Overhaul internals to use KType

examples/src/main/java/com/squareup/moshi/recipes/JsonString.kt

@@ -48,8 +48,8 @@ class JsonStringJsonAdapterFactory : JsonAdapter.Factory {
     override fun fromJson(reader: JsonReader): String =
       reader.nextSource().use(BufferedSource::readUtf8)
 
-    override fun toJson(writer: JsonWriter, value: String?) {
-      writer.valueSink().use { sink -> sink.writeUtf8(checkNotNull(value)) }
+    override fun toJson(writer: JsonWriter, value: String) {
+      writer.valueSink().use { sink -> sink.writeUtf8(value) }
     }
   }
 }
@@ -62,7 +62,7 @@ fun main() {
     .add(JsonStringJsonAdapterFactory())
     .build()
 
-  val example: ExampleClass = moshi.adapter(ExampleClass::class.java).fromJson(json)!!
+  val example: ExampleClass = moshi.adapter(ExampleClass::class.java).fromJson(json)
 
   check(example.type == 1)
 

examples/src/main/java/com/squareup/moshi/recipes/ReadJsonListKt.kt

@@ -16,7 +16,6 @@
 package com.squareup.moshi.recipes
 
 import com.squareup.moshi.Moshi
-import com.squareup.moshi.adapter
 import com.squareup.moshi.recipes.models.Card
 
 class ReadJsonListKt {
@@ -36,7 +35,7 @@ class ReadJsonListKt {
 
   fun readJsonList() {
     val jsonAdapter = Moshi.Builder().build().adapter<List<Card>>()
-    val cards = jsonAdapter.fromJson(jsonString)!!
+    val cards = jsonAdapter.fromJson(jsonString)
     println(cards)
     cards[0].run {
       println(rank)

moshi-adapters/src/main/java/com/squareup/moshi/Rfc3339DateJsonAdapter.kt

@@ -25,7 +25,7 @@ import java.util.Date
   replaceWith = ReplaceWith("com.squareup.moshi.adapters.Rfc3339DateJsonAdapter"),
   level = DeprecationLevel.ERROR
 )
-public class Rfc3339DateJsonAdapter : JsonAdapter<Date>() {
+public class Rfc3339DateJsonAdapter : JsonAdapter<Date?>() {
 
   private val delegate = Rfc3339DateJsonAdapter()
 

moshi-adapters/src/main/java/com/squareup/moshi/adapters/EnumJsonAdapter.kt

@@ -41,7 +41,7 @@ public class EnumJsonAdapter<T : Enum<T>> internal constructor(
   private val enumType: Class<T>,
   private val fallbackValue: T?,
   private val useFallbackValue: Boolean,
-) : JsonAdapter<T>() {
+) : JsonAdapter<T?>() {
 
   private val constants: Array<T>
   private val options: Options

moshi-adapters/src/main/java/com/squareup/moshi/adapters/PolymorphicJsonAdapterFactory.kt

@@ -103,7 +103,7 @@ public class PolymorphicJsonAdapterFactory<T> internal constructor(
   private val labelKey: String,
   private val labels: List<String>,
   private val subtypes: List<Type>,
-  private val fallbackJsonAdapter: JsonAdapter<Any>?
+  private val fallbackJsonAdapter: JsonAdapter<Any?>?
 ) : Factory {
   /** Returns a new factory that decodes instances of `subtype`. */
   public fun withSubtype(subtype: Class<out T>, label: String): PolymorphicJsonAdapterFactory<T> {
@@ -133,7 +133,7 @@ public class PolymorphicJsonAdapterFactory<T> internal constructor(
    * it within your implementation of [JsonAdapter.fromJson]
    */
   public fun withFallbackJsonAdapter(
-    fallbackJsonAdapter: JsonAdapter<Any>?
+    fallbackJsonAdapter: JsonAdapter<Any?>?
   ): PolymorphicJsonAdapterFactory<T> {
     return PolymorphicJsonAdapterFactory(
       baseType = baseType,
@@ -152,8 +152,8 @@ public class PolymorphicJsonAdapterFactory<T> internal constructor(
     return withFallbackJsonAdapter(buildFallbackJsonAdapter(defaultValue))
   }
 
