generateForAnnotatedElement method

  1. @override
dynamic generateForAnnotatedElement(
  1. Element element,
  2. ConstantReader annotation,
  3. BuildStep buildStep
)

Implement to return source code to generate for element.

This method is invoked based on finding elements annotated with an instance of T. The annotation is provided as a ConstantReader.

Supported return values include a single String or multiple String instances within an Iterable or Stream. It is also valid to return a Future of String, Iterable, or Stream.

Implementations should return null when no content is generated. Empty or whitespace-only String instances are also ignored.

Implementation

@override
generateForAnnotatedElement(
  Element element,
  ConstantReader annotation,
  BuildStep buildStep,
) {
  if (element is! ClassElement) {
    throw InvalidGenerationSourceError(
        'Generator cannot target `${element.name}`.',
        todo: 'Remove the EnumGeneration annotation from `${element.name}`.',
        element: element);
  }

  final fields = element.fields
      .where((field) => !field.isStatic && !field.isSynthetic)
      .map((field) => field.name)
      .toList();

  // enumの文字列を生成
  final enumName = '${element.name}Field';
  final enumContent = fields.map((name) => '  $name').join(',\n');

  // enum定義を返す
  return 'enum $enumName {\n$enumContent\n}';
}