[pigeon] added the ability to add a copyright notice to generated files (#377)

packages/pigeon/copyright_header.txt

@@ -0,0 +1,4 @@
+Copyright 2013 The Flutter Authors. All rights reserved.
+Use of this source code is governed by a BSD-style license that can be
+found in the LICENSE file.
+

packages/pigeon/lib/dart_generator.dart

@@ -8,10 +8,13 @@ import 'generator_tools.dart';
 /// Options that control how Dart code will be generated.
 class DartOptions {
   /// Constructor for DartOptions.
-  DartOptions({this.isNullSafe = true});
+  DartOptions({this.isNullSafe = true, this.copyrightHeader});
 
   /// Determines if the generated code has null safety annotations (Dart >=2.12 required).
   bool isNullSafe;
+
+  /// A copyright header that will get prepended to generated code.
+  Iterable<String>? copyrightHeader;
 }
 
 String _escapeForDartSingleQuotedString(String raw) {
@@ -209,6 +212,9 @@ void generateDart(DartOptions opt, Root root, StringSink sink) {
   final List<String> customEnumNames =
       root.enums.map((Enum x) => x.name).toList();
   final Indent indent = Indent(sink);
+  if (opt.copyrightHeader != null) {
+    addLines(indent, opt.copyrightHeader!, linePrefix: '// ');
+  }
   indent.writeln('// $generatedCodeWarning');
   indent.writeln('// $seeAlsoWarning');
   indent.writeln(

packages/pigeon/lib/generator_tools.dart

@@ -211,3 +211,11 @@ class Keys {
 bool isVoid(TypeMirror type) {
   return MirrorSystem.getName(type.simpleName) == 'void';
 }
+
+/// Adds the [lines] to [indent].
+void addLines(Indent indent, Iterable<String> lines, {String? linePrefix}) {
+  final String prefix = linePrefix ?? '';
+  for (final String line in lines) {
+    indent.writeln('$prefix$line');
+  }
+}

packages/pigeon/lib/java_generator.dart

@@ -24,6 +24,7 @@ class JavaOptions {
   JavaOptions({
     this.className,
     this.package,
+    this.copyrightHeader,
   });
 
   /// The name of the class that will house all the generated classes.
@@ -31,6 +32,9 @@ class JavaOptions {
 
   /// The package where the generated class will live.
   String? package;
+
+  /// A copyright header that will get prepended to generated code.
+  Iterable<String>? copyrightHeader;
 }
 
 void _writeHostApi(Indent indent, Api api) {
@@ -226,6 +230,9 @@ void generateJava(JavaOptions options, Root root, StringSink sink) {
   final Set<String> rootEnumNameSet =
       root.enums.map((Enum x) => x.name).toSet();
   final Indent indent = Indent(sink);
+  if (options.copyrightHeader != null) {
+    addLines(indent, options.copyrightHeader!, linePrefix: '// ');
+  }
   indent.writeln('// $generatedCodeWarning');
   indent.writeln('// $seeAlsoWarning');
   indent.addln('');

packages/pigeon/lib/objc_generator.dart

@@ -11,6 +11,7 @@ class ObjcOptions {
   ObjcOptions({
     this.header,
     this.prefix,
+    this.copyrightHeader,
   });
 
   /// The path to the header that will get placed in the source filed (example:
@@ -19,6 +20,9 @@ class ObjcOptions {
 
   /// Prefix that will be appended before all generated classes and protocols.
   String? prefix;
+
+  /// A copyright header that will get prepended to generated code.
+  Iterable<String>? copyrightHeader;
 }
 
 String _className(String? prefix, String className) {
@@ -171,6 +175,9 @@ void _writeFlutterApiDeclaration(Indent indent, Api api, ObjcOptions options) {
 /// provided [options].
 void generateObjcHeader(ObjcOptions options, Root root, StringSink sink) {
   final Indent indent = Indent(sink);
+  if (options.copyrightHeader != null) {
+    addLines(indent, options.copyrightHeader!, linePrefix: '// ');
+  }
   indent.writeln('// $generatedCodeWarning');
   indent.writeln('// $seeAlsoWarning');
   indent.writeln('#import <Foundation/Foundation.h>');
@@ -398,6 +405,9 @@ void generateObjcSource(ObjcOptions options, Root root, StringSink sink) {
       root.classes.map((Class x) => x.name).toList();
   final List<String> enumNames = root.enums.map((Enum x) => x.name).toList();
 
