add auto dispose macro example (#2210)

jakemac53 · web-flow · commit 6cfc61d4318b · 2022-04-21T10:09:04.000-07:00
diff --git a/analysis_options.yaml b/analysis_options.yaml
@@ -2,6 +2,7 @@ analyzer:
   exclude:
     - accepted/2.3/spread-collections/examples/**
     # TODO: remove these when the analyzer supports macros
+    - working/macros/example/lib/auto_dispose.dart
     - working/macros/example/lib/data_class.dart
     - working/macros/example/lib/observable.dart
     - working/macros/example/bin/user_main.dart
diff --git a/working/macros/example/bin/run.dart b/working/macros/example/bin/run.dart
@@ -20,13 +20,21 @@ void main() async {
   log('Bootstrapping macro program (${bootstrapFile.path}).');
   var dataClassUri = Uri.parse('package:macro_proposal/data_class.dart');
   var observableUri = Uri.parse('package:macro_proposal/observable.dart');
+  var autoDisposableUri = Uri.parse('package:macro_proposal/auto_dispose.dart');
   var bootstrapContent = bootstrapMacroIsolate({
     dataClassUri.toString(): {
+      'AutoConstructor': [''],
+      'CopyWith': [''],
       'DataClass': [''],
+      'HashCode': [''],
+      'ToString': [''],
     },
     observableUri.toString(): {
       'Observable': [''],
     },
+    autoDisposableUri.toString(): {
+      'AutoDispose': [''],
+    },
   }, SerializationMode.byteDataClient);
   bootstrapFile.writeAsStringSync(bootstrapContent);
   var bootstrapKernelFile =
@@ -85,6 +93,8 @@ void main() async {
     '$dataClassUri;${bootstrapKernelFile.path}',
     '--precompiled-macro',
     '$observableUri;${bootstrapKernelFile.path}',
+    '--precompiled-macro',
+    '$autoDisposableUri;${bootstrapKernelFile.path}',
     '--macro-serialization-mode=bytedata',
     '--input-linked',
     bootstrapKernelFile.path,
diff --git a/working/macros/example/bin/user_main.dart b/working/macros/example/bin/user_main.dart
@@ -4,6 +4,7 @@
 
 import 'dart:math';
 
+import 'package:macro_proposal/auto_dispose.dart';
 import 'package:macro_proposal/data_class.dart';
 import 'package:macro_proposal/observable.dart';
 
@@ -27,6 +28,9 @@ void main() {
   observableUser
     ..age = 11
     ..name = 'Greg';
+
+  var state = MyState.gen(a: ADisposable(), b: BDisposable(), c: 'hello world');
+  state.dispose();
 }
 
