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

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.*
 
@@ -194,7 +193,7 @@ import kotlin.time.*
  *
  * @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

@@ -64,7 +64,7 @@ import kotlinx.serialization.Serializable
  * @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

@@ -6,8 +6,7 @@
 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
 
 /**
@@ -105,7 +104,7 @@ import kotlinx.serialization.Serializable
  * @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

@@ -7,8 +7,7 @@ package kotlinx.datetime
 
 import kotlinx.datetime.LocalDate.Companion.parse
 import kotlinx.datetime.format.*
-import kotlinx.datetime.serializers.LocalTimeIso8601Serializer
-import kotlinx.datetime.serializers.LocalTimeComponentSerializer
+import kotlinx.datetime.serializers.*
 import kotlinx.serialization.Serializable
 
 
@@ -76,7 +75,7 @@ import kotlinx.serialization.Serializable
  * @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
 
 /**
@@ -53,6 +53,7 @@ import kotlinx.serialization.Serializable
  * @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

@@ -6,6 +6,8 @@
 package kotlinx.datetime.serializers
 
 import kotlinx.datetime.Instant
+import kotlinx.datetime.format
+import kotlinx.datetime.format.DateTimeComponents
 import kotlinx.serialization.*
 import kotlinx.serialization.descriptors.*
 import kotlinx.serialization.encoding.*
@@ -15,19 +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))
     }
 
 }
@@ -75,3 +76,22 @@ public object InstantComponentSerializer : KSerializer<Instant> {
     }
 
 }
+
+/**
+ * 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

@@ -6,6 +6,7 @@
 package kotlinx.datetime.serializers
 
 import kotlinx.datetime.LocalDate
+import kotlinx.datetime.format.DateTimeFormat
 import kotlinx.serialization.*
 import kotlinx.serialization.descriptors.*
 import kotlinx.serialization.encoding.*
@@ -15,22 +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 DateTimeFormatSerializer(LocalDate.Formats.ISO, "kotlinx.datetime.LocalDate")
 
 /**
  * A serializer for [LocalDate] that represents a value as its components.
@@ -76,3 +65,38 @@ public object LocalDateComponentSerializer: KSerializer<LocalDate> {
     }
 
 }
+
+/**
+ * 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())
+    }
+
+}
+
+/**
+ * A general mechanism of implementing [KSerializer] instances using the given [string formats][DateTimeFormat].
+ */
+internal class DateTimeFormatSerializer<T>(val format: DateTimeFormat<T>, className: String): KSerializer<T> {
+    override val descriptor: SerialDescriptor =
+        PrimitiveSerialDescriptor(className, PrimitiveKind.STRING)
+
+    override fun serialize(encoder: Encoder, value: T) {
+        encoder.encodeString(format.format(value))
+    }
+
+    override fun deserialize(decoder: Decoder): T =
+        format.parse(decoder.decodeString())
+
+}

core/common/src/serializers/LocalDateTimeSerializers.kt

@@ -15,22 +15,10 @@ 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 DateTimeFormatSerializer(LocalDateTime.Formats.ISO, "kotlinx.datetime.LocalDateTime")
 
 /**
  * A serializer for [LocalDateTime] that represents a value as its components.
@@ -98,3 +86,22 @@ public object LocalDateTimeComponentSerializer: KSerializer<LocalDateTime> {
     }
 
 }
+
+/**
+ * A serializer for [LocalDateTime] that uses the default [LocalDateTime.toString]/[LocalDateTime.parse].
+ *
+ * JSON example: `"2007-12-31T23:59:01"`
+ */
+public 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

@@ -15,21 +15,10 @@ 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 DateTimeFormatSerializer(LocalTime.Formats.ISO, "kotlinx.datetime.LocalTime")
 
 /**
  * A serializer for [LocalTime] that represents a value as its components.
@@ -81,3 +70,24 @@ public object LocalTimeComponentSerializer : KSerializer<LocalTime> {
         }
     }
 }
+
+/**
+ * A serializer for [LocalTime] that uses the ISO 8601 representation.
+ *
+ * JSON example: `"12:01:03.999"`
+ *
+ * @see LocalDate.parse
+ * @see LocalDate.toString
+ */
+public 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

@@ -5,9 +5,7 @@
 
 package kotlinx.datetime.serializers
 
-import kotlinx.datetime.FixedOffsetTimeZone
-import kotlinx.datetime.TimeZone
-import kotlinx.datetime.UtcOffset
+import kotlinx.datetime.*
 import kotlinx.serialization.*
 import kotlinx.serialization.descriptors.*
 import kotlinx.serialization.encoding.*
@@ -54,13 +52,21 @@ public object FixedOffsetTimeZoneSerializer: KSerializer<FixedOffsetTimeZone> {
 }
 
 /**
- * A serializer for [UtcOffset] that uses the extended ISO 8601 representation.
+ * A serializer for [UtcOffset] that uses the ISO 8601 representation.
  *
  * JSON example: `"+02:00"`
  *
- * @see UtcOffset.parse
- * @see UtcOffset.toString
+ * @see UtcOffset.Formats.ISO
  */
+public object UtcOffsetIso8601Serializer : KSerializer<UtcOffset>
+by DateTimeFormatSerializer(UtcOffset.Formats.ISO, "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/commonJs/src/Instant.kt

@@ -13,13 +13,13 @@ import kotlinx.datetime.internal.JSJoda.ChronoUnit as jtChronoUnit
 import kotlinx.datetime.internal.JSJoda.ZonedDateTime as jtZonedDateTime
 import kotlinx.datetime.internal.safeAdd
 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
 import kotlin.time.Duration.Companion.seconds
 
-@Serializable(with = InstantIso8601Serializer::class)
+@Serializable(with = InstantSerializer::class)
 public actual class Instant internal constructor(internal val value: jtInstant) : Comparable<Instant> {
 
     public actual val epochSeconds: Long

core/commonJs/src/LocalDate.kt

@@ -6,12 +6,12 @@
 package kotlinx.datetime
 
 import kotlinx.datetime.format.*
-import kotlinx.datetime.serializers.LocalDateIso8601Serializer
+import kotlinx.datetime.serializers.*
 import kotlinx.serialization.Serializable
 import kotlinx.datetime.internal.JSJoda.LocalDate as jtLocalDate
 import kotlinx.datetime.internal.JSJoda.ChronoUnit as jtChronoUnit
 
-@Serializable(with = LocalDateIso8601Serializer::class)
+@Serializable(with = LocalDateSerializer::class)
 public actual class LocalDate internal constructor(internal val value: jtLocalDate) : Comparable<LocalDate> {
     public actual companion object {
 

core/commonJs/src/LocalDateTime.kt

@@ -7,11 +7,11 @@ package kotlinx.datetime
 import kotlinx.datetime.format.*
 import kotlinx.datetime.format.ISO_DATETIME
 import kotlinx.datetime.format.LocalDateTimeFormat
-import kotlinx.datetime.serializers.LocalDateTimeIso8601Serializer
+import kotlinx.datetime.serializers.*
 import kotlinx.serialization.Serializable
 import kotlinx.datetime.internal.JSJoda.LocalDateTime as jtLocalDateTime
 
-@Serializable(with = LocalDateTimeIso8601Serializer::class)
+@Serializable(with = LocalDateTimeSerializer::class)
 public actual class LocalDateTime internal constructor(internal val value: jtLocalDateTime) : Comparable<LocalDateTime> {
 
     public actual constructor(year: Int, monthNumber: Int, dayOfMonth: Int, hour: Int, minute: Int, second: Int, nanosecond: Int) :