Support JsonTreeWriter

Uses internal APIs but this library isn't stable anyway. This works around that issue until a fixed future version of GSON that properly supports jsonValue in JsonTreeWriter (if ever) by converting it manually to a `JsonElement` and writing it directly via its `JsonElement` `TypeAdapter`. Resolves #22
slackhq · Nov 18, 2020 · 765e6e2 · 765e6e2
1 parent 0d746fa
commit 765e6e2
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Showing 2 changed files with 88 additions and 7 deletions.
diff --git a/src/main/kotlin/com/slack/moshi/interop/gson/InteropBuilder.kt b/src/main/kotlin/com/slack/moshi/interop/gson/InteropBuilder.kt
@@ -24,6 +24,8 @@ import com.google.gson.JsonParser
 import com.google.gson.JsonPrimitive
 import com.google.gson.TypeAdapter
 import com.google.gson.TypeAdapterFactory
+import com.google.gson.internal.bind.JsonTreeWriter
+import com.google.gson.internal.bind.TypeAdapters
 import com.google.gson.reflect.TypeToken
 import com.slack.moshi.interop.gson.Serializer.GSON
 import com.slack.moshi.interop.gson.Serializer.MOSHI
@@ -187,7 +189,7 @@ internal class GsonDelegatingJsonAdapter<T>(
 private class MoshiGsonInteropTypeAdapterFactory(
   private val interop: MoshiGsonInterop,
   private val checkers: List<ClassChecker>,
-  private val logger: ((String) -> Unit)?,
+  private val logger: ((String) -> Unit)?
 ) : TypeAdapterFactory {
   override fun <T> create(gson: Gson, typeToken: TypeToken<T>): TypeAdapter<T>? {
     val type = typeToken.type
@@ -204,14 +206,22 @@ private class MoshiGsonInteropTypeAdapterFactory(
 }
 
 internal class MoshiDelegatingTypeAdapter<T>(
-  private val delegate: JsonAdapter<T>,
+  private val delegate: JsonAdapter<T>
 ) : TypeAdapter<T>() {
   override fun write(writer: com.google.gson.stream.JsonWriter, value: T?) {
-    val serializedValue = delegate
+    val adjustedDelegate = delegate
       .run { if (writer.serializeNulls) serializeNulls() else this }
       .run { if (writer.isLenient) lenient() else this }
-      .toJson(value)
-    writer.jsonValue(serializedValue)
+    if (writer is JsonTreeWriter) {
+      // https://github.com/slackhq/moshi-gson-interop/issues/22
+      // Pending https://github.com/google/gson/pull/1819
+      val jsonValue = adjustedDelegate.toJsonValue(value)
+      val jsonElement = jsonValue.toJsonElement()
+      TypeAdapters.JSON_ELEMENT.write(writer, jsonElement)
+    } else {
+      val serializedValue = adjustedDelegate.toJson(value)
+      writer.jsonValue(serializedValue)
+    }
   }
 
