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khenaidoo106c61a2021-08-11 18:05:46 -04001// Copyright 2019 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
William Kurkianea869482019-04-09 15:16:11 -04004
5package proto
6
7import (
khenaidoo106c61a2021-08-11 18:05:46 -04008 "google.golang.org/protobuf/reflect/protoreflect"
William Kurkianea869482019-04-09 15:16:11 -04009)
10
William Kurkianea869482019-04-09 15:16:11 -040011// DiscardUnknown recursively discards all unknown fields from this message
12// and all embedded messages.
13//
14// When unmarshaling a message with unrecognized fields, the tags and values
15// of such fields are preserved in the Message. This allows a later call to
16// marshal to be able to produce a message that continues to have those
17// unrecognized fields. To avoid this, DiscardUnknown is used to
18// explicitly clear the unknown fields after unmarshaling.
William Kurkianea869482019-04-09 15:16:11 -040019func DiscardUnknown(m Message) {
khenaidoo106c61a2021-08-11 18:05:46 -040020 if m != nil {
21 discardUnknown(MessageReflect(m))
William Kurkianea869482019-04-09 15:16:11 -040022 }
23}
24
khenaidoo106c61a2021-08-11 18:05:46 -040025func discardUnknown(m protoreflect.Message) {
26 m.Range(func(fd protoreflect.FieldDescriptor, val protoreflect.Value) bool {
27 switch {
28 // Handle singular message.
29 case fd.Cardinality() != protoreflect.Repeated:
30 if fd.Message() != nil {
31 discardUnknown(m.Get(fd).Message())
32 }
33 // Handle list of messages.
34 case fd.IsList():
35 if fd.Message() != nil {
36 ls := m.Get(fd).List()
37 for i := 0; i < ls.Len(); i++ {
38 discardUnknown(ls.Get(i).Message())
William Kurkianea869482019-04-09 15:16:11 -040039 }
40 }
khenaidoo106c61a2021-08-11 18:05:46 -040041 // Handle map of messages.
42 case fd.IsMap():
43 if fd.MapValue().Message() != nil {
44 ms := m.Get(fd).Map()
45 ms.Range(func(_ protoreflect.MapKey, v protoreflect.Value) bool {
46 discardUnknown(v.Message())
47 return true
48 })
William Kurkianea869482019-04-09 15:16:11 -040049 }
50 }
khenaidoo106c61a2021-08-11 18:05:46 -040051 return true
52 })
William Kurkianea869482019-04-09 15:16:11 -040053
khenaidoo106c61a2021-08-11 18:05:46 -040054 // Discard unknown fields.
55 if len(m.GetUnknown()) > 0 {
56 m.SetUnknown(nil)
William Kurkianea869482019-04-09 15:16:11 -040057 }
58}