[pigeon] Implement Screaming Snake Case Conversion for Kotlin Enum Cases (#5918)

This pull request addresses issue flutter/flutter#140938 in the Pigeon package, related to the naming convention of Kotlin enum cases generated from lower camel case Dart enums. The current implementation concatenates the enum cases in uppercase, deviating from the Kotlin naming convention, specifically when dealing with multi-word names.

Changes

- Kotlin Enum Generation: Modified the writeEnum function in the Pigeon package to ensure the Kotlin generator produces enum cases in SCREAMING_SNAKE_CASE. This adheres to the Kotlin coding conventions and allows a consistent cross-platform enum naming convention across Dart, Kotlin, and Swift.
- Regex Handling: Enhanced the regex pattern to correctly transform lower camel case names to screaming snake case, considering edge cases involving numbers and special characters.
- Testing: Updated the Dart unit tests to include cases for validating the correct transformation of multi-word and complex enum names from lower camel case to screaming snake case.

Author: erdzan12

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,11 @@
+## 17.0.0
+
+* **Breaking Change** [kotlin] Converts Kotlin enum case generation to SCREAMING_SNAKE_CASE.
+  * Updates `writeEnum` function to adhere to Kotlin naming conventions.
+  * Improves handling of complex names with enhanced regex patterns.
+  * Expands unit tests for comprehensive name conversion validation.
+  * **Migration Note**: This change modifies the naming convention of Kotlin enum cases generated from the Pigeon package. It is recommended to review the impact on your existing codebase and update any dependent code accordingly.
+
 ## 16.0.5
 
 * Adds ProxyApi to AST generation.

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 = '16.0.5';
+const String pigeonVersion = '17.0.0';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/lib/kotlin_generator.dart

@@ -127,7 +127,11 @@ class KotlinGenerator extends StructuredGenerator<KotlinOptions> {
       enumerate(anEnum.members, (int index, final EnumMember member) {
         addDocumentationComments(
             indent, member.documentationComments, _docCommentSpec);
-        indent.write('${member.name.toUpperCase()}($index)');
+        final String nameScreamingSnakeCase = member.name
+            .replaceAllMapped(
+                RegExp(r'(?<=[a-z])[A-Z]'), (Match m) => '_${m.group(0)}')
+            .toUpperCase();
+        indent.write('$nameScreamingSnakeCase($index)');
         if (index != anEnum.members.length - 1) {
           indent.addln(',');
         } else {

packages/pigeon/pigeons/core_tests.dart

@@ -8,6 +8,8 @@ enum AnEnum {
   one,
   two,
   three,
+  fortyTwo,
+  fourHundredTwentyTwo,
 }
 
 /// A class containing all supported types.

packages/pigeon/pigeons/enum.dart

@@ -18,6 +18,9 @@ enum EnumState {
 
   /// This comment is to test enum member (Error) documentation comments.
   Error,
+
+  /// This comment is to test enum member (SnakeCase) documentation comments.
+  SnakeCase,
 }
 
 /// This comment is to test class documentation comments.

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

@@ -77,7 +77,9 @@ protected static FlutterError createConnectionError(@NonNull String channelName)
   public enum AnEnum {
     ONE(0),
     TWO(1),
-    THREE(2);
+    THREE(2),
+    FORTY_TWO(3),
+    FOUR_HUNDRED_TWENTY_TWO(4);
 
     final int index;
 

packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/CoreTests.gen.h

@@ -18,6 +18,8 @@ typedef NS_ENUM(NSUInteger, AnEnum) {
   AnEnumOne = 0,
   AnEnumTwo = 1,
   AnEnumThree = 2,
+  AnEnumFortyTwo = 3,
+  AnEnumFourHundredTwentyTwo = 4,
 };
 
 /// Wrapper for AnEnum to allow for nullability.

packages/pigeon/platform_tests/alternate_language_test_plugin/macos/Classes/CoreTests.gen.h

@@ -18,6 +18,8 @@ typedef NS_ENUM(NSUInteger, AnEnum) {
   AnEnumOne = 0,
   AnEnumTwo = 1,
   AnEnumThree = 2,
+  AnEnumFortyTwo = 3,
+  AnEnumFourHundredTwentyTwo = 4,
 };
 
 /// Wrapper for AnEnum to allow for nullability.

packages/pigeon/platform_tests/shared_test_plugin_code/lib/integration_tests.dart

@@ -138,7 +138,7 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
       'd': false,
       'e': null
     },
-    anEnum: AnEnum.two,
+    anEnum: AnEnum.fortyTwo,
     anObject: 1,
   );
 
