Terminate pointer-only descriptor traversal

internal/engine/decode.go

@@ -91,19 +91,30 @@ func decodeValue(node *document.Node, base reflect.Value, descriptor *typeDescri
 		}
 	}
 	if descriptor.kind == descriptorPointer {
-		var elementBase reflect.Value
-		if base.IsNil() {
-			elementBase = reflect.Zero(descriptor.typeOf.Elem())
-		} else {
-			elementBase = base.Elem()
+		terminal, ok := terminalDescriptor(descriptor)
+		if !ok {
+			return reflect.Value{}, []decodeIssue{newDecodeIssue(CodeDecodeType, path, node, "configuration type cannot represent a non-null value")}
 		}
-		decoded, issues := decodeValue(node, elementBase, descriptor.element, path, schema, context)
+		var pointers []*typeDescriptor
+		currentBase := base
+		for current := descriptor; current != terminal; current = current.element {
+			pointers = append(pointers, current)
+			if currentBase.IsNil() {
+				currentBase = reflect.Zero(current.typeOf.Elem())
+			} else {
+				currentBase = currentBase.Elem()
+			}
+		}
+		decoded, issues := decodeValue(node, currentBase, terminal, path, schema, context)
 		if len(issues) != 0 {
 			return reflect.Value{}, issues
 		}
-		result := reflect.New(descriptor.typeOf.Elem())
-		result.Elem().Set(decoded)
-		return result, nil
+		for i := len(pointers) - 1; i >= 0; i-- {
+			result := reflect.New(pointers[i].typeOf.Elem())
+			result.Elem().Set(decoded)
+			decoded = result
+		}
+		return decoded, nil
 	}
 
 	switch descriptor.kind {
@@ -392,10 +403,11 @@ func decodeDynamic(node *document.Node, base reflect.Value, path Path, schema *s
 }
 
 func acceptsMapping(descriptor *typeDescriptor) bool {
-	for descriptor != nil && descriptor.kind == descriptorPointer {
-		descriptor = descriptor.element
+	terminal, ok := terminalDescriptor(descriptor)
+	if !ok {
+		return false
 	}
-	return descriptor != nil && (descriptor.kind == descriptorStruct || descriptor.kind == descriptorMap || descriptor.kind == descriptorDynamic)
+	return terminal.kind == descriptorStruct || terminal.kind == descriptorMap || terminal.kind == descriptorDynamic
 }
 
 func fieldForDecode(root reflect.Value, index []int, allocate bool) (reflect.Value, bool) {