 @DataClass()
@@ -54,3 +58,32 @@ class ObservableUser {
   })  : _age = age,
         _name = name;
 }
+
+// TODO: remove @AutoConstructor once we can, today it is required.
+@AutoConstructor()
+class State {
+  void dispose() {
+    print('disposing of State $this');
+  }
+}
+
+@AutoDispose()
+@AutoConstructor()
+class MyState extends State {
+  final ADisposable a;
+  final ADisposable? a2;
+  final BDisposable b;
+  final String c;
+}
+
+class ADisposable implements Disposable {
+  void dispose() {
+    print('disposing of ADisposable');
+  }
+}
+
+class BDisposable implements Disposable {
+  void dispose() {
+    print('disposing of BDisposable');
+  }
+}
diff --git a/working/macros/example/lib/auto_dispose.dart b/working/macros/example/lib/auto_dispose.dart
@@ -0,0 +1,66 @@
+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// There is no public API exposed yet, the in progress api lives here.
+import 'package:_fe_analyzer_shared/src/macros/api.dart';
+
+// Interface for disposable things.
+abstract class Disposable {
+  void dispose();
+}
+
+macro class AutoDispose implements ClassDeclarationsMacro, ClassDefinitionMacro {
+  const AutoDispose();
+
+  @override
+  void buildDeclarationsForClass(
+      ClassDeclaration clazz, ClassMemberDeclarationBuilder builder) async {
+    var methods = await builder.methodsOf(clazz);
+    if (methods.any((d) => d.identifier.name == 'dispose')) {
+      // Don't need to add the dispose method, it already exists.
+      return;
+    }
+
+    builder.declareInClass(DeclarationCode.fromParts([
+      'external void dispose();',
+    ]));
+  }
+
+  @override
+  Future<void> buildDefinitionForClass(
+      ClassDeclaration clazz, ClassDefinitionBuilder builder) async {
+    var disposableIdentifier =
+        // ignore: deprecated_member_use
+        await builder.resolveIdentifier(
+            Uri.parse('package:macro_proposal/auto_dispose.dart'),
+            'Disposable');
+    var disposableType = await builder
+        .resolve(NamedTypeAnnotationCode(name: disposableIdentifier));
+
+    var disposeCalls = <Code>[];
+    var fields = await builder.fieldsOf(clazz);
+    for (var field in fields) {
+      var type = await builder.resolve(field.type.code);
+      if (!await type.isSubtypeOf(disposableType)) continue;
+      disposeCalls.add(Code.fromParts([
+        '\n',
+        field.identifier,
+        if (field.type.isNullable) '?',
+        '.dispose();',
+      ]));
+    }
+    // Augment the dispose method by injecting all the new dispose calls after
+    // the call to `augment super()`, which should be calling `super.dispose()`
+    // already.
+    var disposeMethod = (await builder.methodsOf(clazz))
+        .firstWhere((method) => method.identifier.name == 'dispose');
+    var disposeBuilder = await builder.buildMethod(disposeMethod.identifier);
+    disposeBuilder.augment(FunctionBodyCode.fromParts([
+      '{\n',
+      if (disposeMethod.isExternal) 'super.dispose();' else 'augment super();',
+      ...disposeCalls,
+      '}',
+    ]));
+  }
+}
diff --git a/working/macros/example/lib/data_class.dart b/working/macros/example/lib/data_class.dart
@@ -13,29 +13,27 @@ macro class DataClass
   Future<void> buildDeclarationsForClass(
       ClassDeclaration clazz, ClassMemberDeclarationBuilder context) async {
     await Future.wait([
-      autoConstructor.buildDeclarationsForClass(clazz, context),
-      copyWith.buildDeclarationsForClass(clazz, context),
-      hashCode.buildDeclarationsForClass(clazz, context),
-      equality.buildDeclarationsForClass(clazz, context),
-      toString.buildDeclarationsForClass(clazz, context),
+      AutoConstructor().buildDeclarationsForClass(clazz, context),
+      CopyWith().buildDeclarationsForClass(clazz, context),
+      HashCode().buildDeclarationsForClass(clazz, context),
+      Equality().buildDeclarationsForClass(clazz, context),
+      ToString().buildDeclarationsForClass(clazz, context),
     ]);
   }
 
   @override
   Future<void> buildDefinitionForClass(
       ClassDeclaration clazz, ClassDefinitionBuilder builder) async {
     await Future.wait([
-      hashCode.buildDefinitionForClass(clazz, builder),
-      equality.buildDefinitionForClass(clazz, builder),
-      toString.buildDefinitionForClass(clazz, builder),
+      HashCode().buildDefinitionForClass(clazz, builder),
+      Equality().buildDefinitionForClass(clazz, builder),
+      ToString().buildDefinitionForClass(clazz, builder),
     ]);
   }
 }
 
-const autoConstructor = _AutoConstructor();
-
-macro class _AutoConstructor implements ClassDeclarationsMacro {
-  const _AutoConstructor();
+macro class AutoConstructor implements ClassDeclarationsMacro {
+  const AutoConstructor();
 
   @override
   Future<void> buildDeclarationsForClass(
@@ -46,13 +44,14 @@ macro class _AutoConstructor implements ClassDeclarationsMacro {
           'Cannot generate an unnamed constructor because one already exists');
     }
 
