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gitea/vendor/github.com/pingcap/tidb/util/codec/codec.go

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// Copyright 2015 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package codec
import (
"time"
"github.com/juju/errors"
"github.com/pingcap/tidb/mysql"
"github.com/pingcap/tidb/util/types"
)
const (
nilFlag byte = iota
bytesFlag
compactBytesFlag
intFlag
uintFlag
floatFlag
decimalFlag
durationFlag
)
func encode(b []byte, vals []types.Datum, comparable bool) ([]byte, error) {
for _, val := range vals {
switch val.Kind() {
case types.KindInt64:
b = append(b, intFlag)
b = EncodeInt(b, val.GetInt64())
case types.KindUint64:
b = append(b, uintFlag)
b = EncodeUint(b, val.GetUint64())
case types.KindFloat32, types.KindFloat64:
b = append(b, floatFlag)
b = EncodeFloat(b, val.GetFloat64())
case types.KindString, types.KindBytes:
b = encodeBytes(b, val.GetBytes(), comparable)
case types.KindMysqlTime:
b = encodeBytes(b, []byte(val.GetMysqlTime().String()), comparable)
case types.KindMysqlDuration:
// duration may have negative value, so we cannot use String to encode directly.
b = append(b, durationFlag)
b = EncodeInt(b, int64(val.GetMysqlDuration().Duration))
case types.KindMysqlDecimal:
b = append(b, decimalFlag)
b = EncodeDecimal(b, val.GetMysqlDecimal())
case types.KindMysqlHex:
b = append(b, intFlag)
b = EncodeInt(b, int64(val.GetMysqlHex().ToNumber()))
case types.KindMysqlBit:
b = append(b, uintFlag)
b = EncodeUint(b, uint64(val.GetMysqlBit().ToNumber()))
case types.KindMysqlEnum:
b = append(b, uintFlag)
b = EncodeUint(b, uint64(val.GetMysqlEnum().ToNumber()))
case types.KindMysqlSet:
b = append(b, uintFlag)
b = EncodeUint(b, uint64(val.GetMysqlSet().ToNumber()))
case types.KindNull:
b = append(b, nilFlag)
default:
return nil, errors.Errorf("unsupport encode type %d", val.Kind())
}
}
return b, nil
}
func encodeBytes(b []byte, v []byte, comparable bool) []byte {
if comparable {
b = append(b, bytesFlag)
b = EncodeBytes(b, v)
} else {
b = append(b, compactBytesFlag)
b = EncodeCompactBytes(b, v)
}
return b
}
// EncodeKey appends the encoded values to byte slice b, returns the appended
// slice. It guarantees the encoded value is in ascending order for comparison.
func EncodeKey(b []byte, v ...types.Datum) ([]byte, error) {
return encode(b, v, true)
}
// EncodeValue appends the encoded values to byte slice b, returning the appended
// slice. It does not guarantee the order for comparison.
func EncodeValue(b []byte, v ...types.Datum) ([]byte, error) {
return encode(b, v, false)
}
// Decode decodes values from a byte slice generated with EncodeKey or EncodeValue
// before.
func Decode(b []byte) ([]types.Datum, error) {
if len(b) < 1 {
return nil, errors.New("invalid encoded key")
}
var (
flag byte
err error
values = make([]types.Datum, 0, 1)
)
for len(b) > 0 {
flag = b[0]
b = b[1:]
var d types.Datum
switch flag {
case intFlag:
var v int64
b, v, err = DecodeInt(b)
d.SetInt64(v)
case uintFlag:
var v uint64
b, v, err = DecodeUint(b)
d.SetUint64(v)
case floatFlag:
var v float64
b, v, err = DecodeFloat(b)
d.SetFloat64(v)
case bytesFlag:
var v []byte
b, v, err = DecodeBytes(b)
d.SetBytes(v)
case compactBytesFlag:
var v []byte
b, v, err = DecodeCompactBytes(b)
d.SetBytes(v)
case decimalFlag:
var v mysql.Decimal
b, v, err = DecodeDecimal(b)
d.SetValue(v)
case durationFlag:
var r int64
b, r, err = DecodeInt(b)
if err == nil {
// use max fsp, let outer to do round manually.
v := mysql.Duration{Duration: time.Duration(r), Fsp: mysql.MaxFsp}
d.SetValue(v)
}
case nilFlag:
default:
return nil, errors.Errorf("invalid encoded key flag %v", flag)
}
if err != nil {
return nil, errors.Trace(err)
}
values = append(values, d)
}
return values, nil
}