STYLE: use fallthrough for 'use' action in selections (#926)

- applyToSet() automatically handles NEW like ADD, so no need to do
  so explicitly

src/functionObjects/utilities/ensightWrite/ensightWriteUpdate.C

@@ -35,7 +35,7 @@ namespace Foam
     // A limited selection of actions
     const Enum<topoSetSource::setAction> actionNames
     ({
-        { topoSetSource::NEW, "use" },
+        { topoSetSource::NEW, "use" },  // Reuse NEW for "use" action name
         { topoSetSource::ADD, "add" },
         { topoSetSource::SUBTRACT, "subtract" },
         { topoSetSource::SUBSET, "subset" },
@@ -74,7 +74,7 @@ bool Foam::functionObjects::ensightWrite::updateSubset
 
         const dictionary& dict = dEntry.dict();
 
-        auto action = actionNames.get("action", dict);
+        const auto action = actionNames.get("action", dict);
 
         // Handle manually
         if (action == topoSetSource::INVERT)
@@ -95,19 +95,16 @@ bool Foam::functionObjects::ensightWrite::updateSubset
         {
             case topoSetSource::NEW:  // "use"
             case topoSetSource::ADD:
+            case topoSetSource::SUBTRACT:
                 if (topoSetSource::NEW == action)
                 {
-                    // NEW (use) = CLEAR + ADD  (ie, only use this selection)
+                    // "use": only use this selection (clear + ADD)
+                    // NEW is handled like ADD in applyToSet()
                     cellsToSelect.reset();
-                    action = topoSetSource::ADD;
                 }
                 source->applyToSet(action, cellsToSelect);
                 break;
 
-            case topoSetSource::SUBTRACT:
-                source->applyToSet(action, cellsToSelect);
-                break;
-
             case topoSetSource::SUBSET:
             {
                 cellBitSet other(mesh, false);
@@ -132,41 +129,6 @@ bool Foam::functionObjects::ensightWrite::updateSubset
 }
 
 
-#if 0
-Foam::labelList Foam::functionObjects::ensightWrite::getSelectedPatches
-(
-    const polyBoundaryMesh& patches
-) const
-{
-    DynamicList<label> patchIDs(patches.size());
-
-    for (const polyPatch& pp : patches)
-    {
-        if (isType<emptyPolyPatch>(pp))
-        {
-            continue;
-        }
-        else if (isType<processorPolyPatch>(pp))
-        {
-            break; // No processor patches
-        }
-
-        if
-        (
-            selectPatches_.size()
-          ? selectPatches_.match(pp.name())
-          : true
-        )
-        {
-            patchIDs.append(pp.index());
-        }
-    }
-
-    return patchIDs.shrink();
-}
-#endif
-
-
 bool Foam::functionObjects::ensightWrite::update()
 {
     if (meshState_ == polyMesh::UNCHANGED)

src/functionObjects/utilities/vtkWrite/vtkWriteUpdate.C

@@ -34,7 +34,7 @@ namespace Foam
     // A limited selection of actions
     const Enum<topoSetSource::setAction> actionNames
     ({
-        { topoSetSource::NEW, "use" },
+        { topoSetSource::NEW, "use" },  // Reuse NEW for "use" action name
         { topoSetSource::ADD, "add" },
         { topoSetSource::SUBTRACT, "subtract" },
         { topoSetSource::SUBSET, "subset" },
@@ -72,7 +72,7 @@ bool Foam::functionObjects::vtkWrite::updateSubset
 
         const dictionary& dict = dEntry.dict();
 
-        auto action = actionNames.get("action", dict);
+        const auto action = actionNames.get("action", dict);
 
         // Handle manually
         if (action == topoSetSource::INVERT)
@@ -93,19 +93,16 @@ bool Foam::functionObjects::vtkWrite::updateSubset
         {
             case topoSetSource::NEW:  // "use"
             case topoSetSource::ADD:
+            case topoSetSource::SUBTRACT:
                 if (topoSetSource::NEW == action)
                 {
-                    // NEW (use) = CLEAR + ADD  (ie, only use this selection)
+                    // "use": only use this selection (clear + ADD)
+                    // NEW is handled like ADD in applyToSet()
                     cellsToSelect.reset();
-                    action = topoSetSource::ADD;
                 }
                 source->applyToSet(action, cellsToSelect);
                 break;
 
-            case topoSetSource::SUBTRACT:
-                source->applyToSet(action, cellsToSelect);
-                break;
-
             case topoSetSource::SUBSET:
             {
                 cellBitSet other(mesh, false);