Fixing the generic annotations parsing (#22)

* adding the failing test and shortening the extension name

* test fix

* adding a sophisticated test case

* fixing the generic annotation parsing

* comments, cleanup, and asserts

* extending _typeParametersNames function and removing _typeParametersAnnotation

* naming

* version bump

* minor correction

README.md

@@ -1,4 +1,4 @@
-Provides [source_gen](https://pub.dev/packages/source_gen) `Generator` for generating `copyWith` extensions. For more info on this package check out [my blog article](https://www.alexander-kirsch.com/blog/dart-extensions/).
+Provides [source_gen](https://pub.dev/packages/source_gen) `Generator` for generating `copyWith` extensions. For more info on this package check out [my blog article](https://www.alexander-kirsch.com/blog/dart-extensions/) or the [main documentation file](https://pub.dev/packages/copy_with_extension_gen).
 
 ## copy_with_extension
 * Package: [copy_with_extension](https://pub.dev/packages/copy_with_extension)

copy_with_extension/CHANGELOG.md

@@ -1,3 +1,6 @@
+## 1.4.0 Improving genetic compatibility
+* Fixes issue with generating code for some classes with generic type parameters.
+
 ## 1.3.0 Immutable Fields
 * Fixes the `boolean-expression-must-not-be-null-exception` issue
 * Introduces `immutable` field annotation

copy_with_extension/pubspec.yaml

@@ -1,5 +1,5 @@
 name: copy_with_extension
-version: 1.3.0
+version: 1.4.0
 description: Annotation for generating `copyWith` extensions code using `copy_with_extension_gen`.
 homepage: https://github.com/numen31337/copy_with_extension/tree/master/copy_with_extension
 repository: https://github.com/numen31337/copy_with_extension
@@ -12,4 +12,4 @@ dev_dependencies:
   pedantic: ^1.9.0
   build_runner: ^1.10.3
   test: ^1.0.0
-  copy_with_extension_gen: ^1.3.0
+  copy_with_extension_gen: ^1.4.0

copy_with_extension_gen/CHANGELOG.md

@@ -1,3 +1,6 @@
+## 1.4.0 Improving genetic compatibility
+* Fixes issue with generating code for some classes with generic type parameters.
+
 ## 1.3.1 README Update
 * Update README.md
 

copy_with_extension_gen/README.md

@@ -5,8 +5,8 @@ Provides [Dart Build System](https://pub.dev/packages/build) builder for generat
 ## Usage
 
 #### In your `pubspec.yaml` file:
-- Add to `dependencies` section `copy_with_extension: ^1.3.0`
-- Add to `dev_dependencies` section `copy_with_extension_gen: ^1.3.0`
+- Add to `dependencies` section `copy_with_extension: ^1.4.0`
+- Add to `dev_dependencies` section `copy_with_extension_gen: ^1.4.0`
 - Add to `dev_dependencies` section `build_runner: ^1.10.3`
 - Set `environment` to at least Dart 2.9.0 version like so: `">=2.9.0 <3.0.0"`
 
@@ -22,12 +22,12 @@ environment:
 
 dependencies:
   ...
-  copy_with_extension: ^1.3.0
+  copy_with_extension: ^1.4.0
 
