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Rename cronexpression.go to cronexpr.go

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Raymond Hill
2013-08-31 08:50:51 -04:00
parent 457a81697e
commit 6190b9d9db
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/*!
* Copyright 2013 Raymond Hill
*
* Project: github.com/gorhill/cronexpression
* File: cronexpression.go
* Version: 1.0
* License: GPL v3 see <https://www.gnu.org/licenses/gpl.html>
*
*/
// Package cronexpression parses cron time expressions.
package cronexpression
/******************************************************************************/
import (
"regexp"
"sort"
"strconv"
"strings"
"time"
)
/******************************************************************************/
// A Expression represents a specific cron time expression as defined on
// Wikipedia: https://en.wikipedia.org/wiki/Cron#CRON_expression
type Expression struct {
expression string
secondList []int
minuteList []int
hourList []int
daysOfMonth map[int]bool
workdaysOfMonth map[int]bool
lastDayOfMonth bool
daysOfMonthRestricted bool
actualDaysOfMonthList []int
monthList []int
daysOfWeek map[int]bool
specificWeekDaysOfWeek map[int]bool
lastWeekDaysOfWeek map[int]bool
daysOfWeekRestricted bool
yearList []int
}
/******************************************************************************/
// Parse() returns a new Expression pointer. It expects
// a well-formed cron expression. If a malformed cron expression is
// supplied, the result is undefined.
func Parse(cronLine string) *Expression {
cronLineNormalized := cronNormalize(cronLine)
// Split into fields
cronFields := regexp.MustCompile(`\s+`).Split(cronLineNormalized, -1)
// Our cron expression parser expects 7 fields:
// second minute hour dayofmonth month dayofweek year
// Standard cron is 6 fields with year field being optional
// minute hour dayofmonth month dayofweek {year}
// Thus...
// If we have 5 fields, append wildcard year field
if len(cronFields) < 6 {
cronFields = append(cronFields, "*")
}
// If we have 6 fields, prepend match-once second field
if len(cronFields) < 7 {
cronFields = append(cronFields, "")
copy(cronFields[1:], cronFields[0:])
cronFields[0] = "0"
}
// At this point, we should have at least 7 fields. Fields beyond the
// seventh one, if any, are ignored.
if len(cronFields) < 7 {
panic("Malformed cron expression\n")
}
// Generic parser can be used for most fields
cronExpr := &Expression{
expression: cronLine,
secondList: genericFieldParse(cronFields[0], 0, 59),
minuteList: genericFieldParse(cronFields[1], 0, 59),
hourList: genericFieldParse(cronFields[2], 0, 23),
monthList: genericFieldParse(cronFields[4], 1, 12),
yearList: genericFieldParse(cronFields[6], 1970, 2099),
}
// Days of month/days of week is a bit more complicated, due
// to their extended syntax, and the fact that days per
// month is a variable quantity, and relation between
// days of week and days of month depends on the month/year.
cronExpr.dayofmonthFieldParse(cronFields[3])
cronExpr.dayofweekFieldParse(cronFields[5])
return cronExpr
}
/******************************************************************************/
// Given a time stamp `fromTime`, return the closest following time stamp which
// matches the cron expression `expr`. The `time.Location` of the returned
// time stamp is the same as `fromTime`.
func (expr *Expression) Next(fromTime time.Time) time.Time {
// Special case
if fromTime.IsZero() {
return fromTime
}
// Since expr.nextSecond()-expr.nextMonth() expects that the
// supplied time stamp is a perfect match to the underlying cron
// expression, and since this function is an entry point where `fromTime`
// does not necessarily matches the underlying cron expression,
// we first need to ensure supplied time stamp matches
// the cron expression. If not, this means the supplied time
// stamp falls in between matching time stamps, thus we move
// to closest future matching immediately upon encountering a mismatching
// time stamp.
