kotlinx-datetime/kotlinx.datetime.format/alternativeParsing

alternativeParsing

fun <T : DateTimeFormatBuilder> T.alternativeParsing(vararg alternativeFormats: T.() -> Unit, primaryFormat: T.() -> Unit)(source)

A format along with other ways to parse the same portion of the value.

When parsing, first, primaryFormat is used; if parsing the whole string fails using that, the formats from alternativeFormats are tried in order.

When formatting, the primaryFormat is used to format the value, and alternativeFormats are ignored.

Example:

alternativeParsing(
  { dayOfMonth(); char('-'); monthNumber() },
  { monthNumber(); char(' '); dayOfMonth() },
) { monthNumber(); char('/'); dayOfMonth() }

This will always format a date as MM/DD, but will also accept DD-MM and MM DD.

Samples

import kotlinx.datetime.*
import kotlinx.datetime.format.*
import kotlin.test.*
fun main() { 
   //sampleStart 
   // Defining a custom format that allows parsing one of several alternatives
val format = DateTimeComponents.Format {
    // optionally, date:
    alternativeParsing({
    }) {
        date(LocalDate.Formats.ISO)
    }
    // optionally, time:
    alternativeParsing({
    }) {
        // either the `T` or the `t` character:
        alternativeParsing({ char('t') }) { char('T') }
        time(LocalTime.Formats.ISO)
    }
}
val date = LocalDate(2020, 1, 13)
val time = LocalTime(12, 30, 16)
check(format.parse("2020-01-13t12:30:16").toLocalDateTime() == date.atTime(time))
check(format.parse("2020-01-13").toLocalDate() == date)
check(format.parse("T12:30:16").toLocalTime() == time)
check(format.format { setDate(date); setTime(time) } == "2020-01-13T12:30:16") 
   //sampleEnd
}