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// Go support for Protocol Buffers - Google's data interchange format
//
// Copyright 2010 The Go Authors. All rights reserved.
// https://github.com/golang/protobuf
//
// 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 (
"errors"
)
// 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 = errors.New("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.
type _MessageSet_Item struct {
TypeId *int32 `protobuf:"varint,2,req,name=type_id"`
Message []byte `protobuf:"bytes,3,req,name=message"`
}
type messageSet struct {
Item []*_MessageSet_Item `protobuf:"group,1,rep"`
XXX_unrecognized []byte
// TODO: caching?
}
// Make sure messageSet is a Message.
var _ Message = (*messageSet)(nil)
// 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 Message) *_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 Message) bool {
return ms.find(pb) != nil
}
func (ms *messageSet) Unmarshal(pb Message) 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 Message) 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 errNoMessageTypeID
}
mtid := mti.MessageTypeId()
ms.Item = append(ms.Item, &_MessageSet_Item{
TypeId: &mtid,
Message: msg,
})
return nil
}
func (ms *messageSet) Reset() { *ms = messageSet{} }
func (ms *messageSet) String() string { return CompactTextString(ms) }
func (*messageSet) ProtoMessage() {}
// 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:]
}
// unmarshalMessageSet decodes the extension map encoded in buf in the message set wire format.
// It is called by Unmarshal methods on protocol buffer messages with the message_set_wire_format option.
func unmarshalMessageSet(buf []byte, exts interface{}) error {
var m map[int32]Extension
switch exts := exts.(type) {
case *XXX_InternalExtensions:
m = exts.extensionsWrite()
case map[int32]Extension:
m = exts
default:
return errors.New("proto: not an extension map")
}
ms := new(messageSet)
if err := Unmarshal(buf, ms); err != nil {
return err
}
for _, item := range ms.Item {
id := *item.TypeId
msg := item.Message
// Restore wire type and field number varint, plus length varint.
// Be careful to preserve duplicate items.
b := EncodeVarint(uint64(id)<<3 | WireBytes)
if ext, ok := m[id]; ok {
// Existing data; rip off the tag and length varint
// so we join the new data correctly.
// We can assume that ext.enc is set because we are unmarshaling.
o := ext.enc[len(b):] // skip wire type and field number
_, n := DecodeVarint(o) // calculate length of length varint
o = o[n:] // skip length varint
msg = append(o, msg...) // join old data and new data
}
b = append(b, EncodeVarint(uint64(len(msg)))...)
b = append(b, msg...)
m[id] = Extension{enc: b}
}
return nil
}
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