chore(civil3d): refactor to yield return

Converters/Civil3d/Speckle.Converters.Civil3dShared/Helpers/DisplayValueExtractor.cs

@@ -32,36 +32,40 @@ IConverterSettingsStore<Civil3dConversionSettings> converterSettings
     _converterSettings = converterSettings;
   }
 
-  public List<Base>? GetDisplayValue(CDB.Entity entity)
+  public IEnumerable<Base> GetDisplayValue(CDB.Entity entity)
   {
     switch (entity)
     {
       case CDB.FeatureLine featureline:
         SOG.Polyline featurelinePolyline = _pointCollectionConverter.Convert(
           featureline.GetPoints(Autodesk.Civil.FeatureLinePointType.PIPoint)
         );
-        return new() { featurelinePolyline };
+        yield return featurelinePolyline;
+        break;
 
       // pipe networks: https://help.autodesk.com/view/CIV3D/2025/ENU/?guid=ade47b62-debf-f899-9b94-5645a620ab4f
       case CDB.Part part:
         SOG.Mesh partMesh = _solidConverter.Convert(part.Solid3dBody);
-        return new() { partMesh };
+        yield return partMesh;
+        break;
 
       // surfaces: https://help.autodesk.com/view/CIV3D/2025/ENU/?guid=d741aa49-e7da-9513-6b0b-226ebe3fa43f
       // POC: volume surfaces not supported
       case CDB.TinSurface tinSurface:
         SOG.Mesh tinSurfaceMesh = _tinSurfaceConverter.Convert(tinSurface);
-        return new() { tinSurfaceMesh };
+        yield return tinSurfaceMesh;
+        break;
       case CDB.GridSurface gridSurface:
         SOG.Mesh gridSurfaceMesh = _gridSurfaceConverter.Convert(gridSurface);
-        return new() { gridSurfaceMesh };
+        yield return gridSurfaceMesh;
+        break;
 
       // Corridors are complicated: their display values are extracted in the CorridorHandler when processing corridor children, since they are attached to the corridor subassemblies.
       case CDB.Corridor:
-        return new();
+        yield break;
 
       default:
-        return null;
+        yield break;
     }
   }
 
@@ -73,33 +77,30 @@ IConverterSettingsStore<Civil3dConversionSettings> converterSettings
   /// List of simple curves: lines, polylines, and arcs.
   /// Null if no suitable display curves were found.
   /// </returns>
-  public List<Base>? ProcessICurvesForDisplay(List<ICurve>? iCurves)
+  public IEnumerable<Base> ProcessICurvesForDisplay(List<ICurve>? iCurves)
   {
     if (iCurves is null)
     {
-      return null;
+      yield break;
     }
 
-    List<Base> result = new();
     foreach (ICurve curve in iCurves)
     {
       switch (curve)
       {
         case SOG.Line:
         case SOG.Polyline:
         case SOG.Arc:
-          result.Add((Base)curve);
+          yield return (Base)curve;
           break;
         case SOG.Polycurve polycurve:
-          List<Base>? processedSegments = ProcessICurvesForDisplay(polycurve.segments);
-          if (processedSegments is not null)
+          IEnumerable<Base> processedSegments = ProcessICurvesForDisplay(polycurve.segments);
+          foreach (Base processedSegment in processedSegments)
           {
-            result.AddRange(processedSegments);
+            yield return processedSegment;
           }
           break;
       }
     }
-
-    return result.Count > 0 ? result : null;
   }
 }

Converters/Civil3d/Speckle.Converters.Civil3dShared/ToSpeckle/BuiltElements/CivilEntityToSpeckleTopLevelConverter.cs

@@ -61,11 +61,14 @@ public Base Convert(CDB.Entity target)
 
     // extract display value.
     // If object has no display but has basecurves, use basecurves for display instead (for viewer selection)
-    List<Base>? display =
-      _displayValueExtractor.GetDisplayValue(target) ?? _displayValueExtractor.ProcessICurvesForDisplay(baseCurves);
-    if (display is not null)
+    List<Base> displayValue = _displayValueExtractor.GetDisplayValue(target).ToList();
+    if (displayValue.Count == 0)
     {
-      civilObject["displayValue"] = display;
+      displayValue = _displayValueExtractor.ProcessICurvesForDisplay(baseCurves).ToList();
+    }
+    if (displayValue.Count > 0)
+    {
+      civilObject["displayValue"] = displayValue;
     }
 
     // add any additional class properties
@@ -80,60 +83,69 @@ public Base Convert(CDB.Entity target)
 
     // determine if this entity has any children elements that need to be converted.
     // this is a bespoke method by class type.
-    List<Base>? children = null;
-    switch (target)
+    var children = GetEntityChildren(target).ToList();
+    if (children.Count > 0)
+    {
+      civilObject["elements"] = children;
+    }
+
+    return civilObject;
+  }
+
+  private IEnumerable<Base> GetEntityChildren(CDB.Entity entity)
+  {
+    switch (entity)
     {
       case CDB.Alignment alignment:
-        children = GetAlignmentChildren(alignment);
+        var alignmentChildren = GetAlignmentChildren(alignment);
+        foreach (var child in alignmentChildren)
+        {
+          yield return child;
+        }
         break;
       case CDB.Corridor corridor:
-        children = _corridorHandler.GetCorridorChildren(corridor);
+        var corridorChildren = _corridorHandler.GetCorridorChildren(corridor);
+        foreach (var child in corridorChildren)
+        {
+          yield return child;
+        }
         break;
 
       case CDB.Site site:
-        children = GetSiteChildren(site);
+        var siteChildren = GetSiteChildren(site).ToList();
+        foreach (var child in siteChildren)
+        {
+          yield return child;
+        }
         break;
     }
-
-    if (children is not null)
-    {
-      civilObject["elements"] = children;
-    }
-
-    return civilObject;
   }
 
-  private List<Base>? GetSiteChildren(CDB.Site site)
+  private IEnumerable<Base> GetSiteChildren(CDB.Site site)
   {
-    List<Base> parcels = new();
     using (var tr = _settingsStore.Current.Document.Database.TransactionManager.StartTransaction())
     {
       foreach (ADB.ObjectId parcelId in site.GetParcelIds())
       {
         var parcel = (CDB.Parcel)tr.GetObject(parcelId, ADB.OpenMode.ForRead);
-        parcels.Add(Convert(parcel));
+        yield return Convert(parcel);
       }
 
       tr.Commit();
     }
-
-    return parcels.Count > 0 ? parcels : null;
   }
 
-  private List<Base>? GetAlignmentChildren(CDB.Alignment alignment)
+  private IEnumerable<Base> GetAlignmentChildren(CDB.Alignment alignment)
   {
-    List<Base> profiles = new();
     using (var tr = _settingsStore.Current.Document.Database.TransactionManager.StartTransaction())
     {
       foreach (ADB.ObjectId profileId in alignment.GetProfileIds())
       {
         var profile = (CDB.Profile)tr.GetObject(profileId, ADB.OpenMode.ForRead);
-        profiles.Add(Convert(profile));
+        yield return Convert(profile);
       }
 
       tr.Commit();
     }
-
-    return profiles.Count > 0 ? profiles : null;
   }
 }