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encode.go
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/
encode.go
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// Go support for Protocol Buffers - Google's data interchange format
//
// Copyright 2010 The Go Authors. All rights reserved.
// http://code.google.com/p/goprotobuf/
//
// 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 proto
/*
* Routines for encoding data into the wire format for protocol buffers.
*/
import (
"errors"
"reflect"
"sort"
)
// ErrRequiredNotSet is the error returned if Marshal is called with
// a protocol buffer struct whose required fields have not
// all been initialized. It is also the error returned if Unmarshal is
// called with an encoded protocol buffer that does not include all the
// required fields.
type ErrRequiredNotSet struct {
t reflect.Type
}
func (e *ErrRequiredNotSet) Error() string {
return "proto: required fields not set in " + e.t.String()
}
var (
// ErrRepeatedHasNil is the error returned if Marshal is called with
// a struct with a repeated field containing a nil element.
ErrRepeatedHasNil = errors.New("proto: repeated field has nil element")
// ErrNil is the error returned if Marshal is called with nil.
ErrNil = errors.New("proto: Marshal called with nil")
)
// The fundamental encoders that put bytes on the wire.
// Those that take integer types all accept uint64 and are
// therefore of type valueEncoder.
const maxVarintBytes = 10 // maximum length of a varint
// EncodeVarint returns the varint encoding of x.
// This is the format for the
// int32, int64, uint32, uint64, bool, and enum
// protocol buffer types.
// Not used by the package itself, but helpful to clients
// wishing to use the same encoding.
func EncodeVarint(x uint64) []byte {
var buf [maxVarintBytes]byte
var n int
for n = 0; x > 127; n++ {
buf[n] = 0x80 | uint8(x&0x7F)
x >>= 7
}
buf[n] = uint8(x)
n++
return buf[0:n]
}
// EncodeVarint writes a varint-encoded integer to the Buffer.
// This is the format for the
// int32, int64, uint32, uint64, bool, and enum
// protocol buffer types.
func (p *Buffer) EncodeVarint(x uint64) error {
for x >= 1<<7 {
p.buf = append(p.buf, uint8(x&0x7f|0x80))
x >>= 7
}
p.buf = append(p.buf, uint8(x))
return nil
}
// EncodeFixed64 writes a 64-bit integer to the Buffer.
// This is the format for the
// fixed64, sfixed64, and double protocol buffer types.
func (p *Buffer) EncodeFixed64(x uint64) error {
p.buf = append(p.buf,
uint8(x),
uint8(x>>8),
uint8(x>>16),
uint8(x>>24),
uint8(x>>32),
uint8(x>>40),
uint8(x>>48),
uint8(x>>56))
return nil
}
// EncodeFixed32 writes a 32-bit integer to the Buffer.
// This is the format for the
// fixed32, sfixed32, and float protocol buffer types.
func (p *Buffer) EncodeFixed32(x uint64) error {
p.buf = append(p.buf,
uint8(x),
uint8(x>>8),
uint8(x>>16),
uint8(x>>24))
return nil
}
// EncodeZigzag64 writes a zigzag-encoded 64-bit integer
// to the Buffer.
// This is the format used for the sint64 protocol buffer type.
func (p *Buffer) EncodeZigzag64(x uint64) error {
// use signed number to get arithmetic right shift.
return p.EncodeVarint(uint64((x << 1) ^ uint64((int64(x) >> 63))))
}
// EncodeZigzag32 writes a zigzag-encoded 32-bit integer
// to the Buffer.
// This is the format used for the sint32 protocol buffer type.
func (p *Buffer) EncodeZigzag32(x uint64) error {
// use signed number to get arithmetic right shift.
return p.EncodeVarint(uint64((uint32(x) << 1) ^ uint32((int32(x) >> 31))))
}
// EncodeRawBytes writes a count-delimited byte buffer to the Buffer.
