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equal.go
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equal.go
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// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package pb
import (
"bytes"
"reflect"
"google.golang.org/protobuf/encoding/protowire"
"google.golang.org/protobuf/proto"
"google.golang.org/protobuf/reflect/protoreflect"
anypb "google.golang.org/protobuf/types/known/anypb"
)
// Equal returns whether two proto.Message instances are equal using the following criteria:
//
// - Messages must share the same instance of the type descriptor
// - Known set fields are compared using semantics equality
// - Bytes are compared using bytes.Equal
// - Scalar values are compared with operator ==
// - List and map types are equal if they have the same length and all elements are equal
// - Messages are equal if they share the same descriptor and all set fields are equal
// - Unknown fields are compared using byte equality
// - NaN values are not equal to each other
// - google.protobuf.Any values are unpacked before comparison
// - If the type descriptor for a protobuf.Any cannot be found, byte equality is used rather than
// semantic equality.
//
// This method of proto equality mirrors the behavior of the C++ protobuf MessageDifferencer
// whereas the golang proto.Equal implementation mirrors the Java protobuf equals() methods
// behaviors which needed to treat NaN values as equal due to Java semantics.
func Equal(x, y proto.Message) bool {
if x == nil || y == nil {
return x == nil && y == nil
}
xRef := x.ProtoReflect()
yRef := y.ProtoReflect()
return equalMessage(xRef, yRef)
}
func equalMessage(mx, my protoreflect.Message) bool {
// Note, the original proto.Equal upon which this implementation is based does not specifically handle the
// case when both messages are invalid. It is assumed that the descriptors will be equal and that byte-wise
// comparison will be used, though the semantics of validity are neither clear, nor promised within the
// proto.Equal implementation.
if mx.IsValid() != my.IsValid() || mx.Descriptor() != my.Descriptor() {
return false
}
// This is an innovation on the default proto.Equal where protobuf.Any values are unpacked before comparison
// as otherwise the Any values are compared by bytes rather than structurally.
if isAny(mx) && isAny(my) {
ax := mx.Interface().(*anypb.Any)
ay := my.Interface().(*anypb.Any)
// If the values are not the same type url, return false.
if ax.GetTypeUrl() != ay.GetTypeUrl() {
return false
}
// If the values are byte equal, then return true.
if bytes.Equal(ax.GetValue(), ay.GetValue()) {
return true
}
// Otherwise fall through to the semantic comparison of the any values.
x, err := ax.UnmarshalNew()
if err != nil {
return false
}
y, err := ay.UnmarshalNew()
if err != nil {
return false
}
// Recursively compare the unwrapped messages to ensure nested Any values are unwrapped accordingly.
return equalMessage(x.ProtoReflect(), y.ProtoReflect())
}
// Walk the set fields to determine field-wise equality
nx := 0
equal := true
mx.Range(func(fd protoreflect.FieldDescriptor, vx protoreflect.Value) bool {
nx++
equal = my.Has(fd) && equalField(fd, vx, my.Get(fd))
return equal
})
if !equal {
return false
}
// Establish the count of set fields on message y
ny := 0
my.Range(func(protoreflect.FieldDescriptor, protoreflect.Value) bool {
ny++
return true
})
// If the number of set fields is not equal return false.
if nx != ny {
return false
}
return equalUnknown(mx.GetUnknown(), my.GetUnknown())
}
func equalField(fd protoreflect.FieldDescriptor, x, y protoreflect.Value) bool {
switch {
case fd.IsMap():
return equalMap(fd, x.Map(), y.Map())
case fd.IsList():
return equalList(fd, x.List(), y.List())
default:
return equalValue(fd, x, y)
}
}
func equalMap(fd protoreflect.FieldDescriptor, x, y protoreflect.Map) bool {
if x.Len() != y.Len() {
return false
}
equal := true
x.Range(func(k protoreflect.MapKey, vx protoreflect.Value) bool {
vy := y.Get(k)
equal = y.Has(k) && equalValue(fd.MapValue(), vx, vy)
return equal
})
return equal
}
func equalList(fd protoreflect.FieldDescriptor, x, y protoreflect.List) bool {
if x.Len() != y.Len() {
return false
}
for i := x.Len() - 1; i >= 0; i-- {
if !equalValue(fd, x.Get(i), y.Get(i)) {
return false
}
}
return true
}
func equalValue(fd protoreflect.FieldDescriptor, x, y protoreflect.Value) bool {
switch fd.Kind() {
case protoreflect.BoolKind:
return x.Bool() == y.Bool()
case protoreflect.EnumKind:
return x.Enum() == y.Enum()
case protoreflect.Int32Kind, protoreflect.Sint32Kind,
protoreflect.Int64Kind, protoreflect.Sint64Kind,
protoreflect.Sfixed32Kind, protoreflect.Sfixed64Kind:
return x.Int() == y.Int()
case protoreflect.Uint32Kind, protoreflect.Uint64Kind,
protoreflect.Fixed32Kind, protoreflect.Fixed64Kind:
return x.Uint() == y.Uint()
case protoreflect.FloatKind, protoreflect.DoubleKind:
return x.Float() == y.Float()
case protoreflect.StringKind:
return x.String() == y.String()
case protoreflect.BytesKind:
return bytes.Equal(x.Bytes(), y.Bytes())
case protoreflect.MessageKind, protoreflect.GroupKind:
return equalMessage(x.Message(), y.Message())
default:
return x.Interface() == y.Interface()
}
}
func equalUnknown(x, y protoreflect.RawFields) bool {
lenX := len(x)
lenY := len(y)
if lenX != lenY {
return false
}
if lenX == 0 {
return true
}
if bytes.Equal([]byte(x), []byte(y)) {
return true
}
mx := make(map[protoreflect.FieldNumber]protoreflect.RawFields)
my := make(map[protoreflect.FieldNumber]protoreflect.RawFields)
for len(x) > 0 {
fnum, _, n := protowire.ConsumeField(x)
mx[fnum] = append(mx[fnum], x[:n]...)
x = x[n:]
}
for len(y) > 0 {
fnum, _, n := protowire.ConsumeField(y)
my[fnum] = append(my[fnum], y[:n]...)
y = y[n:]
}
return reflect.DeepEqual(mx, my)
}
func isAny(m protoreflect.Message) bool {
return string(m.Descriptor().FullName()) == "google.protobuf.Any"
}