-  private fun buildFallbackJsonAdapter(defaultValue: T?): JsonAdapter<Any> {
-    return object : JsonAdapter<Any>() {
+  private fun buildFallbackJsonAdapter(defaultValue: T?): JsonAdapter<Any?> {
+    return object : JsonAdapter<Any?>() {
       override fun fromJson(reader: JsonReader): Any? {
         reader.skipValue()
         return defaultValue
@@ -181,8 +181,8 @@ public class PolymorphicJsonAdapterFactory<T> internal constructor(
     private val labels: List<String>,
     private val subtypes: List<Type>,
     private val jsonAdapters: List<JsonAdapter<Any>>,
-    private val fallbackJsonAdapter: JsonAdapter<Any>?
-  ) : JsonAdapter<Any>() {
+    private val fallbackJsonAdapter: JsonAdapter<Any?>?
+  ) : JsonAdapter<Any?>() {
     /** Single-element options containing the label's key only.  */
     private val labelKeyOptions: Options = Options.of(labelKey)
 
@@ -223,12 +223,13 @@ public class PolymorphicJsonAdapterFactory<T> internal constructor(
     override fun toJson(writer: JsonWriter, value: Any?) {
       val type: Class<*> = value!!.javaClass
       val labelIndex = subtypes.indexOf(type)
-      val adapter: JsonAdapter<Any> = if (labelIndex == -1) {
+      val adapter: JsonAdapter<Any?> = if (labelIndex == -1) {
         requireNotNull(fallbackJsonAdapter) {
           "Expected one of $subtypes but found $value, a ${value.javaClass}. Register this subtype."
         }
       } else {
-        jsonAdapters[labelIndex]
+        @Suppress("UNCHECKED_CAST")
+        jsonAdapters[labelIndex] as JsonAdapter<Any?>
       }
       writer.beginObject()
       if (adapter !== fallbackJsonAdapter) {

moshi-adapters/src/main/java/com/squareup/moshi/adapters/Rfc3339DateJsonAdapter.kt

