230 lines
6.8 KiB
Go
230 lines
6.8 KiB
Go
// Go support for Protocol Buffers - Google's data interchange format
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//
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// Copyright 2011 The Go Authors. All rights reserved.
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// https://github.com/golang/protobuf
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Protocol buffer deep copy and merge.
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// TODO: RawMessage.
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package proto
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import (
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"log"
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"reflect"
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"strings"
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)
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// Clone returns a deep copy of a protocol buffer.
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func Clone(pb Message) Message {
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in := reflect.ValueOf(pb)
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if in.IsNil() {
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return pb
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}
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out := reflect.New(in.Type().Elem())
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// out is empty so a merge is a deep copy.
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mergeStruct(out.Elem(), in.Elem())
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return out.Interface().(Message)
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}
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// Merge merges src into dst.
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// Required and optional fields that are set in src will be set to that value in dst.
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// Elements of repeated fields will be appended.
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// Merge panics if src and dst are not the same type, or if dst is nil.
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func Merge(dst, src Message) {
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in := reflect.ValueOf(src)
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out := reflect.ValueOf(dst)
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if out.IsNil() {
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panic("proto: nil destination")
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}
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if in.Type() != out.Type() {
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// Explicit test prior to mergeStruct so that mistyped nils will fail
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panic("proto: type mismatch")
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}
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if in.IsNil() {
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// Merging nil into non-nil is a quiet no-op
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return
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}
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mergeStruct(out.Elem(), in.Elem())
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}
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func mergeStruct(out, in reflect.Value) {
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sprop := GetProperties(in.Type())
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for i := 0; i < in.NumField(); i++ {
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f := in.Type().Field(i)
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if strings.HasPrefix(f.Name, "XXX_") {
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continue
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}
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mergeAny(out.Field(i), in.Field(i), false, sprop.Prop[i])
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}
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if emIn, ok := extendable(in.Addr().Interface()); ok {
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emOut, _ := extendable(out.Addr().Interface())
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mIn, muIn := emIn.extensionsRead()
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if mIn != nil {
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mOut := emOut.extensionsWrite()
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muIn.Lock()
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mergeExtension(mOut, mIn)
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muIn.Unlock()
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}
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}
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uf := in.FieldByName("XXX_unrecognized")
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if !uf.IsValid() {
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return
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}
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uin := uf.Bytes()
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if len(uin) > 0 {
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out.FieldByName("XXX_unrecognized").SetBytes(append([]byte(nil), uin...))
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}
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}
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// mergeAny performs a merge between two values of the same type.
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// viaPtr indicates whether the values were indirected through a pointer (implying proto2).
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// prop is set if this is a struct field (it may be nil).
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func mergeAny(out, in reflect.Value, viaPtr bool, prop *Properties) {
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if in.Type() == protoMessageType {
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if !in.IsNil() {
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if out.IsNil() {
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out.Set(reflect.ValueOf(Clone(in.Interface().(Message))))
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} else {
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Merge(out.Interface().(Message), in.Interface().(Message))
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}
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}
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return
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}
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switch in.Kind() {
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case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64,
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reflect.String, reflect.Uint32, reflect.Uint64:
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if !viaPtr && isProto3Zero(in) {
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return
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}
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out.Set(in)
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case reflect.Interface:
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// Probably a oneof field; copy non-nil values.
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if in.IsNil() {
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return
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}
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// Allocate destination if it is not set, or set to a different type.
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// Otherwise we will merge as normal.
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if out.IsNil() || out.Elem().Type() != in.Elem().Type() {
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out.Set(reflect.New(in.Elem().Elem().Type())) // interface -> *T -> T -> new(T)
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}
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mergeAny(out.Elem(), in.Elem(), false, nil)
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case reflect.Map:
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if in.Len() == 0 {
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return
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}
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if out.IsNil() {
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out.Set(reflect.MakeMap(in.Type()))
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}
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// For maps with value types of *T or []byte we need to deep copy each value.
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elemKind := in.Type().Elem().Kind()
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for _, key := range in.MapKeys() {
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var val reflect.Value
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switch elemKind {
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case reflect.Ptr:
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val = reflect.New(in.Type().Elem().Elem())
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mergeAny(val, in.MapIndex(key), false, nil)
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case reflect.Slice:
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val = in.MapIndex(key)
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val = reflect.ValueOf(append([]byte{}, val.Bytes()...))
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default:
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val = in.MapIndex(key)
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}
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out.SetMapIndex(key, val)
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}
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case reflect.Ptr:
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if in.IsNil() {
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return
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}
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if out.IsNil() {
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out.Set(reflect.New(in.Elem().Type()))
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}
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mergeAny(out.Elem(), in.Elem(), true, nil)
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case reflect.Slice:
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if in.IsNil() {
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return
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}
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if in.Type().Elem().Kind() == reflect.Uint8 {
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// []byte is a scalar bytes field, not a repeated field.
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// Edge case: if this is in a proto3 message, a zero length
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// bytes field is considered the zero value, and should not
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// be merged.
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if prop != nil && prop.proto3 && in.Len() == 0 {
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return
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}
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// Make a deep copy.
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// Append to []byte{} instead of []byte(nil) so that we never end up
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// with a nil result.
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out.SetBytes(append([]byte{}, in.Bytes()...))
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return
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}
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n := in.Len()
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if out.IsNil() {
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out.Set(reflect.MakeSlice(in.Type(), 0, n))
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}
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switch in.Type().Elem().Kind() {
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case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64,
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reflect.String, reflect.Uint32, reflect.Uint64:
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out.Set(reflect.AppendSlice(out, in))
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default:
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for i := 0; i < n; i++ {
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x := reflect.Indirect(reflect.New(in.Type().Elem()))
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mergeAny(x, in.Index(i), false, nil)
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out.Set(reflect.Append(out, x))
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}
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}
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case reflect.Struct:
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mergeStruct(out, in)
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default:
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// unknown type, so not a protocol buffer
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log.Printf("proto: don't know how to copy %v", in)
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}
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}
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func mergeExtension(out, in map[int32]Extension) {
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for extNum, eIn := range in {
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eOut := Extension{desc: eIn.desc}
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if eIn.value != nil {
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v := reflect.New(reflect.TypeOf(eIn.value)).Elem()
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mergeAny(v, reflect.ValueOf(eIn.value), false, nil)
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eOut.value = v.Interface()
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}
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if eIn.enc != nil {
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eOut.enc = make([]byte, len(eIn.enc))
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copy(eOut.enc, eIn.enc)
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}
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out[extNum] = eOut
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}
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}
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