61 lines
1.6 KiB
Go
61 lines
1.6 KiB
Go
// Copyright 2015 PingCAP, Inc.
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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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// See the License for the specific language governing permissions and
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// limitations under the License.
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package codec
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import (
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"github.com/juju/errors"
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"github.com/ngaut/log"
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"github.com/pingcap/tidb/mysql"
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"github.com/pingcap/tidb/util/types"
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)
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// EncodeDecimal encodes a decimal d into a byte slice which can be sorted lexicographically later.
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func EncodeDecimal(b []byte, d types.Datum) []byte {
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dec := d.GetMysqlDecimal()
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precision := d.Length()
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frac := d.Frac()
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if precision == 0 {
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precision, frac = dec.PrecisionAndFrac()
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}
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b = append(b, byte(precision), byte(frac))
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bin, err := dec.ToBin(precision, frac)
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if err != nil {
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log.Errorf("should not happen, precision %d, frac %d %v", precision, frac, err)
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return b
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}
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b = append(b, bin...)
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return b
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}
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// DecodeDecimal decodes bytes to decimal.
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func DecodeDecimal(b []byte) ([]byte, types.Datum, error) {
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var d types.Datum
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if len(b) < 3 {
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return b, d, errors.New("insufficient bytes to decode value")
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}
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precision := int(b[0])
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frac := int(b[1])
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b = b[2:]
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dec := new(mysql.MyDecimal)
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binSize, err := dec.FromBin(b, precision, frac)
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b = b[binSize:]
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if err != nil {
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return b, d, errors.Trace(err)
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}
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d.SetLength(precision)
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d.SetFrac(frac)
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d.SetMysqlDecimal(dec)
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return b, d, nil
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}
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