Simplify custom adapters (#280)

* simplify generic custom adapters

* Update CustomEntryJsonAdapter.java

* fix tests

* allow simple custom adapters

* Format, extract method, add missing test

---------

Co-authored-by: Rob Bygrave <robin.bygrave@gmail.com>

Author: SentryMan

blackbox-test/src/main/java/org/example/other/custom/CustomEntryJsonAdapter.java

@@ -1,6 +1,5 @@
 package org.example.other.custom;
 
-import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.util.AbstractMap.SimpleImmutableEntry;
 import java.util.Map.Entry;
@@ -13,7 +12,7 @@
 import io.avaje.jsonb.Types;
 import io.avaje.jsonb.spi.PropertyNames;
 
-@CustomAdapter(isGeneric = true)
+@CustomAdapter
 public class CustomEntryJsonAdapter<K, V> implements JsonAdapter<Entry<K, V>> {
 
   private final JsonAdapter<K> generic1;

blackbox-test/src/test/java/org/example/customer/customtype/CustomScalarTypeTest.java

@@ -50,6 +50,24 @@ void toJson_fromJson() {
     assertThat(wrapper1.custom()).isEqualTo(wrapper.custom());
   }
 
+  @Test
+  void toJson_fromJson_usingSupplier() {
+    Jsonb jsonb = Jsonb.builder()
+      // register a supplier
+      .add(MyCustomScalarType.class, () -> new CustomTypeAdapter().nullSafe())
+      .build();
+
+    MyWrapper wrapper = new MyWrapper(42, "hello", new MyCustomScalarType("hello".getBytes(StandardCharsets.UTF_8)));
+
+    String asJson = jsonb.toJson(wrapper);
+    assertThat(asJson).isEqualTo("{\"id\":42,\"base\":\"hello\",\"custom\":\"aGVsbG8=\"}");
+
+    MyWrapper wrapper1 = jsonb.type(MyWrapper.class).fromJson(asJson);
+
+    assertThat(wrapper1).isEqualTo(wrapper);
+    assertThat(wrapper1.custom()).isEqualTo(wrapper.custom());
+  }
+
   static class CustomTypeAdapter implements JsonAdapter<MyCustomScalarType> {
 
     @Override

jsonb-generator/src/main/java/io/avaje/jsonb/generator/JsonbProcessor.java

@@ -15,6 +15,7 @@
 
 import io.avaje.prism.GenerateAPContext;
 import io.avaje.prism.GenerateModuleInfoReader;
+import io.avaje.prism.GenerateUtils;
 
 import static java.util.stream.Collectors.joining;
 
@@ -25,6 +26,7 @@
 import java.util.function.Predicate;
 import java.util.stream.Stream;
 
+@GenerateUtils
 @GenerateAPContext
 @GenerateModuleInfoReader
 @SupportedAnnotationTypes({
@@ -112,7 +114,7 @@ private Optional<? extends Set<? extends Element>> getElements(RoundEnvironment
   private void registerCustomAdapters(Set<? extends Element> elements) {
     for (final var typeElement : ElementFilter.typesIn(elements)) {
       final var type = typeElement.getQualifiedName().toString();
-      if (CustomAdapterPrism.getInstanceOn(typeElement).isGeneric()) {
+      if (isGenericJsonAdapter(typeElement)) {
         ElementFilter.fieldsIn(typeElement.getEnclosedElements()).stream()
           .filter(isStaticFactory())
           .findFirst()
@@ -131,13 +133,20 @@ private void registerCustomAdapters(Set<? extends Element> elements) {
           .findAny()
           .ifPresentOrElse(
             x -> {},
-            () -> logError(typeElement, "Non-Generic adapters must have a public constructor with a single Jsonb parameter"));
+            () -> logNote(typeElement, "Non-Generic adapters should have a public constructor with a single Jsonb parameter"));
 
         metaData.add(type);
       }
     }
   }
 
+  private static boolean isGenericJsonAdapter(TypeElement typeElement) {
+    return typeElement.getInterfaces().stream()
+      .map(UType::parse)
+      .filter(u -> u.full().contains("JsonAdapter"))
+      .anyMatch(u -> u.param0().isGeneric());
+  }
+
   private static Predicate<VariableElement> isStaticFactory() {
     return v -> v.getModifiers().contains(Modifier.STATIC) && "FACTORY".equals(v.getSimpleName().toString());
   }

jsonb-generator/src/test/java/io/avaje/jsonb/generator/models/valid/CustomEntryJsonAdapter.java

@@ -12,7 +12,7 @@
 import io.avaje.jsonb.Types;
 import io.avaje.jsonb.spi.PropertyNames;
 
