presence.go•1.17 kB
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package filedesc
import "google.golang.org/protobuf/reflect/protoreflect"
// UsePresenceForField reports whether the presence bitmap should be used for
// the specified field.
func UsePresenceForField(fd protoreflect.FieldDescriptor) (usePresence, canBeLazy bool) {
switch {
case fd.ContainingOneof() != nil && !fd.ContainingOneof().IsSynthetic():
// Oneof fields never use the presence bitmap.
//
// Synthetic oneofs are an exception: Those are used to implement proto3
// optional fields and hence should follow non-oneof field semantics.
return false, false
case fd.IsMap():
// Map-typed fields never use the presence bitmap.
return false, false
case fd.Kind() == protoreflect.MessageKind || fd.Kind() == protoreflect.GroupKind:
// Lazy fields always use the presence bitmap (only messages can be lazy).
isLazy := fd.(interface{ IsLazy() bool }).IsLazy()
return isLazy, isLazy
default:
// If the field has presence, use the presence bitmap.
return fd.HasPresence(), false
}
}