Implement kotlinx immutable adapters (#586)

* Implement kotlinx immutable adapters

* api

* Update build files

gradle/libs.versions.toml

@@ -42,6 +42,8 @@ spotless = { id = "com.diffplug.spotless", version = "6.25.0" }
 [libraries]
 agp = { module = "com.android.tools.build:gradle", version.ref = "agp" }
 
+assertj = "org.assertj:assertj-core:3.25.3"
+
 autoCommon = { module = "com.google.auto:auto-common", version = "1.2.2" }
 
 autoService = { module = "com.google.auto.service:auto-service-annotations", version.ref = "autoService" }
@@ -58,6 +60,7 @@ kotlin-metadata = { module = "org.jetbrains.kotlinx:kotlinx-metadata-jvm", versi
 kotlin-reflect = { module = "org.jetbrains.kotlin:kotlin-reflect", version.ref = "kotlin" }
 kotlin-gradlePlugin = { module = "org.jetbrains.kotlin:kotlin-gradle-plugin", version.ref = "kotlin" }
 kotlin-gradlePlugin-api = { module = "org.jetbrains.kotlin:kotlin-gradle-plugin-api", version.ref = "kotlin" }
+kotlinx-immutable = "org.jetbrains.kotlinx:kotlinx-collections-immutable:0.3.7"
 
 kotlinpoet = { module = "com.squareup:kotlinpoet", version.ref = "kotlinpoet" }
 kotlinpoet-metadata = { module = "com.squareup:kotlinpoet-metadata", version.ref = "kotlinpoet" }

moshi-adapters/build.gradle.kts

@@ -14,17 +14,13 @@
  * limitations under the License.
  */
 
-import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
-
 plugins {
   alias(libs.plugins.kotlinJvm)
   alias(libs.plugins.ksp)
   alias(libs.plugins.mavenPublish)
 }
 
-tasks.named<KotlinCompile>("compileTestKotlin") {
-  compilerOptions { freeCompilerArgs.add("-opt-in=kotlin.ExperimentalStdlibApi") }
-}
+tasks.compileTestKotlin { compilerOptions { optIn.add("kotlin.ExperimentalStdlibApi") } }
 
 dependencies {
   implementation(libs.moshi)

moshi-immutable-adapters/README.md

@@ -0,0 +1,30 @@
+# moshi-adapters
+
+A collection of Moshi adapters for [kotlinx.collections.immutable](https://github.com/Kotlin/kotlinx.collections.immutable).
+
+## Usage
+
+Gradle dependency
+
+```kotlin
+dependencies {
+  implementation("dev.zacsweers.moshix:moshi-immutable-adapters:<version>")
+}
+```
+
+In code
+
+```kotlin
+val moshi = Moshi.Builder().add(ImmutableCollectionsJsonAdapterFactory()).build()
+```
+
+**Supported types**
+
+- `ImmutableCollection`
+- `ImmutableList`
+- `ImmutableSet`
+- `ImmutableMap`
+- `PersistentCollection`
+- `PersistentList`
+- `PersistentSet`
+- `PersistentMap`

moshi-immutable-adapters/api/moshi-immutable-adapters.api

@@ -0,0 +1,5 @@
+public final class dev/zacsweers/moshix/adapters/immutable/ImmutableCollectionsJsonAdapterFactory : com/squareup/moshi/JsonAdapter$Factory {
+	public fun <init> ()V
+	public fun create (Ljava/lang/reflect/Type;Ljava/util/Set;Lcom/squareup/moshi/Moshi;)Lcom/squareup/moshi/JsonAdapter;
+}
+

moshi-immutable-adapters/build.gradle.kts

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2024 Zac Sweers
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+plugins {
+  alias(libs.plugins.kotlinJvm)
+  alias(libs.plugins.ksp)
+  alias(libs.plugins.mavenPublish)
+}
+
+tasks.compileTestKotlin { compilerOptions { optIn.add("kotlin.ExperimentalStdlibApi") } }
+
+dependencies {
+  api(libs.kotlinx.immutable)
+  api(libs.moshi)
+  kspTest(libs.moshi.codegen)
+  testImplementation(libs.moshi.kotlin)
+  testImplementation(libs.junit)
+  testImplementation(libs.truth)
+}

moshi-immutable-adapters/gradle.properties

@@ -0,0 +1,19 @@
+#
+# Copyright (c) 2024 Zac Sweers
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+POM_NAME=Moshi Immutable Adapters
+POM_ARTIFACT_ID=moshi-immutable-adapters
+POM_PACKAGING=jar

moshi-immutable-adapters/src/main/kotlin/dev/zacsweers/moshix/adapters/immutable/ImmutableCollectionsJsonAdapterFactory.kt

