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// Copyright 2014 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.
// This file is a simple protocol buffer encoder and decoder.
//
// A protocol message must implement the message interface:
// decoder() []decoder
// encode(*buffer)
//
// The decode method returns a slice indexed by field number that gives the
// function to decode that field.
// The encode method encodes its receiver into the given buffer.
//
// The two methods are simple enough to be implemented by hand rather than
// by using a protocol compiler.
//
// See profile.go for examples of messages implementing this interface.
//
// There is no support for groups, message sets, or "has" bits.
package profile
import (
"errors"
"fmt"
)
type buffer struct {
field int
typ int
u64 uint64
data []byte
tmp [16]byte
}
type decoder func(*buffer, message) error
type message interface {
decoder() []decoder
encode(*buffer)
}
func marshal(m message) []byte {
var b buffer
m.encode(&b)
return b.data
}
func encodeVarint(b *buffer, x uint64) {
for x >= 128 {
b.data = append(b.data, byte(x)|0x80)
x >>= 7
}
b.data = append(b.data, byte(x))
}
func encodeLength(b *buffer, tag int, len int) {
encodeVarint(b, uint64(tag)<<3|2)
encodeVarint(b, uint64(len))
}
func encodeUint64(b *buffer, tag int, x uint64) {
// append varint to b.data
encodeVarint(b, uint64(tag)<<3|0)
encodeVarint(b, x)
}
func encodeUint64s(b *buffer, tag int, x []uint64) {
if len(x) > 2 {
// Use packed encoding
n1 := len(b.data)
for _, u := range x {
encodeVarint(b, u)
}
n2 := len(b.data)
encodeLength(b, tag, n2-n1)
n3 := len(b.data)
copy(b.tmp[:], b.data[n2:n3])
copy(b.data[n1+(n3-n2):], b.data[n1:n2])
copy(b.data[n1:], b.tmp[:n3-n2])
return
}
for _, u := range x {
encodeUint64(b, tag, u)
}
}
func encodeUint64Opt(b *buffer, tag int, x uint64) {
if x == 0 {
return
}
encodeUint64(b, tag, x)
}
func encodeInt64(b *buffer, tag int, x int64) {
u := uint64(x)
encodeUint64(b, tag, u)
}
func encodeInt64Opt(b *buffer, tag int, x int64) {
if x == 0 {
return
}
encodeInt64(b, tag, x)
}
func encodeInt64s(b *buffer, tag int, x []int64) {
if len(x) > 2 {
// Use packed encoding
n1 := len(b.data)
for _, u := range x {
encodeVarint(b, uint64(u))
}
n2 := len(b.data)
encodeLength(b, tag, n2-n1)
n3 := len(b.data)
copy(b.tmp[:], b.data[n2:n3])
copy(b.data[n1+(n3-n2):], b.data[n1:n2])
copy(b.data[n1:], b.tmp[:n3-n2])
return
}
for _, u := range x {
encodeInt64(b, tag, u)
}
}
func encodeString(b *buffer, tag int, x string) {
encodeLength(b, tag, len(x))
b.data = append(b.data, x...)
