateHandle clone() const = 0;
+    
+    // this function preserves key/value pairs not in other
+    void overwriteWith(const ModuleStateInterface& other);
 
     //non-serialized state: algorithm output needing to be pushed, for instance--TODO: make classes instead of raw string/any
     typedef boost::any TransientValue;