+  if (options.copyrightHeader != null) {
+    addLines(indent, options.copyrightHeader!, linePrefix: '// ');
+  }
   indent.writeln('// $generatedCodeWarning');
   indent.writeln('// $seeAlsoWarning');
   indent.writeln('#import "${options.header}"');

packages/pigeon/lib/pigeon_lib.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:convert';
 import 'dart:io';
 import 'dart:mirrors';
 
@@ -150,6 +151,9 @@ class PigeonOptions {
 
   /// Options that control how Dart will be generated.
   DartOptions? dartOptions = DartOptions();
+
+  /// Path to a copyright header that will get prepended to generated code.
+  String? copyrightHeader;
 }
 
 /// A collection of an AST represented as a [Root] and [Error]'s.
@@ -167,6 +171,152 @@ class ParseResults {
   final List<Error> errors;
 }
 
+String _posixify(String input) {
+  final path.Context context = path.Context(style: path.Style.posix);
+  return context.fromUri(path.toUri(path.absolute(input)));
+}
+
+Iterable<String> _lineReader(String path) sync* {
+  final String contents = File(path).readAsStringSync();
+  const LineSplitter lineSplitter = LineSplitter();
+  final List<String> lines = lineSplitter.convert(contents);
+  for (final String line in lines) {
+    yield line;
+  }
+}
+
+IOSink? _openSink(String? output) {
+  if (output == null) {
+    return null;
+  }
+  IOSink sink;
+  File file;
+  if (output == 'stdout') {
+    sink = stdout;
+  } else {
+    file = File(output);
+    sink = file.openWrite();
+  }
+  return sink;
+}
+
+/// A generator that will write code to a sink based on the contents of [PigeonOptions].
+abstract class Generator {
+  /// Returns an [IOSink] instance to be written to if the [Generator] should
+  /// generate.  If it returns `null`, the [Generator] will be skipped.
+  IOSink? shouldGenerate(PigeonOptions options);
+
+  /// Write the generated code described in [root] to [sink] using the
+  /// [options].
+  void generate(StringSink sink, PigeonOptions options, Root root);
+}
+
+/// A [Generator] that generates Dart source code.
+class DartGenerator implements Generator {
+  /// Constructor for [DartGenerator].
+  const DartGenerator();
+
+  @override
+  void generate(StringSink sink, PigeonOptions options, Root root) {
+    final DartOptions dartOptions = options.dartOptions ?? DartOptions();
+    dartOptions.copyrightHeader = options.copyrightHeader != null
+        ? _lineReader(options.copyrightHeader!)
+        : null;
+    generateDart(dartOptions, root, sink);
+  }
+
+  @override
+  IOSink? shouldGenerate(PigeonOptions options) => _openSink(options.dartOut);
+}
+
+/// A [Generator] that generates Dart test source code.
+class DartTestGenerator implements Generator {
+  /// Constructor for [DartTestGenerator].
+  const DartTestGenerator();
+
+  @override
+  void generate(StringSink sink, PigeonOptions options, Root root) {
+    final String mainPath = context.relative(
+      _posixify(options.dartOut!),
+      from: _posixify(path.dirname(options.dartTestOut!)),
