mirror of
https://github.com/protocolbuffers/protobuf-go.git
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79 lines
2.4 KiB
Go
79 lines
2.4 KiB
Go
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// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package proto
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import "google.golang.org/protobuf/reflect/protoreflect"
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// Merge merges src into dst, which must be messages with the same descriptor.
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//
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// Populated scalar fields in src are copied to dst, while populated
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// singular messages in src are merged into dst by recursively calling Merge.
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// The elements of every list field in src is appended to the corresponded
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// list fields in dst. The entries of every map field in src is copied into
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// the corresponding map field in dst, possibly replacing existing entries.
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// The unknown fields of src are appended to the unknown fields of dst.
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func Merge(dst, src Message) {
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mergeMessage(dst.ProtoReflect(), src.ProtoReflect())
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}
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func mergeMessage(dst, src protoreflect.Message) {
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if dst.Descriptor() != src.Descriptor() {
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panic("descriptor mismatch")
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}
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src.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
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switch {
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case fd.IsList():
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mergeList(dst.Mutable(fd).List(), v.List(), fd)
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case fd.IsMap():
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mergeMap(dst.Mutable(fd).Map(), v.Map(), fd.MapValue())
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case fd.Message() != nil:
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mergeMessage(dst.Mutable(fd).Message(), v.Message())
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case fd.Kind() == protoreflect.BytesKind:
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dst.Set(fd, cloneBytes(v))
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default:
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dst.Set(fd, v)
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}
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return true
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})
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dst.SetUnknown(append(dst.GetUnknown(), src.GetUnknown()...))
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}
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func mergeList(dst, src protoreflect.List, fd protoreflect.FieldDescriptor) {
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for i := 0; i < src.Len(); i++ {
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switch v := src.Get(i); {
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case fd.Message() != nil:
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m := dst.NewMessage()
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mergeMessage(m, v.Message())
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dst.Append(protoreflect.ValueOf(m))
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case fd.Kind() == protoreflect.BytesKind:
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dst.Append(cloneBytes(v))
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default:
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dst.Append(v)
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}
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}
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}
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func mergeMap(dst, src protoreflect.Map, fd protoreflect.FieldDescriptor) {
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src.Range(func(k protoreflect.MapKey, v protoreflect.Value) bool {
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switch {
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case fd.Message() != nil:
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m := dst.NewMessage()
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mergeMessage(m, v.Message())
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dst.Set(k, protoreflect.ValueOf(m)) // may replace existing entry
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case fd.Kind() == protoreflect.BytesKind:
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dst.Set(k, cloneBytes(v))
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default:
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dst.Set(k, v)
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}
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return true
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})
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}
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func cloneBytes(v protoreflect.Value) protoreflect.Value {
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return protoreflect.ValueOf(append([]byte{}, v.Bytes()...))
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}
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