// This is the format used for the bytes protocol buffer
// type and for embedded messages.
func (p *Buffer) EncodeRawBytes(b []byte) error {
p.EncodeVarint(uint64(len(b)))
p.buf = append(p.buf, b...)
return nil
}
// EncodeStringBytes writes an encoded string to the Buffer.
// This is the format used for the proto2 string type.
func (p *Buffer) EncodeStringBytes(s string) error {
p.EncodeVarint(uint64(len(s)))
p.buf = append(p.buf, s...)
return nil
}
// Marshaler is the interface representing objects that can marshal themselves.
type Marshaler interface {
Marshal() ([]byte, error)
}
// Marshal takes the protocol buffer
// and encodes it into the wire format, returning the data.
func Marshal(pb Message) ([]byte, error) {
// Can the object marshal itself?
if m, ok := pb.(Marshaler); ok {
return m.Marshal()
}
p := NewBuffer(nil)
err := p.Marshal(pb)
if err != nil {
return nil, err
}
return p.buf, err
}
// Marshal takes the protocol buffer
// and encodes it into the wire format, writing the result to the
// Buffer.
func (p *Buffer) Marshal(pb Message) error {
// Can the object marshal itself?
if m, ok := pb.(Marshaler); ok {
data, err := m.Marshal()
if err != nil {
return err
}
p.buf = append(p.buf, data...)
return nil
}
t, base, err := getbase(pb)
if structPointer_IsNil(base) {
return ErrNil
}
if err == nil {
err = p.enc_struct(t.Elem(), GetProperties(t.Elem()), base)
}
if collectStats {
stats.Encode++
}
return err
}
// Individual type encoders.
// Encode a bool.
func (o *Buffer) enc_bool(p *Properties, base structPointer) error {
v := *structPointer_Bool(base, p.field)
if v == nil {
return ErrNil
}
x := 0
if *v {
x = 1
}
o.buf = append(o.buf, p.tagcode...)
p.valEnc(o, uint64(x))
return nil
}
// Encode an int32.
func (o *Buffer) enc_int32(p *Properties, base structPointer) error {
v := structPointer_Word32(base, p.field)
if word32_IsNil(v) {
return ErrNil
}
x := word32_Get(v)
o.buf = append(o.buf, p.tagcode...)
p.valEnc(o, uint64(x))
return nil
}
// Encode an int64.
func (o *Buffer) enc_int64(p *Properties, base structPointer) error {
v := structPointer_Word64(base, p.field)
if word64_IsNil(v) {
return ErrNil
}
x := word64_Get(v)
o.buf = append(o.buf, p.tagcode...)
p.valEnc(o, x)
return nil
}
// Encode a string.
func (o *Buffer) enc_string(p *Properties, base structPointer) error {
v := *structPointer_String(base, p.field)
if v == nil {
return ErrNil
}
x := *v
o.buf = append(o.buf, p.tagcode...)
o.EncodeStringBytes(x)
return nil
}
// All protocol buffer fields are nillable, but be careful.
func isNil(v reflect.Value) bool {
switch v.Kind() {
case reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
return v.IsNil()
}
return false
}
// Encode a message struct.
func (o *Buffer) enc_struct_message(p *Properties, base structPointer) error {
structp := structPointer_GetStructPointer(base, p.field)
if structPointer_IsNil(structp) {
return ErrNil
}
// Can the object marshal itself?
if p.isMarshaler {
m := structPointer_Interface(structp, p.stype).(Marshaler)
data, err := m.Marshal()
if err != nil {
return err
}
o.buf = append(o.buf, p.tagcode...)
o.EncodeRawBytes(data)
return nil
}
// need the length before we can write out the message itself,
// so marshal into a separate byte buffer first.
obuf := o.buf
o.buf = o.bufalloc()
err := o.enc_struct(p.stype, p.sprop, structp)
nbuf := o.buf
o.buf = obuf
if err != nil {
o.buffree(nbuf)
return err
}
o.buf = append(o.buf, p.tagcode...)
o.EncodeRawBytes(nbuf)
o.buffree(nbuf)
return nil
}
// Encode a group struct.
