315 lines
9.1 KiB
Go
315 lines
9.1 KiB
Go
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// Go support for Protocol Buffers - Google's data interchange format
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//
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// Copyright 2010 The Go Authors. All rights reserved.
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// https://github.com/golang/protobuf
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package proto
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/*
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* Support for message sets.
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*/
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import (
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"bytes"
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"encoding/json"
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"errors"
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"fmt"
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"reflect"
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"sort"
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"sync"
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)
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// errNoMessageTypeID occurs when a protocol buffer does not have a message type ID.
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// A message type ID is required for storing a protocol buffer in a message set.
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var errNoMessageTypeID = errors.New("proto does not have a message type ID")
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// The first two types (_MessageSet_Item and messageSet)
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// model what the protocol compiler produces for the following protocol message:
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// message MessageSet {
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// repeated group Item = 1 {
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// required int32 type_id = 2;
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// required string message = 3;
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// };
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// }
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// That is the MessageSet wire format. We can't use a proto to generate these
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// because that would introduce a circular dependency between it and this package.
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type _MessageSet_Item struct {
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TypeId *int32 `protobuf:"varint,2,req,name=type_id"`
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Message []byte `protobuf:"bytes,3,req,name=message"`
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}
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type messageSet struct {
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Item []*_MessageSet_Item `protobuf:"group,1,rep"`
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XXX_unrecognized []byte
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// TODO: caching?
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}
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// Make sure messageSet is a Message.
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var _ Message = (*messageSet)(nil)
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// messageTypeIder is an interface satisfied by a protocol buffer type
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// that may be stored in a MessageSet.
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type messageTypeIder interface {
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MessageTypeId() int32
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}
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func (ms *messageSet) find(pb Message) *_MessageSet_Item {
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mti, ok := pb.(messageTypeIder)
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if !ok {
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return nil
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}
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id := mti.MessageTypeId()
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for _, item := range ms.Item {
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if *item.TypeId == id {
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return item
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}
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}
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return nil
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}
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func (ms *messageSet) Has(pb Message) bool {
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return ms.find(pb) != nil
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}
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func (ms *messageSet) Unmarshal(pb Message) error {
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if item := ms.find(pb); item != nil {
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return Unmarshal(item.Message, pb)
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}
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if _, ok := pb.(messageTypeIder); !ok {
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return errNoMessageTypeID
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}
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return nil // TODO: return error instead?
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}
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func (ms *messageSet) Marshal(pb Message) error {
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msg, err := Marshal(pb)
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if err != nil {
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return err
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}
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if item := ms.find(pb); item != nil {
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// reuse existing item
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item.Message = msg
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return nil
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}
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mti, ok := pb.(messageTypeIder)
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if !ok {
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return errNoMessageTypeID
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}
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mtid := mti.MessageTypeId()
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ms.Item = append(ms.Item, &_MessageSet_Item{
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TypeId: &mtid,
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Message: msg,
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})
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return nil
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}
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func (ms *messageSet) Reset() { *ms = messageSet{} }
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func (ms *messageSet) String() string { return CompactTextString(ms) }
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func (*messageSet) ProtoMessage() {}
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// Support for the message_set_wire_format message option.
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func skipVarint(buf []byte) []byte {
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i := 0
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for ; buf[i]&0x80 != 0; i++ {
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}
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return buf[i+1:]
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}
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// MarshalMessageSet encodes the extension map represented by m in the message set wire format.
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// It is called by generated Marshal methods on protocol buffer messages with the message_set_wire_format option.
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func MarshalMessageSet(exts interface{}) ([]byte, error) {
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return marshalMessageSet(exts, false)
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}
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// marshaMessageSet implements above function, with the opt to turn on / off deterministic during Marshal.
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func marshalMessageSet(exts interface{}, deterministic bool) ([]byte, error) {
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switch exts := exts.(type) {
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case *XXX_InternalExtensions:
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var u marshalInfo
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siz := u.sizeMessageSet(exts)
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b := make([]byte, 0, siz)
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return u.appendMessageSet(b, exts, deterministic)
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case map[int32]Extension:
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// This is an old-style extension map.
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// Wrap it in a new-style XXX_InternalExtensions.