@@ -33,7 +33,7 @@ import java.util.Date
  *   .build();
  * ```
  */
-public class Rfc3339DateJsonAdapter : JsonAdapter<Date>() {
+public class Rfc3339DateJsonAdapter : JsonAdapter<Date?>() {
   @Synchronized
   @Throws(IOException::class)
   override fun fromJson(reader: JsonReader): Date? {

moshi-kotlin-codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/AdapterGenerator.kt

@@ -137,7 +137,7 @@ public class AdapterGenerator(
   // https://github.com/square/moshi/issues/1502
   private val valueParam = ParameterSpec.builder(
     "value",
-    originalTypeName.copy(nullable = true)
+    originalTypeName
   )
     .build()
   private val jsonAdapterTypeName = JsonAdapter::class.asClassName().parameterizedBy(
@@ -260,7 +260,8 @@ public class AdapterGenerator(
 
     val typeRenderer: TypeRenderer = object : TypeRenderer() {
       override fun renderTypeVariable(typeVariable: TypeVariableName): CodeBlock {
-        val index = typeVariables.indexOfFirst { it == typeVariable }
+        val nonNull = typeVariable.copy(nullable = false)
+        val index = typeVariables.indexOfFirst { it == nonNull }
         check(index != -1) { "Unexpected type variable $typeVariable" }
         return CodeBlock.of("%N[%L]", typesParam, index)
       }
@@ -419,23 +420,12 @@ public class AdapterGenerator(
       // Proceed as usual
       if (property.hasLocalIsPresentName || property.hasConstructorDefault) {
         result.beginControlFlow("%L ->", propertyIndex)
-        if (property.delegateKey.nullable) {
-          result.addStatement(
-            "%N = %N.fromJson(%N)",
-            property.localName,
-            nameAllocator[property.delegateKey],
-            readerParam
-          )
-        } else {
-          val exception = unexpectedNull(property, readerParam)
-          result.addStatement(
-            "%N = %N.fromJson(%N) ?: throw·%L",
-            property.localName,
-            nameAllocator[property.delegateKey],
-            readerParam,
-            exception
-          )
-        }
+        result.addStatement(
+          "%N = %N.fromJson(%N)",
+          property.localName,
+          nameAllocator[property.delegateKey],
+          readerParam
+        )
         if (property.hasConstructorDefault) {
           val inverted = (1 shl maskIndex).inv()
           if (input is ParameterComponent && input.parameter.hasDefault) {
@@ -453,25 +443,13 @@ public class AdapterGenerator(
         }
         result.endControlFlow()
       } else {
-        if (property.delegateKey.nullable) {
-          result.addStatement(
-            "%L -> %N = %N.fromJson(%N)",
-            propertyIndex,
-            property.localName,
-            nameAllocator[property.delegateKey],
-            readerParam
-          )
-        } else {
-          val exception = unexpectedNull(property, readerParam)
-          result.addStatement(
-            "%L -> %N = %N.fromJson(%N) ?: throw·%L",
-            propertyIndex,
-            property.localName,
-            nameAllocator[property.delegateKey],
-            readerParam,
-            exception
-          )
-        }
+        result.addStatement(
+          "%L -> %N = %N.fromJson(%N)",
+          propertyIndex,
+          property.localName,
+          nameAllocator[property.delegateKey],
+          readerParam
+        )
       }
       if (property.hasConstructorParameter) {
         constructorPropertyTypes += property.target.type.asTypeBlock()
@@ -672,14 +650,6 @@ public class AdapterGenerator(
       .addParameter(writerParam)
       .addParameter(valueParam)
 
-    result.beginControlFlow("if (%N == null)", valueParam)
-    result.addStatement(
-      "throw·%T(%S)",
-      NullPointerException::class,
-      "${valueParam.name} was null! Wrap in .nullSafe() to write nullable values."
-    )
-    result.endControlFlow()
-
     result.addStatement("%N.beginObject()", writerParam)
     nonTransientProperties.forEach { property ->
       // We manually put in quotes because we know the jsonName is already escaped

moshi-kotlin-codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/TypeRenderer.kt

@@ -15,25 +15,17 @@
  */
 package com.squareup.moshi.kotlin.codegen.api
 
-import com.squareup.kotlinpoet.ARRAY
-import com.squareup.kotlinpoet.BOOLEAN
-import com.squareup.kotlinpoet.BYTE
-import com.squareup.kotlinpoet.CHAR
 import com.squareup.kotlinpoet.ClassName
 import com.squareup.kotlinpoet.CodeBlock
-import com.squareup.kotlinpoet.DOUBLE
-import com.squareup.kotlinpoet.FLOAT
-import com.squareup.kotlinpoet.INT
-import com.squareup.kotlinpoet.LONG
+import com.squareup.kotlinpoet.LambdaTypeName
+import com.squareup.kotlinpoet.MemberName
 import com.squareup.kotlinpoet.ParameterizedTypeName
-import com.squareup.kotlinpoet.SHORT
 import com.squareup.kotlinpoet.TypeName
 import com.squareup.kotlinpoet.TypeVariableName
 import com.squareup.kotlinpoet.WildcardTypeName
-import com.squareup.moshi.Types
 
 /**
- * Renders literals like `Types.newParameterizedType(List::class.java, String::class.java)`.
+ * Renders literals like `List::class.parameterizedBy(String::class.asKTypeProjection(...))`.
  * Rendering is pluggable so that type variables can either be resolved or emitted as other code
  * blocks.
  */
@@ -44,83 +36,17 @@ internal abstract class TypeRenderer {
     if (typeName.annotations.isNotEmpty()) {
       return render(typeName.copy(annotations = emptyList()), forceBox)
     }
-    if (typeName.isNullable) {
