KOptional type adapter

gradle.properties

@@ -4,7 +4,7 @@ kotlin.code.style=official
 specifyKotlinAsDependency=false
 
 projectGroup=ru.dbotthepony.kommons
-projectVersion=1.6.0
+projectVersion=1.7.0
 
 guavaDepVersion=33.0.0
 gsonDepVersion=2.8.9

gson/src/main/kotlin/ru/dbotthepony/kommons/gson/KOptionalTypeAdapter.kt

@@ -0,0 +1,53 @@
+package ru.dbotthepony.kommons.gson
+
+import com.google.gson.Gson
+import com.google.gson.JsonSyntaxException
+import com.google.gson.TypeAdapter
+import com.google.gson.TypeAdapterFactory
+import com.google.gson.reflect.TypeToken
+import com.google.gson.stream.JsonReader
+import com.google.gson.stream.JsonWriter
+import ru.dbotthepony.kommons.core.KOptional
+import java.lang.reflect.ParameterizedType
+
+@Suppress("DEPRECATION")
+object KOptionalTypeAdapter : TypeAdapterFactory {
+	override fun <T : Any> create(gson: Gson, type: TypeToken<T>): TypeAdapter<T>? {
+		if (type.rawType === KOptional.Nullable::class.java || type.rawType === KOptional::class.java || type.rawType === KOptional.NotNull::class.java) {
+			val notnull = type.rawType === KOptional.NotNull::class.java
+			val param = (type.type as? ParameterizedType ?: return null).actualTypeArguments[0]
+			val token = TypeToken.get(param)
+			val isBool = token.rawType === Boolean::class.java
+
+			return object : TypeAdapter<KOptional<Any?>>() {
+				private val adapter0 = gson.getAdapter(token) as TypeAdapter<Any?>
+
+				override fun write(out: JsonWriter, value: KOptional<Any?>?) {
+					if (value === null) {
+						out.nullValue()
+					} else if (value.isPresent) {
+						adapter0.write(out, value.value)
+					}
+				}
+
+				override fun read(`in`: JsonReader): KOptional<Any?> {
+					if (isBool) {
+						if (notnull) {
+							return KOptional((adapter0.read(`in`) ?: throw JsonSyntaxException("This KOptional does not accept nulls")) as Boolean) as KOptional<Any?>
+						} else {
+							return KOptional(adapter0.read(`in`) as Boolean?) as KOptional<Any?>
+						}
+					} else {
+						if (notnull) {
+							return KOptional(adapter0.read(`in`) ?: throw JsonSyntaxException("This KOptional does not accept nulls"))
+						} else {
+							return KOptional(adapter0.read(`in`))
+						}
+					}
+				}
+			} as TypeAdapter<T>
+		} else {
+			return null
+		}
+	}
+}

src/main/kotlin/ru/dbotthepony/kommons/core/KOptional.kt

@@ -95,10 +95,10 @@ class KOptional<T> private constructor(private val _value: T, val isPresent: Boo
 	}
 
 	// gson hack since type token can't diff between nullable and non-null types
-	@Deprecated("internal class")
-	internal class Nullable<T : Any?> private constructor()
-	@Deprecated("internal class")
-	internal class NotNull<T : Any> private constructor()
+	@Deprecated("reflection class, don't use directly")
+	class Nullable<T : Any?> private constructor()
+	@Deprecated("reflection class, don't use directly")
+	class NotNull<T : Any> private constructor()
 
 	companion object {
 		private val EMPTY = KOptional(null, false)