LocalTime#toSecondOfDay & LocalTime#ofSecondOfDay.

Author: vanniktech

core/common/src/LocalTime.kt

@@ -40,6 +40,11 @@ public expect class LocalTime : Comparable<LocalTime> {
          */
         public fun parse(isoString: String): LocalTime
 
+        /**
+         * Returns a LocalTime with the specified [secondOfDay]. The nanosecond field will be set to zero.
+         */
+        public fun ofSecondOfDay(secondOfDay: Int): LocalTime
+
         internal val MIN: LocalTime
         internal val MAX: LocalTime
     }
@@ -84,6 +89,9 @@ public expect class LocalTime : Comparable<LocalTime> {
      * @see LocalDateTime.parse
      */
     public override fun toString(): String
+
+    /** Returns the time as seconds of day, from 0 to 24 * 60 * 60 - 1. */
+    public fun toSecondOfDay(): Int
 }
 
 /**
@@ -110,4 +118,4 @@ public fun LocalTime.atDate(year: Int, month: Month, dayOfMonth: Int = 0): Local
 /**
  * Combines this time's components with the specified [LocalDate] components into a [LocalDateTime] value.
  */
-public fun LocalTime.atDate(date: LocalDate): LocalDateTime = LocalDateTime(date, this)
+public fun LocalTime.atDate(date: LocalDate): LocalDateTime = LocalDateTime(date, this)

core/common/test/LocalTimeTest.kt

@@ -85,6 +85,29 @@ class LocalTimeTest {
         assertFailsWith<IllegalArgumentException> { LocalTime(0, 0, 0, 1_000_000_000) }
     }
 
+    @Test
+    fun toSecondOfDay() {
+        val data = mapOf(
+            0 to LocalTime(0, 0),
+            5 to LocalTime(0, 0, 5),
+            44105 to LocalTime(12, 15, 5),
+            86399 to LocalTime(23, 59, 59),
+        )
+
+        data.forEach { (secondOfDay, localTime) ->
+            assertEquals(secondOfDay, localTime.toSecondOfDay())
+            assertEquals(localTime, LocalTime.ofSecondOfDay(secondOfDay))
+        }
+    }
+
+    @Test
+    fun toSecondOfDayIgnoredNanosecond() {
+        assertEquals(
+            0,
+            LocalTime(0, 0, 0, 100).toSecondOfDay(),
+        )
+    }
+
     @Test
     fun atDate() {
         val time = LocalTime(12, 1, 59)

core/js/src/LocalTime.kt

@@ -34,6 +34,8 @@ public actual class LocalTime internal constructor(internal val value: jtLocalTi
 
     actual override fun toString(): String = value.toString()
 
+    public actual fun toSecondOfDay(): Int = value.toSecondOfDay().toInt()
+
     actual override fun compareTo(other: LocalTime): Int = this.value.compareTo(other.value).toInt()
 
     public actual companion object {
@@ -44,7 +46,9 @@ public actual class LocalTime internal constructor(internal val value: jtLocalTi
             throw e
         }
 
+        public actual fun ofSecondOfDay(secondOfDay: Int): LocalTime = jtLocalTime.ofSecondOfDay(secondOfDay, 0).let(::LocalTime)
+
         internal actual val MIN: LocalTime = LocalTime(jtLocalTime.MIN)
         internal actual val MAX: LocalTime = LocalTime(jtLocalTime.MAX)
     }
-}
+}

core/jvm/src/LocalTime.kt

@@ -39,14 +39,18 @@ public actual class LocalTime internal constructor(internal val value: jtLocalTi
 
     actual override fun compareTo(other: LocalTime): Int = this.value.compareTo(other.value)
 
+    public actual fun toSecondOfDay(): Int = value.toSecondOfDay()
+
     public actual companion object {
         public actual fun parse(isoString: String): LocalTime = try {
             jtLocalTime.parse(isoString).let(::LocalTime)
         } catch (e: DateTimeParseException) {
             throw DateTimeFormatException(e)
         }
 
+        public actual fun ofSecondOfDay(secondOfDay: Int): LocalTime = jtLocalTime.ofSecondOfDay(secondOfDay.toLong()).let(::LocalTime)
+
         internal actual val MIN: LocalTime = LocalTime(jtLocalTime.MIN)
         internal actual val MAX: LocalTime = LocalTime(jtLocalTime.MAX)
     }
-}
+}

core/native/src/LocalTime.kt

@@ -62,6 +62,9 @@ public actual class LocalTime actual constructor(
         public actual fun parse(isoString: String): LocalTime =
             localTimeParser.parse(isoString)
 
+        public actual fun ofSecondOfDay(secondOfDay: Int): LocalTime =
+            ofSecondOfDay(secondOfDay, 0)
+
         // org.threeten.bp.LocalTime#ofSecondOfDay(long, int)
         internal fun ofSecondOfDay(secondOfDay: Int, nanoOfSecond: Int): LocalTime {
             // Unidiomatic code due to https://github.com/Kotlin/kotlinx-datetime/issues/5
@@ -127,7 +130,7 @@ public actual class LocalTime actual constructor(
     }
 
     // org.threeten.bp.LocalTime#toSecondOfDay
-    internal fun toSecondOfDay(): Int {
+    public actual fun toSecondOfDay(): Int {
         var total: Int = hour * SECONDS_PER_HOUR
         total += minute * SECONDS_PER_MINUTE
         total += second