Allow delegates for intermediates in adapters.

moshi/src/main/java/com/squareup/moshi/AdapterMethodsFactory.java

@@ -165,7 +165,8 @@ final class AdapterMethodsFactory implements JsonAdapter.Factory {
     } else if (parameterTypes.length == 1 && returnType != void.class) {
       // List<Integer> pointToJson(Point point) {
       final Set<? extends Annotation> returnTypeAnnotations = jsonAnnotations(method);
-      Set<? extends Annotation> qualifierAnnotations = jsonAnnotations(parameterAnnotations[0]);
+      final Set<? extends Annotation> qualifierAnnotations =
+          jsonAnnotations(parameterAnnotations[0]);
       boolean nullable = Util.hasNullable(parameterAnnotations[0]);
       return new AdapterMethod(parameterTypes[0], qualifierAnnotations, adapter, method,
           parameterTypes.length, 1, nullable) {
@@ -173,7 +174,10 @@ final class AdapterMethodsFactory implements JsonAdapter.Factory {
 
         @Override public void bind(Moshi moshi, JsonAdapter.Factory factory) {
           super.bind(moshi, factory);
-          delegate = moshi.adapter(returnType, returnTypeAnnotations);
+          delegate = Types.equals(parameterTypes[0], returnType)
+              && qualifierAnnotations.equals(returnTypeAnnotations)
+              ? moshi.nextAdapter(factory, returnType, returnTypeAnnotations)
+              : moshi.adapter(returnType, returnTypeAnnotations);
         }
 
         @Override public void toJson(Moshi moshi, JsonWriter writer, @Nullable Object value)
@@ -211,7 +215,7 @@ final class AdapterMethodsFactory implements JsonAdapter.Factory {
   static AdapterMethod fromAdapter(Object adapter, Method method) {
     method.setAccessible(true);
     final Type returnType = method.getGenericReturnType();
-    Set<? extends Annotation> returnTypeAnnotations = jsonAnnotations(method);
+    final Set<? extends Annotation> returnTypeAnnotations = jsonAnnotations(method);
     final Type[] parameterTypes = method.getGenericParameterTypes();
     Annotation[][] parameterAnnotations = method.getParameterAnnotations();
 
@@ -240,7 +244,10 @@ final class AdapterMethodsFactory implements JsonAdapter.Factory {
 
         @Override public void bind(Moshi moshi, JsonAdapter.Factory factory) {
           super.bind(moshi, factory);
-          delegate = moshi.adapter(parameterTypes[0], qualifierAnnotations);
+          delegate = Types.equals(parameterTypes[0], returnType)
+              && qualifierAnnotations.equals(returnTypeAnnotations)
+              ? moshi.nextAdapter(factory, parameterTypes[0], qualifierAnnotations)
+              : moshi.adapter(parameterTypes[0], qualifierAnnotations);
         }
 
         @Override public Object fromJson(Moshi moshi, JsonReader reader)
@@ -265,7 +272,7 @@ final class AdapterMethodsFactory implements JsonAdapter.Factory {
       List<AdapterMethod> adapterMethods, Type type, Set<? extends Annotation> annotations) {
     for (int i = 0, size = adapterMethods.size(); i < size; i++) {
       AdapterMethod adapterMethod = adapterMethods.get(i);
-      if (adapterMethod.type.equals(type) && adapterMethod.annotations.equals(annotations)) {
+      if (Types.equals(adapterMethod.type, type) && adapterMethod.annotations.equals(annotations)) {
         return adapterMethod;
       }
     }

moshi/src/test/java/com/squareup/moshi/AdapterMethodsTest.java

@@ -15,6 +15,8 @@
  */
 package com.squareup.moshi;
 
+import com.squareup.moshi.MoshiTest.Uppercase;
+import com.squareup.moshi.MoshiTest.UppercaseAdapterFactory;
 import java.io.IOException;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -130,6 +132,36 @@ public final class AdapterMethodsTest {
     assertThat(adapter.fromJson("[{\"x\":5,\"y\":8}]")).isEqualTo(point);
   }
 
+  @Test public void toAndFromWithIntermediate() throws Exception {
+    Moshi moshi = new Moshi.Builder().add(new Object() {
+      @FromJson String fromJson(String string) {
+        return string.substring(1, string.length() - 1);
+      }
+
+      @ToJson String toJson(String value) {
+        return "|" + value + "|";
+      }
+    }).build();
+    JsonAdapter<String> adapter = moshi.adapter(String.class);
+    assertThat(adapter.toJson("pizza")).isEqualTo("\"|pizza|\"");
+    assertThat(adapter.fromJson("\"|pizza|\"")).isEqualTo("pizza");
+  }
+
+  @Test public void toAndFromWithIntermediateWithQualifier() throws Exception {
+    Moshi moshi = new Moshi.Builder().add(new Object() {
+      @FromJson @Uppercase String fromJson(@Uppercase String string) {
+        return string.substring(1, string.length() - 1);
+      }
+
+      @ToJson @Uppercase String toJson(@Uppercase String value) {
+        return "|" + value + "|";
+      }
+    }).add(new UppercaseAdapterFactory()).build();
+    JsonAdapter<String> adapter = moshi.adapter(String.class, Uppercase.class);
+    assertThat(adapter.toJson("pizza")).isEqualTo("\"|PIZZA|\"");
+    assertThat(adapter.fromJson("\"|pizza|\"")).isEqualTo("PIZZA");
+  }
+
   @Test public void toJsonOnly() throws Exception {
     Moshi moshi = new Moshi.Builder()
         .add(new PointAsListOfIntegersToAdapter())