Method InsertNewItemUsingPreferences

libraries/lib-registries/Registry.cpp:247–284

For each group node, this is called only in the first pass of merging of items. It might fail to place an item in the first visitation of a registry, but then succeed in later visitations in the same or later runs of the program, because of persistent side-effects on the preferences done at the very end of the visitation.

// runs of the program, because of persistent side-effects on the
// preferences done at the very end of the visitation.
auto CollectedItems::InsertNewItemUsingPreferences(
   ItemOrdering &itemOrdering, BaseItem *pItem )
   -> bool
{
   // Note that if more than one plug-in registers items under the same
   // node, then it is not specified which plug-in is handled first,
   // the first time registration happens.  It might happen that you
   // add a plug-in, run the program, then add another, then run again;
   // registration order determined by those actions might not
   // correspond to the order of re-loading of modules in later
   // sessions.  But whatever ordering is chosen the first time some
   // plug-in is seen -- that ordering gets remembered in preferences.

   if ( !pItem->name.empty() ) {
      // Check saved ordering first, and rebuild that as well as is possible
      auto &ordering = itemOrdering.Get();
      auto begin2 = ordering.begin(), end2 = ordering.end(),
         found2 = std::find( begin2, end2, pItem->name );
      if ( found2 != end2 ) {
         auto insertPoint = items.end();
         // Find the next name in the saved ordering that is known already
         // in the collection.
         while ( ++found2 != end2 ) {
            auto known = Find( *found2 );
            if ( known != insertPoint ) {
               insertPoint = known;
               break;
            }
         }
         items.insert( insertPoint, {pItem, nullptr,
            // Hints no longer matter:
            {}} );
         return true;
      }
   }

   return false;
}

// For each group node, this may be called in the second and later passes
// of merging of items