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8cc9e46 Nov 8, 2017
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@dsymonds @matloob @dsnet
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// Go support for Protocol Buffers - Google's data interchange format
//
// Copyright 2011 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.
// Protocol buffer deep copy and merge.
// TODO: RawMessage.
package proto
import (
"fmt"
"log"
"reflect"
"strings"
)
// Clone returns a deep copy of a protocol buffer.
func Clone(src Message) Message {
in := reflect.ValueOf(src)
if in.IsNil() {
return src
}
out := reflect.New(in.Type().Elem())
dst := out.Interface().(Message)
Merge(dst, src)
return dst
}
// Merger is the interface representing objects that can merge messages of the same type.
type Merger interface {
// Merge merges src into this message.
// Required and optional fields that are set in src will be set to that value in dst.
// Elements of repeated fields will be appended.
//
// Merge may panic if called with a different argument type than the receiver.
Merge(src Message)
}
// generatedMerger is the custom merge method that generated protos will have.
// We must add this method since a generate Merge method will conflict with
// many existing protos that have a Merge data field already defined.
type generatedMerger interface {
XXX_Merge(src Message)
}
// Merge merges src into dst.
// Required and optional fields that are set in src will be set to that value in dst.
// Elements of repeated fields will be appended.
// Merge panics if src and dst are not the same type, or if dst is nil.
func Merge(dst, src Message) {
if m, ok := dst.(Merger); ok {
m.Merge(src)
return
}
in := reflect.ValueOf(src)
out := reflect.ValueOf(dst)
if out.IsNil() {
panic("proto: nil destination")
}
if in.Type() != out.Type() {
panic(fmt.Sprintf("proto.Merge(%T, %T) type mismatch", dst, src))
}
if in.IsNil() {
return // Merge from nil src is a noop
}
if m, ok := dst.(generatedMerger); ok {
m.XXX_Merge(src)
return
}
mergeStruct(out.Elem(), in.Elem())
}
func mergeStruct(out, in reflect.Value) {
sprop := GetProperties(in.Type())
for i := 0; i < in.NumField(); i++ {
f := in.Type().Field(i)
if strings.HasPrefix(f.Name, "XXX_") {
continue
}
mergeAny(out.Field(i), in.Field(i), false, sprop.Prop[i])
}
if emIn, err := extendable(in.Addr().Interface()); err == nil {
emOut, _ := extendable(out.Addr().Interface())
mIn, muIn := emIn.extensionsRead()
if mIn != nil {
mOut := emOut.extensionsWrite()
muIn.Lock()
mergeExtension(mOut, mIn)
muIn.Unlock()
}
}
uf := in.FieldByName("XXX_unrecognized")
if !uf.IsValid() {
return
}
uin := uf.Bytes()
if len(uin) > 0 {
out.FieldByName("XXX_unrecognized").SetBytes(append([]byte(nil), uin...))
}
}
// mergeAny performs a merge between two values of the same type.
// viaPtr indicates whether the values were indirected through a pointer (implying proto2).
// prop is set if this is a struct field (it may be nil).
func mergeAny(out, in reflect.Value, viaPtr bool, prop *Properties) {
if in.Type() == protoMessageType {
if !in.IsNil() {
if out.IsNil() {
out.Set(reflect.ValueOf(Clone(in.Interface().(Message))))
} else {
Merge(out.Interface().(Message), in.Interface().(Message))
}
}
return
}
switch in.Kind() {
case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64,
reflect.String, reflect.Uint32, reflect.Uint64:
if !viaPtr && isProto3Zero(in) {
return
}
out.Set(in)
case reflect.Interface:
// Probably a oneof field; copy non-nil values.
if in.IsNil() {
return
}
// Allocate destination if it is not set, or set to a different type.
// Otherwise we will merge as normal.
if out.IsNil() || out.Elem().Type() != in.Elem().Type() {
out.Set(reflect.New(in.Elem().Elem().Type())) // interface -> *T -> T -> new(T)
}
mergeAny(out.Elem(), in.Elem(), false, nil)
case reflect.Map:
if in.Len() == 0 {
return
}
if out.IsNil() {
out.Set(reflect.MakeMap(in.Type()))
}
// For maps with value types of *T or []byte we need to deep copy each value.
elemKind := in.Type().Elem().Kind()
for _, key := range in.MapKeys() {
var val reflect.Value
switch elemKind {
case reflect.Ptr:
val = reflect.New(in.Type().Elem().Elem())
mergeAny(val, in.MapIndex(key), false, nil)
case reflect.Slice:
val = in.MapIndex(key)
val = reflect.ValueOf(append([]byte{}, val.Bytes()...))
default:
val = in.MapIndex(key)
}
out.SetMapIndex(key, val)
}
case reflect.Ptr:
if in.IsNil() {
return
}
if out.IsNil() {
out.Set(reflect.New(in.Elem().Type()))
}
mergeAny(out.Elem(), in.Elem(), true, nil)
case reflect.Slice:
if in.IsNil() {
return
}
if in.Type().Elem().Kind() == reflect.Uint8 {
// []byte is a scalar bytes field, not a repeated field.
// Edge case: if this is in a proto3 message, a zero length
// bytes field is considered the zero value, and should not
// be merged.
if prop != nil && prop.proto3 && in.Len() == 0 {
return
}
// Make a deep copy.
// Append to []byte{} instead of []byte(nil) so that we never end up
// with a nil result.
out.SetBytes(append([]byte{}, in.Bytes()...))
return
}
n := in.Len()
if out.IsNil() {
out.Set(reflect.MakeSlice(in.Type(), 0, n))
}
switch in.Type().Elem().Kind() {
case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64,
reflect.String, reflect.Uint32, reflect.Uint64:
out.Set(reflect.AppendSlice(out, in))
default:
for i := 0; i < n; i++ {
x := reflect.Indirect(reflect.New(in.Type().Elem()))
mergeAny(x, in.Index(i), false, nil)
out.Set(reflect.Append(out, x))
}
}
case reflect.Struct:
mergeStruct(out, in)
default:
// unknown type, so not a protocol buffer
log.Printf("proto: don't know how to copy %v", in)
}
}
func mergeExtension(out, in map[int32]Extension) {
for extNum, eIn := range in {
eOut := Extension{desc: eIn.desc}
if eIn.value != nil {
v := reflect.New(reflect.TypeOf(eIn.value)).Elem()
mergeAny(v, reflect.ValueOf(eIn.value), false, nil)
eOut.value = v.Interface()
}
if eIn.enc != nil {
eOut.enc = make([]byte, len(eIn.enc))
copy(eOut.enc, eIn.enc)
}
out[extNum] = eOut
}
}