protobuf-go/proto/size.go
Joe Tsai ac31a352ca reflect/protoreflect: add helper methods to FieldDescriptor
Added API:
	FieldDescriptor.IsExtension
	FieldDescriptor.IsList
	FieldDescriptor.MapKey
	FieldDescriptor.MapValue
	FieldDescriptor.ContainingOneof
	FieldDescriptor.ContainingMessage

Deprecated API (to be removed in subsequent CL):
	FieldDescriptor.Oneof
	FieldDescriptor.Extendee

These methods help cleanup several common usage patterns.

Change-Id: I9a3ffabc2edb2173c536509b22f330f98bba7cf3
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/176977
Reviewed-by: Damien Neil <dneil@google.com>
2019-05-14 17:14:05 +00:00

92 lines
2.6 KiB
Go

// 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 (
"fmt"
"github.com/golang/protobuf/v2/internal/encoding/wire"
"github.com/golang/protobuf/v2/reflect/protoreflect"
)
// Size returns the size in bytes of the wire-format encoding of m.
func Size(m Message) int {
return MarshalOptions{}.Size(m)
}
// Size returns the size in bytes of the wire-format encoding of m.
func (o MarshalOptions) Size(m Message) int {
if size, err := sizeMessageFast(m); err == nil {
return size
}
return sizeMessage(m.ProtoReflect())
}
func sizeMessageFast(m Message) (int, error) {
// TODO: Pass MarshalOptions to size to permit disabling fast path?
methods := protoMethods(m)
if methods == nil || methods.Size == nil {
return 0, errInternalNoFast
}
return methods.Size(m), nil
}
func sizeMessage(m protoreflect.Message) (size int) {
fieldDescs := m.Descriptor().Fields()
knownFields := m.KnownFields()
m.KnownFields().Range(func(num protoreflect.FieldNumber, value protoreflect.Value) bool {
field := fieldDescs.ByNumber(num)
if field == nil {
field = knownFields.ExtensionTypes().ByNumber(num).Descriptor()
if field == nil {
panic(fmt.Errorf("no descriptor for field %d in %q", num, m.Descriptor().FullName()))
}
}
size += sizeField(field, value)
return true
})
m.UnknownFields().Range(func(_ protoreflect.FieldNumber, raw protoreflect.RawFields) bool {
size += len(raw)
return true
})
return size
}
func sizeField(fd protoreflect.FieldDescriptor, value protoreflect.Value) (size int) {
num := fd.Number()
switch {
case fd.IsList():
return sizeList(num, fd, value.List())
case fd.IsMap():
return sizeMap(num, fd, value.Map())
default:
return wire.SizeTag(num) + sizeSingular(num, fd.Kind(), value)
}
}
func sizeList(num wire.Number, fd protoreflect.FieldDescriptor, list protoreflect.List) (size int) {
if fd.IsPacked() {
content := 0
for i, llen := 0, list.Len(); i < llen; i++ {
content += sizeSingular(num, fd.Kind(), list.Get(i))
}
return wire.SizeTag(num) + wire.SizeBytes(content)
}
for i, llen := 0, list.Len(); i < llen; i++ {
size += wire.SizeTag(num) + sizeSingular(num, fd.Kind(), list.Get(i))
}
return size
}
func sizeMap(num wire.Number, fd protoreflect.FieldDescriptor, mapv protoreflect.Map) (size int) {
mapv.Range(func(key protoreflect.MapKey, value protoreflect.Value) bool {
size += wire.SizeTag(num)
size += wire.SizeBytes(sizeField(fd.MapKey(), key.Value()) + sizeField(fd.MapValue(), value))
return true
})
return size
}