+    );
+    generateTestDart(
+      options.dartOptions ?? DartOptions(),
+      root,
+      sink,
+      mainPath,
+    );
+  }
+
+  @override
+  IOSink? shouldGenerate(PigeonOptions options) {
+    if (options.dartTestOut != null && options.dartOut != null) {
+      return _openSink(options.dartTestOut);
+    } else {
+      return null;
+    }
+  }
+}
+
+/// A [Generator] that generates Objective-C header code.
+class ObjcHeaderGenerator implements Generator {
+  /// Constructor for [ObjcHeaderGenerator].
+  const ObjcHeaderGenerator();
+
+  @override
+  void generate(StringSink sink, PigeonOptions options, Root root) {
+    final ObjcOptions objcOptions = options.objcOptions ?? ObjcOptions();
+    objcOptions.copyrightHeader = options.copyrightHeader != null
+        ? _lineReader(options.copyrightHeader!)
+        : null;
+    generateObjcHeader(objcOptions, root, sink);
+  }
+
+  @override
+  IOSink? shouldGenerate(PigeonOptions options) =>
+      _openSink(options.objcHeaderOut);
+}
+
+/// A [Generator] that generates Objective-C source code.
+class ObjcSourceGenerator implements Generator {
+  /// Constructor for [ObjcSourceGenerator].
+  const ObjcSourceGenerator();
+
+  @override
+  void generate(StringSink sink, PigeonOptions options, Root root) {
+    final ObjcOptions objcOptions = options.objcOptions ?? ObjcOptions();
+    objcOptions.copyrightHeader = options.copyrightHeader != null
+        ? _lineReader(options.copyrightHeader!)
+        : null;
+    generateObjcSource(objcOptions, root, sink);
+  }
+
+  @override
+  IOSink? shouldGenerate(PigeonOptions options) =>
+      _openSink(options.objcSourceOut);
+}
+
+/// A [Generator] that generates Java source code.
+class JavaGenerator implements Generator {
+  /// Constructor for [JavaGenerator].
+  const JavaGenerator();
+
+  @override
+  void generate(StringSink sink, PigeonOptions options, Root root) {
+    if (options.javaOptions!.className == null) {
+      options.javaOptions!.className =
+          path.basenameWithoutExtension(options.javaOut!);
+    }
+    options.javaOptions!.copyrightHeader = options.copyrightHeader != null
+        ? _lineReader(options.copyrightHeader!)
+        : null;
+    generateJava(options.javaOptions ?? JavaOptions(), root, sink);
+  }
+
+  @override
+  IOSink? shouldGenerate(PigeonOptions options) => _openSink(options.javaOut);
+}
+
 /// Tool for generating code to facilitate platform channels usage.
 class Pigeon {
   /// Create and setup a [Pigeon] instance.
@@ -356,7 +506,10 @@ options:
     ..addOption('objc_header_out',
         help: 'Path to generated Objective-C header file (.h).')
     ..addOption('objc_prefix',
-        help: 'Prefix for generated Objective-C classes and protocols.');
+        help: 'Prefix for generated Objective-C classes and protocols.')
+    ..addOption('copyright_header',
+        help:
+            'Path to file with copyright header to be prepended to generated code.');
 
