add parsing of strings with values

src/commonMain/kotlin/com/github/insanusmokrassar/krontab/CronDateTime.kt

@@ -9,20 +9,6 @@ private val incomeHourRange = 0 .. 23
 private val incomeMinuteRange = 0 .. 59
 private val incomeSecondRange = 0 .. 59
 
-fun CronDateTime(
-    month: Int? = null,
-    dayOfMonth: Int? = null,
-    hours: Int? = null,
-    minutes: Int? = null,
-    seconds: Int? = null
-) = CronDateTime(
-    month ?.clamp(incomeMonthRange) ?.toByte(),
-    dayOfMonth ?.clamp(incomeDayOfMonthRange) ?.toByte(),
-    hours ?.clamp(incomeHourRange) ?.toByte(),
-    minutes ?.clamp(incomeMinuteRange) ?.toByte(),
-    seconds ?.clamp(incomeSecondRange) ?.toByte()
-)
-
 /**
  * [month] 0-11
  * [dayOfMonth] 0-31
@@ -46,6 +32,22 @@ data class CronDateTime(
     }
 
     internal val klockDayOfMonth = dayOfMonth ?.plus(1)
+
+    companion object {
+        fun create(
+            month: Int? = null,
+            dayOfMonth: Int? = null,
+            hours: Int? = null,
+            minutes: Int? = null,
+            seconds: Int? = null
+        ) = CronDateTime(
+            month ?.clamp(incomeMonthRange) ?.toByte(),
+            dayOfMonth ?.clamp(incomeDayOfMonthRange) ?.toByte(),
+            hours ?.clamp(incomeHourRange) ?.toByte(),
+            minutes ?.clamp(incomeMinuteRange) ?.toByte(),
+            seconds ?.clamp(incomeSecondRange) ?.toByte()
+        )
+    }
 }
 
 fun CronDateTime.toNearDateTime(relativelyTo: DateTime = DateTime.now()): DateTime {

src/commonMain/kotlin/com/github/insanusmokrassar/krontab/CronParser.kt

@@ -0,0 +1,84 @@
+package com.github.insanusmokrassar.krontab
+
+import com.github.insanusmokrassar.krontab.utils.*
+import com.github.insanusmokrassar.krontab.utils.clamp
+import com.github.insanusmokrassar.krontab.utils.minutesRange
+import com.github.insanusmokrassar.krontab.utils.secondsRange
+
+private fun parse(from: String, dataRange: IntRange): Array<Byte>? {
+    val things = from.split(",")
+
+    val results = things.flatMap {
+        when {
+            it.contains("/") -> {
+                val (start, step) = it.split("/")
+                val startNum = (if (start.isEmpty() || start == "*") {
+                    0
+                } else {
+                    start.toInt()
+                }).clamp(dataRange)
+                val stepNum = step.toInt().clamp(dataRange)
+                (startNum .. dataRange.last step stepNum).map { it }
+            }
+            it == "*" -> return null
+            else -> listOf(it.toInt().clamp(dataRange))
+        }
+    }
+
+    return results.map { it.toByte() }.toTypedArray()
+}
+
+private fun parseMonths(from: String) = parse(from, monthRange)
+private fun parseDaysOfMonth(from: String) = parse(from, dayOfMonthRange)
+private fun parseHours(from: String) = parse(from, hoursRange)
+private fun parseMinutes(from: String) = parse(from, minutesRange)
+private fun parseSeconds(from: String) = parse(from, secondsRange)
+
+private fun Array<Byte>.fillWith(
+    whereToPut: MutableList<CronDateTime>,
+    createFactory: (CronDateTime, Byte) -> CronDateTime
+) {
+    val previousValues = whereToPut.toList()
+
+    whereToPut.clear()
+
+    previousValues.forEach { previousValue ->
+        forEach {
+            whereToPut.add(createFactory(previousValue, it))
+        }
+    }
+}
+
+internal fun parse(incoming: String): List<CronDateTime> {
+    val (secondsSource, minutesSource, hoursSource, dayOfMonthSource, monthSource) = incoming.split(" ")
+
+    val secondsParsed = parseSeconds(secondsSource)
+    val minutesParsed = parseSeconds(minutesSource)
+    val hoursParsed = parseSeconds(hoursSource)
+    val dayOfMonthParsed = parseSeconds(dayOfMonthSource)
+    val monthParsed = parseSeconds(monthSource)
+
+    val resultCronDateTimes = mutableListOf(CronDateTime())
+
+    secondsParsed ?.fillWith(resultCronDateTimes) { previousCronDateTime: CronDateTime, currentTime: Byte ->
+        previousCronDateTime.copy(seconds = currentTime)
+    }
+
+    minutesParsed ?.fillWith(resultCronDateTimes) { previousCronDateTime: CronDateTime, currentTime: Byte ->
+        previousCronDateTime.copy(minutes = currentTime)
+    }
+
+    hoursParsed ?.fillWith(resultCronDateTimes) { previousCronDateTime: CronDateTime, currentTime: Byte ->
+        previousCronDateTime.copy(hours = currentTime)
+    }
+
+    dayOfMonthParsed ?.fillWith(resultCronDateTimes) { previousCronDateTime: CronDateTime, currentTime: Byte ->
+        previousCronDateTime.copy(dayOfMonth = currentTime)
+    }
+
+    monthParsed ?.fillWith(resultCronDateTimes) { previousCronDateTime: CronDateTime, currentTime: Byte ->
+        previousCronDateTime.copy(month = currentTime)
+    }
+
+    return resultCronDateTimes.toList()
+}

src/commonMain/kotlin/com/github/insanusmokrassar/krontab/CronRegularExpression.kt

@@ -10,3 +10,9 @@ internal val dayOfMonthRegex = Regex("[*]|((${dayOfMonthNumberRegex.pattern})(,(
 internal val hoursRegex = Regex("[*]|((${hoursNumberRegex.pattern})(,(${hoursNumberRegex.pattern})){0,23})")
 internal val minutesRegex = Regex("[*]|((${minutesOrSecondsNumberRegex.pattern})(,(${minutesOrSecondsNumberRegex.pattern})){0,59})")
 internal val secondsRegex = minutesRegex
+
+internal val monthRange = 0 .. 11
+internal val dayOfMonthRange = 0 .. 31
+internal val hoursRange = 0 .. 23
+internal val minutesRange = 0 .. 59
+internal val secondsRange = minutesRange