Share indexed fallback locations during effective projection

internal/engine/validation.go

@@ -124,6 +124,10 @@ func validationMutationDiagnostic(path Path) Diagnostic {
 }
 
 func nearestDocumentLocation(root *document.Node, path Path) (document.Location, bool) {
+	return nearestDocumentLocationWithLookup(root, path, nil)
+}
+
+func nearestDocumentLocationWithLookup(root *document.Node, path Path, lookup *documentLookup) (document.Location, bool) {
 	if root == nil || !path.valid() {
 		return document.Location{}, false
 	}
@@ -135,18 +139,22 @@ func nearestDocumentLocation(root *document.Node, path Path) (document.Location,
 			if segment.kind == pathSegmentIndex {
 				return nearest, locationKnown(nearest)
 			}
-			found := false
-			for _, entry := range current.Mapping {
-				if entry.Key == segment.key {
-					current = entry.Value
-					nearest = current.Location
-					found = true
-					break
+			position := -1
+			if lookup != nil {
+				position = lookup.find(current, segment.key)
+			} else {
+				for index, entry := range current.Mapping {
+					if entry.Key == segment.key {
+						position = index
+						break
+					}
 				}
 			}
-			if !found {
+			if position < 0 {
 				return nearest, locationKnown(nearest)
 			}
+			current = current.Mapping[position].Value
+			nearest = current.Location
 		case document.Sequence:
 			index, ok := schemaIndex(segment)
 			if !ok || index >= len(current.Sequence) {