generateForAnnotatedElement method

@override FutureOr<String> generateForAnnotatedElement(covariant ClassElement 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
FutureOr<String> generateForAnnotatedElement(
  covariant ClassElement element,
  ConstantReader annotation,
  BuildStep buildStep,
) async {
  final className = element.name;
  final classConstructor = element.unnamedConstructor!;
  final combineAspects = classConstructor.parameters.any(_isAspectParameter);
  final objectValue = annotation.objectValue;
  final baseClassType = objectValue.getField('base')!.toTypeValue()!;
  final realBaseClassName = baseClassType.element!.name;
  final isBaseClassEntityProcessingSystem =
      realBaseClassName == 'EntityProcessingSystem';
  final baseClassTypeParameters =
      (baseClassType.element! as ClassElement).typeParameters;
  final mapper = _getValues(objectValue, 'mapper');
  final systems = _getValues(objectValue, 'systems');
  final managers = _getValues(objectValue, 'manager');
  final allOfAspects = _getValues(objectValue, 'allOf');
  final oneOfAspects = _getValues(objectValue, 'oneOf');
  final excludedAspects = _getValues(objectValue, 'exclude');
  final shouldCreateCustomProcessEntity = isBaseClassEntityProcessingSystem &&
      (allOfAspects.isNotEmpty || oneOfAspects.isNotEmpty);
  final baseClassName =
      shouldCreateCustomProcessEntity ? 'EntitySystem' : realBaseClassName;
  final baseClassConstructor =
      (annotation.read('base').typeValue.element! as ClassElement)
          .unnamedConstructor!;
  final hasGeneratedAspects = allOfAspects.isNotEmpty ||
      oneOfAspects.isNotEmpty ||
      excludedAspects.isNotEmpty;
  final useSuperParameters = !hasGeneratedAspects;
  final constructorParameter = baseClassConstructor.parameters
      .where(
        (parameterElement) =>
            !_isAspectParameter(parameterElement) ||
            combineAspects ||
            useSuperParameters,
      )
      .map(
        (parameterElement) => useSuperParameters
            ? 'super.${parameterElement.name}'
            : '''${parameterElement.type.getDisplayString(withNullability: false)} ${parameterElement.name}''',
      )
      .join(', ');
  final superCallParameter = useSuperParameters
      ? ''
      : baseClassConstructor.parameters
          .map(
            (parameterElement) => _isAspectParameter(parameterElement)
                ? _createAspectParameter(
                    allOfAspects,
                    oneOfAspects,
                    excludedAspects,
                    combineAspects,
                  )
                : parameterElement.name,
          )
          .join(', ');
  final components = {...allOfAspects, ...mapper};
  final optionalComponents = {...oneOfAspects};
  final mapperDeclarations = components
      .map(
        (component) =>
            '  late final Mapper<$component> ${_toMapperName(component)};',
      )
      .join('\n');
  final optionalMapperDeclarations = optionalComponents
      .map(
        (component) =>
            '''  late final OptionalMapper<$component> ${_toMapperName(component)};''',
      )
      .join('\n');
  final systemDeclarations = systems
      .map((system) => '  late final $system ${_toVariableName(system)};')
      .join('\n');
  final managerDeclarations = managers
      .map((manager) => '  late final $manager ${_toVariableName(manager)};')
      .join('\n');
  final mapperInitializations = components
      .map(
        (component) =>
            '    ${_toMapperName(component)} = Mapper<$component>(world);',
      )
      .join('\n');
  final optionalMapperInitializations = optionalComponents
      .map(
        (component) =>
            '''    ${_toMapperName(component)} = OptionalMapper<$component>(world);''',
      )
      .join('\n');
  final systemInitializations = systems
      .map(
        (system) =>
            '    ${_toVariableName(system)} = world.getSystem<$system>();',
      )
      .join('\n');
  final managerInitializations = managers
      .map(
        (manager) =>
            '    ${_toVariableName(manager)} = world.getManager<$manager>();',
      )
      .join('\n');
  final result = baseClassTypeParameters.isEmpty
      ? StringBuffer('abstract class _\$$className extends $baseClassName {')
      : StringBuffer(
          '''abstract class _\$$className<${_baseClassBoundedTypeParameters(baseClassTypeParameters)}> extends $baseClassName<${_baseClassUnboundedTypeParameters(baseClassTypeParameters)}> {''',
        );
  final hasFields =
      _declaresFields(components, optionalComponents, systems, managers);
  if (hasFields) {
    result.writeln();
    if (components.isNotEmpty) {
      result.writeln(mapperDeclarations);
    }
    if (optionalComponents.isNotEmpty) {
      result.writeln(optionalMapperDeclarations);
    }
    if (systems.isNotEmpty) {
      result.writeln(systemDeclarations);
    }
    if (managers.isNotEmpty) {
      result.writeln(managerDeclarations);
    }
  }
  if (constructorParameter.isNotEmpty || superCallParameter.isNotEmpty) {
    if (!hasFields) {
      result.writeln();
    }
    result.write('  _\$$className($constructorParameter)');
    if (!useSuperParameters) {
      result.write(' : super($superCallParameter)');
    }
    result.writeln(';');
  }

  if (hasFields) {
    result
      ..writeln('  @override')
      ..writeln('  void initialize() {')
      ..writeln('    super.initialize();');
    if (components.isNotEmpty) {
      result.writeln(mapperInitializations);
    }
    if (optionalComponents.isNotEmpty) {
      result.writeln(optionalMapperInitializations);
    }
    if (systems.isNotEmpty) {
      result.writeln(systemInitializations);
    }
    if (managers.isNotEmpty) {
      result.writeln(managerInitializations);
    }
    result.writeln('  }');
  }

  if (shouldCreateCustomProcessEntity) {
    result
      ..writeln('  @override')
      ..writeln('  void processEntities(Iterable<int> entities) {');
    for (final aspect in allOfAspects.followedBy(oneOfAspects)) {
      final mapperName = _toMapperName(aspect);
      result.writeln('    final $mapperName = this.$mapperName;');
    }
    final arguments = allOfAspects
        .followedBy(oneOfAspects)
        .map((e) => '${_toMapperName(e)}[entity]')
        .join(', ');
    result
      ..writeln('    for (final entity in entities) {')
      ..writeln('      processEntity(entity, $arguments);')
      ..writeln('    }')
      ..writeln('  }');

    final parameters = [
      ...allOfAspects.map((e) => '$e ${_toVariableName(e)}'),
      ...oneOfAspects.map((e) => '$e? ${_toVariableName(e)}'),
    ].join(', ');
    result.writeln('  void processEntity(int entity, $parameters);');
  }

  result.writeln('}');

  return result.toString();
}