Source: equal.go in package google.golang.org/protobuf/proto


package proto

import (
	"bytes"
	"math"
	"reflect"

	"google.golang.org/protobuf/encoding/protowire"
	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 := 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)