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/*!
* Copyright 2013 Raymond Hill
*
* Project: github.com/gorhill/cronexpr
* File: main.go
* Version: 1.0
* License: GPL v3 see <https://www.gnu.org/licenses/gpl.html>
*
*/
package main
/******************************************************************************/
import (
"flag"
"fmt"
"os"
"time"
"github.com/gorhill/cronexpr"
)
/******************************************************************************/
var (
usage = func() {
fmt.Fprintf(os.Stderr, "usage:\n %s [options] \"{cron expression}\"\noptions:\n", os.Args[0])
flag.PrintDefaults()
}
inTimeStr string
outTimeCount uint
outTimeLayout string
)
/******************************************************************************/
func main() {
var err error
flag.Usage = usage
flag.StringVar(&inTimeStr, "t", "", `whole or partial RFC3339 time value (i.e. "2006-01-02T15:04:05Z07:00") against which the cron expression is evaluated, now if not present`)
flag.UintVar(&outTimeCount, "n", 1, `number of resulting time values to output`)
flag.StringVar(&outTimeLayout, "l", "Mon, 02 Jan 2006 15:04:05 MST", `Go-compliant time layout to use for outputting time value(s), see <http://golang.org/pkg/time/#pkg-constants>`)
flag.Parse()
cronStr := flag.Arg(0)
if len(cronStr) == 0 {
flag.Usage()
return
}
inTime := time.Now()
inTimeLayout := ""
timeStrLen := len(inTimeStr)
if timeStrLen == 2 {
inTimeLayout = "06"
} else if timeStrLen >= 4 {
inTimeLayout += "2006"
if timeStrLen >= 7 {
inTimeLayout += "-01"
if timeStrLen >= 10 {
inTimeLayout += "-02"
if timeStrLen >= 13 {
inTimeLayout += "T15"
if timeStrLen >= 16 {
inTimeLayout += ":04"
if timeStrLen >= 19 {
inTimeLayout += ":05"
if timeStrLen >= 20 {
inTimeLayout += "Z07:00"
}
}
}
}
}
}
}
if len(inTimeLayout) > 0 {
// default to local time zone
if timeStrLen < 20 {
inTime, err = time.ParseInLocation(inTimeLayout, inTimeStr, time.Local)
} else {
inTime, err = time.Parse(inTimeLayout, inTimeStr)
}
if err != nil {
fmt.Fprintf(os.Stderr, "# error: unparseable time value: \"%s\"\n", inTimeStr)
os.Exit(1)
}
}
expr, err := cronexpr.Parse(cronStr)
if err != nil {
fmt.Fprintf(os.Stderr, "# %s: %s\n", os.Args[0], err)
os.Exit(1)
}
// Anything on the output which starts with '#' can be ignored if the caller
// is interested only in the time values. There is only one time
// value per line, and they are always in chronological ascending order.
fmt.Printf("# \"%s\" + \"%s\" =\n", cronStr, inTime.Format(time.RFC3339))
if outTimeCount < 1 {
outTimeCount = 1
}
outTimes := expr.NextN(inTime, outTimeCount)
for _, outTime := range outTimes {
fmt.Println(outTime.Format(outTimeLayout))
}
}
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