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// 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 (
"bytes"
"math"
"reflect"
"google.golang.org/protobuf/internal/encoding/wire"
pref "google.golang.org/protobuf/reflect/protoreflect"
)
// Equal reports whether two messages are equal.
// If two messages marshal to the same bytes under deterministic serialization,
// then Equal is guaranteed to report true.
//
// Two messages are equal if they belong to the same message descriptor,
// have the same set of populated known and extension field values,
// and the same set of unknown fields values. If either of the top-level
// messages are invalid, then Equal reports true only if both are invalid.
//
// Scalar values are compared with the equivalent of the == operator in Go,
// except bytes values which are compared using bytes.Equal and
// floating point values which specially treat NaNs as equal.
// Message values are compared by recursively calling Equal.
// Lists are equal if each element value is also equal.
// Maps are equal if they have the same set of keys, where the pair of values
// for each key is also equal.
func Equal(x, y Message) bool {
if x == nil || y == nil {
return x == nil && y == nil
}
mx := x.ProtoReflect()
my := y.ProtoReflect()
if mx.IsValid() != my.IsValid() {
return false
}
return equalMessage(mx, my)
}
// equalMessage compares two messages.
func equalMessage(mx, my pref.Message) bool {
if mx.Descriptor() != my.Descriptor() {
return false
}
nx := 0
equal := true
mx.Range(func(fd pref.FieldDescriptor, vx pref.Value) bool {
nx++
vy := my.Get(fd)
equal = my.Has(fd) && equalField(fd, vx, vy)
return equal
})
if !equal {
return false
}
ny := 0
my.Range(func(fd pref.FieldDescriptor, vx pref.Value) bool {
ny++
return true
})
if nx != ny {
return false
}
return equalUnknown(mx.GetUnknown(), my.GetUnknown())
}
// equalField compares two fields.
func equalField(fd pref.FieldDescriptor, x, y pref.Value) bool {
switch {
case fd.IsList():
return equalList(fd, x.List(), y.List())
case fd.IsMap():
return equalMap(fd, x.Map(), y.Map())
default:
return equalValue(fd, x, y)
}
}
// equalMap compares two maps.
func equalMap(fd pref.FieldDescriptor, x, y pref.Map) bool {
if x.Len() != y.Len() {
return false
}
equal := true
x.Range(func(k pref.MapKey, vx pref.Value) bool {
vy := y.Get(k)
equal = y.Has(k) && equalValue(fd.MapValue(), vx, vy)
return equal
})
return equal
}
// equalList compares two lists.
func equalList(fd pref.FieldDescriptor, x, y pref.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
}
// equalValue compares two singular values.
func equalValue(fd pref.FieldDescriptor, x, y pref.Value) bool {
switch {
case fd.Message() != nil:
return equalMessage(x.Message(), y.Message())
case fd.Kind() == pref.BytesKind:
return bytes.Equal(x.Bytes(), y.Bytes())
case fd.Kind() == pref.FloatKind, fd.Kind() == pref.DoubleKind:
fx := x.Float()
fy := y.Float()
if math.IsNaN(fx) || math.IsNaN(fy) {
return math.IsNaN(fx) && math.IsNaN(fy)
}
return fx == fy
default:
return x.Interface() == y.Interface()
}
}
// equalUnknown compares unknown fields by direct comparison on the raw bytes
// of each individual field number.
func equalUnknown(x, y pref.RawFields) bool {
if len(x) != len(y) {
return false
}
if bytes.Equal([]byte(x), []byte(y)) {
return true
}
mx := make(map[pref.FieldNumber]pref.RawFields)
my := make(map[pref.FieldNumber]pref.RawFields)
for len(x) > 0 {
fnum, _, n := wire.ConsumeField(x)
mx[fnum] = append(mx[fnum], x[:n]...)
x = x[n:]
}
for len(y) > 0 {
fnum, _, n := wire.ConsumeField(y)
my[fnum] = append(my[fnum], y[:n]...)
y = y[n:]
}
return reflect.DeepEqual(mx, my)
}