generateForAnnotatedElement method

  1. @override
FutureOr<String> 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. When multiple values are returned through an iterable or stream they will be deduplicated. Typically each value will be an independent unit of code and the deduplication prevents re-defining the same member multiple times. For example if multiple annotated elements may need a specific utility method available it can be output for each one, and the single deduplicated definition can be shared.

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

Implementation

@override
FutureOr<String> generateForAnnotatedElement(
  Element element,
  ConstantReader annotation,
  BuildStep buildStep,
) async {
  if (element is! ClassElement) {
    throw InvalidGenerationSourceError(
      'ShellScripts annotation can only be applied to classes.',
      element: element,
    );
  }

  final scriptsPath = annotation.read('scriptsPath').stringValue;
  final className = '${element.name}Scripts';
  final enableParameters = annotation.read('enableParameters').boolValue;
  final methodPrefix = annotation.read('methodPrefix').stringValue;

  final annotatedMethods = _getAnnotatedMethods(element);
  if (annotatedMethods.isEmpty) {
    throw InvalidGenerationSourceError(
      'No methods with @ShellScript annotation found in class ${element.name}',
      element: element,
    );
  }

  final methodsWithContent = <_MethodWithContent>[];

  // Process all annotated methods, read their associated script assets
  for (final method in annotatedMethods) {
    final scriptAnnotation = _getShellScriptAnnotation(method);
    if (scriptAnnotation == null) continue;

    final fileName = scriptAnnotation.read('fileName').stringValue;
    final assetId = AssetId(
      buildStep.inputId.package,
      path.join(scriptsPath, fileName),
    );

    if (await buildStep.canRead(assetId)) {
      final content = await buildStep.readAsString(assetId);
      methodsWithContent.add(_MethodWithContent(method, content));
    } else {
      log.warning(
          'Script asset not found: ${assetId.path} for method ${method.name}');
    }
  }

  if (methodsWithContent.isEmpty) {
    throw InvalidGenerationSourceError(
      'No valid script assets found for annotated methods in class ${element.name}',
      element: element,
    );
  }

  final buffer = StringBuffer();
  _generateClassHeader(buffer, className);

  // Generate constants for all valid methods
  for (final item in methodsWithContent) {
    _generateScriptConstant(
      buffer,
      item.content,
      item.method.name,
      methodPrefix,
    );
  }

  // Generate accessor methods
  for (final item in methodsWithContent) {
    _generateAccessMethod(
      buffer,
      item.method,
      methodPrefix,
      enableParameters,
    );
  }

  if (enableParameters) {
    buffer.writeln(ShellScriptParameterizer.generateBuildScriptMethod());
  }

  buffer.writeln('}');

  return buffer.toString();
}