// year
v := fromTime.Year()
i := sort.SearchInts(expr.yearList, v)
if i == len(expr.yearList) {
return time.Time{}
}
if v != expr.yearList[i] {
return expr.nextYear(fromTime)
}
// month
v = int(fromTime.Month())
i = sort.SearchInts(expr.monthList, v)
if i == len(expr.monthList) {
return expr.nextYear(fromTime)
}
if v != expr.monthList[i] {
return expr.nextMonth(fromTime)
}
expr.actualDaysOfMonthList = expr.calculateActualDaysOfMonth(fromTime.Year(), int(fromTime.Month()))
if len(expr.actualDaysOfMonthList) == 0 {
return expr.nextMonth(fromTime)
}
// day of month
v = fromTime.Day()
i = sort.SearchInts(expr.actualDaysOfMonthList, v)
if i == len(expr.actualDaysOfMonthList) {
return expr.nextMonth(fromTime)
}
if v != expr.actualDaysOfMonthList[i] {
return expr.nextDayOfMonth(fromTime)
}
// hour
v = fromTime.Hour()
i = sort.SearchInts(expr.hourList, v)
if i == len(expr.hourList) {
return expr.nextDayOfMonth(fromTime)
}
if v != expr.hourList[i] {
return expr.nextHour(fromTime)
}
// minute
v = fromTime.Minute()
i = sort.SearchInts(expr.minuteList, v)
if i == len(expr.minuteList) {
return expr.nextHour(fromTime)
}
if v != expr.minuteList[i] {
return expr.nextMinute(fromTime)
}
// second
v = fromTime.Second()
i = sort.SearchInts(expr.secondList, v)
if i == len(expr.secondList) {
return expr.nextMinute(fromTime)
}
// If we reach this point, there is nothing better to do
// than to move to the next second
return expr.nextSecond(fromTime)
}
/******************************************************************************/
// Given a time stamp `fromTime`, return a slice of `n` closest following time
// stamps which match the cron expression `expr`. The time stamps in the
// returned slice are in chronological ascending order. The `time.Location` of
// the returned time stamps is the same as `fromTime`.
func (expr *Expression) NextN(fromTime time.Time, n int) []time.Time {
if n <= 0 {
panic("Expression.NextN(): invalid count")
}
nextTimes := make([]time.Time, 0)
fromTime = expr.Next(fromTime)
for {
if fromTime.IsZero() {
break
}
nextTimes = append(nextTimes, fromTime)
n -= 1
if n == 0 {
break
}
fromTime = expr.nextSecond(fromTime)
}
return nextTimes
}
/******************************************************************************/
func (expr *Expression) nextYear(t time.Time) time.Time {
// Find index at which item in list is greater or equal to
// candidate year
i := sort.SearchInts(expr.yearList, t.Year()+1)
if i == len(expr.yearList) {
return time.Time{}
}
// Year changed, need to recalculate actual days of month
expr.actualDaysOfMonthList = expr.calculateActualDaysOfMonth(expr.yearList[i], expr.monthList[0])
if len(expr.actualDaysOfMonthList) == 0 {
return expr.nextMonth(time.Date(
expr.yearList[i],
time.Month(expr.monthList[0]),
1,
expr.hourList[0],
expr.minuteList[0],
expr.secondList[0],
0,
time.Local))
}
return time.Date(
expr.yearList[i],
time.Month(expr.monthList[0]),
expr.actualDaysOfMonthList[0],
expr.hourList[0],
expr.minuteList[0],
expr.secondList[0],
0,
time.Local)
}
/******************************************************************************/
func (expr *Expression) nextMonth(t time.Time) time.Time {
// Find index at which item in list is greater or equal to
// candidate month
i := sort.SearchInts(expr.monthList, int(t.Month())+1)
if i == len(expr.monthList) {
return expr.nextYear(t)
}
// Month changed, need to recalculate actual days of month
expr.actualDaysOfMonthList = expr.calculateActualDaysOfMonth(t.Year(), expr.monthList[i])
if len(expr.actualDaysOfMonthList) == 0 {
return expr.nextMonth(time.Date(
t.Year(),
time.Month(expr.monthList[i]),
1,
expr.hourList[0],
expr.minuteList[0],
expr.secondList[0],
0,
time.Local))
}
return time.Date(
t.Year(),
time.Month(expr.monthList[i]),
expr.actualDaysOfMonthList[0],
expr.hourList[0],
expr.minuteList[0],
expr.secondList[0],
0,
time.Local)
}
/******************************************************************************/
func (expr *Expression) calculateActualDaysOfMonth(year, month int) []int {
actualDaysOfMonthMap := make(map[int]bool)
timeOrigin := time.Date(year, time.Month(month), 1, 0, 0, 0, 0, time.UTC)
lastDayOfMonth := timeOrigin.AddDate(0, 1, -1).Day()
// As per crontab man page (http://linux.die.net/man/5/crontab#):
// "The day of a command's execution can be specified by two
// "fields - day of month, and day of week. If both fields are
// "restricted (ie, aren't *), the command will be run when
// "either field matches the current time"
if expr.daysOfMonthRestricted || expr.daysOfWeekRestricted == false {
// Last day of month
if expr.lastDayOfMonth {
actualDaysOfMonthMap[lastDayOfMonth] = true
}
// Days of month
for v, _ := range expr.daysOfMonth {
// Ignore days beyond end of month
if v <= lastDayOfMonth {
actualDaysOfMonthMap[v] = true
}
}
// Work days of month
// As per Wikipedia: month boundaries are not crossed.
