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package typeurl
import (
"encoding/json"
"path"
"reflect"
"sync"
"github.com/gogo/protobuf/proto"
"github.com/gogo/protobuf/types"
"github.com/pkg/errors"
)
var (
mu sync.Mutex
registry = make(map[reflect.Type]string)
)
var ErrNotFound = errors.New("not found")
// Register a type with the base url of the type
func Register(v interface{}, args ...string) {
var (
t = tryDereference(v)
p = path.Join(args...)
)
mu.Lock()
defer mu.Unlock()
if et, ok := registry[t]; ok {
if et != p {
panic(errors.Errorf("type registred with alternate path %q != %q", et, p))
}
return
}
registry[t] = p
}
// TypeURL returns the type url for a registred type
func TypeURL(v interface{}) (string, error) {
mu.Lock()
u, ok := registry[tryDereference(v)]
mu.Unlock()
if !ok {
// fallback to the proto registry if it is a proto message
pb, ok := v.(proto.Message)
if !ok {
return "", errors.Wrapf(ErrNotFound, "type %s", reflect.TypeOf(v))
}
return proto.MessageName(pb), nil
}
return u, nil
}
// Is returns true if the type of the Any is the same as v
func Is(any *types.Any, v interface{}) bool {
// call to check that v is a pointer
tryDereference(v)
url, err := TypeURL(v)
if err != nil {
return false
}
return any.TypeUrl == url
}
// MarshalAny marshals the value v into an any with the correct TypeUrl
func MarshalAny(v interface{}) (*types.Any, error) {
var marshal func(v interface{}) ([]byte, error)
switch t := v.(type) {
case *types.Any:
// avoid reserializing the type if we have an any.
return t, nil
case proto.Message:
marshal = func(v interface{}) ([]byte, error) {
return proto.Marshal(t)
}
default:
marshal = json.Marshal
}
url, err := TypeURL(v)
if err != nil {
return nil, err
}
data, err := marshal(v)
if err != nil {
return nil, err
}
return &types.Any{
TypeUrl: url,
Value: data,
}, nil
}
// UnmarshalAny unmarshals the any type into a concrete type
func UnmarshalAny(any *types.Any) (interface{}, error) {
t, err := getTypeByUrl(any.TypeUrl)
if err != nil {
return nil, err
}
v := reflect.New(t.t).Interface()
if t.isProto {
err = proto.Unmarshal(any.Value, v.(proto.Message))
} else {
err = json.Unmarshal(any.Value, v)
}
return v, err
}
type urlType struct {
t reflect.Type
isProto bool
}
func getTypeByUrl(url string) (urlType, error) {
for t, u := range registry {
if u == url {
return urlType{
t: t,
}, nil
}
}
// fallback to proto registry
t := proto.MessageType(url)
if t != nil {
return urlType{
// get the underlying Elem because proto returns a pointer to the type
t: t.Elem(),
isProto: true,
}, nil
}
return urlType{}, errors.Wrapf(ErrNotFound, "type with url %s", url)
}
func tryDereference(v interface{}) reflect.Type {
t := reflect.TypeOf(v)
if t.Kind() == reflect.Ptr {
// require check of pointer but dereference to register
return t.Elem()
}
panic("v is not a pointer to a type")
}
|