 dev_dependencies:
   ...
   build_runner: ^1.10.3
-  copy_with_extension_gen: ^1.3.0
+  copy_with_extension_gen: ^1.4.0
 ```
 
 #### Annotate your class with `CopyWith` annotation:

copy_with_extension_gen/lib/src/copy_with_generator.dart

@@ -20,52 +20,52 @@ class CopyWithGenerator extends GeneratorForAnnotation<CopyWith> {
     BuildStep buildStep,
   ) {
     if (element is! ClassElement) throw '$element is not a ClassElement';
+
     final classElement = element as ClassElement;
     final sortedFields = _sortedConstructorFields(classElement);
     final generateCopyWithNull =
         annotation.read('generateCopyWithNull').boolValue;
 
-    final typeParametersAnnotation = _typeParametersAnnotation(classElement);
-    final typeParametersNames = _typeParametersNames(classElement);
+    final typeParametersAnnotation = _typeParametersString(classElement, false);
+    final typeParametersNames = _typeParametersString(classElement, true);
     final typeAnnotation = classElement.name + typeParametersNames;
 
     return '''
-    extension ${classElement.name}CopyWithExtension$typeParametersAnnotation on ${classElement.name}$typeParametersNames {
+    extension ${classElement.name}CopyWith$typeParametersAnnotation on ${classElement.name}$typeParametersNames {
       ${_copyWithPart(typeAnnotation, sortedFields)}
       ${generateCopyWithNull ? _copyWithNullPart(typeAnnotation, sortedFields) : ""}
     }
     ''';
   }
 
-  String _typeParametersNames(ClassElement classElement) {
-    final names = classElement.typeParameters.map((e) => e.name).join(',');
+  ///Returns parameter names or full parameters declaration declared by this class or an empty string.
+  ///
+  ///If `nameOnly` is `true`: `class MyClass<T extends String, Y>` returns `<T, Y>`.
+  ///
+  ///If `nameOnly` is `false`: `class MyClass<T extends String, Y>` returns `<T extends String, Y>`.
+  String _typeParametersString(ClassElement classElement, bool nameOnly) {
+    assert(classElement is ClassElement);
+    assert(nameOnly is bool);
+
+    final names = classElement.typeParameters
+        .map(
+          (e) => nameOnly ? e.name : e.getDisplayString(withNullability: false),
+        )
+        .join(',');
     if (names.isNotEmpty) {
       return '<$names>';
     } else {
       return '';
     }
   }
 
-  String _typeParametersAnnotation(ClassElement classElement) {
-    final classDisplayString =
-        classElement.getDisplayString(withNullability: false);
-    final startIndex = classDisplayString.indexOf('<');
-    final endIndex = classDisplayString.indexOf('>');
-
-    if (startIndex != -1 && endIndex != -1) {
-      return classDisplayString.substring(
-        startIndex,
-        endIndex + 1,
-      );
-    } else {
-      return '';
-    }
-  }
-
+  ///Generates the complete `copyWith` function.
   String _copyWithPart(
     String typeAnnotation,
     List<_FieldInfo> sortedFields,
   ) {
+    assert(typeAnnotation is String && sortedFields is List<_FieldInfo>);
+
     final constructorInput = sortedFields.fold<String>(
       '',
       (r, v) {
@@ -94,10 +94,13 @@ class CopyWithGenerator extends GeneratorForAnnotation<CopyWith> {
     ''';
   }
 
+  ///Generates the complete `copyWithNull` function.
   String _copyWithNullPart(
     String typeAnnotation,
     List<_FieldInfo> sortedFields,
   ) {
+    assert(typeAnnotation is String && sortedFields is List<_FieldInfo>);
+
     final nullConstructorInput = sortedFields.fold<String>(
       '',
       (r, v) {
@@ -126,6 +129,8 @@ class CopyWithGenerator extends GeneratorForAnnotation<CopyWith> {
     ''';
   }
 
+  ///Generates a list of `_FieldInfo` for each class field that will be a part of the code generation process.
+  ///The resulting array is sorted by the field name. `Throws` on error.
   List<_FieldInfo> _sortedConstructorFields(ClassElement element) {
     assert(element is ClassElement);
 
@@ -152,6 +157,7 @@ class CopyWithGenerator extends GeneratorForAnnotation<CopyWith> {
   }
 }
 
+///Represents a single class field with the additional metadata needed for code generation.
 class _FieldInfo {
   final String name;
   final String type;
@@ -160,12 +166,18 @@ class _FieldInfo {
   _FieldInfo(ParameterElement element, ClassElement classElement)
       : name = element.name,
         type = element.type.getDisplayString(withNullability: false),
-        immutable = _readFieldOptions(element, classElement).immutable;
+        immutable = _readFieldOptions(element, classElement).immutable,
+        assert(element.name is String),
+        assert(element.type.getDisplayString(withNullability: false) is String),
+        assert(_readFieldOptions(element, classElement).immutable is bool);
 
   static CopyWithField _readFieldOptions(
     ParameterElement element,
     ClassElement classElement,
   ) {
+    assert(element is Element);
+    assert(classElement is ClassElement);
+
     final fieldElement = classElement.getField(element.name);
     if (fieldElement is! FieldElement) {
       return CopyWithField();

copy_with_extension_gen/pubspec.yaml

@@ -1,5 +1,5 @@
 name: copy_with_extension_gen
-version: 1.3.1
+version: 1.4.0
 description: Automatically generating `copyWith` extensions code for classes with `@CopyWith()` annotation.
 repository: https://github.com/numen31337/copy_with_extension
 homepage: https://github.com/numen31337/copy_with_extension/tree/master/copy_with_extension_gen
@@ -12,7 +12,7 @@ dependencies:
   analyzer: ">=0.39.0 <1.0.0"
   build: ^1.0.0
   source_gen: ">=0.9.0 <1.0.0"
-  copy_with_extension: ^1.3.0
+  copy_with_extension: ^1.4.0
 
 dev_dependencies:
   pedantic: ^1.9.0

copy_with_extension_gen/test/constants.dart

@@ -39,8 +39,7 @@ part of 'test_case_class.dart';
 // CopyWithGenerator
 // **************************************************************************
 
-extension Test_Case_ClassCopyWithExtension<T extends String>
-    on Test_Case_Class<T> {
+extension Test_Case_ClassCopyWith<T extends String> on Test_Case_Class<T> {
   Test_Case_Class<T> copyWith({
     T id,
   }) {

copy_with_extension_test/lib/implements_test_case.dart

@@ -0,0 +1,81 @@
+import 'package:meta/meta.dart';
+import 'package:copy_with_extension/copy_with_extension.dart';
+
+//Won't work without it!
+part 'implements_test_case.g.dart';
+
+abstract class Abstract {
+  final String aField;
+  Abstract(this.aField);
+}
+
+abstract class AbstractWithType<T> {
+  final T tField;
+  AbstractWithType(this.tField);
+}
+
+abstract class AbstractWithType1<T> {
+  final T t1Field;
+  AbstractWithType1(this.t1Field);
+}
+
+abstract class AbstractWithType2<T, Y> {
+  final T saField;
+  final Y sa1Field;
+  AbstractWithType2(this.saField, this.sa1Field);
+}
+
+@immutable
+@CopyWith()
+class Basic implements Abstract {
+  Basic({this.aField});
+
+  @override
+  final String aField;
+}
+
+@immutable
+@CopyWith()
+class WithGenericType<T> implements AbstractWithType<T> {
+  WithGenericType({this.tField});
+
+  @override
+  final T tField;
+}
+
+@immutable
+@CopyWith()
+class WithSpecificType implements AbstractWithType<String> {
+  WithSpecificType({this.tField});
+
+  @override
+  final String tField;
+}
+
+@immutable
+@CopyWith()
+class WithBoth<T extends String, Y>
+    implements
+        Abstract,
+        AbstractWithType<T>,
+        AbstractWithType1<int>,
+        AbstractWithType2<String, Y> {
+  WithBoth({
+    this.aField,
+    this.tField,
+    this.t1Field,
+    this.saField,
+    this.sa1Field,
+  });
+
+  @override
+  final String aField;
+  @override
+  final T tField;
+  @override
+  final int t1Field;
+  @override
+  final String saField;
+  @override
+  final Y sa1Field;
+}