   override fun read(reader: com.google.gson.stream.JsonReader): T? {
@@ -245,3 +255,38 @@ private fun JsonElement.toJsonValue(): Any? {
     else -> error("Not possible")
   }
 }
+
+private fun Any?.toJsonElement(): JsonElement {
+  return when (this) {
+    null -> JsonNull.INSTANCE
+    is Boolean -> JsonPrimitive(this)
+    is Char -> JsonPrimitive(this)
+    is Number -> JsonPrimitive(this)
+    is String -> JsonPrimitive(this)
+    is Array<*> -> {
+      JsonArray(size).apply {
+        for (element in this) {
+          add(element.toJsonElement())
+        }
+      }
+    }
+    is Collection<*> -> {
+      JsonArray(size).apply {
+        for (element in this@toJsonElement) {
+          add(element.toJsonElement())
+        }
+      }
+    }
+    is Map<*, *> -> {
+      JsonObject().apply {
+        for ((k, v) in entries) {
+          check(k is String) {
+            "JSON only supports String keys!"
+          }
+          add(k, v.toJsonElement())
+        }
+      }
+    }
+    else -> error("Unrecognized JsonValue type: $this")
+  }
+}
diff --git a/src/test/kotlin/com/slack/moshi/interop/gson/MoshiGsonInteropTest.kt b/src/test/kotlin/com/slack/moshi/interop/gson/MoshiGsonInteropTest.kt
@@ -19,6 +19,7 @@ import com.google.common.truth.Truth.assertThat
 import com.google.gson.GsonBuilder
 import com.google.gson.TypeAdapter
 import com.google.gson.annotations.SerializedName
+import com.google.gson.internal.bind.JsonTreeWriter
 import com.google.gson.reflect.TypeToken
 import com.squareup.moshi.Json
 import com.squareup.moshi.JsonClass
@@ -279,6 +280,41 @@ class MoshiGsonInteropTest {
       .toJson(GsonNumber(value = Double.NaN))
     assertThat(withNaN).isEqualTo("""{"value":NaN}""")
   }
+
+  @Test
+  fun jsonTreeWriter_simple() {
+    val writer = JsonTreeWriter()
+    val moshiDelegate = moshi.adapter<Any>()
+    val typeAdapter = MoshiDelegatingTypeAdapter(moshiDelegate)
+    typeAdapter.write(writer, "yay")
+    assertThat(writer.get().toString()).isEqualTo("\"yay\"")
+  }
+
+  @Test
+  fun jsonTreeWriter_large() {
+    val writer = JsonTreeWriter()
+    val moshiDelegate = moshi.adapter<MoshiClass>()
+    val typeAdapter = MoshiDelegatingTypeAdapter(moshiDelegate)
+    val instance = MoshiClass(
+      SimpleMoshiClass("moshi!"),
+      SimpleGsonClass("gson!"),
+      RegularEnum.TYPE,
+      MoshiEnum.TYPE,
+      GsonEnum.TYPE,
+      listOf(SimpleMoshiClass("moshi!")),
+      listOf(SimpleGsonClass("gson!")),
+      SimpleGenericMoshiClass(MoshiEnum.TYPE),
+      SimpleGenericGsonClass(GsonEnum.TYPE),
+      SimpleMixedGenericGsonClass(SimpleGenericMoshiClass(GsonEnum.TYPE)),
+      SimpleMixedGenericMoshiClass(SimpleGenericGsonClass(MoshiEnum.TYPE))
+    )
+    typeAdapter.write(writer, instance)
+    val serialized = writer.get().toString()
+
+    // Now read the serialized one with a real instance and ensure they're equal
+    val secondInstance = moshi.adapter<MoshiClass>().fromJson(serialized)
+    assertThat(secondInstance).isEqualTo(instance)
+  }
 }
 
 @JsonClass(generateAdapter = true)
@@ -293,7 +329,7 @@ data class MoshiClass(
   val genericMoshiClass: SimpleGenericMoshiClass<MoshiEnum>,
   val genericGsonClass: SimpleGenericGsonClass<GsonEnum>,
   val mixedGenericGsonClass: SimpleMixedGenericGsonClass<SimpleGenericMoshiClass<GsonEnum>>,
-  val mixedGenericMoshiClass: SimpleMixedGenericMoshiClass<SimpleGenericGsonClass<MoshiEnum>>
+  val mixedGenericMoshiClass: SimpleMixedGenericMoshiClass<SimpleGenericGsonClass<MoshiEnum>>,
 )
 
 data class GsonClass(
@@ -307,7 +343,7 @@ data class GsonClass(
   val genericMoshiClass: SimpleGenericMoshiClass<MoshiEnum>,
   val genericGsonClass: SimpleGenericGsonClass<GsonEnum>,
   val mixedGenericGsonClass: SimpleMixedGenericGsonClass<SimpleGenericMoshiClass<GsonEnum>>,
-  val mixedGenericMoshiClass: SimpleMixedGenericMoshiClass<SimpleGenericGsonClass<MoshiEnum>>
+  val mixedGenericMoshiClass: SimpleMixedGenericMoshiClass<SimpleGenericGsonClass<MoshiEnum>>,
 )
 
 data class Complex(val value: ComplexNestedOne)