   /// Convert command-line arguments to [PigeonOptions].
   static PigeonOptions parseArgs(List<String> args) {
@@ -380,23 +533,10 @@ options:
       package: results['java_package'],
     );
     opts.dartOptions = DartOptions()..isNullSafe = results['dart_null_safety'];
+    opts.copyrightHeader = results['copyright_header'];
     return opts;
   }
 
-  static Future<void> _runGenerator(
-      String output, void Function(IOSink sink) func) async {
-    IOSink sink;
-    File file;
-    if (output == 'stdout') {
-      sink = stdout;
-    } else {
-      file = File(output);
-      sink = file.openWrite();
-    }
-    func(sink);
-    await sink.flush();
-  }
-
   List<Error> _validateAst(Root root) {
     final List<Error> result = <Error>[];
     final List<String> customClasses =
@@ -451,17 +591,21 @@ options:
     }
   }
 
-  static String _posixify(String input) {
-    final path.Context context = path.Context(style: path.Style.posix);
-    return context.fromUri(path.toUri(path.absolute(input)));
-  }
-
   /// The 'main' entrypoint used by the command-line tool.  [args] are the
-  /// command-line arguments.
-  static Future<int> run(List<String> args) async {
+  /// command-line arguments.  The optional parameter [generators] allows you to
+  /// customize the generators that pigeon will use.
+  static Future<int> run(List<String> args,
+      {List<Generator>? generators}) async {
     final Pigeon pigeon = Pigeon.setup();
     final PigeonOptions options = Pigeon.parseArgs(args);
-
+    final List<Generator> safeGenerators = generators ??
+        <Generator>[
+          const DartGenerator(),
+          const JavaGenerator(),
+          const DartTestGenerator(),
+          const ObjcHeaderGenerator(),
+          const ObjcSourceGenerator(),
+        ];
     _executeConfigurePigeon(options);
 
     if (options.input == null || options.dartOut == null) {
@@ -489,48 +633,12 @@ options:
       for (final Error err in parseResults.errors) {
         errors.add(Error(message: err.message, filename: options.input));
       }
-      if (options.dartOut != null) {
-        await _runGenerator(
-            options.dartOut!,
-            (StringSink sink) => generateDart(
-                options.dartOptions ?? DartOptions(), parseResults.root, sink));
+      for (final Generator generator in safeGenerators) {
+        final IOSink? sink = generator.shouldGenerate(options);
+        if (sink != null) {
+          generator.generate(sink, options, parseResults.root);
+          await sink.flush();
         }
-      if (options.dartTestOut != null && options.dartOut != null) {
-        final String mainPath = context.relative(
-          _posixify(options.dartOut!),
-          from: _posixify(path.dirname(options.dartTestOut!)),
-        );
-        await _runGenerator(
-          options.dartTestOut!,
-          (StringSink sink) => generateTestDart(
-            options.dartOptions ?? DartOptions(),
-            parseResults.root,
-            sink,
-            mainPath,
-          ),
-        );
-      }
-      if (options.objcHeaderOut != null) {
-        await _runGenerator(
-            options.objcHeaderOut!,
-            (StringSink sink) => generateObjcHeader(
-                options.objcOptions ?? ObjcOptions(), parseResults.root, sink));
-      }
-      if (options.objcSourceOut != null) {
-        await _runGenerator(
-            options.objcSourceOut!,
-            (StringSink sink) => generateObjcSource(
-                options.objcOptions ?? ObjcOptions(), parseResults.root, sink));
-      }
-      if (options.javaOut != null) {
-        if (options.javaOptions!.className == null) {
-          options.javaOptions!.className =
-              path.basenameWithoutExtension(options.javaOut!);
-        }
-        await _runGenerator(
-            options.javaOut!,
-            (StringSink sink) => generateJava(
-                options.javaOptions ?? JavaOptions(), parseResults.root, sink));
       }
     } else {
       errors.add(Error(message: 'No pigeon classes found, nothing generated.'));

packages/pigeon/run_tests.sh

@@ -40,6 +40,7 @@ if [ $java_version == "8" ]; then
 else
   javac_bootclasspath=
 fi
+run_pigeon="pub run pigeon --copyright_header ./copyright_header.txt"
 
 ###############################################################################
 # Helper Functions
@@ -60,7 +61,7 @@ test_pigeon_ios() {
   echo "test_pigeon_ios($1)"
   temp_dir=$(mktmpdir)
 
-  pub run pigeon \
+  $run_pigeon \
     --no-dart_null_safety \
     --input $1 \
     --dart_out $temp_dir/pigeon.dart \
@@ -88,7 +89,7 @@ test_pigeon_android() {
   echo "test_pigeon_android($1)"
   temp_dir=$(mktmpdir)
 
-  pub run pigeon \
+  $run_pigeon \
     --input $1 \
     --dart_out $temp_dir/pigeon.dart \
     --java_out $temp_dir/Pigeon.java \
@@ -119,12 +120,12 @@ test_pigeon_dart() {
   temp_dir_1=$(mktmpdir)
   temp_dir_2=$(mktmpdir)
 
-  pub run pigeon \
+  $run_pigeon \
     --input $1 \
     --dart_out $temp_dir_1/pigeon.dart &
   null_safe_gen_pid=$!
 
