vendor/github.com/golang/protobuf/proto/message_set.go

   1 // Go support for Protocol Buffers - Google's data interchange format
   2 //
   3 // Copyright 2010 The Go Authors.  All rights reserved.
   4 // https://github.com/golang/protobuf
   5 //
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   7 // modification, are permitted provided that the following conditions are
   8 // met:
   9 //
  10 //     * Redistributions of source code must retain the above copyright
  11 // notice, this list of conditions and the following disclaimer.
  12 //     * Redistributions in binary form must reproduce the above
  13 // copyright notice, this list of conditions and the following disclaimer
  14 // in the documentation and/or other materials provided with the
  15 // distribution.
  16 //     * Neither the name of Google Inc. nor the names of its
  17 // contributors may be used to endorse or promote products derived from
  18 // this software without specific prior written permission.
  19 //
  20 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  21 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  22 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  23 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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  29 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  30 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31
  32 package proto
  33
  34 /*
  35  * Support for message sets.
  36  */
  37
  38 import (
  39         "errors"
  40 )
  41
  42 // errNoMessageTypeID occurs when a protocol buffer does not have a message type ID.
  43 // A message type ID is required for storing a protocol buffer in a message set.
  44 var errNoMessageTypeID = errors.New("proto does not have a message type ID")
  45
  46 // The first two types (_MessageSet_Item and messageSet)
  47 // model what the protocol compiler produces for the following protocol message:
  48 //   message MessageSet {
  49 //     repeated group Item = 1 {
  50 //       required int32 type_id = 2;
  51 //       required string message = 3;
  52 //     };
  53 //   }
  54 // That is the MessageSet wire format. We can't use a proto to generate these
  55 // because that would introduce a circular dependency between it and this package.
  56
  57 type _MessageSet_Item struct {
  58         TypeId  *int32 `protobuf:"varint,2,req,name=type_id"`
  59         Message []byte `protobuf:"bytes,3,req,name=message"`
  60 }
  61
  62 type messageSet struct {
  63         Item             []*_MessageSet_Item `protobuf:"group,1,rep"`
  64         XXX_unrecognized []byte
  65         // TODO: caching?
  66 }
  67
  68 // Make sure messageSet is a Message.
  69 var _ Message = (*messageSet)(nil)
  70
  71 // messageTypeIder is an interface satisfied by a protocol buffer type
  72 // that may be stored in a MessageSet.
  73 type messageTypeIder interface {
  74         MessageTypeId() int32
  75 }
  76
  77 func (ms *messageSet) find(pb Message) *_MessageSet_Item {
  78         mti, ok := pb.(messageTypeIder)
  79         if !ok {
  80                 return nil
  81         }
  82         id := mti.MessageTypeId()
  83         for _, item := range ms.Item {
  84                 if *item.TypeId == id {
  85                         return item
  86                 }
  87         }
  88         return nil
  89 }
  90
  91 func (ms *messageSet) Has(pb Message) bool {
  92         return ms.find(pb) != nil
  93 }
  94
  95 func (ms *messageSet) Unmarshal(pb Message) error {
  96         if item := ms.find(pb); item != nil {
  97                 return Unmarshal(item.Message, pb)
  98         }
  99         if _, ok := pb.(messageTypeIder); !ok {
 100                 return errNoMessageTypeID
 101         }
 102         return nil // TODO: return error instead?
 103 }
 104
 105 func (ms *messageSet) Marshal(pb Message) error {
 106         msg, err := Marshal(pb)
 107         if err != nil {
 108                 return err
 109         }
 110         if item := ms.find(pb); item != nil {
 111                 // reuse existing item
 112                 item.Message = msg
 113                 return nil
 114         }
 115
 116         mti, ok := pb.(messageTypeIder)
 117         if !ok {
 118                 return errNoMessageTypeID
 119         }
 120
 121         mtid := mti.MessageTypeId()
 122         ms.Item = append(ms.Item, &_MessageSet_Item{
 123                 TypeId:  &mtid,
 124                 Message: msg,
 125         })
 126         return nil
 127 }
 128
 129 func (ms *messageSet) Reset()         { *ms = messageSet{} }
 130 func (ms *messageSet) String() string { return CompactTextString(ms) }
 131 func (*messageSet) ProtoMessage()     {}
 132
 133 // Support for the message_set_wire_format message option.
 134
 135 func skipVarint(buf []byte) []byte {
 136         i := 0
 137         for ; buf[i]&0x80 != 0; i++ {
 138         }
 139         return buf[i+1:]
 140 }
 141
 142 // unmarshalMessageSet decodes the extension map encoded in buf in the message set wire format.
 143 // It is called by Unmarshal methods on protocol buffer messages with the message_set_wire_format option.
 144 func unmarshalMessageSet(buf []byte, exts interface{}) error {
 145         var m map[int32]Extension
 146         switch exts := exts.(type) {
 147         case *XXX_InternalExtensions:
 148                 m = exts.extensionsWrite()
 149         case map[int32]Extension:
 150                 m = exts
 151         default:
 152                 return errors.New("proto: not an extension map")
 153         }
 154
 155         ms := new(messageSet)
 156         if err := Unmarshal(buf, ms); err != nil {
 157                 return err
 158         }
 159         for _, item := range ms.Item {
 160                 id := *item.TypeId
 161                 msg := item.Message
 162
 163                 // Restore wire type and field number varint, plus length varint.
 164                 // Be careful to preserve duplicate items.
 165                 b := EncodeVarint(uint64(id)<<3 | WireBytes)
 166                 if ext, ok := m[id]; ok {
 167                         // Existing data; rip off the tag and length varint
 168                         // so we join the new data correctly.
 169                         // We can assume that ext.enc is set because we are unmarshaling.
 170                         o := ext.enc[len(b):]   // skip wire type and field number
 171                         _, n := DecodeVarint(o) // calculate length of length varint
 172                         o = o[n:]               // skip length varint
 173                         msg = append(o, msg...) // join old data and new data
 174                 }
 175                 b = append(b, EncodeVarint(uint64(len(msg)))...)
 176                 b = append(b, msg...)
 177
 178                 m[id] = Extension{enc: b}
 179         }
 180         return nil
 181 }