Separate ISO and default serializers

Sometimes, `X.Formats.ISO` and `X.parse()`/`X.toString()` behave
subtly differently; currently, it's the case for `LocalDateTime`
and `LocalTime`.

With this change, every entity that supports custom formats obtains
a separate default serializer in addition to the
ISO 8601 serializer, which now properly delegates to the
corresponding `DateTimeFormat`.

Fixes #351

Author: dkhalanskyjb

core/common/src/Instant.kt

@@ -7,8 +7,7 @@ package kotlinx.datetime
 
 import kotlinx.datetime.format.*
 import kotlinx.datetime.internal.*
-import kotlinx.datetime.serializers.InstantIso8601Serializer
-import kotlinx.datetime.serializers.InstantComponentSerializer
+import kotlinx.datetime.serializers.*
 import kotlinx.serialization.Serializable
 import kotlin.time.*
 
@@ -189,12 +188,13 @@ import kotlin.time.*
  * ```
  *
  * Additionally, there are several `kotlinx-serialization` serializers for [Instant]:
+ * - The default serializer, delegating to [toString] and [parse].
  * - [InstantIso8601Serializer] for the ISO 8601 extended format.
  * - [InstantComponentSerializer] for an object with components.
  *
  * @see LocalDateTime for a user-visible representation of moments in time in an unspecified time zone.
  */
-@Serializable(with = InstantIso8601Serializer::class)
+@Serializable(with = InstantSerializer::class)
 public expect class Instant : Comparable<Instant> {
 
     /**

core/common/src/LocalDate.kt

@@ -57,6 +57,7 @@ import kotlin.internal.*
  * See sample 4.
  *
  * Additionally, there are several `kotlinx-serialization` serializers for [LocalDate]:
+ * - The default serializer, delegating to [toString] and [parse].
  * - [LocalDateIso8601Serializer] for the ISO 8601 extended format.
  * - [LocalDateComponentSerializer] for an object with components.
  *
@@ -65,7 +66,7 @@ import kotlin.internal.*
  * @sample kotlinx.datetime.test.samples.LocalDateSamples.simpleParsingAndFormatting
  * @sample kotlinx.datetime.test.samples.LocalDateSamples.customFormat
  */
-@Serializable(with = LocalDateIso8601Serializer::class)
+@Serializable(with = LocalDateSerializer::class)
 public expect class LocalDate : Comparable<LocalDate> {
     public companion object {
         /**

core/common/src/LocalDateTime.kt

@@ -8,8 +8,7 @@
 package kotlinx.datetime
 
 import kotlinx.datetime.format.*
-import kotlinx.datetime.serializers.LocalDateTimeIso8601Serializer
-import kotlinx.datetime.serializers.LocalDateTimeComponentSerializer
+import kotlinx.datetime.serializers.*
 import kotlinx.serialization.Serializable
 import kotlin.internal.*
 import kotlin.jvm.JvmMultifileClass
@@ -99,6 +98,7 @@ import kotlin.jvm.JvmName
  * See sample 4.
  *
  * Additionally, there are several `kotlinx-serialization` serializers for [LocalDateTime]:
+ * - The default serializer, delegating to [toString] and [parse].
  * - [LocalDateTimeIso8601Serializer] for the ISO 8601 extended format.
  * - [LocalDateTimeComponentSerializer] for an object with components.
  *
@@ -110,7 +110,7 @@ import kotlin.jvm.JvmName
  * @sample kotlinx.datetime.test.samples.LocalDateTimeSamples.simpleParsingAndFormatting
  * @sample kotlinx.datetime.test.samples.LocalDateTimeSamples.customFormat
  */
-@Serializable(with = LocalDateTimeIso8601Serializer::class)
+@Serializable(with = LocalDateTimeSerializer::class)
 public expect class LocalDateTime : Comparable<LocalDateTime> {
     public companion object {
 

core/common/src/LocalTime.kt

@@ -8,8 +8,7 @@
 package kotlinx.datetime
 
 import kotlinx.datetime.format.*
-import kotlinx.datetime.serializers.LocalTimeIso8601Serializer
-import kotlinx.datetime.serializers.LocalTimeComponentSerializer
+import kotlinx.datetime.serializers.*
 import kotlinx.serialization.Serializable
 import kotlin.internal.*
 import kotlin.jvm.JvmMultifileClass
@@ -72,6 +71,7 @@ import kotlin.jvm.JvmName
  * See sample 4.
  *
  * Additionally, there are several `kotlinx-serialization` serializers for [LocalTime]:
+ * - The default serializer, delegating to [toString] and [parse].
