generateForAnnotatedElement method

@override String generateForAnnotatedElement(Element element, ConstantReader annotation, 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
String generateForAnnotatedElement(
    Element element, ConstantReader annotation, BuildStep buildStep) {
  if (element is! ClassElement) {
    throw InvalidGenerationSourceError(
        '${element.displayName} is not a class and cannot be annotated with @CopyWith',
        element: element,
        todo: 'Add CopyWith annotation to a class');
  }

  final extension = Extension((b) => b //
    ..name = '${element.displayName}CopyWithExtension'
    ..on = refer(element.displayName)
    ..methods.add(_generateCopyWith(element)));

  final emitter = DartEmitter();
  return '${extension.accept(emitter)}';
}