@@ -0,0 +1,145 @@
+package dev.zacsweers.moshix.adapters.immutable
+
+import com.squareup.moshi.JsonAdapter
+import com.squareup.moshi.JsonDataException
+import com.squareup.moshi.JsonReader
+import com.squareup.moshi.JsonWriter
+import com.squareup.moshi.Moshi
+import java.lang.reflect.ParameterizedType
+import java.lang.reflect.Type
+import kotlinx.collections.immutable.ImmutableCollection
+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.ImmutableMap
+import kotlinx.collections.immutable.ImmutableSet
+import kotlinx.collections.immutable.PersistentCollection
+import kotlinx.collections.immutable.PersistentList
+import kotlinx.collections.immutable.PersistentMap
+import kotlinx.collections.immutable.PersistentSet
+import kotlinx.collections.immutable.mutate
+import kotlinx.collections.immutable.persistentListOf
+import kotlinx.collections.immutable.persistentMapOf
+import kotlinx.collections.immutable.persistentSetOf
+
+/**
+ * A [JsonAdapter.Factory] that creates immutable collection adapters for the following supported
+ * types:
+ * - [ImmutableCollection]
+ * - [ImmutableList]
+ * - [ImmutableSet]
+ * - [ImmutableMap]
+ * - [PersistentCollection]
+ * - [PersistentList]
+ * - [PersistentSet]
+ * - [PersistentMap]
+ */
+public class ImmutableCollectionsJsonAdapterFactory : JsonAdapter.Factory {
+  override fun create(type: Type, annotations: Set<Annotation>, moshi: Moshi): JsonAdapter<*>? {
+    if (type !is ParameterizedType) return null
+    when (type.rawType) {
+      ImmutableList::class.java,
+      ImmutableCollection::class.java,
+      PersistentList::class.java,
+      PersistentCollection::class.java -> {
+        val elementType = type.actualTypeArguments[0]
+        val elementAdapter = moshi.adapter<Any>(elementType, annotations)
+        return ImmutableListAdapter(elementAdapter)
+      }
+      ImmutableSet::class.java,
+      PersistentSet::class.java -> {
+        val elementType = type.actualTypeArguments[0]
+        val elementAdapter = moshi.adapter<Any>(elementType, annotations)
+        return ImmutableSetAdapter(elementAdapter)
+      }
+      ImmutableMap::class.java,
+      PersistentMap::class.java -> {
+        val keyType = type.actualTypeArguments[0]
+        val valueType = type.actualTypeArguments[1]
+        val keyAdapter = moshi.adapter<Any>(keyType, annotations)
+        val valueAdapter = moshi.adapter<Any>(valueType, annotations)
+        return ImmutableMapAdapter(keyAdapter, valueAdapter)
+      }
+      else -> return null
+    }
+  }
+}
+
+private sealed class ImmutableCollectionAdapter<C : ImmutableCollection<E>, E>(
+  private val elementAdapter: JsonAdapter<E>
+) : JsonAdapter<C>() {
+
+  abstract fun buildCollection(body: (MutableCollection<E>) -> Unit): C
+
+  override fun fromJson(reader: JsonReader): C? {
+    reader.beginArray()
+    val collection = buildCollection { builder ->
+      while (reader.hasNext()) {
+        builder += elementAdapter.fromJson(reader) ?: error("Null element at ${reader.path}")
+      }
+    }
+    reader.endArray()
+    return collection
+  }
+
+  override fun toJson(writer: JsonWriter, value: C?) {
+    if (value == null) {
+      writer.nullValue()
+    } else {
+      writer.beginArray()
+      for (element in value) {
+        elementAdapter.toJson(writer, element)
+      }
+      writer.endArray()
+    }
+  }
+}
+
+private class ImmutableListAdapter<E>(elementAdapter: JsonAdapter<E>) :
+  ImmutableCollectionAdapter<ImmutableList<E>, E>(elementAdapter) {
+  override fun buildCollection(body: (MutableCollection<E>) -> Unit) =
+    persistentListOf<E>().mutate(body)
+}
+
+private class ImmutableSetAdapter<E>(elementAdapter: JsonAdapter<E>) :
+  ImmutableCollectionAdapter<ImmutableSet<E>, E>(elementAdapter) {
+  override fun buildCollection(body: (MutableCollection<E>) -> Unit) =
+    persistentSetOf<E>().mutate(body)
+}
+
+private class ImmutableMapAdapter<K, V>(
+  private val keyAdapter: JsonAdapter<K>,
+  private val valueAdapter: JsonAdapter<V>,
+) : JsonAdapter<ImmutableMap<K, V>>() {
+
+  override fun fromJson(reader: JsonReader): ImmutableMap<K, V> {
+    reader.beginObject()
+    return persistentMapOf<K, V>()
+      .mutate {
+        while (reader.hasNext()) {
+          reader.promoteNameToValue()
+          val key = keyAdapter.fromJson(reader) ?: error("Null key at ${reader.path}")
+          val value = valueAdapter.fromJson(reader) ?: error("Null value at ${reader.path}")
+          val replaced = it.put(key, value)
+          if (replaced != null) {
+            throw JsonDataException(
+              "Duplicate element '$key' with value '$replaced' at ${reader.path}"
+            )
+          }
+        }
+      }
+      .also { reader.endObject() }
+  }
+
+  override fun toJson(writer: JsonWriter, value: ImmutableMap<K, V>?) {
+    if (value == null) {
+      writer.nullValue()
+    } else {
+      writer.beginObject()
+      for ((k, v) in value) {
+        writer.promoteValueToName()
+        keyAdapter.toJson(writer, k)
+        valueAdapter.toJson(writer, v)
+      }
+      writer.endObject()
+    }
+  }
+}

moshi-immutable-adapters/src/test/kotlin/dev/zacsweers/moshix/adapters/immutable/ImmutableCollectionsJsonAdapterFactoryTest.kt