  * - [LocalTimeIso8601Serializer] for the ISO 8601 extended format,
  * - [LocalTimeComponentSerializer] for an object with components.
  *
@@ -80,7 +80,7 @@ import kotlin.jvm.JvmName
  * @sample kotlinx.datetime.test.samples.LocalTimeSamples.simpleParsingAndFormatting
  * @sample kotlinx.datetime.test.samples.LocalTimeSamples.customFormat
  */
-@Serializable(LocalTimeIso8601Serializer::class)
+@Serializable(LocalTimeSerializer::class)
 public expect class LocalTime : Comparable<LocalTime> {
     public companion object {
 

core/common/src/UtcOffset.kt

@@ -6,7 +6,7 @@
 package kotlinx.datetime
 
 import kotlinx.datetime.format.*
-import kotlinx.datetime.serializers.UtcOffsetSerializer
+import kotlinx.datetime.serializers.*
 import kotlinx.serialization.Serializable
 
 /**
@@ -47,12 +47,14 @@ import kotlinx.serialization.Serializable
  * [parse] and [UtcOffset.format] both support custom formats created with [Format] or defined in [Formats].
  * See sample 3.
  *
- * To serialize and deserialize [UtcOffset] values with `kotlinx-serialization`, use the [UtcOffsetSerializer].
+ * To serialize and deserialize [UtcOffset] values with `kotlinx-serialization`, use the default serializer,
+ * or [UtcOffsetIso8601Serializer] for the ISO 8601 format explicitly.
  *
  * @sample kotlinx.datetime.test.samples.UtcOffsetSamples.construction
  * @sample kotlinx.datetime.test.samples.UtcOffsetSamples.simpleParsingAndFormatting
  * @sample kotlinx.datetime.test.samples.UtcOffsetSamples.customFormat
  */
+@Suppress("DEPRECATION")
 @Serializable(with = UtcOffsetSerializer::class)
 public expect class UtcOffset {
     /**

core/common/src/serializers/InstantSerializers.kt

@@ -17,19 +17,18 @@ import kotlinx.serialization.encoding.*
  *
  * JSON example: `"2020-12-09T09:16:56.000124Z"`
  *
- * @see Instant.toString
- * @see Instant.parse
+ * @see DateTimeComponents.Formats.ISO_DATE_TIME_OFFSET
  */
 public object InstantIso8601Serializer : KSerializer<Instant> {
 
     override val descriptor: SerialDescriptor =
         PrimitiveSerialDescriptor("kotlinx.datetime.Instant", PrimitiveKind.STRING)
 
     override fun deserialize(decoder: Decoder): Instant =
-        Instant.parse(decoder.decodeString())
+        Instant.parse(decoder.decodeString(), DateTimeComponents.Formats.ISO_DATE_TIME_OFFSET)
 
     override fun serialize(encoder: Encoder, value: Instant) {
-        encoder.encodeString(value.toString())
+        encoder.encodeString(value.format(DateTimeComponents.Formats.ISO_DATE_TIME_OFFSET))
     }
 
 }
@@ -125,3 +124,22 @@ public abstract class FormattedInstantSerializer(
     @OptIn(ExperimentalSerializationApi::class)
     override fun toString(): String = descriptor.serialName
 }
+
+/**
+ * A serializer for [Instant] that uses the default [Instant.toString]/[Instant.parse].
+ *
+ * JSON example: `"2020-12-09T09:16:56.000124Z"`
+ */
+@PublishedApi internal object InstantSerializer : KSerializer<Instant> {
+
+    override val descriptor: SerialDescriptor =
+        PrimitiveSerialDescriptor("kotlinx.datetime.Instant", PrimitiveKind.STRING)
+
+    override fun deserialize(decoder: Decoder): Instant =
+        Instant.parse(decoder.decodeString())
+
+    override fun serialize(encoder: Encoder, value: Instant) {
+        encoder.encodeString(value.toString())
+    }
+
+}

core/common/src/serializers/LocalDateSerializers.kt

@@ -16,22 +16,10 @@ import kotlinx.serialization.encoding.*
  *
  * JSON example: `"2020-01-01"`
  *
- * @see LocalDate.parse
- * @see LocalDate.toString
+ * @see LocalDate.Formats.ISO
  */
-public object LocalDateIso8601Serializer: KSerializer<LocalDate> {
-
-    override val descriptor: SerialDescriptor =
-        PrimitiveSerialDescriptor("kotlinx.datetime.LocalDate", PrimitiveKind.STRING)
-
-    override fun deserialize(decoder: Decoder): LocalDate =
-        LocalDate.parse(decoder.decodeString())
-
-    override fun serialize(encoder: Encoder, value: LocalDate) {
-        encoder.encodeString(value.toString())
-    }
-
-}
+public object LocalDateIso8601Serializer : KSerializer<LocalDate>