for v, _ := range expr.workdaysOfMonth {
// Ignore days beyond end of month
if v <= lastDayOfMonth {
// If saturday, then friday
if timeOrigin.AddDate(0, 0, v-1).Weekday() == time.Saturday {
if v > 1 {
v -= 1
} else {
v += 2
}
// If sunday, then monday
} else if timeOrigin.AddDate(0, 0, v-1).Weekday() == time.Sunday {
if v < lastDayOfMonth {
v += 1
} else {
v -= 2
}
}
actualDaysOfMonthMap[v] = true
}
}
}
if expr.daysOfWeekRestricted {
// How far first sunday is from first day of month
offset := 7 - int(timeOrigin.Weekday())
// days of week
// offset : (7 - day_of_week_of_1st_day_of_month)
// target : 1 + (7 * week_of_month) + (offset + day_of_week) % 7
for w := 0; w <= 4; w += 1 {
for v, _ := range expr.daysOfWeek {
v := 1 + w*7 + (offset+v)%7
if v <= lastDayOfMonth {
actualDaysOfMonthMap[v] = true
}
}
}
// days of week of specific week in the month
// offset : (7 - day_of_week_of_1st_day_of_month)
// target : 1 + (7 * week_of_month) + (offset + day_of_week) % 7
for v, _ := range expr.specificWeekDaysOfWeek {
v := 1 + 7*(v/7) + (offset+v)%7
if v <= lastDayOfMonth {
actualDaysOfMonthMap[v] = true
}
}
// Last days of week of the month
lastWeekOrigin := timeOrigin.AddDate(0, 1, -7)
offset = 7 - int(lastWeekOrigin.Weekday())
for v, _ := range expr.lastWeekDaysOfWeek {
v := lastWeekOrigin.Day() + (offset+v)%7
if v <= lastDayOfMonth {
actualDaysOfMonthMap[v] = true
}
}
}
return toList(actualDaysOfMonthMap)
}
/******************************************************************************/
func (expr *Expression) nextDayOfMonth(t time.Time) time.Time {
// Find index at which item in list is greater or equal to
// candidate day of month
i := sort.SearchInts(expr.actualDaysOfMonthList, t.Day()+1)
if i == len(expr.actualDaysOfMonthList) {
return expr.nextMonth(t)
}
return time.Date(
t.Year(),
t.Month(),
expr.actualDaysOfMonthList[i],
expr.hourList[0],
expr.minuteList[0],
expr.secondList[0],
0,
t.Location())
}
/******************************************************************************/
func (expr *Expression) nextHour(t time.Time) time.Time {
// Find index at which item in list is greater or equal to
// candidate hour
i := sort.SearchInts(expr.hourList, t.Hour()+1)
if i == len(expr.hourList) {
return expr.nextDayOfMonth(t)
}
return time.Date(
t.Year(),
t.Month(),
t.Day(),
expr.hourList[i],
expr.minuteList[0],
expr.secondList[0],
0,
t.Location())
}
/******************************************************************************/
func (expr *Expression) nextMinute(t time.Time) time.Time {
// Find index at which item in list is greater or equal to
// candidate minute
i := sort.SearchInts(expr.minuteList, t.Minute()+1)
if i == len(expr.minuteList) {
return expr.nextHour(t)
}
return time.Date(
t.Year(),
t.Month(),
t.Day(),
t.Hour(),
expr.minuteList[i],
expr.secondList[0],
0,
t.Location())
}
/******************************************************************************/
func (expr *Expression) nextSecond(t time.Time) time.Time {
// nextSecond() assumes all other fields are exactly matched
// to the cron expression
// Find index at which item in list is greater or equal to
// candidate second
i := sort.SearchInts(expr.secondList, t.Second()+1)
if i == len(expr.secondList) {
return expr.nextMinute(t)
}
return time.Date(
t.Year(),
t.Month(),
t.Day(),
t.Hour(),
t.Minute(),
expr.secondList[i],
0,
t.Location())
}
/******************************************************************************/
var cronNormalizer = strings.NewReplacer(
// Order is important!
