equal.go raw
1 // Copyright 2024 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
5 package impl
6
7 import (
8 "bytes"
9
10 "google.golang.org/protobuf/encoding/protowire"
11 "google.golang.org/protobuf/reflect/protoreflect"
12 "google.golang.org/protobuf/runtime/protoiface"
13 )
14
15 func equal(in protoiface.EqualInput) protoiface.EqualOutput {
16 return protoiface.EqualOutput{Equal: equalMessage(in.MessageA, in.MessageB)}
17 }
18
19 // equalMessage is a fast-path variant of protoreflect.equalMessage.
20 // It takes advantage of the internal messageState type to avoid
21 // unnecessary allocations, type assertions.
22 func equalMessage(mx, my protoreflect.Message) bool {
23 if mx == nil || my == nil {
24 return mx == my
25 }
26 if mx.Descriptor() != my.Descriptor() {
27 return false
28 }
29
30 msx, ok := mx.(*messageState)
31 if !ok {
32 return protoreflect.ValueOfMessage(mx).Equal(protoreflect.ValueOfMessage(my))
33 }
34 msy, ok := my.(*messageState)
35 if !ok {
36 return protoreflect.ValueOfMessage(mx).Equal(protoreflect.ValueOfMessage(my))
37 }
38
39 mi := msx.messageInfo()
40 miy := msy.messageInfo()
41 if mi != miy {
42 return protoreflect.ValueOfMessage(mx).Equal(protoreflect.ValueOfMessage(my))
43 }
44 mi.init()
45 // Compares regular fields
46 // Modified Message.Range code that compares two messages of the same type
47 // while going over the fields.
48 for _, ri := range mi.rangeInfos {
49 var fd protoreflect.FieldDescriptor
50 var vx, vy protoreflect.Value
51
52 switch ri := ri.(type) {
53 case *fieldInfo:
54 hx := ri.has(msx.pointer())
55 hy := ri.has(msy.pointer())
56 if hx != hy {
57 return false
58 }
59 if !hx {
60 continue
61 }
62 fd = ri.fieldDesc
63 vx = ri.get(msx.pointer())
64 vy = ri.get(msy.pointer())
65 case *oneofInfo:
66 fnx := ri.which(msx.pointer())
67 fny := ri.which(msy.pointer())
68 if fnx != fny {
69 return false
70 }
71 if fnx <= 0 {
72 continue
73 }
74 fi := mi.fields[fnx]
75 fd = fi.fieldDesc
76 vx = fi.get(msx.pointer())
77 vy = fi.get(msy.pointer())
78 }
79
80 if !equalValue(fd, vx, vy) {
81 return false
82 }
83 }
84
85 // Compare extensions.
86 // This is more complicated because mx or my could have empty/nil extension maps,
87 // however some populated extension map values are equal to nil extension maps.
88 emx := mi.extensionMap(msx.pointer())
89 emy := mi.extensionMap(msy.pointer())
90 if emx != nil {
91 for k, x := range *emx {
92 xd := x.Type().TypeDescriptor()
93 xv := x.Value()
94 var y ExtensionField
95 ok := false
96 if emy != nil {
97 y, ok = (*emy)[k]
98 }
99 // We need to treat empty lists as equal to nil values
100 if emy == nil || !ok {
101 if xd.IsList() && xv.List().Len() == 0 {
102 continue
103 }
104 return false
105 }
106
107 if !equalValue(xd, xv, y.Value()) {
108 return false
109 }
110 }
111 }
112 if emy != nil {
113 // emy may have extensions emx does not have, need to check them as well
114 for k, y := range *emy {
115 if emx != nil {
116 // emx has the field, so we already checked it
117 if _, ok := (*emx)[k]; ok {
118 continue
119 }
120 }
121 // Empty lists are equal to nil
122 if y.Type().TypeDescriptor().IsList() && y.Value().List().Len() == 0 {
123 continue
124 }
125
126 // Cant be equal if the extension is populated
127 return false
128 }
129 }
130
131 return equalUnknown(mx.GetUnknown(), my.GetUnknown())
132 }
133
134 func equalValue(fd protoreflect.FieldDescriptor, vx, vy protoreflect.Value) bool {
135 // slow path
136 if fd.Kind() != protoreflect.MessageKind {
137 return vx.Equal(vy)
138 }
139
140 // fast path special cases
141 if fd.IsMap() {
142 if fd.MapValue().Kind() == protoreflect.MessageKind {
143 return equalMessageMap(vx.Map(), vy.Map())
144 }
145 return vx.Equal(vy)
146 }
147
148 if fd.IsList() {
149 return equalMessageList(vx.List(), vy.List())
150 }
151
152 return equalMessage(vx.Message(), vy.Message())
153 }
154
155 // Mostly copied from protoreflect.equalMap.
156 // This variant only works for messages as map types.
157 // All other map types should be handled via Value.Equal.
158 func equalMessageMap(mx, my protoreflect.Map) bool {
159 if mx.Len() != my.Len() {
160 return false
161 }
162 equal := true
163 mx.Range(func(k protoreflect.MapKey, vx protoreflect.Value) bool {
164 if !my.Has(k) {
165 equal = false
166 return false
167 }
168 vy := my.Get(k)
169 equal = equalMessage(vx.Message(), vy.Message())
170 return equal
171 })
172 return equal
173 }
174
175 // Mostly copied from protoreflect.equalList.
176 // The only change is the usage of equalImpl instead of protoreflect.equalValue.
177 func equalMessageList(lx, ly protoreflect.List) bool {
178 if lx.Len() != ly.Len() {
179 return false
180 }
181 for i := 0; i < lx.Len(); i++ {
182 // We only operate on messages here since equalImpl will not call us in any other case.
183 if !equalMessage(lx.Get(i).Message(), ly.Get(i).Message()) {
184 return false
185 }
186 }
187 return true
188 }
189
190 // equalUnknown compares unknown fields by direct comparison on the raw bytes
191 // of each individual field number.
192 // Copied from protoreflect.equalUnknown.
193 func equalUnknown(x, y protoreflect.RawFields) bool {
194 if len(x) != len(y) {
195 return false
196 }
197 if bytes.Equal([]byte(x), []byte(y)) {
198 return true
199 }
200
201 mx := make(map[protoreflect.FieldNumber]protoreflect.RawFields)
202 my := make(map[protoreflect.FieldNumber]protoreflect.RawFields)
203 for len(x) > 0 {
204 fnum, _, n := protowire.ConsumeField(x)
205 mx[fnum] = append(mx[fnum], x[:n]...)
206 x = x[n:]
207 }
208 for len(y) > 0 {
209 fnum, _, n := protowire.ConsumeField(y)
210 my[fnum] = append(my[fnum], y[:n]...)
211 y = y[n:]
212 }
213 if len(mx) != len(my) {
214 return false
215 }
216
217 for k, v1 := range mx {
218 if v2, ok := my[k]; !ok || !bytes.Equal([]byte(v1), []byte(v2)) {
219 return false
220 }
221 }
222
223 return true
224 }
225