aboutsummaryrefslogtreecommitdiffstats
path: root/vendor/google.golang.org/protobuf/proto/merge.go
blob: df72f989529442b7dc2d6f1d258a6b3853862d28 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
// 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 (
	"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) {
	dstMsg, srcMsg := dst.ProtoReflect(), src.ProtoReflect()
	if dstMsg.Descriptor() != srcMsg.Descriptor() {
		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("cannot merge into invalid destination message")
	}

	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()...))
}