-@CustomAdapter(isGeneric = true)
+@CustomAdapter
 public class CustomEntryJsonAdapter<K, V> implements JsonAdapter<Entry<K, V>> {
 
   private final JsonAdapter<K> generic1;

jsonb-generator/src/test/java/io/avaje/jsonb/generator/models/valid/CustomJsonAdapter.java

@@ -4,14 +4,11 @@
 import io.avaje.jsonb.JsonAdapter;
 import io.avaje.jsonb.JsonReader;
 import io.avaje.jsonb.JsonWriter;
-import io.avaje.jsonb.Jsonb;
 import io.avaje.jsonb.generator.models.valid.Example3Packet.Example2Packet;
 
 @CustomAdapter
 public class CustomJsonAdapter implements JsonAdapter<Example2Packet> {
 
-  public CustomJsonAdapter(Jsonb jsonb) {}
-
   @Override
   public void toJson(JsonWriter writer, Example2Packet value) {}
 

jsonb/src/main/java/io/avaje/jsonb/CustomAdapter.java

@@ -6,7 +6,6 @@
 import java.lang.annotation.Retention;
 import java.lang.annotation.Target;
 
-
 /**
  * Marks a type as a basic user-provided JsonAdapter to be registered automatically.
  *
@@ -35,7 +34,7 @@
  *
  * <pre>{@code
  *
- * @CustomAdapter(isGeneric=true)
+ * @CustomAdapter
  * public class CustomJsonAdapter<T> implements JsonAdapter<GenericType<T>> {
  *
  *   private final JsonAdapter<T> genericTypeAdapter;
@@ -60,10 +59,4 @@
  */
 @Target(TYPE)
 @Retention(SOURCE)
-public @interface CustomAdapter {
-
-  /**
-   * Set to true when the adapter is for a type that uses generics.
-   */
-  boolean isGeneric() default false;
-}
+public @interface CustomAdapter {}

jsonb/src/main/java/io/avaje/jsonb/Jsonb.java

@@ -13,6 +13,7 @@
 import java.io.Reader;
 import java.io.Writer;
 import java.lang.reflect.Type;
+import java.util.function.Supplier;
 
 /**
  * Provides access to json adapters by type.
@@ -386,6 +387,11 @@ interface Builder {
      */
     <T> Builder add(Type type, JsonAdapter<T> jsonAdapter);
 
+    /**
+     * Add a Supplier which provides a JsonAdapter to use for the given type.
+     */
+    <T> Builder add(Type type, Supplier<JsonAdapter<T>> builder);
+
     /**
      * Add a AdapterBuilder which provides a JsonAdapter to use for the given type.
      */

jsonb/src/main/java/io/avaje/jsonb/core/DJsonb.java

@@ -13,6 +13,7 @@
 import java.lang.reflect.Type;
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Supplier;
 
 import static io.avaje.jsonb.core.Util.*;
 import static java.util.Objects.requireNonNull;
@@ -276,6 +277,11 @@ public <T> Builder add(Type type, JsonAdapter<T> jsonAdapter) {
       return add(newAdapterFactory(type, jsonAdapter));
     }
 
+    @Override
+    public <T> Builder add(Type type, Supplier<JsonAdapter<T>> jsonAdapter) {
+      return add(newAdapterFactory(type, jsonAdapter));
+    }
+
     @Override
     public Builder add(JsonbComponent component) {
       component.register(this);
@@ -301,14 +307,7 @@ private void registerComponents() {
     @Override
     public DJsonb build() {
       registerComponents();
-      return new DJsonb(
-          adapter,
-          factories,
-          serializeNulls,
-          serializeEmpty,
-          failOnUnknown,
-          mathTypesAsString,
-          strategy);
+      return new DJsonb(adapter, factories, serializeNulls, serializeEmpty, failOnUnknown, mathTypesAsString, strategy);
     }
 
     static <T> JsonAdapter.Factory newAdapterFactory(Type type, JsonAdapter<T> jsonAdapter) {
@@ -317,6 +316,12 @@ static <T> JsonAdapter.Factory newAdapterFactory(Type type, JsonAdapter<T> jsonA
       return (targetType, jsonb) -> simpleMatch(type, targetType) ? jsonAdapter : null;
     }
 
+    static <T> JsonAdapter.Factory newAdapterFactory(Type type, Supplier<JsonAdapter<T>> jsonAdapter) {
+      requireNonNull(type);
+      requireNonNull(jsonAdapter);
+      return (targetType, jsonb) -> simpleMatch(type, targetType) ? jsonAdapter.get() : null;
+    }
+
     static JsonAdapter.Factory newAdapterFactory(Type type, AdapterBuilder builder) {
       requireNonNull(type);
       requireNonNull(builder);