com.blr19c.falowp.bot.system.scheduling.cron.CronExpression.kt Maven / Gradle / Ivy
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package com.blr19c.falowp.bot.system.scheduling.cron
import java.time.temporal.ChronoUnit
import java.time.temporal.Temporal
@Suppress("UNCHECKED_CAST", "UNUSED")
class CronExpression private constructor(
seconds: CronField,
minutes: CronField,
hours: CronField,
daysOfMonth: CronField,
months: CronField,
daysOfWeek: CronField,
private val expression: String
) {
// reverse order, to make big changes first
// to make sure we end up at 0 nanos, we add an extra field
private val fields: Array =
arrayOf(daysOfWeek, months, daysOfMonth, hours, minutes, seconds, CronField.zeroNanos())
/**
* Calculate the next [Temporal] that matches this expression.
*
* @param temporal the seed value
* @param the type of temporal
* @return the next temporal that matches this expression, or `null`
* if no such temporal can be found
*/
fun next(temporal: T): T? where T : Temporal? {
return nextOrSame(ChronoUnit.NANOS.addTo(temporal, 1))
}
private fun nextOrSame(temp: T): T? where T : Temporal? {
var temporal = temp
for (i in 0 until MAX_ATTEMPTS) {
val result = nextOrSameInternal(temporal) as Temporal
if (result == temporal) {
return result as T?
}
temporal = result as T
}
return null
}
private fun nextOrSameInternal(temp: T): T? where T : Temporal? {
var temporal: T? = temp
for (field in fields) {
temporal = field.nextOrSame(temporal)
if (temporal == null) {
return null
}
}
return temporal
}
override fun hashCode(): Int {
return fields.contentHashCode()
}
override fun equals(other: Any?): Boolean {
if (this === other) {
return true
}
return if (other is CronExpression) {
fields.contentEquals(other.fields)
} else {
false
}
}
/**
* Return the expression string used to create this `CronExpression`.
*
* @return the expression string
*/
override fun toString(): String {
return expression
}
companion object {
const val MAX_ATTEMPTS = 366
private val MACROS = arrayOf(
"@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 * * *",
"@midnight", "0 0 0 * * *",
"@hourly", "0 0 * * * *"
)
/**
* Parse the given
* [crontab expression](https://www.manpagez.com/man/5/crontab/)
* string into a `CronExpression`.
* The string has six single space-separated time and date fields:
*
* ┌───────────── second (0-59)
* │ ┌───────────── minute (0 - 59)
* │ │ ┌───────────── hour (0 - 23)
* │ │ │ ┌───────────── day of the month (1 - 31)
* │ │ │ │ ┌───────────── month (1 - 12) (or JAN-DEC)
* │ │ │ │ │ ┌───────────── day of the week (0 - 7)
* │ │ │ │ │ │ (0 or 7 is Sunday, or MON-SUN)
* │ │ │ │ │ │
* * * * * * *
*
*
*
* The following rules apply:
*
* *
* A field may be an asterisk (`*`), which always stands for
* "first-last". For the "day of the month" or "day of the week" fields, a
* question mark (`?`) may be used instead of an asterisk.
*
* *
* Ranges of numbers are expressed by two numbers separated with a hyphen
* (`-`). The specified range is inclusive.
*
* * Following a range (or `*`) with `/n` specifies
* the interval of the number's value through the range.
*
* *
* English names can also be used for the "month" and "day of week" fields.
* Use the first three letters of the particular day or month (case does not
* matter).
*
* *
* The "day of month" and "day of week" fields can contain a
* `L`-character, which stands for "last", and has a different meaning
* in each field:
*
* *
* In the "day of month" field, `L` stands for "the last day of the
* month". If followed by an negative offset (i.e. `L-n`), it means
* "`n`th-to-last day of the month". If followed by `W` (i.e.
* `LW`), it means "the last weekday of the month".
*
* *
* *
* The "day of month" field can be `nW`, which stands for "the nearest
* weekday to day of the month `n`".
