139 lines
4.4 KiB
Go
139 lines
4.4 KiB
Go
// Copyright 2019 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package proto
|
|
|
|
import (
|
|
"fmt"
|
|
|
|
"google.golang.org/protobuf/reflect/protoreflect"
|
|
"google.golang.org/protobuf/runtime/protoiface"
|
|
)
|
|
|
|
// Merge merges src into dst, which must be a message with the same descriptor.
|
|
//
|
|
// Populated scalar fields in src are copied to dst, while populated
|
|
// singular messages in src are merged into dst by recursively calling Merge.
|
|
// The elements of every list field in src is appended to the corresponded
|
|
// list fields in dst. The entries of every map field in src is copied into
|
|
// the corresponding map field in dst, possibly replacing existing entries.
|
|
// The unknown fields of src are appended to the unknown fields of dst.
|
|
//
|
|
// It is semantically equivalent to unmarshaling the encoded form of src
|
|
// into dst with the UnmarshalOptions.Merge option specified.
|
|
func Merge(dst, src Message) {
|
|
// TODO: Should nil src be treated as semantically equivalent to a
|
|
// untyped, read-only, empty message? What about a nil dst?
|
|
|
|
dstMsg, srcMsg := dst.ProtoReflect(), src.ProtoReflect()
|
|
if dstMsg.Descriptor() != srcMsg.Descriptor() {
|
|
if got, want := dstMsg.Descriptor().FullName(), srcMsg.Descriptor().FullName(); got != want {
|
|
panic(fmt.Sprintf("descriptor mismatch: %v != %v", got, want))
|
|
}
|
|
panic("descriptor mismatch")
|
|
}
|
|
mergeOptions{}.mergeMessage(dstMsg, srcMsg)
|
|
}
|
|
|
|
// Clone returns a deep copy of m.
|
|
// If the top-level message is invalid, it returns an invalid message as well.
|
|
func Clone(m Message) Message {
|
|
// NOTE: Most usages of Clone assume the following properties:
|
|
// t := reflect.TypeOf(m)
|
|
// t == reflect.TypeOf(m.ProtoReflect().New().Interface())
|
|
// t == reflect.TypeOf(m.ProtoReflect().Type().Zero().Interface())
|
|
//
|
|
// Embedding protobuf messages breaks this since the parent type will have
|
|
// a forwarded ProtoReflect method, but the Interface method will return
|
|
// the underlying embedded message type.
|
|
if m == nil {
|
|
return nil
|
|
}
|
|
src := m.ProtoReflect()
|
|
if !src.IsValid() {
|
|
return src.Type().Zero().Interface()
|
|
}
|
|
dst := src.New()
|
|
mergeOptions{}.mergeMessage(dst, src)
|
|
return dst.Interface()
|
|
}
|
|
|
|
// mergeOptions provides a namespace for merge functions, and can be
|
|
// exported in the future if we add user-visible merge options.
|
|
type mergeOptions struct{}
|
|
|
|
func (o mergeOptions) mergeMessage(dst, src protoreflect.Message) {
|
|
methods := protoMethods(dst)
|
|
if methods != nil && methods.Merge != nil {
|
|
in := protoiface.MergeInput{
|
|
Destination: dst,
|
|
Source: src,
|
|
}
|
|
out := methods.Merge(in)
|
|
if out.Flags&protoiface.MergeComplete != 0 {
|
|
return
|
|
}
|
|
}
|
|
|
|
if !dst.IsValid() {
|
|
panic(fmt.Sprintf("cannot merge into invalid %v message", dst.Descriptor().FullName()))
|
|
}
|
|
|
|
src.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
|
|
switch {
|
|
case fd.IsList():
|
|
o.mergeList(dst.Mutable(fd).List(), v.List(), fd)
|
|
case fd.IsMap():
|
|
o.mergeMap(dst.Mutable(fd).Map(), v.Map(), fd.MapValue())
|
|
case fd.Message() != nil:
|
|
o.mergeMessage(dst.Mutable(fd).Message(), v.Message())
|
|
case fd.Kind() == protoreflect.BytesKind:
|
|
dst.Set(fd, o.cloneBytes(v))
|
|
default:
|
|
dst.Set(fd, v)
|
|
}
|
|
return true
|
|
})
|
|
|
|
if len(src.GetUnknown()) > 0 {
|
|
dst.SetUnknown(append(dst.GetUnknown(), src.GetUnknown()...))
|
|
}
|
|
}
|
|
|
|
func (o mergeOptions) mergeList(dst, src protoreflect.List, fd protoreflect.FieldDescriptor) {
|
|
// Merge semantics appends to the end of the existing list.
|
|
for i, n := 0, src.Len(); i < n; i++ {
|
|
switch v := src.Get(i); {
|
|
case fd.Message() != nil:
|
|
dstv := dst.NewElement()
|
|
o.mergeMessage(dstv.Message(), v.Message())
|
|
dst.Append(dstv)
|
|
case fd.Kind() == protoreflect.BytesKind:
|
|
dst.Append(o.cloneBytes(v))
|
|
default:
|
|
dst.Append(v)
|
|
}
|
|
}
|
|
}
|
|
|
|
func (o mergeOptions) mergeMap(dst, src protoreflect.Map, fd protoreflect.FieldDescriptor) {
|
|
// Merge semantics replaces, rather than merges into existing entries.
|
|
src.Range(func(k protoreflect.MapKey, v protoreflect.Value) bool {
|
|
switch {
|
|
case fd.Message() != nil:
|
|
dstv := dst.NewValue()
|
|
o.mergeMessage(dstv.Message(), v.Message())
|
|
dst.Set(k, dstv)
|
|
case fd.Kind() == protoreflect.BytesKind:
|
|
dst.Set(k, o.cloneBytes(v))
|
|
default:
|
|
dst.Set(k, v)
|
|
}
|
|
return true
|
|
})
|
|
}
|
|
|
|
func (o mergeOptions) cloneBytes(v protoreflect.Value) protoreflect.Value {
|
|
return protoreflect.ValueOfBytes(append([]byte{}, v.Bytes()...))
|
|
}
|