[pigeon] java non null void (flutter#5786)

Fixes java requiring `Null` to be `NonNull`.

fixes: flutter/flutter#139194

apparently also fixes an extra space that I removed a month ago and never merged.

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 16.0.0
+
+* [java] Adds `VoidResult` type for `Void` returns.
+* **Breaking Change** [java] Updates all `Void` return types to use new `VoidResult`.
+
 ## 15.0.3
 
 * Fixes new lint warnings.

packages/pigeon/example/app/android/app/src/main/java/io/flutter/plugins/Messages.java

@@ -216,6 +216,14 @@ public interface NullableResult<T> {
     /** Failure case callback method for handling errors. */
     void error(@NonNull Throwable error);
   }
+  /** Asynchronous error handling return type for void API method returns. */
+  public interface VoidResult {
+    /** Success case callback method for handling returns. */
+    void success();
+
+    /** Failure case callback method for handling errors. */
+    void error(@NonNull Throwable error);
+  }
 
   private static class ExampleHostApiCodec extends StandardMessageCodec {
     public static final ExampleHostApiCodec INSTANCE = new ExampleHostApiCodec();

packages/pigeon/lib/generator_tools.dart

@@ -13,7 +13,7 @@ import 'ast.dart';
 /// The current version of pigeon.
 ///
 /// This must match the version in pubspec.yaml.
-const String pigeonVersion = '15.0.3';
+const String pigeonVersion = '16.0.0';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/lib/java_generator.dart

@@ -448,17 +448,16 @@ class JavaGenerator extends StructuredGenerator<JavaOptions> {
       });
 
       for (final Method func in api.methods) {
-        final String resultType =
-            func.returnType.isNullable ? 'NullableResult' : 'Result';
+        final String resultType = _getResultType(func.returnType);
         final String returnType = func.returnType.isVoid
             ? 'Void'
             : _javaTypeForDartType(func.returnType);
         String sendArgument;
         addDocumentationComments(
             indent, func.documentationComments, _docCommentSpec);
         if (func.parameters.isEmpty) {
-          indent.write(
-              'public void ${func.name}(@NonNull $resultType<$returnType> result) ');
+          indent
+              .write('public void ${func.name}(@NonNull $resultType result) ');
           sendArgument = 'null';
         } else {
           final Iterable<String> argTypes = func.parameters
@@ -478,7 +477,7 @@ class JavaGenerator extends StructuredGenerator<JavaOptions> {
               map2(argTypes, argNames, (String x, String y) => '$x $y')
                   .join(', ');
           indent.write(
-              'public void ${func.name}($argsSignature, @NonNull $resultType<$returnType> result) ');
+              'public void ${func.name}($argsSignature, @NonNull $resultType result) ');
         }
         indent.addScoped('{', '}', () {
           const String channel = 'channel';
@@ -513,7 +512,7 @@ class JavaGenerator extends StructuredGenerator<JavaOptions> {
                 }
                 indent.addScoped('else {', '}', () {
                   if (func.returnType.isVoid) {
-                    indent.writeln('result.success(null);');
+                    indent.writeln('result.success();');
                   } else {
                     const String output = 'output';
                     final String outputExpression;
@@ -633,8 +632,7 @@ class JavaGenerator extends StructuredGenerator<JavaOptions> {
   ///   int add(int x, int y);
   void _writeInterfaceMethod(JavaOptions generatorOptions, Root root,
       Indent indent, Api api, final Method method) {
-    final String resultType =
-        method.returnType.isNullable ? 'NullableResult' : 'Result';
+    final String resultType = _getResultType(method.returnType);
     final String nullableType = method.isAsynchronous
         ? ''
         : _nullabilityAnnotationFromType(method.returnType);
@@ -653,10 +651,7 @@ class JavaGenerator extends StructuredGenerator<JavaOptions> {
       }));
     }
     if (method.isAsynchronous) {
-      final String returnType = method.returnType.isVoid
-          ? 'Void'
-          : _javaTypeForDartType(method.returnType);
-      argSignature.add('@NonNull $resultType<$returnType> result');
+      argSignature.add('@NonNull $resultType result');
     }
     if (method.documentationComments.isNotEmpty) {
       addDocumentationComments(
@@ -748,14 +743,17 @@ class JavaGenerator extends StructuredGenerator<JavaOptions> {
                     ? ' == null ? null : $resultValue.index'
                     : '.index';
               }
-              final String resultType =
-                  method.returnType.isNullable ? 'NullableResult' : 'Result';
+              final String resultType = _getResultType(method.returnType);
+              final String resultParam =
+                  method.returnType.isVoid ? '' : '$returnType result';
+              final String addResultArg =
+                  method.returnType.isVoid ? 'null' : '$resultValue$enumTag';
               const String resultName = 'resultCallback';
               indent.format('''
-$resultType<$returnType> $resultName =
-\t\tnew $resultType<$returnType>() {
-\t\t\tpublic void success($returnType result) {
-\t\t\t\twrapped.add(0, $resultValue$enumTag);
+$resultType $resultName =
+\t\tnew $resultType() {
+\t\t\tpublic void success($resultParam) {
+\t\t\t\twrapped.add(0, $addResultArg);
 \t\t\t\treply.reply(wrapped);
 \t\t\t}
 
