all: implement proto1 weak fields
This implements generation of and reflection support for weak fields.
Weak fields are a proto1 feature where the "weak" option can be specified
on a singular message field. A weak reference results in generated code
that does not directly link in the dependency containing the weak message.
Weak field support is not added to any of the serialization logic.
Change-Id: I08ccfa72bc80b2ffb6af527a1677a0a81dcf33fb
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/185399
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/internal/impl/message_field.go b/internal/impl/message_field.go
index 7cba71d..1787f32 100644
--- a/internal/impl/message_field.go
+++ b/internal/impl/message_field.go
@@ -9,8 +9,10 @@
"math"
"reflect"
+ "google.golang.org/protobuf/internal/flags"
pvalue "google.golang.org/protobuf/internal/value"
pref "google.golang.org/protobuf/reflect/protoreflect"
+ preg "google.golang.org/protobuf/reflect/protoregistry"
piface "google.golang.org/protobuf/runtime/protoiface"
)
@@ -289,6 +291,89 @@
}
}
+func fieldInfoForWeakMessage(fd pref.FieldDescriptor, weakOffset offset) fieldInfo {
+ if !flags.Proto1Legacy {
+ panic("no support for proto1 weak fields")
+ }
+
+ messageName := fd.Message().FullName()
+ messageType, _ := preg.GlobalTypes.FindMessageByName(messageName)
+ if messageType == nil {
+ return fieldInfo{
+ fieldDesc: fd,
+ has: func(p pointer) bool { return false },
+ clear: func(p pointer) {},
+ get: func(p pointer) pref.Value {
+ panic(fmt.Sprintf("weak message %v is not linked in", messageName))
+ },
+ set: func(p pointer, v pref.Value) {
+ panic(fmt.Sprintf("weak message %v is not linked in", messageName))
+ },
+ mutable: func(p pointer) pref.Value {
+ panic(fmt.Sprintf("weak message %v is not linked in", messageName))
+ },
+ newMessage: func() pref.Message {
+ panic(fmt.Sprintf("weak message %v is not linked in", messageName))
+ },
+ }
+ }
+
+ num := int32(fd.Number())
+ frozenEmpty := pref.ValueOf(frozenMessage{messageType.New()})
+ return fieldInfo{
+ fieldDesc: fd,
+ has: func(p pointer) bool {
+ if p.IsNil() {
+ return false
+ }
+ fs := p.Apply(weakOffset).WeakFields()
+ _, ok := (*fs)[num]
+ return ok
+ },
+ clear: func(p pointer) {
+ fs := p.Apply(weakOffset).WeakFields()
+ delete(*fs, num)
+ },
+ get: func(p pointer) pref.Value {
+ if p.IsNil() {
+ return frozenEmpty
+ }
+ fs := p.Apply(weakOffset).WeakFields()
+ m, ok := (*fs)[num]
+ if !ok {
+ return frozenEmpty
+ }
+ return pref.ValueOf(m.(pref.ProtoMessage).ProtoReflect())
+ },
+ set: func(p pointer, v pref.Value) {
+ m := v.Message()
+ if m.Descriptor() != messageType.Descriptor() {
+ panic("mismatching message descriptor")
+ }
+ fs := p.Apply(weakOffset).WeakFields()
+ if *fs == nil {
+ *fs = make(WeakFields)
+ }
+ (*fs)[num] = m.Interface().(piface.MessageV1)
+ },
+ mutable: func(p pointer) pref.Value {
+ fs := p.Apply(weakOffset).WeakFields()
+ if *fs == nil {
+ *fs = make(WeakFields)
+ }
+ m, ok := (*fs)[num]
+ if !ok {
+ m = messageType.New().Interface().(piface.MessageV1)
+ (*fs)[num] = m
+ }
+ return pref.ValueOf(m.(pref.ProtoMessage).ProtoReflect())
+ },
+ newMessage: func() pref.Message {
+ return messageType.New()
+ },
+ }
+}
+
func fieldInfoForMessage(fd pref.FieldDescriptor, fs reflect.StructField, x exporter) fieldInfo {
ft := fs.Type
conv, _ := newConverter(ft, fd.Kind())