goprotobuf: Generate JSON marshal/unmarshal methods for MessageSet.
This only implements marshaling. Unmarshaling is much fiddlier,
and it's not even clear that people care about that, so I'm punting
it to a later date.
LGTM=gmlewis
R=gmlewis
CC=golang-codereviews
https://codereview.appspot.com/156950045
diff --git a/proto/message_set.go b/proto/message_set.go
index 1a17809..5504855 100644
--- a/proto/message_set.go
+++ b/proto/message_set.go
@@ -36,7 +36,10 @@
*/
import (
+ "bytes"
+ "encoding/json"
"errors"
+ "fmt"
"reflect"
"sort"
)
@@ -211,6 +214,61 @@
return nil
}
+// MarshalMessageSetJSON encodes the extension map represented by m in JSON format.
+// It is called by generated MarshalJSON methods on protocol buffer messages with the message_set_wire_format option.
+func MarshalMessageSetJSON(m map[int32]Extension) ([]byte, error) {
+ var b bytes.Buffer
+ b.WriteByte('{')
+
+ // Process the map in key order for deterministic output.
+ ids := make([]int32, 0, len(m))
+ for id := range m {
+ ids = append(ids, id)
+ }
+ sort.Sort(int32Slice(ids)) // int32Slice defined in text.go
+
+ for i, id := range ids {
+ ext := m[id]
+ if i > 0 {
+ b.WriteByte(',')
+ }
+
+ msd, ok := messageSetMap[id]
+ if !ok {
+ // Unknown type; we can't render it, so skip it.
+ continue
+ }
+ fmt.Fprintf(&b, `"[%s]":`, msd.name)
+
+ x := ext.value
+ if x == nil {
+ x = reflect.New(msd.t.Elem()).Interface()
+ if err := Unmarshal(ext.enc, x.(Message)); err != nil {
+ return nil, err
+ }
+ }
+ d, err := json.Marshal(x)
+ if err != nil {
+ return nil, err
+ }
+ b.Write(d)
+ }
+ b.WriteByte('}')
+ return b.Bytes(), nil
+}
+
+// UnmarshalMessageSetJSON decodes the extension map encoded in buf in JSON format.
+// It is called by generated UnmarshalJSON methods on protocol buffer messages with the message_set_wire_format option.
+func UnmarshalMessageSetJSON(buf []byte, m map[int32]Extension) error {
+ // Common-case fast path.
+ if len(buf) == 0 || bytes.Equal(buf, []byte("{}")) {
+ return nil
+ }
+
+ // This is fairly tricky, and it's not clear that it is needed.
+ return errors.New("TODO: UnmarshalMessageSetJSON not yet implemented")
+}
+
// A global registry of types that can be used in a MessageSet.
var messageSetMap = make(map[int32]messageSetDesc)
@@ -221,9 +279,9 @@
}
// RegisterMessageSetType is called from the generated code.
-func RegisterMessageSetType(i messageTypeIder, name string) {
- messageSetMap[i.MessageTypeId()] = messageSetDesc{
- t: reflect.TypeOf(i),
+func RegisterMessageSetType(m Message, fieldNum int32, name string) {
+ messageSetMap[fieldNum] = messageSetDesc{
+ t: reflect.TypeOf(m),
name: name,
}
}