@@ -895,6 +893,19 @@ $resultType<$returnType> $resultName =
           .writeln('/** Failure case callback method for handling errors. */');
       indent.writeln('void error(@NonNull Throwable error);');
     });
+
+    indent.writeln(
+        '/** Asynchronous error handling return type for void API method returns. */');
+    indent.write('public interface VoidResult ');
+    indent.addScoped('{', '}', () {
+      indent
+          .writeln('/** Success case callback method for handling returns. */');
+      indent.writeln('void success();');
+      indent.newln();
+      indent
+          .writeln('/** Failure case callback method for handling errors. */');
+      indent.writeln('void error(@NonNull Throwable error);');
+    });
   }
 
   void _writeErrorClass(Indent indent) {
@@ -1102,3 +1113,14 @@ String _castObject(NamedType field, String varName) {
     return _cast(varName, javaType: hostDatatype.datatype);
   }
 }
+
+/// Returns string of Result class type for method based on [TypeDeclaration].
+String _getResultType(TypeDeclaration type) {
+  if (type.isVoid) {
+    return 'VoidResult';
+  }
+  if (type.isNullable) {
+    return 'NullableResult<${_javaTypeForDartType(type)}>';
+  }
+  return 'Result<${_javaTypeForDartType(type)}>';
+}

packages/pigeon/platform_tests/alternate_language_test_plugin/android/src/main/java/com/example/alternate_language_test_plugin/AlternateLanguageTestPlugin.java

@@ -14,6 +14,7 @@
 import com.example.alternate_language_test_plugin.CoreTests.HostIntegrationCoreApi;
 import com.example.alternate_language_test_plugin.CoreTests.NullableResult;
 import com.example.alternate_language_test_plugin.CoreTests.Result;
+import com.example.alternate_language_test_plugin.CoreTests.VoidResult;
 import io.flutter.embedding.engine.plugins.FlutterPlugin;
 import java.util.List;
 import java.util.Map;
@@ -208,8 +209,8 @@ public void throwErrorFromVoid() {
   }
 
   @Override
-  public void noopAsync(@NonNull Result<Void> result) {
-    result.success(null);
+  public void noopAsync(@NonNull VoidResult result) {
+    result.success();
   }
 
   @Override
@@ -218,7 +219,7 @@ public void throwAsyncError(@NonNull NullableResult<Object> result) {
   }
 
   @Override
-  public void throwAsyncErrorFromVoid(@NonNull Result<Void> result) {
+  public void throwAsyncErrorFromVoid(@NonNull VoidResult result) {
     result.error(new RuntimeException("An error"));
   }
 
@@ -338,7 +339,7 @@ public void echoAsyncNullableEnum(
   }
 
   @Override
-  public void callFlutterNoop(@NonNull Result<Void> result) {
+  public void callFlutterNoop(@NonNull VoidResult result) {
     flutterApi.noop(result);
   }
 
@@ -348,7 +349,7 @@ public void callFlutterThrowError(@NonNull NullableResult<Object> result) {
   }
 