+by LocalDate.Formats.ISO.asKSerializer("kotlinx.datetime.LocalDate")
 
 /**
  * A serializer for [LocalDate] that represents a value as its components.
@@ -117,3 +105,23 @@ internal fun <T> DateTimeFormat<T>.asKSerializer(serialName: String): KSerialize
 
         override fun toString(): String = serialName
     }
+
+/**
+ * A serializer for [LocalDate] that uses the default [LocalDate.toString]/[LocalDate.parse].
+ *
+ * JSON example: `"2020-01-01"`
+ */
+@PublishedApi
+internal object LocalDateSerializer: KSerializer<LocalDate> {
+
+    override val descriptor: SerialDescriptor =
+        PrimitiveSerialDescriptor("kotlinx.datetime.LocalDate", PrimitiveKind.STRING)
+
+    override fun deserialize(decoder: Decoder): LocalDate =
+        LocalDate.parse(decoder.decodeString())
+
+    override fun serialize(encoder: Encoder, value: LocalDate) {
+        encoder.encodeString(value.toString())
+    }
+
+}

core/common/src/serializers/LocalDateTimeSerializers.kt

@@ -16,22 +16,10 @@ import kotlinx.serialization.encoding.*
  *
  * JSON example: `"2007-12-31T23:59:01"`
  *
- * @see LocalDateTime.parse
- * @see LocalDateTime.toString
+ * @see LocalDateTime.Formats.ISO
  */
-public object LocalDateTimeIso8601Serializer: KSerializer<LocalDateTime> {
-
-    override val descriptor: SerialDescriptor =
-        PrimitiveSerialDescriptor("kotlinx.datetime.LocalDateTime", PrimitiveKind.STRING)
-
-    override fun deserialize(decoder: Decoder): LocalDateTime =
-        LocalDateTime.parse(decoder.decodeString())
-
-    override fun serialize(encoder: Encoder, value: LocalDateTime) {
-        encoder.encodeString(value.toString())
-    }
-
-}
+public object LocalDateTimeIso8601Serializer : KSerializer<LocalDateTime>
+by LocalDateTime.Formats.ISO.asKSerializer("kotlinx.datetime.LocalDateTime")
 
 /**
  * A serializer for [LocalDateTime] that represents a value as its components.
@@ -130,3 +118,23 @@ public object LocalDateTimeComponentSerializer: KSerializer<LocalDateTime> {
 public abstract class FormattedLocalDateTimeSerializer(
     name: String, format: DateTimeFormat<LocalDateTime>
 ) : KSerializer<LocalDateTime> by format.asKSerializer("kotlinx.datetime.LocalDateTime serializer $name")
+
+/**
+ * A serializer for [LocalDateTime] that uses the default [LocalDateTime.toString]/[LocalDateTime.parse].
+ *
+ * JSON example: `"2007-12-31T23:59:01"`
+ */
+@PublishedApi
+internal object LocalDateTimeSerializer: KSerializer<LocalDateTime> {
+
+    override val descriptor: SerialDescriptor =
+        PrimitiveSerialDescriptor("kotlinx.datetime.LocalDateTime", PrimitiveKind.STRING)
+
+    override fun deserialize(decoder: Decoder): LocalDateTime =
+        LocalDateTime.parse(decoder.decodeString())
+
+    override fun serialize(encoder: Encoder, value: LocalDateTime) {
+        encoder.encodeString(value.toString())
+    }
+
+}

core/common/src/serializers/LocalTimeSerializers.kt

@@ -16,21 +16,10 @@ import kotlinx.serialization.encoding.*
  *
  * JSON example: `"12:01:03.999"`
  *
- * @see LocalDate.parse
- * @see LocalDate.toString
+ * @see LocalTime.Formats.ISO
  */
-public object LocalTimeIso8601Serializer : KSerializer<LocalTime> {
-
-    override val descriptor: SerialDescriptor =
-        PrimitiveSerialDescriptor("kotlinx.datetime.LocalTime", PrimitiveKind.STRING)
-
-    override fun deserialize(decoder: Decoder): LocalTime =
-        LocalTime.parse(decoder.decodeString())
-
-    override fun serialize(encoder: Encoder, value: LocalTime) {
-        encoder.encodeString(value.toString())
-    }
-}
+public object LocalTimeIso8601Serializer : KSerializer<LocalTime>
+by LocalTime.Formats.ISO.asKSerializer("kotlinx.datetime.LocalTime")
 
 /**
  * A serializer for [LocalTime] that represents a value as its components.
@@ -109,3 +98,25 @@ public object LocalTimeComponentSerializer : KSerializer<LocalTime> {
 public abstract class FormattedLocalTimeSerializer(
     name: String, format: DateTimeFormat<LocalTime>
 ) : KSerializer<LocalTime> by format.asKSerializer("kotlinx.datetime.LocalTime serializer $name")
+
+/**