-    // Don't use the identifier here because it should just be the raw name.
-    var parts = <Object>[clazz.identifier.name, '.gen({'];
+    var params = <Object>[];
     // Add all the fields of `declaration` as named parameters.
     var fields = await builder.fieldsOf(clazz);
-    for (var field in fields) {
-      var requiredKeyword = field.type.isNullable ? '' : 'required ';
-      parts.addAll(['\n${requiredKeyword}', field.identifier, ',']);
+    if (fields.isNotEmpty) {
+      for (var field in fields) {
+        var requiredKeyword = field.type.isNullable ? '' : 'required ';
+        params.addAll(['\n${requiredKeyword}', field.identifier, ',']);
+      }
     }
 
     // The object type from dart:core.
@@ -78,22 +77,32 @@ macro class _AutoConstructor implements ClassDeclarationsMacro {
       // parameters in this constructor.
       for (var param in superconstructor.positionalParameters) {
         var requiredKeyword = param.isRequired ? 'required' : '';
-        parts.addAll([
+        params.addAll([
           '\n$requiredKeyword',
           param.type.code,
           ' ${param.identifier.name},',
         ]);
       }
       for (var param in superconstructor.namedParameters) {
         var requiredKeyword = param.isRequired ? '' : 'required ';
-        parts.addAll([
+        params.addAll([
           '\n$requiredKeyword',
           param.type.code,
           ' ${param.identifier.name},',
         ]);
       }
     }
-    parts.add('\n})');
+
+    bool hasParams = params.isNotEmpty;
+    List<Object> parts = [
+    // Don't use the identifier here because it should just be the raw name.
+      clazz.identifier.name,
+      '.gen(',
+      if (hasParams) '{',
+      ...params,
+      if (hasParams) '}',
+      ')',
+    ];
     if (superconstructor != null) {
       parts.addAll([' : super.', superconstructor.identifier.name, '(']);
       for (var param in superconstructor.positionalParameters) {
@@ -111,11 +120,9 @@ macro class _AutoConstructor implements ClassDeclarationsMacro {
   }
 }
 
-const copyWith = _CopyWith();
-
 // TODO: How to deal with overriding nullable fields to `null`?
-macro class _CopyWith implements ClassDeclarationsMacro {
-  const _CopyWith();
+macro class CopyWith implements ClassDeclarationsMacro {
+  const CopyWith();
 
   @override
   Future<void> buildDeclarationsForClass(
@@ -141,24 +148,25 @@ macro class _CopyWith implements ClassDeclarationsMacro {
           field.identifier,
         ]),
     ];
+    var hasParams = namedParams.isNotEmpty;
     builder.declareInClass(DeclarationCode.fromParts([
       clazz.identifier,
-      ' copyWith({',
+      ' copyWith(',
+      if (hasParams) '{',
       ...namedParams.joinAsCode(', '),
-      ',})',
+      if (hasParams) '}',
+      ')',
       // TODO: We assume this constructor exists, but should check
       '=> ', clazz.identifier, '.gen(',
       ...args.joinAsCode(', '),
-      ', );',
+      ');',
     ]));
   }
 }
 
-const hashCode = _HashCode();
-
-macro class _HashCode
+macro class HashCode
     implements ClassDeclarationsMacro, ClassDefinitionMacro {
-  const _HashCode();
+  const HashCode();
 
   @override
   Future<void> buildDeclarationsForClass(
@@ -189,11 +197,9 @@ macro class _HashCode
   }
 }
 
-const equality = _Equality();
-
-macro class _Equality
+macro class Equality
     implements ClassDeclarationsMacro, ClassDefinitionMacro {
-  const _Equality();
+  const Equality();
 
   @override
   Future<void> buildDeclarationsForClass(
@@ -234,11 +240,10 @@ macro class _Equality
   }
 }
 
-const toString = _ToString();
 
-macro class _ToString
+macro class ToString
     implements ClassDeclarationsMacro, ClassDefinitionMacro {
-  const _ToString();
+  const ToString();
 
   @override
   Future<void> buildDeclarationsForClass(