}
func encodeStrings(b *buffer, tag int, x []string) {
for _, s := range x {
encodeString(b, tag, s)
}
}
func encodeBool(b *buffer, tag int, x bool) {
if x {
encodeUint64(b, tag, 1)
} else {
encodeUint64(b, tag, 0)
}
}
func encodeBoolOpt(b *buffer, tag int, x bool) {
if !x {
return
}
encodeBool(b, tag, x)
}
func encodeMessage(b *buffer, tag int, m message) {
n1 := len(b.data)
m.encode(b)
n2 := len(b.data)
encodeLength(b, tag, n2-n1)
n3 := len(b.data)
copy(b.tmp[:], b.data[n2:n3])
copy(b.data[n1+(n3-n2):], b.data[n1:n2])
copy(b.data[n1:], b.tmp[:n3-n2])
}
func unmarshal(data []byte, m message) (err error) {
b := buffer{data: data, typ: 2}
return decodeMessage(&b, m)
}
func le64(p []byte) uint64 {
return uint64(p[0]) | uint64(p[1])<<8 | uint64(p[2])<<16 | uint64(p[3])<<24 | uint64(p[4])<<32 | uint64(p[5])<<40 | uint64(p[6])<<48 | uint64(p[7])<<56
}
func le32(p []byte) uint32 {
return uint32(p[0]) | uint32(p[1])<<8 | uint32(p[2])<<16 | uint32(p[3])<<24
}
func decodeVarint(data []byte) (uint64, []byte, error) {
var i int
var u uint64
for i = 0; ; i++ {
if i >= 10 || i >= len(data) {
return 0, nil, errors.New("bad varint")
}
u |= uint64(data[i]&0x7F) << uint(7*i)
if data[i]&0x80 == 0 {
return u, data[i+1:], nil
}
}
}
func decodeField(b *buffer, data []byte) ([]byte, error) {
x, data, err := decodeVarint(data)
if err != nil {
return nil, err
}
b.field = int(x >> 3)
b.typ = int(x & 7)
b.data = nil
b.u64 = 0
switch b.typ {
case 0:
b.u64, data, err = decodeVarint(data)
if err != nil {
return nil, err
}
case 1:
if len(data) < 8 {
return nil, errors.New("not enough data")
}
b.u64 = le64(data[:8])
data = data[8:]
case 2:
var n uint64
n, data, err = decodeVarint(data)
if err != nil {
return nil, err
}
if n > uint64(len(data)) {
return nil, errors.New("too much data")
}
b.data = data[:n]
data = data[n:]
case 5:
if len(data) < 4 {
return nil, errors.New("not enough data")
}
b.u64 = uint64(le32(data[:4]))
data = data[4:]
default:
return nil, fmt.Errorf("unknown wire type: %d", b.typ)
}
return data, nil
}
func checkType(b *buffer, typ int) error {
if b.typ != typ {
return errors.New("type mismatch")
}
return nil
}
func decodeMessage(b *buffer, m message) error {
if err := checkType(b, 2); err != nil {
return err
}
dec := m.decoder()
data := b.data
for len(data) > 0 {
// pull varint field# + type
var err error
data, err = decodeField(b, data)
if err != nil {
return err
}
if b.field >= len(dec) || dec[b.field] == nil {
continue
}
if err := dec[b.field](b, m); err != nil {
return err
}
}
return nil
}
func decodeInt64(b *buffer, x *int64) error {
if err := checkType(b, 0); err != nil {
return err
}
*x = int64(b.u64)
return nil
}
func decodeInt64s(b *buffer, x *[]int64) error {
if b.typ == 2 {
// Packed encoding
data := b.data
for len(data) > 0 {
var u uint64
var err error
if u, data, err = decodeVarint(data); err != nil {
return err
}
*x = append(*x, int64(u))
}
return nil
}
var i int64
if err := decodeInt64(b, &i); err != nil {
return err
}
*x = append(*x, i)
return nil
}
func decodeUint64(b *buffer, x *uint64) error {
if err := checkType(b, 0); err != nil {
return err
}
*x = b.u64
return nil
}
func decodeUint64s(b *buffer, x *[]uint64) error {
if b.typ == 2 {
data := b.data
// Packed encoding
for len(data) > 0 {
var u uint64
var err error
if u, data, err = decodeVarint(data); err != nil {
return err
}
*x = append(*x, u)
}
return nil
}
var u uint64
if err := decodeUint64(b, &u); err != nil {
return err
}
*x = append(*x, u)
return nil
}
func decodeString(b *buffer, x *string) error {
if err := checkType(b, 2); err != nil {
return err
}
*x = string(b.data)
return nil
}
func decodeStrings(b *buffer, x *[]string) error {
var s string
if err := decodeString(b, &s); err != nil {
return err
}
*x = append(*x, s)
return nil
}
func decodeBool(b *buffer, x *bool) error {
if err := checkType(b, 0); err != nil {
return err
}
if int64(b.u64) == 0 {
*x = false
} else {
*x = true
}
return nil
}
|
