Big sync from internal version:
- include MessageSet support code
- support message_set_wire_format for extensions
- use append throughout encode.go
R=r
CC=golang-dev
http://codereview.appspot.com/3023041
diff --git a/proto/message_set.go b/proto/message_set.go
new file mode 100644
index 0000000..482e26b
--- /dev/null
+++ b/proto/message_set.go
@@ -0,0 +1,180 @@
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2010 Google Inc. All rights reserved.
+// http://code.google.com/p/goprotobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package proto
+
+/*
+ * Support for message sets.
+ */
+
+import (
+ "bytes"
+ "os"
+)
+
+// ErrNoMessageTypeId occurs when a protocol buffer does not have a message type ID.
+// A message type ID is required for storing a protocol buffer in a message set.
+var ErrNoMessageTypeId = os.NewError("proto does not have a message type ID")
+
+// The first two types (_MessageSet_Item and MessageSet)
+// model what the protocol compiler produces for the following protocol message:
+// message MessageSet {
+// repeated group Item = 1 {
+// required int32 type_id = 2;
+// required string message = 3;
+// };
+// }
+// That is the MessageSet wire format. We can't use a proto to generate these
+// because that would introduce a circular dependency between it and this package.
+//
+// When a proto1 proto has a field that looks like:
+// optional message<MessageSet> info = 3;
+// the protocol compiler produces a field in the generated struct that looks like:
+// Info *_proto_.MessageSet "PB(bytes,3,opt,name=info)"
+// The package is automatically inserted so there is no need for that proto file to
+// import this package.
+
+type _MessageSet_Item struct {
+ TypeId *int32 "PB(varint,2,req,name=type_id)"
+ Message []byte "PB(bytes,3,req,name=message)"
+}
+
+type MessageSet struct {
+ Item []*_MessageSet_Item "PB(group,1,rep)"
+ XXX_unrecognized *bytes.Buffer
+ // TODO: caching?
+}
+
+// messageTypeIder is an interface satisfied by a protocol buffer type
+// that may be stored in a MessageSet.
+type messageTypeIder interface {
+ MessageTypeId() int32
+}
+
+func (ms *MessageSet) find(pb interface{}) *_MessageSet_Item {
+ mti, ok := pb.(messageTypeIder)
+ if !ok {
+ return nil
+ }
+ id := mti.MessageTypeId()
+ for _, item := range ms.Item {
+ if *item.TypeId == id {
+ return item
+ }
+ }
+ return nil
+}
+
+func (ms *MessageSet) Has(pb interface{}) bool {
+ if ms.find(pb) != nil {
+ return true
+ }
+ return false
+}
+
+func (ms *MessageSet) Unmarshal(pb interface{}) os.Error {
+ if item := ms.find(pb); item != nil {
+ return Unmarshal(item.Message, pb)
+ }
+ if _, ok := pb.(messageTypeIder); !ok {
+ return ErrNoMessageTypeId
+ }
+ return nil // TODO: return error instead?
+}
+
+func (ms *MessageSet) Marshal(pb interface{}) os.Error {
+ msg, err := Marshal(pb)
+ if err != nil {
+ return err
+ }
+ if item := ms.find(pb); item != nil {
+ // reuse existing item
+ item.Message = msg
+ return nil
+ }
+
+ mti, ok := pb.(messageTypeIder)
+ if !ok {
+ return ErrWrongType // TODO: custom error?
+ }
+
+ mtid := mti.MessageTypeId()
+ ms.Item = append(ms.Item, &_MessageSet_Item{
+ TypeId: &mtid,
+ Message: msg,
+ })
+ return nil
+}
+
+// Support for the message_set_wire_format message option.
+
+func skipVarint(buf []byte) []byte {
+ i := 0
+ for ; buf[i]&0x80 != 0; i++ {
+ }
+ return buf[i+1:]
+}
+
+// MarshalMessageSet encodes the extension map represented by m in the message set wire format.
+// It is called by generated Marshal methods on protocol buffer messages with the message_set_wire_format option.
+func MarshalMessageSet(m map[int32][]byte) ([]byte, os.Error) {
+ ms := &MessageSet{Item: make([]*_MessageSet_Item, len(m))}
+ i := 0
+ for k, v := range m {
+ // Remove the wire type and field number varint, as well as the length varint.
+ v = skipVarint(skipVarint(v))
+
+ ms.Item[i] = &_MessageSet_Item{
+ TypeId: Int32(k),
+ Message: v,
+ }
+ i++
+ }
+ return Marshal(ms)
+}
+
+// UnmarshalMessageSet decodes the extension map encoded in buf in the message set wire format.
+// It is called by generated Unmarshal methods on protocol buffer messages with the message_set_wire_format option.
+func UnmarshalMessageSet(buf []byte, m map[int32][]byte) os.Error {
+ ms := new(MessageSet)
+ if err := Unmarshal(buf, ms); err != nil {
+ return err
+ }
+ for _, item := range ms.Item {
+ // restore wire type and field number varint, plus length varint.
+ b := EncodeVarint(uint64(*item.TypeId)<<3 | WireBytes)
+ b = append(b, EncodeVarint(uint64(len(item.Message)))...)
+ b = append(b, item.Message...)
+
+ m[*item.TypeId] = b
+ }
+ return nil
+}