368 lines
7.4 KiB
Go
368 lines
7.4 KiB
Go
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// Copyright 2014 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// This file is a simple protocol buffer encoder and decoder.
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// The format is described at
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// https://developers.google.com/protocol-buffers/docs/encoding
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//
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// A protocol message must implement the message interface:
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// decoder() []decoder
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// encode(*buffer)
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//
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// The decode method returns a slice indexed by field number that gives the
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// function to decode that field.
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// The encode method encodes its receiver into the given buffer.
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//
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// The two methods are simple enough to be implemented by hand rather than
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// by using a protocol compiler.
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//
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// See profile.go for examples of messages implementing this interface.
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//
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// There is no support for groups, message sets, or "has" bits.
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package profile
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import (
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"errors"
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"fmt"
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)
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type buffer struct {
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field int // field tag
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typ int // proto wire type code for field
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u64 uint64
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data []byte
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tmp [16]byte
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tmpLines []Line // temporary storage used while decoding "repeated Line".
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}
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type decoder func(*buffer, message) error
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type message interface {
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decoder() []decoder
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encode(*buffer)
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}
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func marshal(m message) []byte {
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var b buffer
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m.encode(&b)
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return b.data
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}
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func encodeVarint(b *buffer, x uint64) {
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for x >= 128 {
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b.data = append(b.data, byte(x)|0x80)
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x >>= 7
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}
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b.data = append(b.data, byte(x))
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}
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func encodeLength(b *buffer, tag int, len int) {
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encodeVarint(b, uint64(tag)<<3|2)
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encodeVarint(b, uint64(len))
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}
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func encodeUint64(b *buffer, tag int, x uint64) {
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// append varint to b.data
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encodeVarint(b, uint64(tag)<<3)
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encodeVarint(b, x)
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}
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func encodeUint64s(b *buffer, tag int, x []uint64) {
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if len(x) > 2 {
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// Use packed encoding
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n1 := len(b.data)
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for _, u := range x {
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encodeVarint(b, u)
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}
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n2 := len(b.data)
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encodeLength(b, tag, n2-n1)
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n3 := len(b.data)
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copy(b.tmp[:], b.data[n2:n3])
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copy(b.data[n1+(n3-n2):], b.data[n1:n2])
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copy(b.data[n1:], b.tmp[:n3-n2])
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return
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}
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for _, u := range x {
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encodeUint64(b, tag, u)
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}
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}
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func encodeUint64Opt(b *buffer, tag int, x uint64) {
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if x == 0 {
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return
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}
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encodeUint64(b, tag, x)
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}
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func encodeInt64(b *buffer, tag int, x int64) {
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u := uint64(x)
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encodeUint64(b, tag, u)
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}
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func encodeInt64s(b *buffer, tag int, x []int64) {
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if len(x) > 2 {
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// Use packed encoding
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n1 := len(b.data)
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for _, u := range x {
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encodeVarint(b, uint64(u))
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}
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n2 := len(b.data)
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encodeLength(b, tag, n2-n1)
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n3 := len(b.data)
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copy(b.tmp[:], b.data[n2:n3])
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copy(b.data[n1+(n3-n2):], b.data[n1:n2])
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copy(b.data[n1:], b.tmp[:n3-n2])
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return
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}
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for _, u := range x {
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encodeInt64(b, tag, u)
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}
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}
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func encodeInt64Opt(b *buffer, tag int, x int64) {
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if x == 0 {
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return
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}
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encodeInt64(b, tag, x)
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}
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func encodeString(b *buffer, tag int, x string) {
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encodeLength(b, tag, len(x))
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b.data = append(b.data, x...)