-      return renderObjectType(typeName.copy(nullable = false))
-    }
 
     return when (typeName) {
-      is ClassName -> {
-        if (forceBox) {
-          renderObjectType(typeName)
-        } else {
-          CodeBlock.of("%T::class.java", typeName)
-        }
-      }
-
-      is ParameterizedTypeName -> {
-        // If it's an Array type, we shortcut this to return Types.arrayOf()
-        if (typeName.rawType == ARRAY) {
-          CodeBlock.of(
-            "%T.arrayOf(%L)",
-            Types::class,
-            renderObjectType(typeName.typeArguments[0])
-          )
-        } else {
-          val builder = CodeBlock.builder().apply {
-            add("%T.", Types::class)
-            val enclosingClassName = typeName.rawType.enclosingClassName()
-            if (enclosingClassName != null) {
-              add("newParameterizedTypeWithOwner(%L, ", render(enclosingClassName))
-            } else {
-              add("newParameterizedType(")
-            }
-            add("%T::class.java", typeName.rawType)
-            for (typeArgument in typeName.typeArguments) {
-              add(", %L", renderObjectType(typeArgument))
-            }
-            add(")")
-          }
-          builder.build()
-        }
-      }
-
-      is WildcardTypeName -> {
-        val target: TypeName
-        val method: String
-        when {
-          typeName.inTypes.size == 1 -> {
-            target = typeName.inTypes[0]
-            method = "supertypeOf"
-          }
-          typeName.outTypes.size == 1 -> {
-            target = typeName.outTypes[0]
-            method = "subtypeOf"
-          }
-          else -> throw IllegalArgumentException(
-            "Unrepresentable wildcard type. Cannot have more than one bound: $typeName"
-          )
-        }
-        CodeBlock.of("%T.%L(%L)", Types::class, method, render(target, forceBox = true))
-      }
-
       is TypeVariableName -> renderTypeVariable(typeName)
-
+      is ClassName, is LambdaTypeName, is ParameterizedTypeName, is WildcardTypeName -> {
+        CodeBlock.of(
+          "%M<%T>()",
+          MemberName("kotlin.reflect", "typeOf"),
+          typeName
+        )
+      }
       else -> throw IllegalArgumentException("Unrepresentable type: $typeName")
     }
   }
-
-  private fun renderObjectType(typeName: TypeName): CodeBlock {
-    return if (typeName.isPrimitive()) {
-      CodeBlock.of("%T::class.javaObjectType", typeName)
-    } else {
-      render(typeName)
-    }
-  }
-
-  private fun TypeName.isPrimitive(): Boolean {
-    return when (this) {
-      BOOLEAN, BYTE, SHORT, INT, LONG, CHAR, FLOAT, DOUBLE -> true
-      else -> false
-    }
-  }
 }

moshi-kotlin-tests/codegen-only/src/test/kotlin/com/squareup/moshi/kotlin/codegen/ComplexGenericsInheritanceTest.kt

@@ -35,7 +35,7 @@ class ComplexGenericsInheritanceTest {
     val json =
       """{"data":{"name":"foo"},"data2":"bar","data3":"baz"}"""
 
-    val instance = adapter.fromJson(json)!!
+    val instance = adapter.fromJson(json)
     val testInstance = PersonResponse().apply {
       data = Person("foo")
     }
@@ -51,7 +51,7 @@ class ComplexGenericsInheritanceTest {
     val json =
       """{"data":{"name":"foo"},"data2":"bar","data3":"baz"}"""
 
-    val instance = adapter.fromJson(json)!!
+    val instance = adapter.fromJson(json)
     val testInstance = NestedPersonResponse().apply {
       data = Person("foo")
     }
@@ -67,7 +67,7 @@ class ComplexGenericsInheritanceTest {
     val json =
       """{"data":{"name":"foo"},"data2":"bar","data3":"baz"}"""
 
-    val instance = adapter.fromJson(json)!!
+    val instance = adapter.fromJson(json)
     val testInstance = UntypedNestedPersonResponse<Person>().apply {
       data = Person("foo")
     }
@@ -83,7 +83,7 @@ class ComplexGenericsInheritanceTest {
     val json =
       """{"layer4E":{"name":"layer4E"},"layer4F":{"data":{"name":"layer4F"},"data2":"layer4F","data3":"layer4F"},"layer3C":[1,2,3],"layer3D":"layer3D","layer2":"layer2","layer1":"layer1"}"""
 
-    val instance = adapter.fromJson(json)!!
+    val instance = adapter.fromJson(json)
     val testInstance = Layer4(
       layer4E = Person("layer4E"),
       layer4F = UntypedNestedPersonResponse<Person>().apply {

moshi-kotlin-tests/codegen-only/src/test/kotlin/com/squareup/moshi/kotlin/codegen/DefaultConstructorTest.kt

@@ -26,7 +26,7 @@ class DefaultConstructorTest {
     val json =
       """{"required":"requiredClass"}"""
     val instance = Moshi.Builder().build().adapter<TestClass>()
-      .fromJson(json)!!
+      .fromJson(json)
     check(instance == expected) {
       "No match:\nActual  : $instance\nExpected: $expected"
     }
@@ -37,7 +37,7 @@ class DefaultConstructorTest {
     val json =
       """{"required":"requiredClass","optional":"customOptional","optional2":4,"dynamicSelfReferenceOptional":"setDynamic","dynamicOptional":5,"dynamicInlineOptional":6}"""
     val instance = Moshi.Builder().build().adapter<TestClass>()
-      .fromJson(json)!!
+      .fromJson(json)
     check(instance == expected) {
       "No match:\nActual  : $instance\nExpected: $expected"
     }
@@ -48,7 +48,7 @@ class DefaultConstructorTest {
     val json =
       """{"required":"requiredClass","optional":"customOptional"}"""
     val instance = Moshi.Builder().build().adapter<TestClass>()
-      .fromJson(json)!!
+      .fromJson(json)
     check(instance == expected) {
       "No match:\nActual  : $instance\nExpected: $expected"
     }