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100 lines
2.5 KiB
100 lines
2.5 KiB
// 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 types
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import (
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"math"
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"strconv"
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"strings"
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"github.com/pingcap/errors"
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)
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const (
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// UnspecifiedFsp is the unspecified fractional seconds part.
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UnspecifiedFsp = int8(-1)
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// MaxFsp is the maximum digit of fractional seconds part.
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MaxFsp = int8(6)
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// MinFsp is the minimum digit of fractional seconds part.
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MinFsp = int8(0)
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// DefaultFsp is the default digit of fractional seconds part.
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// MySQL use 0 as the default Fsp.
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DefaultFsp = int8(0)
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)
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// CheckFsp checks whether fsp is in valid range.
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func CheckFsp(fsp int) (int8, error) {
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if fsp == int(UnspecifiedFsp) {
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return DefaultFsp, nil
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}
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if fsp < int(MinFsp) || fsp > int(MaxFsp) {
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return DefaultFsp, errors.Errorf("Invalid fsp %d", fsp)
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}
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return int8(fsp), nil
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}
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// ParseFrac parses the input string according to fsp, returns the microsecond,
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// and also a bool value to indice overflow. eg:
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// "999" fsp=2 will overflow.
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func ParseFrac(s string, fsp int8) (v int, overflow bool, err error) {
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if len(s) == 0 {
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return 0, false, nil
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}
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fsp, err = CheckFsp(int(fsp))
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if err != nil {
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return 0, false, errors.Trace(err)
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}
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if int(fsp) >= len(s) {
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tmp, e := strconv.ParseInt(s, 10, 64)
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if e != nil {
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return 0, false, errors.Trace(e)
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}
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v = int(float64(tmp) * math.Pow10(int(MaxFsp)-len(s)))
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return
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}
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// Round when fsp < string length.
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tmp, e := strconv.ParseInt(s[:fsp+1], 10, 64)
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if e != nil {
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return 0, false, errors.Trace(e)
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}
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tmp = (tmp + 5) / 10
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if float64(tmp) >= math.Pow10(int(fsp)) {
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// overflow
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return 0, true, nil
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}
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// Get the final frac, with 6 digit number
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// 1236 round 3 -> 124 -> 124000
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// 0312 round 2 -> 3 -> 30000
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// 999 round 2 -> 100 -> overflow
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v = int(float64(tmp) * math.Pow10(int(MaxFsp-fsp)))
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return
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}
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// alignFrac is used to generate alignment frac, like `100` -> `100000` ,`-100` -> `-100000`
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func alignFrac(s string, fsp int) string {
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sl := len(s)
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if sl > 0 && s[0] == '-' {
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sl = sl - 1
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}
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if sl < fsp {
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return s + strings.Repeat("0", fsp-sl)
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}
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return s
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}
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