"@yearly", "0 0 0 1 1 * *",
"@annually", "0 0 0 1 1 * *",
"@monthly", "0 0 0 1 * * *",
"@weekly", "0 0 0 * * 0 *",
"@daily", "0 0 0 * * * *",
"@hourly", "0 0 * * * * *",
"january", "1",
"february", "2",
"march", "3",
"april", "4",
"may", "5",
"june", "6",
"july", "7",
"august", "8",
"september", "9",
"october", "0",
"november", "1",
"december", "2",
"sunday", "0",
"monday", "1",
"tuesday", "2",
"wednesday", "3",
"thursday", "4",
"friday", "5",
"saturday", "6",
"jan", "1",
"feb", "2",
"mar", "3",
"apr", "4",
"jun", "6",
"jul", "7",
"aug", "8",
"sep", "9",
"oct", "10",
"nov", "11",
"dec", "12",
"sun", "0",
"mon", "1",
"tue", "2",
"wed", "3",
"thu", "4",
"fri", "5",
"sat", "6",
"?", "*")
func cronNormalize(cronLine string) string {
cronLine = strings.TrimSpace(cronLine)
cronLine = strings.ToLower(cronLine)
cronLine = cronNormalizer.Replace(cronLine)
return cronLine
}
/******************************************************************************/
func (expr *Expression) dayofweekFieldParse(cronField string) error {
// Defaults
expr.daysOfWeekRestricted = true
expr.lastWeekDaysOfWeek = make(map[int]bool)
expr.daysOfWeek = make(map[int]bool)
// "You can also mix all of the above, as in: 1-5,10,12,20-30/5"
cronList := strings.Split(cronField, ",")
for _, s := range cronList {
// "/"
step, s := extractInterval(s)
// "*"
if s == "*" {
expr.daysOfWeekRestricted = (step > 1)
populateMany(expr.daysOfWeek, 0, 6, step)
continue
}
// "-"
// week day interval for all weeks
i := strings.Index(s, "-")
if i >= 0 {
min := atoi(s[:i]) % 7
max := atoi(s[i+1:]) % 7
populateMany(expr.daysOfWeek, min, max, step)
continue
}
// single value
// "l": week day for last week
i = strings.Index(s, "l")
if i >= 0 {
populateOne(expr.lastWeekDaysOfWeek, atoi(s[:i])%7)
continue
}
// "#": week day for specific week
i = strings.Index(s, "#")
if i >= 0 {
// v#w
v := atoi(s[:i]) % 7
w := atoi(s[i+1:])
// v domain = [0,7]
// w domain = [1,5]
populateOne(expr.specificWeekDaysOfWeek, (w-1)*7+(v%7))
continue
}
// week day interval for all weeks
if step > 0 {
v := atoi(s) % 7
populateMany(expr.daysOfWeek, v, 6, step)
continue
}
// single week day for all weeks
v := atoi(s) % 7
populateOne(expr.daysOfWeek, v)
}
return nil
}
/******************************************************************************/
func (expr *Expression) dayofmonthFieldParse(cronField string) error {
// Defaults
expr.daysOfMonthRestricted = true
expr.lastDayOfMonth = false
expr.daysOfMonth = make(map[int]bool) // days of month map
expr.workdaysOfMonth = make(map[int]bool) // work day of month map
// Comma separator is used to mix different allowed syntax
cronList := strings.Split(cronField, ",")
for _, s := range cronList {
// "/"
step, s := extractInterval(s)
// "*"
if s == "*" {
expr.daysOfMonthRestricted = (step > 1)
populateMany(expr.daysOfMonth, 1, 31, step)
continue
}
// "-"
i := strings.Index(s, "-")
if i >= 0 {
populateMany(expr.daysOfMonth, atoi(s[:i]), atoi(s[i+1:]), step)
continue
}
// single value
// "l": last day of month
if s == "l" {
expr.lastDayOfMonth = true
continue
}
// "w": week day
i = strings.Index(s, "w")
if i >= 0 {
populateOne(expr.workdaysOfMonth, atoi(s[:i]))
continue
}
// single value with interval
if step > 0 {
populateMany(expr.daysOfMonth, atoi(s), 31, step)
continue
}
// single value
populateOne(expr.daysOfMonth, atoi(s))
}
return nil
}
/******************************************************************************/
func genericFieldParse(cronField string, min, max int) []int {
// Defaults
values := make(map[int]bool)
// Comma separator is used to mix different allowed syntax
cronList := strings.Split(cronField, ",")
for _, s := range cronList {
// "/"
step, s := extractInterval(s)
// "*"
if s == "*" {
populateMany(values, min, max, step)
continue
}
// "-"
i := strings.Index(s, "-")
if i >= 0 {
populateMany(values, atoi(s[:i]), atoi(s[i+1:]), step)
continue
}
// single value with interval
if step > 0 {
populateMany(values, atoi(s), max, step)
continue
}
// single value
populateOne(values, atoi(s))
}
return toList(values)
}
/******************************************************************************/
// Local helpers
func extractInterval(s string) (int, string) {
step := 0
i := strings.Index(s, "/")
if i >= 0 {
step = atoi(s[i+1:])
s = s[:i]
}
return step, s
}
func atoi(s string) int {
v, err := strconv.Atoi(s)
if err != nil {
panic(err)
}
return v
}
func populateOne(values map[int]bool, v int) {
values[v] = true
}
func populateMany(values map[int]bool, min, max, step int) {
if step == 0 {
step = 1
}
for i := min; i <= max; i += step {
values[i] = true
}
}
func toList(set map[int]bool) []int {
list := make([]int, len(set))
i := 0
for k, _ := range set {
list[i] = k
i += 1
}
sort.Ints(list)
return list
}