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 '@BleObject can only be used on classes';
  }

  final className = element.name;
  print('Generating parser for class: $className');

  // Read default values from @BleObject annotation
  final defaultEndian = _readDefaultEndian(annotation);
  final defaultSigned = _readDefaultSigned(annotation);

  final buffer = StringBuffer();

  // Generate private parsing function: _$ClassNameFromBytes
  buffer.writeln('$className _\$${className}FromBytes(List<int> rawData) {');
  buffer.writeln(
    '  final view = ByteData.sublistView(Uint8List.fromList(rawData));',
  );

  int autoOffset = 0;
  List<String> constructorArgs = [];

  // Iterate through all fields
  for (var field in element.fields) {
    if (field.isStatic) continue;

    // Get @BleField annotation with defaults applied
    final fieldAnn = _getAnnotation(field, defaultEndian, defaultSigned);
    if (fieldAnn == null) continue;

    // 1. Determine offset
    int currentOffset = fieldAnn.offset ?? autoOffset;

    // 2. Generate read expression
    String readExpr = _genReadExpr(fieldAnn, currentOffset);

    // 3. Store constructor arguments
    constructorArgs.add('${field.name}: $readExpr');

    // 4. Update auto offset
    autoOffset = currentOffset + fieldAnn.length;
  }

  // Generate return statement
  buffer.writeln('  return $className(');
  buffer.writeln(constructorArgs.join(',\n'));
  buffer.writeln('  );');
  buffer.writeln('}');

  return buffer.toString();
}