@@ -166,7 +166,7 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
     ],
     nullableMapWithAnnotations: <String?, String?>{},
     nullableMapWithObject: <String?, Object?>{},
-    aNullableEnum: AnEnum.two,
+    aNullableEnum: AnEnum.fourHundredTwentyTwo,
     aNullableObject: 0,
   );
 
@@ -443,6 +443,15 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
       expect(receivedEnum, sentEnum);
     });
 
+    testWidgets('multi word enums serialize and deserialize correctly',
+        (WidgetTester _) async {
+      final HostIntegrationCoreApi api = HostIntegrationCoreApi();
+
+      const AnEnum sentEnum = AnEnum.fortyTwo;
+      final AnEnum receivedEnum = await api.echoEnum(sentEnum);
+      expect(receivedEnum, sentEnum);
+    });
+
     testWidgets('required named parameter', (WidgetTester _) async {
       final HostIntegrationCoreApi api = HostIntegrationCoreApi();
       // This number corresponds with the default value of this method.
@@ -648,6 +657,15 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
       expect(echoEnum, sentEnum);
     });
 
+    testWidgets('multi word nullable enums serialize and deserialize correctly',
+        (WidgetTester _) async {
+      final HostIntegrationCoreApi api = HostIntegrationCoreApi();
+
+      const AnEnum sentEnum = AnEnum.fourHundredTwentyTwo;
+      final AnEnum? echoEnum = await api.echoNullableEnum(sentEnum);
+      expect(echoEnum, sentEnum);
+    });
+
     testWidgets('null lists serialize and deserialize correctly',
         (WidgetTester _) async {
       final HostIntegrationCoreApi api = HostIntegrationCoreApi();
@@ -887,6 +905,15 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
       expect(echoEnum, sentEnum);
     });
 
+    testWidgets('multi word enums serialize and deserialize correctly',
+        (WidgetTester _) async {
+      final HostIntegrationCoreApi api = HostIntegrationCoreApi();
+
+      const AnEnum sentEnum = AnEnum.fourHundredTwentyTwo;
+      final AnEnum echoEnum = await api.echoAsyncEnum(sentEnum);
+      expect(echoEnum, sentEnum);
+    });
+
     testWidgets('nullable Int async serialize and deserialize correctly',
         (WidgetTester _) async {
       final HostIntegrationCoreApi api = HostIntegrationCoreApi();
@@ -1004,6 +1031,15 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
       expect(echoEnum, sentEnum);
     });
 
+    testWidgets('nullable enums serialize and deserialize correctly',
+        (WidgetTester _) async {
+      final HostIntegrationCoreApi api = HostIntegrationCoreApi();
+
+      const AnEnum sentEnum = AnEnum.fortyTwo;
+      final AnEnum? echoEnum = await api.echoAsyncNullableEnum(sentEnum);
+      expect(echoEnum, sentEnum);
+    });
+
     testWidgets('null Ints async serialize and deserialize correctly',
         (WidgetTester _) async {
       final HostIntegrationCoreApi api = HostIntegrationCoreApi();
@@ -1243,6 +1279,15 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
       expect(echoEnum, sentEnum);
     });
 
+    testWidgets('multi word enums serialize and deserialize correctly',
+        (WidgetTester _) async {
+      final HostIntegrationCoreApi api = HostIntegrationCoreApi();
+
+      const AnEnum sentEnum = AnEnum.fortyTwo;
+      final AnEnum echoEnum = await api.callFlutterEchoEnum(sentEnum);
+      expect(echoEnum, sentEnum);
+    });
+
     testWidgets('nullable booleans serialize and deserialize correctly',
         (WidgetTester _) async {
       final HostIntegrationCoreApi api = HostIntegrationCoreApi();
@@ -1407,6 +1452,15 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
       expect(echoEnum, sentEnum);
     });
 
+    testWidgets('multi word nullable enums serialize and deserialize correctly',
+        (WidgetTester _) async {
+      final HostIntegrationCoreApi api = HostIntegrationCoreApi();
+
+      const AnEnum sentEnum = AnEnum.fourHundredTwentyTwo;
+      final AnEnum? echoEnum = await api.callFlutterEchoNullableEnum(sentEnum);
+      expect(echoEnum, sentEnum);
+    });
+
     testWidgets('null enums serialize and deserialize correctly',
         (WidgetTester _) async {
       final HostIntegrationCoreApi api = HostIntegrationCoreApi();

packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/core_tests.gen.dart

@@ -34,6 +34,8 @@ enum AnEnum {
   one,
   two,
   three,
+  fortyTwo,
+  fourHundredTwentyTwo,
 }
 
 /// A class containing all supported types.