   @Override
-  public void callFlutterThrowErrorFromVoid(@NonNull Result<Void> result) {
+  public void callFlutterThrowErrorFromVoid(@NonNull VoidResult result) {
     flutterApi.throwErrorFromVoid(result);
   }
 

packages/pigeon/platform_tests/alternate_language_test_plugin/android/src/main/java/com/example/alternate_language_test_plugin/CoreTests.java

@@ -980,6 +980,14 @@ public interface NullableResult<T> {
     /** Failure case callback method for handling errors. */
     void error(@NonNull Throwable error);
   }
+  /** Asynchronous error handling return type for void API method returns. */
+  public interface VoidResult {
+    /** Success case callback method for handling returns. */
+    void success();
+
+    /** Failure case callback method for handling errors. */
+    void error(@NonNull Throwable error);
+  }
 
   private static class HostIntegrationCoreApiCodec extends StandardMessageCodec {
     public static final HostIntegrationCoreApiCodec INSTANCE = new HostIntegrationCoreApiCodec();
@@ -1139,7 +1147,7 @@ AllNullableTypes sendMultipleNullableTypes(
      * A no-op function taking no arguments and returning no value, to sanity test basic
      * asynchronous calling.
      */
-    void noopAsync(@NonNull Result<Void> result);
+    void noopAsync(@NonNull VoidResult result);
     /** Returns passed in int asynchronously. */
     void echoAsyncInt(@NonNull Long anInt, @NonNull Result<Long> result);
     /** Returns passed in double asynchronously. */
@@ -1162,7 +1170,7 @@ void echoAsyncMap(
     /** Responds with an error from an async function returning a value. */
     void throwAsyncError(@NonNull NullableResult<Object> result);
     /** Responds with an error from an async void function. */
-    void throwAsyncErrorFromVoid(@NonNull Result<Void> result);
+    void throwAsyncErrorFromVoid(@NonNull VoidResult result);
     /** Responds with a Flutter error from an async function returning a value. */
     void throwAsyncFlutterError(@NonNull NullableResult<Object> result);
     /** Returns the passed object, to test async serialization and deserialization. */
@@ -1192,11 +1200,11 @@ void echoAsyncNullableMap(
     /** Returns the passed enum, to test asynchronous serialization and deserialization. */
     void echoAsyncNullableEnum(@Nullable AnEnum anEnum, @NonNull NullableResult<AnEnum> result);
 
-    void callFlutterNoop(@NonNull Result<Void> result);
+    void callFlutterNoop(@NonNull VoidResult result);
 
     void callFlutterThrowError(@NonNull NullableResult<Object> result);
 
-    void callFlutterThrowErrorFromVoid(@NonNull Result<Void> result);
+    void callFlutterThrowErrorFromVoid(@NonNull VoidResult result);
 
     void callFlutterEchoAllTypes(@NonNull AllTypes everything, @NonNull Result<AllTypes> result);
 
