IfcFile: possibility to mark an entity as modified so that potential cache is invalidated.

src/ifcparse/IfcFile.h

@@ -148,6 +148,10 @@ public:
 	/// in the first function argument.
 	IfcEntityList::ptr traverse(IfcUtil::IfcBaseClass* instance, int max_level=-1);
 
+	/// Marks entity as modified so that potential cache for it is invalidated.
+	/// @todo Currently the whole cache is invalidated. Implement more fine-grained invalidation.
+	void mark_entity_as_modified(int id);
+
 #ifdef USE_MMAP
 	bool Init(const std::string& fn, bool mmap=false);
 #else

src/ifcparse/IfcParse.cpp

@@ -1213,7 +1213,9 @@ void IfcEntityInstanceData::setArgument(unsigned int i, Argument* a, IfcUtil::Ar
 	if (this->file) {
 		register_inverse_visitor visitor(*this->file, *this);
 		apply_individual_instance_visitor(copy).apply(visitor);
-	}	
+
+		this->file->mark_entity_as_modified(id_);
+	}
 
 	if (i < attributes_.size()) {
 		attributes_[i] = copy;
@@ -1429,6 +1431,11 @@ IfcEntityList::ptr IfcFile::traverse(IfcUtil::IfcBaseClass* instance, int max_le
 	return IfcParse::traverse(instance, max_level);
 }
 
+void IfcFile::mark_entity_as_modified(int /*id*/)
+{
+	by_ref_cached_.clear();
+}
+
 void IfcFile::addEntities(IfcEntityList::ptr es) {
 	for( IfcEntityList::it i = es->begin(); i != es->end(); ++ i ) {
 		addEntity(*i);