-  pub run pigeon \
+  $run_pigeon \
     --no-dart_null_safety \
     --input $1 \
     --dart_out $temp_dir_2/pigeon.dart &
@@ -190,12 +191,12 @@ run_dart_unittests() {
 }
 
 test_running_without_arguments() {
-  pub run pigeon 1>/dev/null
+  $run_pigeon 1>/dev/null
 }
 
 run_flutter_unittests() {
   pushd $PWD
-  pub run pigeon \
+  $run_pigeon \
     --input pigeons/flutter_unittests.dart \
     --dart_out platform_tests/flutter_null_safe_unit_tests/lib/null_safe_pigeon.dart
   cd platform_tests/flutter_null_safe_unit_tests
@@ -206,7 +207,7 @@ run_flutter_unittests() {
 
 run_mock_handler_tests() {
   pushd $PWD
-  pub run pigeon \
+  $run_pigeon \
     --input pigeons/message.dart \
     --dart_out mock_handler_tester/test/message.dart \
     --dart_test_out mock_handler_tester/test/test.dart
@@ -273,13 +274,13 @@ run_objc_compilation_tests() {
 }
 
 run_ios_unittests() {
-  pub run pigeon \
+  $run_pigeon \
     --no-dart_null_safety \
     --input pigeons/message.dart \
     --dart_out /dev/null \
     --objc_header_out platform_tests/ios_unit_tests/ios/Runner/messages.h \
     --objc_source_out platform_tests/ios_unit_tests/ios/Runner/messages.m
-  pub run pigeon \
+  $run_pigeon \
     --no-dart_null_safety \
     --input pigeons/async_handlers.dart \
     --dart_out /dev/null \
@@ -307,7 +308,7 @@ run_ios_e2e_tests() {
   DARTLE_M="e2e_tests/test_objc/ios/Runner/dartle.m"
   DARTLE_DART="e2e_tests/test_objc/lib/dartle.dart"
   PIGEON_JAVA="e2e_tests/test_objc/android/app/src/main/java/io/flutter/plugins/Pigeon.java"
-  pub run pigeon \
+  $run_pigeon \
     --input pigeons/message.dart \
     --dart_out $DARTLE_DART \
     --objc_header_out $DARTLE_H \
@@ -335,7 +336,7 @@ run_formatter() {
 
 run_android_unittests() {
   pushd $PWD
-  pub run pigeon \
+  $run_pigeon \
     --input pigeons/android_unittests.dart \
     --dart_out /dev/null \
     --java_out platform_tests/android_unit_tests/android/app/src/main/java/com/example/android_unit_tests/Pigeon.java \

packages/pigeon/test/dart_generator_test.dart

@@ -454,4 +454,20 @@ void main() {
     final String code = sink.toString();
     expect(code, matches('channel.send[(]null[)]'));
   });
+
+  Iterable<String> _makeIterable(String string) sync* {
+    yield string;
+  }
+
+  test('header', () {
+    final Root root = Root(apis: <Api>[], classes: <Class>[], enums: <Enum>[]);
+    final StringBuffer sink = StringBuffer();
+    generateDart(
+        DartOptions(
+            isNullSafe: false, copyrightHeader: _makeIterable('hello world')),
+        root,
+        sink);
+    final String code = sink.toString();
+    expect(code, startsWith('// hello world'));
+  });
 }

packages/pigeon/test/java_generator_test.dart

@@ -413,4 +413,20 @@ void main() {
     expect(code, contains('toMapResult.put("enum1", enum1.index);'));
     expect(code, contains('fromMapResult.enum1 = Enum1.values()[(int)enum1];'));
   });
+
+  Iterable<String> _makeIterable(String string) sync* {
+    yield string;
+  }
+
+  test('header', () {
+    final Root root = Root(apis: <Api>[], classes: <Class>[], enums: <Enum>[]);
+    final StringBuffer sink = StringBuffer();
+    final JavaOptions javaOptions = JavaOptions(
+      className: 'Messages',
+      copyrightHeader: _makeIterable('hello world'),
+    );
+    generateJava(javaOptions, root, sink);
+    final String code = sink.toString();
+    expect(code, startsWith('// hello world'));
+  });
 }