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}
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func encodeStrings(b *buffer, tag int, x []string) {
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for _, s := range x {
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encodeString(b, tag, s)
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}
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}
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func encodeBool(b *buffer, tag int, x bool) {
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if x {
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encodeUint64(b, tag, 1)
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} else {
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encodeUint64(b, tag, 0)
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}
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}
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func encodeBoolOpt(b *buffer, tag int, x bool) {
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if x {
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encodeBool(b, tag, x)
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}
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}
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func encodeMessage(b *buffer, tag int, m message) {
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n1 := len(b.data)
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m.encode(b)
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n2 := len(b.data)
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encodeLength(b, tag, n2-n1)
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n3 := len(b.data)
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copy(b.tmp[:], b.data[n2:n3])
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copy(b.data[n1+(n3-n2):], b.data[n1:n2])
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copy(b.data[n1:], b.tmp[:n3-n2])
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}
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func unmarshal(data []byte, m message) (err error) {
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b := buffer{data: data, typ: 2}
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return decodeMessage(&b, m)
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}
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func le64(p []byte) uint64 {
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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
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}
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func le32(p []byte) uint32 {
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return uint32(p[0]) | uint32(p[1])<<8 | uint32(p[2])<<16 | uint32(p[3])<<24
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}
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func decodeVarint(data []byte) (uint64, []byte, error) {
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var u uint64
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for i := 0; ; i++ {
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if i >= 10 || i >= len(data) {
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return 0, nil, errors.New("bad varint")
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}
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u |= uint64(data[i]&0x7F) << uint(7*i)
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if data[i]&0x80 == 0 {
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return u, data[i+1:], nil
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}
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}
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}
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func decodeField(b *buffer, data []byte) ([]byte, error) {
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x, data, err := decodeVarint(data)
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if err != nil {
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return nil, err
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}
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b.field = int(x >> 3)
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b.typ = int(x & 7)
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b.data = nil
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b.u64 = 0
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switch b.typ {
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case 0:
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b.u64, data, err = decodeVarint(data)
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if err != nil {
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return nil, err
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}
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case 1:
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if len(data) < 8 {
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return nil, errors.New("not enough data")
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}
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b.u64 = le64(data[:8])
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data = data[8:]
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case 2:
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var n uint64
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n, data, err = decodeVarint(data)
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if err != nil {
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return nil, err
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}
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if n > uint64(len(data)) {
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return nil, errors.New("too much data")
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}
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b.data = data[:n]
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data = data[n:]
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case 5:
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if len(data) < 4 {
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return nil, errors.New("not enough data")
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}
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b.u64 = uint64(le32(data[:4]))
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data = data[4:]
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default:
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return nil, fmt.Errorf("unknown wire type: %d", b.typ)
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}
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return data, nil
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}
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func checkType(b *buffer, typ int) error {
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if b.typ != typ {
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return errors.New("type mismatch")
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}
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return nil
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}
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func decodeMessage(b *buffer, m message) error {
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if err := checkType(b, 2); err != nil {
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return err
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}
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dec := m.decoder()
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data := b.data
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for len(data) > 0 {
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// pull varint field# + type
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var err error
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data, err = decodeField(b, data)
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if err != nil {
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return err
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}
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if b.field >= len(dec) || dec[b.field] == nil {
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continue
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}
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if err := dec[b.field](b, m); err != nil {
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return err
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}
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}
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return nil
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}
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func decodeInt64(b *buffer, x *int64) error {
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if err := checkType(b, 0); err != nil {
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return err
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}
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*x = int64(b.u64)
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return nil
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}
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func decodeInt64s(b *buffer, x *[]int64) error {
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if b.typ == 2 {
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// Packed encoding
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data := b.data
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for len(data) > 0 {
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var u uint64
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var err error
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if u, data, err = decodeVarint(data); err != nil {
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return err
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}
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*x = append(*x, int64(u))
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}
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return nil
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}
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var i int64
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if err := decodeInt64(b, &i); err != nil {
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return err
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}
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*x = append(*x, i)
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return nil
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}
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func decodeUint64(b *buffer, x *uint64) error {
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if err := checkType(b, 0); err != nil {
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return err
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}
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*x = b.u64
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return nil
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}
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func decodeUint64s(b *buffer, x *[]uint64) error {
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if b.typ == 2 {
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data := b.data
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// Packed encoding
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for len(data) > 0 {
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var u uint64
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var err error
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if u, data, err = decodeVarint(data); err != nil {
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return err
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}
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*x = append(*x, u)
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}
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return nil
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}
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var u uint64
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if err := decodeUint64(b, &u); err != nil {
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return err
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}
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*x = append(*x, u)
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return nil
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}
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func decodeString(b *buffer, x *string) error {
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if err := checkType(b, 2); err != nil {
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return err
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}
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*x = string(b.data)
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return nil
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}
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func decodeStrings(b *buffer, x *[]string) error {
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var s string
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if err := decodeString(b, &s); err != nil {
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return err
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}
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*x = append(*x, s)
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return nil
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}
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func decodeBool(b *buffer, x *bool) error {
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if err := checkType(b, 0); err != nil {
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return err
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}
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if int64(b.u64) == 0 {
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*x = false
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} else {
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*x = true
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}
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return nil
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}
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