1// Copyright 2019 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package proto
6
7import (
8	"google.golang.org/protobuf/encoding/protowire"
9	"google.golang.org/protobuf/internal/encoding/messageset"
10	"google.golang.org/protobuf/reflect/protoreflect"
11	"google.golang.org/protobuf/runtime/protoiface"
12)
13
14// Size returns the size in bytes of the wire-format encoding of m.
15func Size(m Message) int {
16	return MarshalOptions{}.Size(m)
17}
18
19// Size returns the size in bytes of the wire-format encoding of m.
20func (o MarshalOptions) Size(m Message) int {
21	// Treat a nil message interface as an empty message; nothing to output.
22	if m == nil {
23		return 0
24	}
25
26	return o.size(m.ProtoReflect())
27}
28
29// size is a centralized function that all size operations go through.
30// For profiling purposes, avoid changing the name of this function or
31// introducing other code paths for size that do not go through this.
32func (o MarshalOptions) size(m protoreflect.Message) (size int) {
33	methods := protoMethods(m)
34	if methods != nil && methods.Size != nil {
35		out := methods.Size(protoiface.SizeInput{
36			Message: m,
37		})
38		return out.Size
39	}
40	if methods != nil && methods.Marshal != nil {
41		// This is not efficient, but we don't have any choice.
42		// This case is mainly used for legacy types with a Marshal method.
43		out, _ := methods.Marshal(protoiface.MarshalInput{
44			Message: m,
45		})
46		return len(out.Buf)
47	}
48	return o.sizeMessageSlow(m)
49}
50
51func (o MarshalOptions) sizeMessageSlow(m protoreflect.Message) (size int) {
52	if messageset.IsMessageSet(m.Descriptor()) {
53		return o.sizeMessageSet(m)
54	}
55	m.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
56		size += o.sizeField(fd, v)
57		return true
58	})
59	size += len(m.GetUnknown())
60	return size
61}
62
63func (o MarshalOptions) sizeField(fd protoreflect.FieldDescriptor, value protoreflect.Value) (size int) {
64	num := fd.Number()
65	switch {
66	case fd.IsList():
67		return o.sizeList(num, fd, value.List())
68	case fd.IsMap():
69		return o.sizeMap(num, fd, value.Map())
70	default:
71		return protowire.SizeTag(num) + o.sizeSingular(num, fd.Kind(), value)
72	}
73}
74
75func (o MarshalOptions) sizeList(num protowire.Number, fd protoreflect.FieldDescriptor, list protoreflect.List) (size int) {
76	if fd.IsPacked() && list.Len() > 0 {
77		content := 0
78		for i, llen := 0, list.Len(); i < llen; i++ {
79			content += o.sizeSingular(num, fd.Kind(), list.Get(i))
80		}
81		return protowire.SizeTag(num) + protowire.SizeBytes(content)
82	}
83
84	for i, llen := 0, list.Len(); i < llen; i++ {
85		size += protowire.SizeTag(num) + o.sizeSingular(num, fd.Kind(), list.Get(i))
86	}
87	return size
88}
89
90func (o MarshalOptions) sizeMap(num protowire.Number, fd protoreflect.FieldDescriptor, mapv protoreflect.Map) (size int) {
91	mapv.Range(func(key protoreflect.MapKey, value protoreflect.Value) bool {
92		size += protowire.SizeTag(num)
93		size += protowire.SizeBytes(o.sizeField(fd.MapKey(), key.Value()) + o.sizeField(fd.MapValue(), value))
94		return true
95	})
96	return size
97}
98