gtsocial-umbx

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discard.go (1618B)

      1 // 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.
      4 
      5 package proto
      6 
      7 import (
      8 	"google.golang.org/protobuf/reflect/protoreflect"
      9 )
     10 
     11 // 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.
     19 func DiscardUnknown(m Message) {
     20 	if m != nil {
     21 		discardUnknown(MessageReflect(m))
     22 	}
     23 }
     24 
     25 func 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())
     39 				}
     40 			}
     41 		// 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 				})
     49 			}
     50 		}
     51 		return true
     52 	})
     53 
     54 	// Discard unknown fields.
     55 	if len(m.GetUnknown()) > 0 {
     56 		m.SetUnknown(nil)
     57 	}
     58 }