in proto/properties.go [227:302]
func newProperties(t reflect.Type) *StructProperties {
if t.Kind() != reflect.Struct {
panic(fmt.Sprintf("%v is not a generated message in the open-struct API", t))
}
var hasOneof bool
prop := new(StructProperties)
// Construct a list of properties for each field in the struct.
for i := 0; i < t.NumField(); i++ {
p := new(Properties)
f := t.Field(i)
tagField := f.Tag.Get("protobuf")
p.Init(f.Type, f.Name, tagField, &f)
tagOneof := f.Tag.Get("protobuf_oneof")
if tagOneof != "" {
hasOneof = true
p.OrigName = tagOneof
}
// Rename unrelated struct fields with the "XXX_" prefix since so much
// user code simply checks for this to exclude special fields.
if tagField == "" && tagOneof == "" && !strings.HasPrefix(p.Name, "XXX_") {
p.Name = "XXX_" + p.Name
p.OrigName = "XXX_" + p.OrigName
} else if p.Weak != "" {
p.Name = p.OrigName // avoid possible "XXX_" prefix on weak field
}
prop.Prop = append(prop.Prop, p)
}
// Construct a mapping of oneof field names to properties.
if hasOneof {
var oneofWrappers []interface{}
if fn, ok := reflect.PtrTo(t).MethodByName("XXX_OneofFuncs"); ok {
oneofWrappers = fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[3].Interface().([]interface{})
}
if fn, ok := reflect.PtrTo(t).MethodByName("XXX_OneofWrappers"); ok {
oneofWrappers = fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[0].Interface().([]interface{})
}
if m, ok := reflect.Zero(reflect.PtrTo(t)).Interface().(protoreflect.ProtoMessage); ok {
if m, ok := m.ProtoReflect().(interface{ ProtoMessageInfo() *protoimpl.MessageInfo }); ok {
oneofWrappers = m.ProtoMessageInfo().OneofWrappers
}
}
prop.OneofTypes = make(map[string]*OneofProperties)
for _, wrapper := range oneofWrappers {
p := &OneofProperties{
Type: reflect.ValueOf(wrapper).Type(), // *T
Prop: new(Properties),
}
f := p.Type.Elem().Field(0)
p.Prop.Name = f.Name
p.Prop.Parse(f.Tag.Get("protobuf"))
// Determine the struct field that contains this oneof.
// Each wrapper is assignable to exactly one parent field.
var foundOneof bool
for i := 0; i < t.NumField() && !foundOneof; i++ {
if p.Type.AssignableTo(t.Field(i).Type) {
p.Field = i
foundOneof = true
}
}
if !foundOneof {
panic(fmt.Sprintf("%v is not a generated message in the open-struct API", t))
}
prop.OneofTypes[p.Prop.OrigName] = p
}
}
return prop
}