@@ -2097,9 +2105,9 @@ static void setUp(
           channel.setMessageHandler(
               (message, reply) -> {
                 ArrayList<Object> wrapped = new ArrayList<Object>();
-                Result<Void> resultCallback =
-                    new Result<Void>() {
-                      public void success(Void result) {
+                VoidResult resultCallback =
+                    new VoidResult() {
+                      public void success() {
                         wrapped.add(0, null);
                         reply.reply(wrapped);
                       }
@@ -2434,9 +2442,9 @@ public void error(Throwable error) {
           channel.setMessageHandler(
               (message, reply) -> {
                 ArrayList<Object> wrapped = new ArrayList<Object>();
-                Result<Void> resultCallback =
-                    new Result<Void>() {
-                      public void success(Void result) {
+                VoidResult resultCallback =
+                    new VoidResult() {
+                      public void success() {
                         wrapped.add(0, null);
                         reply.reply(wrapped);
                       }
@@ -2834,9 +2842,9 @@ public void error(Throwable error) {
           channel.setMessageHandler(
               (message, reply) -> {
                 ArrayList<Object> wrapped = new ArrayList<Object>();
-                Result<Void> resultCallback =
-                    new Result<Void>() {
-                      public void success(Void result) {
+                VoidResult resultCallback =
+                    new VoidResult() {
+                      public void success() {
                         wrapped.add(0, null);
                         reply.reply(wrapped);
                       }
@@ -2892,9 +2900,9 @@ public void error(Throwable error) {
           channel.setMessageHandler(
               (message, reply) -> {
                 ArrayList<Object> wrapped = new ArrayList<Object>();
-                Result<Void> resultCallback =
-                    new Result<Void>() {
-                      public void success(Void result) {
+                VoidResult resultCallback =
+                    new VoidResult() {
+                      public void success() {
                         wrapped.add(0, null);
                         reply.reply(wrapped);
                       }
@@ -3574,7 +3582,7 @@ public FlutterIntegrationCoreApi(@NonNull BinaryMessenger argBinaryMessenger) {
     /**
      * A no-op function taking no arguments and returning no value, to sanity test basic calling.
      */
-    public void noop(@NonNull Result<Void> result) {
+    public void noop(@NonNull VoidResult result) {
       final String channelName =
           "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.noop";
       BasicMessageChannel<Object> channel =
@@ -3591,7 +3599,7 @@ public void noop(@NonNull Result<Void> result) {
                         (String) listReply.get(1),
                         (String) listReply.get(2)));
               } else {
-                result.success(null);
+                result.success();
               }
             } else {
               result.error(createConnectionError(channelName));
@@ -3626,7 +3634,7 @@ public void throwError(@NonNull NullableResult<Object> result) {
           });
     }
     /** Responds with an error from an async void function. */
-    public void throwErrorFromVoid(@NonNull Result<Void> result) {
+    public void throwErrorFromVoid(@NonNull VoidResult result) {
       final String channelName =
           "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.throwErrorFromVoid";
       BasicMessageChannel<Object> channel =
@@ -3643,7 +3651,7 @@ public void throwErrorFromVoid(@NonNull Result<Void> result) {
                         (String) listReply.get(1),
                         (String) listReply.get(2)));
               } else {
-                result.success(null);
+                result.success();
               }
             } else {
               result.error(createConnectionError(channelName));
@@ -4251,7 +4259,7 @@ public void echoNullableEnum(
      * A no-op function taking no arguments and returning no value, to sanity test basic
      * asynchronous calling.
      */
-    public void noopAsync(@NonNull Result<Void> result) {
+    public void noopAsync(@NonNull VoidResult result) {
       final String channelName =
           "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.noopAsync";
       BasicMessageChannel<Object> channel =
@@ -4268,7 +4276,7 @@ public void noopAsync(@NonNull Result<Void> result) {
                         (String) listReply.get(1),
                         (String) listReply.get(2)));
               } else {
-                result.success(null);
+                result.success();
               }
             } else {
               result.error(createConnectionError(channelName));
@@ -4358,7 +4366,7 @@ public interface HostSmallApi {
 
     void echo(@NonNull String aString, @NonNull Result<String> result);
 
-    void voidVoid(@NonNull Result<Void> result);
+    void voidVoid(@NonNull VoidResult result);
 
     /** The codec used by HostSmallApi. */
     static @NonNull MessageCodec<Object> getCodec() {
@@ -4407,9 +4415,9 @@ public void error(Throwable error) {
           channel.setMessageHandler(
               (message, reply) -> {
                 ArrayList<Object> wrapped = new ArrayList<Object>();
-                Result<Void> resultCallback =
-                    new Result<Void>() {
-                      public void success(Void result) {
+                VoidResult resultCallback =
+                    new VoidResult() {
+                      public void success() {
                         wrapped.add(0, null);
                         reply.reply(wrapped);
                       }

packages/pigeon/platform_tests/alternate_language_test_plugin/android/src/test/java/com/example/alternate_language_test_plugin/AsyncTest.java

@@ -24,8 +24,8 @@ public void echo(@NonNull String value, Result<String> result) {
     }
 
     @Override
-    public void voidVoid(Result<Void> result) {
-      result.success(null);
+    public void voidVoid(VoidResult result) {
+      result.success();
     }
   }
 
@@ -36,7 +36,7 @@ public void echo(@NonNull String value, Result<String> result) {
     }
 
     @Override
-    public void voidVoid(Result<Void> result) {
+    public void voidVoid(VoidResult result) {
       result.error(new Exception("error"));
     }
   }