// Given two variants, which are maps merge the properties from v2 into v1 that
// don't already exist in v1.
void variant_map_merge(variant& v1, const variant& v2)
{
std::map<variant, variant>::const_iterator v2it = v2.as_map().begin();
std::map<variant, variant>::const_iterator v2end = v2.as_map().end();
while(v2it != v2end) {
std::map<variant, variant>::const_iterator v1it = v1.as_map().find(v2it->first);
if(v1it == v1.as_map().end()) {
v1.add_attr(v2it->first, v2it->second);
}
v2it++;
}
}