packages/pigeon/test/objc_generator_test.dart

@@ -682,4 +682,36 @@ void main() {
         contains(
             '[api doSomething:^(ABCOutput *_Nullable output, FlutterError *_Nullable error) {'));
   });
+
+  Iterable<String> _makeIterable(String string) sync* {
+    yield string;
+  }
+
+  test('source copyright', () {
+    final Root root = Root(apis: <Api>[], classes: <Class>[], enums: <Enum>[]);
+    final StringBuffer sink = StringBuffer();
+    generateObjcSource(
+        ObjcOptions(
+            header: 'foo.h',
+            prefix: 'ABC',
+            copyrightHeader: _makeIterable('hello world')),
+        root,
+        sink);
+    final String code = sink.toString();
+    expect(code, startsWith('// hello world'));
+  });
+
+  test('header copyright', () {
+    final Root root = Root(apis: <Api>[], classes: <Class>[], enums: <Enum>[]);
+    final StringBuffer sink = StringBuffer();
+    generateObjcHeader(
+        ObjcOptions(
+            header: 'foo.h',
+            prefix: 'ABC',
+            copyrightHeader: _makeIterable('hello world')),
+        root,
+        sink);
+    final String code = sink.toString();
+    expect(code, startsWith('// hello world'));
+  });
 }

packages/pigeon/test/pigeon_lib_test.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:pigeon/ast.dart';
+import 'package:pigeon/java_generator.dart';
 import 'package:pigeon/pigeon_lib.dart';
 import 'package:test/test.dart';
 
@@ -263,4 +264,52 @@ void main() {
         Pigeon.parseArgs(<String>['--dart_null_safety']);
     expect(results.dartOptions?.isNullSafe, isTrue);
   });
+
+  test('copyright flag', () {
+    final PigeonOptions results =
+        Pigeon.parseArgs(<String>['--copyright_header', 'foobar.txt']);
+    expect(results.copyrightHeader, 'foobar.txt');
+  });
+
+  test('Dart generater copyright flag', () {
+    final Root root = Root(apis: <Api>[], classes: <Class>[], enums: <Enum>[]);
+    final PigeonOptions options = PigeonOptions();
+    options.copyrightHeader = './copyright_header.txt';
+    const DartGenerator dartGenerator = DartGenerator();
+    final StringBuffer buffer = StringBuffer();
+    dartGenerator.generate(buffer, options, root);
+    expect(buffer.toString(), startsWith('// Copyright 2013'));
+  });
+
+  test('Java generater copyright flag', () {
+    final Root root = Root(apis: <Api>[], classes: <Class>[], enums: <Enum>[]);
+    final PigeonOptions options = PigeonOptions();
+    options.javaOut = 'Foo.java';
+    options.javaOptions = JavaOptions();
+    options.copyrightHeader = './copyright_header.txt';
+    const JavaGenerator javaGenerator = JavaGenerator();
+    final StringBuffer buffer = StringBuffer();
+    javaGenerator.generate(buffer, options, root);
+    expect(buffer.toString(), startsWith('// Copyright 2013'));
+  });
+
+  test('Objc header generater copyright flag', () {
+    final Root root = Root(apis: <Api>[], classes: <Class>[], enums: <Enum>[]);
+    final PigeonOptions options = PigeonOptions();
+    options.copyrightHeader = './copyright_header.txt';
+    const ObjcHeaderGenerator objcHeaderGenerator = ObjcHeaderGenerator();
+    final StringBuffer buffer = StringBuffer();
+    objcHeaderGenerator.generate(buffer, options, root);
+    expect(buffer.toString(), startsWith('// Copyright 2013'));
+  });
+
+  test('Objc source generater copyright flag', () {
+    final Root root = Root(apis: <Api>[], classes: <Class>[], enums: <Enum>[]);
+    final PigeonOptions options = PigeonOptions();
+    options.copyrightHeader = './copyright_header.txt';
+    const ObjcSourceGenerator objcSourceGenerator = ObjcSourceGenerator();
+    final StringBuffer buffer = StringBuffer();
+    objcSourceGenerator.generate(buffer, options, root);
+    expect(buffer.toString(), startsWith('// Copyright 2013'));
+  });
 }