func (o *Buffer) enc_struct_group(p *Properties, base structPointer) error {
b := structPointer_GetStructPointer(base, p.field)
if structPointer_IsNil(b) {
return ErrNil
}
o.EncodeVarint(uint64((p.Tag << 3) | WireStartGroup))
err := o.enc_struct(p.stype, p.sprop, b)
if err != nil {
return err
}
o.EncodeVarint(uint64((p.Tag << 3) | WireEndGroup))
return nil
}
// Encode a slice of bools ([]bool).
func (o *Buffer) enc_slice_bool(p *Properties, base structPointer) error {
s := *structPointer_BoolSlice(base, p.field)
l := len(s)
if l == 0 {
return ErrNil
}
for _, x := range s {
o.buf = append(o.buf, p.tagcode...)
v := uint64(0)
if x {
v = 1
}
p.valEnc(o, v)
}
return nil
}
// Encode a slice of bools ([]bool) in packed format.
func (o *Buffer) enc_slice_packed_bool(p *Properties, base structPointer) error {
s := *structPointer_BoolSlice(base, p.field)
l := len(s)
if l == 0 {
return ErrNil
}
o.buf = append(o.buf, p.tagcode...)
o.EncodeVarint(uint64(l)) // each bool takes exactly one byte
for _, x := range s {
v := uint64(0)
if x {
v = 1
}
p.valEnc(o, v)
}
return nil
}
// Encode a slice of bytes ([]byte).
func (o *Buffer) enc_slice_byte(p *Properties, base structPointer) error {
s := *structPointer_Bytes(base, p.field)
if s == nil {
return ErrNil
}
o.buf = append(o.buf, p.tagcode...)
o.EncodeRawBytes(s)
return nil
}
// Encode a slice of int32s ([]int32).
func (o *Buffer) enc_slice_int32(p *Properties, base structPointer) error {
s := structPointer_Word32Slice(base, p.field)
l := s.Len()
if l == 0 {
return ErrNil
}
for i := 0; i < l; i++ {
o.buf = append(o.buf, p.tagcode...)
x := s.Index(i)
p.valEnc(o, uint64(x))
}
return nil
}
// Encode a slice of int32s ([]int32) in packed format.
func (o *Buffer) enc_slice_packed_int32(p *Properties, base structPointer) error {
s := structPointer_Word32Slice(base, p.field)
l := s.Len()
if l == 0 {
return ErrNil
}
// TODO: Reuse a Buffer.
buf := NewBuffer(nil)
for i := 0; i < l; i++ {
p.valEnc(buf, uint64(s.Index(i)))
}
o.buf = append(o.buf, p.tagcode...)
o.EncodeVarint(uint64(len(buf.buf)))
o.buf = append(o.buf, buf.buf...)
return nil
}
// Encode a slice of int64s ([]int64).
func (o *Buffer) enc_slice_int64(p *Properties, base structPointer) error {
s := structPointer_Word64Slice(base, p.field)
l := s.Len()
if l == 0 {
return ErrNil
}
for i := 0; i < l; i++ {
o.buf = append(o.buf, p.tagcode...)
p.valEnc(o, s.Index(i))
}
return nil
}
// Encode a slice of int64s ([]int64) in packed format.
func (o *Buffer) enc_slice_packed_int64(p *Properties, base structPointer) error {
s := structPointer_Word64Slice(base, p.field)
l := s.Len()
if l == 0 {
return ErrNil
}
// TODO: Reuse a Buffer.
buf := NewBuffer(nil)
for i := 0; i < l; i++ {
p.valEnc(buf, s.Index(i))
}
o.buf = append(o.buf, p.tagcode...)
o.EncodeVarint(uint64(len(buf.buf)))
o.buf = append(o.buf, buf.buf...)
return nil
}
// Encode a slice of slice of bytes ([][]byte).