+ * A serializer for [LocalTime] that uses the ISO 8601 representation.
+ *
+ * JSON example: `"12:01:03.999"`
+ *
+ * @see LocalDate.parse
+ * @see LocalDate.toString
+ */
+@PublishedApi
+internal object LocalTimeSerializer : KSerializer<LocalTime> {
+
+    override val descriptor: SerialDescriptor =
+        PrimitiveSerialDescriptor("kotlinx.datetime.LocalTime", PrimitiveKind.STRING)
+
+    override fun deserialize(decoder: Decoder): LocalTime =
+        LocalTime.parse(decoder.decodeString())
+
+    override fun serialize(encoder: Encoder, value: LocalTime) {
+        encoder.encodeString(value.toString())
+    }
+}

core/common/src/serializers/TimeZoneSerializers.kt

@@ -57,9 +57,17 @@ public object FixedOffsetTimeZoneSerializer: KSerializer<FixedOffsetTimeZone> {
  *
  * JSON example: `"+02:00"`
  *
- * @see UtcOffset.parse
- * @see UtcOffset.toString
+ * @see UtcOffset.Formats.ISO
  */
+public object UtcOffsetIso8601Serializer : KSerializer<UtcOffset>
+by UtcOffset.Formats.ISO.asKSerializer("kotlinx.datetime.UtcOffset")
+
+/**
+ * A serializer for [UtcOffset] that uses the default [UtcOffset.toString]/[UtcOffset.parse].
+ *
+ * JSON example: `"+02:00"`
+ */
+@Deprecated("Use UtcOffset.serializer() instead", ReplaceWith("UtcOffset.serializer()"))
 public object UtcOffsetSerializer: KSerializer<UtcOffset> {
 
     override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("kotlinx.datetime.UtcOffset", PrimitiveKind.STRING)

core/commonKotlin/src/Instant.kt

@@ -10,7 +10,7 @@ package kotlinx.datetime
 
 import kotlinx.datetime.format.*
 import kotlinx.datetime.internal.*
-import kotlinx.datetime.serializers.InstantIso8601Serializer
+import kotlinx.datetime.serializers.*
 import kotlinx.serialization.Serializable
 import kotlin.time.*
 import kotlin.time.Duration.Companion.nanoseconds
@@ -26,7 +26,7 @@ private const val MIN_SECOND = -31557014167219200L // -1000000000-01-01T00:00:00
  */
 private const val MAX_SECOND = 31556889864403199L // +1000000000-12-31T23:59:59
 
-@Serializable(with = InstantIso8601Serializer::class)
+@Serializable(with = InstantSerializer::class)
 public actual class Instant internal constructor(public actual val epochSeconds: Long, public actual val nanosecondsOfSecond: Int) : Comparable<Instant> {
 
     init {

core/commonKotlin/src/LocalDate.kt

@@ -12,7 +12,7 @@ import kotlinx.datetime.format.*
 import kotlinx.datetime.internal.*
 import kotlinx.datetime.internal.safeAdd
 import kotlinx.datetime.internal.safeMultiply
-import kotlinx.datetime.serializers.LocalDateIso8601Serializer
+import kotlinx.datetime.serializers.*
 import kotlinx.serialization.Serializable
 import kotlin.math.*
 
@@ -22,7 +22,7 @@ internal const val YEAR_MAX = 999_999_999
 private fun isValidYear(year: Int): Boolean =
     year >= YEAR_MIN && year <= YEAR_MAX
 
-@Serializable(with = LocalDateIso8601Serializer::class)
+@Serializable(with = LocalDateSerializer::class)
 public actual class LocalDate actual constructor(public actual val year: Int, month: Int, public actual val day: Int) : Comparable<LocalDate> {
 
     private val _month: Int = month

core/commonKotlin/src/LocalDateTime.kt

@@ -13,7 +13,7 @@ import kotlinx.datetime.internal.*
 import kotlinx.datetime.serializers.*
 import kotlinx.serialization.*
 
-@Serializable(with = LocalDateTimeIso8601Serializer::class)
+@Serializable(with = LocalDateTimeSerializer::class)
 public actual class LocalDateTime
 public actual constructor(public actual val date: LocalDate, public actual val time: LocalTime) : Comparable<LocalDateTime> {
     public actual companion object {

core/commonKotlin/src/LocalTime.kt

@@ -10,10 +10,10 @@ package kotlinx.datetime
 
 import kotlinx.datetime.internal.*
 import kotlinx.datetime.format.*
-import kotlinx.datetime.serializers.LocalTimeIso8601Serializer
+import kotlinx.datetime.serializers.*
 import kotlinx.serialization.Serializable
 
-@Serializable(LocalTimeIso8601Serializer::class)
+@Serializable(LocalTimeSerializer::class)
 public actual class LocalTime actual constructor(
     public actual val hour: Int,
     public actual val minute: Int,