Share recursive mapping merge across configuration assembly

internal/engine/overlay.go

@@ -53,40 +53,29 @@ func (a *assemblyAccumulator) applyOverlay(overlay *document.Node, incomingOrigi
 }
 
 func mergeOverlayMappings(result *composedDocument, target, overlay *document.Node, current Path, layer Layer, recordReplacements bool, incomingOrigins map[string]Origin, index *mappingIndex) {
-	for _, incoming := range overlay.Mapping {
-		path := current.Key(incoming.Key)
-		position := index.find(target, incoming.Key)
-		if position < 0 {
-			cloned := incoming
-			cloned.Value = document.Clone(incoming.Value)
-			index.append(target, cloned)
-			collectOverlayOriginsFrom(result.origins, incomingOrigins, incoming.Value, path, layer)
-			continue
-		}
-
-		existing := target.Mapping[position].Value
-		if existing.Kind == document.Mapping && incoming.Value.Kind == document.Mapping {
-			mergeOriginContribution(result.origins, path, incomingOrigin(incomingOrigins, path, incoming.Value, layer))
-			mergeOverlayMappings(result, existing, incoming.Value, path, layer, recordReplacements, incomingOrigins, index)
-			continue
-		}
-
-		displaced := displacedOrigins(existing, result.origins, path)
-		previous := cloneOrigin(result.origins[path.String()])
-		deleteOriginSubtree(result.origins, path, existing)
-		target.Mapping[position] = incoming
-		target.Mapping[position].Value = document.Clone(incoming.Value)
-		collectOverlayOriginsFrom(result.origins, incomingOrigins, incoming.Value, path, layer)
-		if recordReplacements {
-			result.overlays = append(result.overlays, overlayRecord{
-				change: Change{
-					Path: path.clone(), Origin: incomingOrigin(incomingOrigins, path, incoming.Value, layer),
-					Previous: previousOrigins(previous),
-				},
-				displaced: displaced,
-			})
-		}
-	}
+	mergeRecursiveMappings(target, overlay, current, index, recursiveMergeHooks{
+		added: func(path Path, incoming *document.Node) {
+			collectOverlayOriginsFrom(result.origins, incomingOrigins, incoming, path, layer)
+		},
+		combined: func(path Path, incoming *document.Node) {
+			mergeOriginContribution(result.origins, path, incomingOrigin(incomingOrigins, path, incoming, layer))
+		},
+		replaced: func(path Path, existing, incoming *document.Node) {
+			displaced := displacedOrigins(existing, result.origins, path)
+			previous := cloneOrigin(result.origins[path.String()])
+			deleteOriginSubtree(result.origins, path, existing)
+			collectOverlayOriginsFrom(result.origins, incomingOrigins, incoming, path, layer)
+			if recordReplacements {
+				result.overlays = append(result.overlays, overlayRecord{
+					change: Change{
+						Path: path.clone(), Origin: incomingOrigin(incomingOrigins, path, incoming, layer),
+						Previous: previousOrigins(previous),
+					},
+					displaced: displaced,
+				})
+			}
+		},
+	})
 }
 
 func collectOverlayOrigins(origins map[string]Origin, node *document.Node, path Path, layer Layer) {