perkeep/pkg/fs/time.go

152 lines
3.3 KiB
Go

// +build linux darwin
/*
Copyright 2013 The Perkeep Authors
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,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package fs
import (
"errors"
"fmt"
"math"
"strconv"
"time"
)
var timeFormats = []string{
time.RFC3339Nano,
time.RFC3339,
time.RFC1123Z,
time.RFC1123,
time.UnixDate,
time.ANSIC,
time.RubyDate,
"2006-01-02T15:04",
"2006-01-02T15",
"2006-01-02",
"2006-01",
"2006",
}
var errUnparseableTimestamp = errors.New("unparsable timestamp")
var powTable = []int{
10e8,
10e7,
10e6,
10e5,
10e4,
10e3,
10e2,
10e1,
10,
1,
}
// Hand crafted this parser since it's a really common path.
func parseCanonicalTime(in string) (time.Time, error) {
if len(in) < 20 || in[len(in)-1] != 'Z' {
return time.Time{}, errUnparseableTimestamp
}
if !(in[4] == '-' && in[7] == '-' && in[10] == 'T' &&
in[13] == ':' && in[16] == ':' && (in[19] == '.' || in[19] == 'Z')) {
return time.Time{}, fmt.Errorf("positionally incorrect: %v", in)
}
// 2012-08-28T21:24:35.37465188Z
// 4 7 10 13 16 19
// -----------------------------
// 0-4 5 8 11 14 17 20
year, err := strconv.Atoi(in[0:4])
if err != nil {
return time.Time{}, fmt.Errorf("error parsing year: %v", err)
}
month, err := strconv.Atoi(in[5:7])
if err != nil {
return time.Time{}, fmt.Errorf("error parsing month: %v", err)
}
day, err := strconv.Atoi(in[8:10])
if err != nil {
return time.Time{}, fmt.Errorf("error parsing day: %v", err)
}
hour, err := strconv.Atoi(in[11:13])
if err != nil {
return time.Time{}, fmt.Errorf("error parsing hour: %v", err)
}
minute, err := strconv.Atoi(in[14:16])
if err != nil {
return time.Time{}, fmt.Errorf("error parsing minute: %v", err)
}
second, err := strconv.Atoi(in[17:19])
if err != nil {
return time.Time{}, fmt.Errorf("error parsing second: %v", err)
}
var nsecstr string
if in[19] != 'Z' {
nsecstr = in[20 : len(in)-1]
}
var nsec int
if nsecstr != "" {
nsec, err = strconv.Atoi(nsecstr)
if err != nil {
return time.Time{}, fmt.Errorf("error parsing nanoseconds: %v", err)
}
}
nsec *= powTable[len(nsecstr)]
return time.Date(year, time.Month(month), day,
hour, minute, second, nsec, time.UTC), nil
}
func parseTime(in string) (time.Time, error) {
// First, try a few numerics
n, err := strconv.ParseInt(in, 10, 64)
if err == nil {
switch {
case n > int64(math.MaxInt32)*1000:
// nanosecond timestamps
return time.Unix(n/1e9, n%1e9), nil
case n > int64(math.MaxInt32):
// millisecond timestamps
return time.Unix(n/1000, (n%1000)*1e6), nil
case n > 10000:
// second timestamps
return time.Unix(n, 0), nil
}
}
rv, err := parseCanonicalTime(in)
if err == nil {
return rv, nil
}
for _, f := range timeFormats {
parsed, err := time.Parse(f, in)
if err == nil {
return parsed, nil
}
}
return time.Time{}, errUnparseableTimestamp
}