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ie := XXX_InternalExtensions{
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p: &struct {
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mu sync.Mutex
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extensionMap map[int32]Extension
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}{
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extensionMap: exts,
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},
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}
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var u marshalInfo
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siz := u.sizeMessageSet(&ie)
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b := make([]byte, 0, siz)
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return u.appendMessageSet(b, &ie, deterministic)
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default:
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return nil, errors.New("proto: not an extension map")
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}
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}
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// UnmarshalMessageSet decodes the extension map encoded in buf in the message set wire format.
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// It is called by Unmarshal methods on protocol buffer messages with the message_set_wire_format option.
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func UnmarshalMessageSet(buf []byte, exts interface{}) error {
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var m map[int32]Extension
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switch exts := exts.(type) {
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case *XXX_InternalExtensions:
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m = exts.extensionsWrite()
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case map[int32]Extension:
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m = exts
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default:
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return errors.New("proto: not an extension map")
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}
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ms := new(messageSet)
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if err := Unmarshal(buf, ms); err != nil {
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return err
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}
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for _, item := range ms.Item {
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id := *item.TypeId
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msg := item.Message
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// Restore wire type and field number varint, plus length varint.
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// Be careful to preserve duplicate items.
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b := EncodeVarint(uint64(id)<<3 | WireBytes)
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if ext, ok := m[id]; ok {
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// Existing data; rip off the tag and length varint
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// so we join the new data correctly.
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// We can assume that ext.enc is set because we are unmarshaling.
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o := ext.enc[len(b):] // skip wire type and field number
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_, n := DecodeVarint(o) // calculate length of length varint
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o = o[n:] // skip length varint
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msg = append(o, msg...) // join old data and new data
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}
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b = append(b, EncodeVarint(uint64(len(msg)))...)
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b = append(b, msg...)
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m[id] = Extension{enc: b}
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}
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return nil
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}
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// MarshalMessageSetJSON encodes the extension map represented by m in JSON format.
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// It is called by generated MarshalJSON methods on protocol buffer messages with the message_set_wire_format option.
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func MarshalMessageSetJSON(exts interface{}) ([]byte, error) {
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var m map[int32]Extension
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switch exts := exts.(type) {
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case *XXX_InternalExtensions:
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var mu sync.Locker
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m, mu = exts.extensionsRead()
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if m != nil {
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// Keep the extensions map locked until we're done marshaling to prevent
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// races between marshaling and unmarshaling the lazily-{en,de}coded
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// values.
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mu.Lock()
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defer mu.Unlock()
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}
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case map[int32]Extension:
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m = exts
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default:
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return nil, errors.New("proto: not an extension map")
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}
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var b bytes.Buffer
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b.WriteByte('{')
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// Process the map in key order for deterministic output.
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ids := make([]int32, 0, len(m))
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for id := range m {
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ids = append(ids, id)
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}
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sort.Sort(int32Slice(ids)) // int32Slice defined in text.go
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for i, id := range ids {
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ext := m[id]
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msd, ok := messageSetMap[id]
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if !ok {
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// Unknown type; we can't render it, so skip it.
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continue
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}
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if i > 0 && b.Len() > 1 {
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b.WriteByte(',')
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}
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fmt.Fprintf(&b, `"[%s]":`, msd.name)
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x := ext.value
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if x == nil {
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x = reflect.New(msd.t.Elem()).Interface()
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if err := Unmarshal(ext.enc, x.(Message)); err != nil {
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return nil, err
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}
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}
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d, err := json.Marshal(x)
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if err != nil {
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return nil, err
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}
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b.Write(d)
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}
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b.WriteByte('}')
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return b.Bytes(), nil
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}
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// UnmarshalMessageSetJSON decodes the extension map encoded in buf in JSON format.
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// It is called by generated UnmarshalJSON methods on protocol buffer messages with the message_set_wire_format option.
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func UnmarshalMessageSetJSON(buf []byte, exts interface{}) error {
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// Common-case fast path.
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if len(buf) == 0 || bytes.Equal(buf, []byte("{}")) {
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return nil
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}
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// This is fairly tricky, and it's not clear that it is needed.
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return errors.New("TODO: UnmarshalMessageSetJSON not yet implemented")
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}
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// A global registry of types that can be used in a MessageSet.
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var messageSetMap = make(map[int32]messageSetDesc)
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type messageSetDesc struct {
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t reflect.Type // pointer to struct
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name string
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}
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// RegisterMessageSetType is called from the generated code.
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func RegisterMessageSetType(m Message, fieldNum int32, name string) {
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messageSetMap[fieldNum] = messageSetDesc{
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t: reflect.TypeOf(m),
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name: name,
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}
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}
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