@@ -0,0 +1,101 @@
+package dev.zacsweers.moshix.adapters.immutable
+
+import com.squareup.moshi.Moshi
+import com.squareup.moshi.adapter
+import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
+import kotlinx.collections.immutable.ImmutableCollection
+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.ImmutableMap
+import kotlinx.collections.immutable.ImmutableSet
+import kotlinx.collections.immutable.PersistentCollection
+import kotlinx.collections.immutable.PersistentList
+import kotlinx.collections.immutable.PersistentMap
+import kotlinx.collections.immutable.PersistentSet
+import kotlinx.collections.immutable.persistentListOf
+import kotlinx.collections.immutable.persistentMapOf
+import kotlinx.collections.immutable.persistentSetOf
+import org.junit.Test
+
+class ImmutableCollectionsJsonAdapterFactoryTest {
+  private val moshi =
+    Moshi.Builder()
+      .add(ImmutableCollectionsJsonAdapterFactory())
+      .addLast(KotlinJsonAdapterFactory())
+      .build()
+
+  // language=JSON
+  private val json =
+    """
+      {
+        "list": [1, 2, 3],
+        "set": [1, 2, 3],
+        "collection": [1, 2, 3],
+        "map": {
+          "a": 1,
+          "b": 2,
+          "c": 3
+        },
+        "nested": {
+          "a": [1, 2, 3],
+          "b": [1, 2, 3],
+          "c": [1, 2, 3]
+        },
+        "persistentList": [1, 2, 3],
+        "persistentSet": [1, 2, 3],
+        "persistentCollection": [1, 2, 3],
+        "persistentMap": {
+          "a": 1,
+          "b": 2,
+          "c": 3
+        },
+        "persistentNested": {
+          "a": [1, 2, 3],
+          "b": [1, 2, 3],
+          "c": [1, 2, 3]
+        }
+      }
+        """
+      .trimIndent()
+
+  @Test
+  fun smokeTest() {
+    val adapter = moshi.adapter<ClassWithImmutables>()
+    val instance = adapter.fromJson(json)!!
+    val expectedInstance =
+      ClassWithImmutables(
+        list = persistentListOf(1, 2, 3),
+        set = persistentSetOf(1, 2, 3),
+        collection = persistentListOf(1, 2, 3),
+        map = persistentMapOf("a" to 1, "b" to 2, "c" to 3),
+        nested =
+          persistentMapOf(
+            "a" to persistentListOf(1, 2, 3),
+            "b" to persistentListOf(1, 2, 3),
+            "c" to persistentListOf(1, 2, 3),
+          ),
+        persistentList = persistentListOf(1, 2, 3),
+        persistentSet = persistentSetOf(1, 2, 3),
+        persistentCollection = persistentListOf(1, 2, 3),
+        persistentMap = persistentMapOf("a" to 1, "b" to 2, "c" to 3),
+        persistentNested =
+          persistentMapOf(
+            "a" to persistentListOf(1, 2, 3),
+            "b" to persistentListOf(1, 2, 3),
+            "c" to persistentListOf(1, 2, 3),
+          ),
+      )
+  }
+
+  class ClassWithImmutables(
+    val list: ImmutableList<Int>,
+    val set: ImmutableSet<Int>,
+    val collection: ImmutableCollection<Int>,
+    val map: ImmutableMap<String, Int>,
+    val nested: ImmutableMap<String, ImmutableList<Int>>,
+    val persistentList: PersistentList<Int>,
+    val persistentSet: PersistentSet<Int>,
+    val persistentCollection: PersistentCollection<Int>,
+    val persistentMap: PersistentMap<String, Int>,
+    val persistentNested: PersistentMap<String, PersistentList<Int>>,
+  )
+}

moshi-metadata-reflect/build.gradle.kts

@@ -14,23 +14,19 @@
  * limitations under the License.
  */
 
-import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
-
 plugins {
   kotlin("jvm")
   id("com.google.devtools.ksp")
   id("com.vanniktech.maven.publish")
 }
 
-tasks.named<KotlinCompile>("compileTestKotlin") {
-  compilerOptions { freeCompilerArgs.add("-opt-in=kotlin.ExperimentalStdlibApi") }
-}
+tasks.compileTestKotlin { compilerOptions { optIn.add("kotlin.ExperimentalStdlibApi") } }
 
 dependencies {
   implementation(libs.kotlin.metadata)
   implementation(libs.moshi)
   kspTest(libs.moshi.codegen)
-  testImplementation("org.assertj:assertj-core:3.25.3")
+  testImplementation(libs.assertj)
   testImplementation(libs.junit)
   testImplementation(libs.truth)
 }