forked from golang/protobuf
/
descriptor.go
180 lines (159 loc) · 5.81 KB
/
descriptor.go
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// Copyright 2016 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 descriptor provides functions for obtaining the protocol buffer
// descriptors of generated Go types.
//
// Deprecated: See the "google.golang.org/protobuf/reflect/protoreflect" package
// for how to obtain an EnumDescriptor or MessageDescriptor in order to
// programatically interact with the protobuf type system.
package descriptor
import (
"bytes"
"compress/gzip"
"io/ioutil"
"sync"
"github.com/averyboy/protobuf/proto"
"google.golang.org/protobuf/reflect/protodesc"
"google.golang.org/protobuf/reflect/protoreflect"
"google.golang.org/protobuf/runtime/protoimpl"
descriptorpb "github.com/averyboy/protobuf/protoc-gen-go/descriptor"
)
// Message is proto.Message with a method to return its descriptor.
//
// Deprecated: The Descriptor method may not be generated by future
// versions of protoc-gen-go, meaning that this interface may not
// be implemented by many concrete message types.
type Message interface {
proto.Message
Descriptor() ([]byte, []int)
}
// ForMessage returns the file descriptor proto containing
// the message and the message descriptor proto for the message itself.
// The returned proto messages must not be mutated.
//
// Deprecated: Not all concrete message types satisfy the Message interface.
// Use MessageDescriptorProto instead. If possible, the calling code should
// be rewritten to use protobuf reflection instead.
// See package "google.golang.org/protobuf/reflect/protoreflect" for details.
func ForMessage(m Message) (*descriptorpb.FileDescriptorProto, *descriptorpb.DescriptorProto) {
return MessageDescriptorProto(m)
}
type rawDesc struct {
fileDesc []byte
indexes []int
}
var rawDescCache sync.Map // map[protoreflect.Descriptor]*rawDesc
func deriveRawDescriptor(d protoreflect.Descriptor) ([]byte, []int) {
// Fast-path: check whether raw descriptors are already cached.
origDesc := d
if v, ok := rawDescCache.Load(origDesc); ok {
return v.(*rawDesc).fileDesc, v.(*rawDesc).indexes
}
// Slow-path: derive the raw descriptor from the v2 descriptor.
// Start with the leaf (a given enum or message declaration) and
// ascend upwards until we hit the parent file descriptor.
var idxs []int
for {
idxs = append(idxs, d.Index())
d = d.Parent()
if d == nil {
// TODO: We could construct a FileDescriptor stub for standalone
// descriptors to satisfy the API.
return nil, nil
}
if _, ok := d.(protoreflect.FileDescriptor); ok {
break
}
}
// Obtain the raw file descriptor.
fd := d.(protoreflect.FileDescriptor)
b, _ := proto.Marshal(protodesc.ToFileDescriptorProto(fd))
file := protoimpl.X.CompressGZIP(b)
// Reverse the indexes, since we populated it in reverse.
for i, j := 0, len(idxs)-1; i < j; i, j = i+1, j-1 {
idxs[i], idxs[j] = idxs[j], idxs[i]
}
if v, ok := rawDescCache.LoadOrStore(origDesc, &rawDesc{file, idxs}); ok {
return v.(*rawDesc).fileDesc, v.(*rawDesc).indexes
}
return file, idxs
}
// EnumRawDescriptor returns the GZIP'd raw file descriptor representing
// the enum and the index path to reach the enum declaration.
// The returned slices must not be mutated.
func EnumRawDescriptor(e proto.GeneratedEnum) ([]byte, []int) {
if ev, ok := e.(interface{ EnumDescriptor() ([]byte, []int) }); ok {
return ev.EnumDescriptor()
}
ed := protoimpl.X.EnumTypeOf(e)
return deriveRawDescriptor(ed.Descriptor())
}
// MessageRawDescriptor returns the GZIP'd raw file descriptor representing
// the message and the index path to reach the message declaration.
// The returned slices must not be mutated.
func MessageRawDescriptor(m proto.GeneratedMessage) ([]byte, []int) {
if mv, ok := m.(interface{ Descriptor() ([]byte, []int) }); ok {
return mv.Descriptor()
}
md := protoimpl.X.MessageTypeOf(m)
return deriveRawDescriptor(md.Descriptor())
}
var fileDescCache sync.Map // map[*byte]*descriptorpb.FileDescriptorProto
func deriveFileDescriptor(rawDesc []byte) *descriptorpb.FileDescriptorProto {
// Fast-path: check whether descriptor protos are already cached.
if v, ok := fileDescCache.Load(&rawDesc[0]); ok {
return v.(*descriptorpb.FileDescriptorProto)
}
// Slow-path: derive the descriptor proto from the GZIP'd message.
zr, err := gzip.NewReader(bytes.NewReader(rawDesc))
if err != nil {
panic(err)
}
b, err := ioutil.ReadAll(zr)
if err != nil {
panic(err)
}
fd := new(descriptorpb.FileDescriptorProto)
if err := proto.Unmarshal(b, fd); err != nil {
panic(err)
}
if v, ok := fileDescCache.LoadOrStore(&rawDesc[0], fd); ok {
return v.(*descriptorpb.FileDescriptorProto)
}
return fd
}
// EnumDescriptorProto returns the file descriptor proto representing
// the enum and the enum descriptor proto for the enum itself.
// The returned proto messages must not be mutated.
func EnumDescriptorProto(e proto.GeneratedEnum) (*descriptorpb.FileDescriptorProto, *descriptorpb.EnumDescriptorProto) {
rawDesc, idxs := EnumRawDescriptor(e)
if rawDesc == nil || idxs == nil {
return nil, nil
}
fd := deriveFileDescriptor(rawDesc)
if len(idxs) == 1 {
return fd, fd.EnumType[idxs[0]]
}
md := fd.MessageType[idxs[0]]
for _, i := range idxs[1 : len(idxs)-1] {
md = md.NestedType[i]
}
ed := md.EnumType[idxs[len(idxs)-1]]
return fd, ed
}
// MessageDescriptorProto returns the file descriptor proto representing
// the message and the message descriptor proto for the message itself.
// The returned proto messages must not be mutated.
func MessageDescriptorProto(m proto.GeneratedMessage) (*descriptorpb.FileDescriptorProto, *descriptorpb.DescriptorProto) {
rawDesc, idxs := MessageRawDescriptor(m)
if rawDesc == nil || idxs == nil {
return nil, nil
}
fd := deriveFileDescriptor(rawDesc)
md := fd.MessageType[idxs[0]]
for _, i := range idxs[1:] {
md = md.NestedType[i]
}
return fd, md
}