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

   1 // Go support for Protocol Buffers - Google's data interchange format
   2 //
   3 // Copyright 2011 The Go Authors.  All rights reserved.
   4 // https://github.com/golang/protobuf
   5 //
   6 // Redistribution and use in source and binary forms, with or without
   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
  24 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  25 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  26 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  27 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  28 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  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 // Protocol buffer deep copy and merge.
  33 // TODO: RawMessage.
  34
  35 package proto
  36
  37 import (
  38         "fmt"
  39         "log"
  40         "reflect"
  41         "strings"
  42 )
  43
  44 // Clone returns a deep copy of a protocol buffer.
  45 func Clone(src Message) Message {
  46         in := reflect.ValueOf(src)
  47         if in.IsNil() {
  48                 return src
  49         }
  50         out := reflect.New(in.Type().Elem())
  51         dst := out.Interface().(Message)
  52         Merge(dst, src)
  53         return dst
  54 }
  55
  56 // Merger is the interface representing objects that can merge messages of the same type.
  57 type Merger interface {
  58         // Merge merges src into this message.
  59         // Required and optional fields that are set in src will be set to that value in dst.
  60         // Elements of repeated fields will be appended.
  61         //
  62         // Merge may panic if called with a different argument type than the receiver.
  63         Merge(src Message)
  64 }
  65
  66 // generatedMerger is the custom merge method that generated protos will have.
  67 // We must add this method since a generate Merge method will conflict with
  68 // many existing protos that have a Merge data field already defined.
  69 type generatedMerger interface {
  70         XXX_Merge(src Message)
  71 }
  72
  73 // Merge merges src into dst.
  74 // Required and optional fields that are set in src will be set to that value in dst.
  75 // Elements of repeated fields will be appended.
  76 // Merge panics if src and dst are not the same type, or if dst is nil.
  77 func Merge(dst, src Message) {
  78         if m, ok := dst.(Merger); ok {
  79                 m.Merge(src)
  80                 return
  81         }
  82
  83         in := reflect.ValueOf(src)
  84         out := reflect.ValueOf(dst)
  85         if out.IsNil() {
  86                 panic("proto: nil destination")
  87         }
  88         if in.Type() != out.Type() {
  89                 panic(fmt.Sprintf("proto.Merge(%T, %T) type mismatch", dst, src))
  90         }
  91         if in.IsNil() {
  92                 return // Merge from nil src is a noop
  93         }
  94         if m, ok := dst.(generatedMerger); ok {
  95                 m.XXX_Merge(src)
  96                 return
  97         }
  98         mergeStruct(out.Elem(), in.Elem())
  99 }
 100
 101 func mergeStruct(out, in reflect.Value) {
 102         sprop := GetProperties(in.Type())
 103         for i := 0; i < in.NumField(); i++ {
 104                 f := in.Type().Field(i)
 105                 if strings.HasPrefix(f.Name, "XXX_") {
 106                         continue
 107                 }
 108                 mergeAny(out.Field(i), in.Field(i), false, sprop.Prop[i])
 109         }
 110
 111         if emIn, err := extendable(in.Addr().Interface()); err == nil {
 112                 emOut, _ := extendable(out.Addr().Interface())
 113                 mIn, muIn := emIn.extensionsRead()
 114                 if mIn != nil {
 115                         mOut := emOut.extensionsWrite()
 116                         muIn.Lock()
 117                         mergeExtension(mOut, mIn)
 118                         muIn.Unlock()
 119                 }
 120         }
 121
 122         uf := in.FieldByName("XXX_unrecognized")
 123         if !uf.IsValid() {
 124                 return
 125         }
 126         uin := uf.Bytes()
 127         if len(uin) > 0 {
 128                 out.FieldByName("XXX_unrecognized").SetBytes(append([]byte(nil), uin...))
 129         }
 130 }
 131
 132 // mergeAny performs a merge between two values of the same type.
 133 // viaPtr indicates whether the values were indirected through a pointer (implying proto2).
 134 // prop is set if this is a struct field (it may be nil).
 135 func mergeAny(out, in reflect.Value, viaPtr bool, prop *Properties) {
 136         if in.Type() == protoMessageType {
 137                 if !in.IsNil() {
 138                         if out.IsNil() {
 139                                 out.Set(reflect.ValueOf(Clone(in.Interface().(Message))))
 140                         } else {
 141                                 Merge(out.Interface().(Message), in.Interface().(Message))
 142                         }
 143                 }
 144                 return
 145         }
 146         switch in.Kind() {
 147         case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64,
 148                 reflect.String, reflect.Uint32, reflect.Uint64:
 149                 if !viaPtr && isProto3Zero(in) {
 150                         return
 151                 }
 152                 out.Set(in)
 153         case reflect.Interface:
 154                 // Probably a oneof field; copy non-nil values.