func (o *Buffer) enc_slice_slice_byte(p *Properties, base structPointer) error {
ss := *structPointer_BytesSlice(base, p.field)
l := len(ss)
if l == 0 {
return ErrNil
}
for i := 0; i < l; i++ {
o.buf = append(o.buf, p.tagcode...)
s := ss[i]
o.EncodeRawBytes(s)
}
return nil
}
// Encode a slice of strings ([]string).
func (o *Buffer) enc_slice_string(p *Properties, base structPointer) error {
ss := *structPointer_StringSlice(base, p.field)
l := len(ss)
for i := 0; i < l; i++ {
o.buf = append(o.buf, p.tagcode...)
s := ss[i]
o.EncodeStringBytes(s)
}
return nil
}
// Encode a slice of message structs ([]*struct).
func (o *Buffer) enc_slice_struct_message(p *Properties, base structPointer) error {
s := structPointer_StructPointerSlice(base, p.field)
l := s.Len()
for i := 0; i < l; i++ {
structp := s.Index(i)
if structPointer_IsNil(structp) {
return ErrRepeatedHasNil
}
// Can the object marshal itself?
if p.isMarshaler {
m := structPointer_Interface(structp, p.stype).(Marshaler)
data, err := m.Marshal()
if err != nil {
return err
}
o.buf = append(o.buf, p.tagcode...)
o.EncodeRawBytes(data)
continue
}
obuf := o.buf
o.buf = o.bufalloc()
err := o.enc_struct(p.stype, p.sprop, structp)
nbuf := o.buf
o.buf = obuf
if err != nil {
o.buffree(nbuf)
if err == ErrNil {
return ErrRepeatedHasNil
}
return err
}
o.buf = append(o.buf, p.tagcode...)
o.EncodeRawBytes(nbuf)
o.buffree(nbuf)
}
return nil
}
// Encode a slice of group structs ([]*struct).
func (o *Buffer) enc_slice_struct_group(p *Properties, base structPointer) error {
s := structPointer_StructPointerSlice(base, p.field)
l := s.Len()
for i := 0; i < l; i++ {
b := s.Index(i)
if structPointer_IsNil(b) {
return ErrRepeatedHasNil
}
o.EncodeVarint(uint64((p.Tag << 3) | WireStartGroup))
err := o.enc_struct(p.stype, p.sprop, b)
if err != nil {
if err == ErrNil {
return ErrRepeatedHasNil
}
return err
}
o.EncodeVarint(uint64((p.Tag << 3) | WireEndGroup))
}
return nil
}
// Encode an extension map.
func (o *Buffer) enc_map(p *Properties, base structPointer) error {
v := *structPointer_ExtMap(base, p.field)
if err := encodeExtensionMap(v); err != nil {
return err
}
// Fast-path for common cases: zero or one extensions.
if len(v) <= 1 {
for _, e := range v {
o.buf = append(o.buf, e.enc...)
}
return nil
}
// Sort keys to provide a deterministic encoding.
keys := make([]int, 0, len(v))
for k := range v {
keys = append(keys, int(k))
}
sort.Ints(keys)
for _, k := range keys {
o.buf = append(o.buf, v[int32(k)].enc...)
}
return nil
}
// Encode a struct.
func (o *Buffer) enc_struct(t reflect.Type, prop *StructProperties, base structPointer) error {
required := prop.reqCount
// Encode fields in tag order so that decoders may use optimizations
// that depend on the ordering.
// http://code.google.com/apis/protocolbuffers/docs/encoding.html#order
for _, i := range prop.order {
p := prop.Prop[i]
if p.enc != nil {
err := p.enc(o, p, base)
if err != nil {
if err != ErrNil {
return err
}
} else if p.Required {
required--
}
}
}
// See if we encoded all required fields.
if required > 0 {
return &ErrRequiredNotSet{t}
}
// Add unrecognized fields at the end.
if prop.unrecField.IsValid() {
v := *structPointer_Bytes(base, prop.unrecField)
if len(v) > 0 {
o.buf = append(o.buf, v...)
}
}
return nil
}