router_gen/lib/generator/router_generator.dart

import 'package:analyzer/dart/element/element.dart';
import 'package:build/build.dart';
import 'package:router_gen/annotation/router_page.dart';
import 'package:router_gen/annotation/router_param.dart';
import 'package:router_gen/model/router.dart';
import 'package:router_gen/util/utils.dart';
import 'package:source_gen/source_gen.dart';
import 'package:path/path.dart' as Path;

/// save router annotation
class RouterGenerator extends GeneratorForAnnotation<RouterPage> {
  final _paramChecker = const TypeChecker.fromRuntime(RouterParam);

  @override
  generateForAnnotatedElement(
      Element element, ConstantReader annotation, BuildStep buildStep) async {
    if (element.kind == ElementKind.CLASS) {
      router.imports.add(getImportStr(buildStep));

      String path = buildStep.inputId.path; // lib/xxx.dart
      String basename = Path.basename(buildStep.inputId.path); // xxx.dart

      // router name
      String className = element.name;
      String aptPath = annotation.peek("path")?.stringValue;
      String routerName =
          toCamelCase(aptPath == null || aptPath.isEmpty ? className : aptPath);

      var page = Page();
      page.name = className;
      page.path = routerName.startsWith("/")
          ? routerName
          : Path.join(path.replaceFirst("lib", "").replaceFirst(basename, ""),
              routerName);
      page.arguments = [];

      for (FieldElement e in (element as ClassElement).fields) {
        if (_paramChecker.hasAnnotationOf(e)) {
          String type = e.type.getDisplayString(withNullability: false);
          bool required =
              e.computeConstantValue()?.getField("required")?.toBoolValue();
          page.arguments.add(Argument(
            e.name,
            type,
            required ?? true,
          ));
        }
      }
      router.routerMap[Path.basename(routerName)] = page;
    }
    return null;
  }
}