 155                 if in.IsNil() {
 156                         return
 157                 }
 158                 // Allocate destination if it is not set, or set to a different type.
 159                 // Otherwise we will merge as normal.
 160                 if out.IsNil() || out.Elem().Type() != in.Elem().Type() {
 161                         out.Set(reflect.New(in.Elem().Elem().Type())) // interface -> *T -> T -> new(T)
 162                 }
 163                 mergeAny(out.Elem(), in.Elem(), false, nil)
 164         case reflect.Map:
 165                 if in.Len() == 0 {
 166                         return
 167                 }
 168                 if out.IsNil() {
 169                         out.Set(reflect.MakeMap(in.Type()))
 170                 }
 171                 // For maps with value types of *T or []byte we need to deep copy each value.
 172                 elemKind := in.Type().Elem().Kind()
 173                 for _, key := range in.MapKeys() {
 174                         var val reflect.Value
 175                         switch elemKind {
 176                         case reflect.Ptr:
 177                                 val = reflect.New(in.Type().Elem().Elem())
 178                                 mergeAny(val, in.MapIndex(key), false, nil)
 179                         case reflect.Slice:
 180                                 val = in.MapIndex(key)
 181                                 val = reflect.ValueOf(append([]byte{}, val.Bytes()...))
 182                         default:
 183                                 val = in.MapIndex(key)
 184                         }
 185                         out.SetMapIndex(key, val)
 186                 }
 187         case reflect.Ptr:
 188                 if in.IsNil() {
 189                         return
 190                 }
 191                 if out.IsNil() {
 192                         out.Set(reflect.New(in.Elem().Type()))
 193                 }
 194                 mergeAny(out.Elem(), in.Elem(), true, nil)
 195         case reflect.Slice:
 196                 if in.IsNil() {
 197                         return
 198                 }
 199                 if in.Type().Elem().Kind() == reflect.Uint8 {
 200                         // []byte is a scalar bytes field, not a repeated field.
 201
 202                         // Edge case: if this is in a proto3 message, a zero length
 203                         // bytes field is considered the zero value, and should not
 204                         // be merged.
 205                         if prop != nil && prop.proto3 && in.Len() == 0 {
 206                                 return
 207                         }
 208
 209                         // Make a deep copy.
 210                         // Append to []byte{} instead of []byte(nil) so that we never end up
 211                         // with a nil result.
 212                         out.SetBytes(append([]byte{}, in.Bytes()...))
 213                         return
 214                 }
 215                 n := in.Len()
 216                 if out.IsNil() {
 217                         out.Set(reflect.MakeSlice(in.Type(), 0, n))
 218                 }
 219                 switch in.Type().Elem().Kind() {
 220                 case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64,
 221                         reflect.String, reflect.Uint32, reflect.Uint64:
 222                         out.Set(reflect.AppendSlice(out, in))
 223                 default:
 224                         for i := 0; i < n; i++ {
 225                                 x := reflect.Indirect(reflect.New(in.Type().Elem()))
 226                                 mergeAny(x, in.Index(i), false, nil)
 227                                 out.Set(reflect.Append(out, x))
 228                         }
 229                 }
 230         case reflect.Struct:
 231                 mergeStruct(out, in)
 232         default:
 233                 // unknown type, so not a protocol buffer
 234                 log.Printf("proto: don't know how to copy %v", in)
 235         }
 236 }
 237
 238 func mergeExtension(out, in map[int32]Extension) {
 239         for extNum, eIn := range in {
 240                 eOut := Extension{desc: eIn.desc}
 241                 if eIn.value != nil {
 242                         v := reflect.New(reflect.TypeOf(eIn.value)).Elem()
 243                         mergeAny(v, reflect.ValueOf(eIn.value), false, nil)
 244                         eOut.value = v.Interface()
 245                 }
 246                 if eIn.enc != nil {
 247                         eOut.enc = make([]byte, len(eIn.enc))
 248                         copy(eOut.enc, eIn.enc)
 249                 }
 250
 251                 out[extNum] = eOut
 252         }
 253 }