* If `n` falls on Saturday, this yields the Friday before it.
* If `n` falls on Sunday, this yields the Monday after,
* which also happens if `n` is `1` and falls on a Saturday
* (i.e. `1W` stands for "the first weekday of the month").
*
* *
* The "day of week" field can be `d#n` (or `DDD#n`), which
* stands for "the `n`-th day of week `d` (or `DDD`) in
* the month".
*
*
*
*
* Example expressions:
*
* * `"0 0 * * * *"` = the top of every hour of every day.
* * `"*/10 * * * * *"` = every ten seconds.
* * `"0 0 8-10 * * *"` = 8, 9 and 10 o'clock of every day.
* * `"0 0 6,19 * * *"` = 6:00 AM and 7:00 PM every day.
* * `"0 0/30 8-10 * * *"` = 8:00, 8:30, 9:00, 9:30, 10:00 and 10:30 every day.
* * `"0 0 9-17 * * MON-FRI"` = on the hour nine-to-five weekdays
* * `"0 0 0 25 12 ?"` = every Christmas Day at midnight
* * `"0 0 0 L * *"` = last day of the month at midnight
* * `"0 0 0 L-3 * *"` = third-to-last day of the month at midnight
* * `"0 0 0 1W * *"` = first weekday of the month at midnight
* * `"0 0 0 LW * *"` = last weekday of the month at midnight
* * `"0 0 0 * * 5L"` = last Friday of the month at midnight
* * `"0 0 0 * * TH UL"` = last Thursday of the month at midnight
* * `"0 0 0 ? * 5#2"` = the second Friday in the month at midnight
* * `"0 0 0 ? * MON#1"` = the first Monday in the month at midnight
*
*
*
* The following macros are also supported:
*
* * `"@yearly"` (or `"@annually"`) to run un once a year, i.e. `"0 0 0 1 1 *"`,
* * `"@monthly"` to run once a month, i.e. `"0 0 0 1 * *"`,
* * `"@weekly"` to run once a week, i.e. `"0 0 0 * * 0"`,
* * `"@daily"` (or `"@midnight"`) to run once a day, i.e. `"0 0 0 * * *"`,
* * `"@hourly"` to run once an hour, i.e. `"0 0 * * * *"`.
*
*
* @param exp the expression string to parse
* @return the parsed `CronExpression` object
* @throws IllegalArgumentException in the expression does not conform to
* the cron format
*/
fun parse(exp: String): CronExpression {
var expression = exp
expression = resolveMacros(expression)
val fields: Array = expression.split(" ").toTypedArray()
require(fields.size == 6) {
String.format(
"Cron expression must consist of 6 fields (found %d in \"%s\")", fields.size, expression
)
}
return try {
val seconds = CronField.parseSeconds(fields[0])
val minutes = CronField.parseMinutes(fields[1])
val hours = CronField.parseHours(fields[2])
val daysOfMonth = CronField.parseDaysOfMonth(fields[3])
val months = CronField.parseMonth(fields[4])
val daysOfWeek = CronField.parseDaysOfWeek(fields[5])
CronExpression(seconds, minutes, hours, daysOfMonth, months, daysOfWeek, expression)
} catch (ex: IllegalArgumentException) {
val msg = ex.message + " in cron expression \"" + expression + "\""
throw IllegalArgumentException(msg, ex)
}
}
/**
* Determine whether the given string represents a valid cron expression.
*
* @param expression the expression to evaluate
* @return `true` if the given expression is a valid cron expression
* @since 5.3.8
*/
fun isValidExpression(expression: String?): Boolean {
return if (expression == null) {
false
} else try {
parse(expression)
true
} catch (ex: IllegalArgumentException) {
false
}
}
private fun resolveMacros(exp: String): String {
var expression = exp
expression = expression.trim { it <= ' ' }
var i = 0
while (i < MACROS.size) {
if (MACROS[i].equals(expression, ignoreCase = true)) {
return MACROS[i + 1]
}
i += 2
}
return expression
}
}
}