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any.go
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/
any.go
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// Go support for Protocol Buffers - Google's data interchange format
//
// Copyright 2016 The Go Authors. All rights reserved.
// https://github.com/golang/protobuf
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package ptypes
// This file implements functions to marshal proto.Message to/from
// google.protobuf.Any message.
import (
"fmt"
"reflect"
"strings"
"github.com/golang/protobuf/proto"
"github.com/golang/protobuf/ptypes/any"
)
const googleApis = "type.googleapis.com/"
// AnyMessageName returns the name of the message contained in a google.protobuf.Any message.
//
// Note that regular type assertions should be done using the Is
// function. AnyMessageName is provided for less common use cases like filtering a
// sequence of Any messages based on a set of allowed message type names.
func AnyMessageName(any *any.Any) (string, error) {
if any == nil {
return "", fmt.Errorf("message is nil")
}
slash := strings.LastIndex(any.TypeUrl, "/")
if slash < 0 {
return "", fmt.Errorf("message type url %q is invalid", any.TypeUrl)
}
return any.TypeUrl[slash+1:], nil
}
// MarshalAny takes the protocol buffer and encodes it into google.protobuf.Any.
func MarshalAny(pb proto.Message) (*any.Any, error) {
value, err := proto.Marshal(pb)
if err != nil {
return nil, err
}
return &any.Any{TypeUrl: googleApis + proto.MessageName(pb), Value: value}, nil
}
// DynamicAny is a value that can be passed to UnmarshalAny to automatically
// allocate a proto.Message for the type specified in a google.protobuf.Any
// message. The allocated message is stored in the embedded proto.Message.
//
// Example:
//
// var x ptypes.DynamicAny
// if err := ptypes.UnmarshalAny(a, &x); err != nil { ... }
// fmt.Printf("unmarshaled message: %v", x.Message)
type DynamicAny struct {
proto.Message
}
// Empty returns a new proto.Message of the type specified in a
// google.protobuf.Any message. It returns an error if corresponding message
// type isn't linked in.
func Empty(any *any.Any) (proto.Message, error) {
aname, err := AnyMessageName(any)
if err != nil {
return nil, err
}
t := proto.MessageType(aname)
if t == nil {
return nil, fmt.Errorf("any: message type %q isn't linked in", aname)
}
return reflect.New(t.Elem()).Interface().(proto.Message), nil
}
// UnmarshalAny parses the protocol buffer representation in a google.protobuf.Any
// message and places the decoded result in pb. It returns an error if type of
// contents of Any message does not match type of pb message.
//
// pb can be a proto.Message, or a *DynamicAny.
func UnmarshalAny(any *any.Any, pb proto.Message) error {
if d, ok := pb.(*DynamicAny); ok {
if d.Message == nil {
var err error
d.Message, err = Empty(any)
if err != nil {
return err
}
}
return UnmarshalAny(any, d.Message)
}
aname, err := AnyMessageName(any)
if err != nil {
return err
}
mname := proto.MessageName(pb)
if aname != mname {
return fmt.Errorf("mismatched message type: got %q want %q", aname, mname)
}
return proto.Unmarshal(any.Value, pb)
}
// Is returns true if any value contains a given message type.
func Is(any *any.Any, pb proto.Message) bool {
aname, err := AnyMessageName(any)
if err != nil {
return false
}
return aname == proto.MessageName(pb)
}