A package to help generate Dart code from existing code.
This package is useful when you need to generate code without using build_runner, example usages would be CLIs or when you need to generate code once and let the user edit it afterwards.

First you'll need to create a class that implements Generator, afterwards you create a CodeGenerator passing your custom generator as argument, and then use CodeGenerator.generateFor to generate code for code in a given directory.

import 'package:code_generator/code_generator.dart';

void main() {
  final codeGenerator = CodeGenerator(
    generators: [MyCustomGenerator()],
  );
  codeGenerator.generateFor(Directory('path/to/source_code'));
}

class MyCustomGenerator extends Generator<ClassDeclaration> {

  GeneratorResult generate(ClassDeclaration member, String path) {
    ...
  }
}

Generator is the base class used to generate code. It contains the methods shouldGenerateFor, which is used to determine if this generator should be used to generate code for a given CompilationUnitMember, and generate, which generates the code for the filtered members.
Example implementation:

import 'package:code_generator/code_generator.dart';
import 'package:path/path.dart' as path;

class RepositoryGenerator extends Generator<ClassDeclaration> {
  bool shouldGenerateFor(ClassDeclaration member, String path) {
    return member.name.name.endsWith('Entity');
  }

  @override
  GeneratorResult generate(ClassDeclaration member, String path) {
    final memberName = member.name.name;
    final repositoryName = '${memberName}Repository';
    return GeneratorResult.single(
      path: join(path, '../../repository/repository.dart'),
      content: 'class $repositoryName {}',
    );
  }
}

There are some premade Generators so that you don't need to check for member types, they are:

• GeneratorForClass
• GeneratorForMixin
• GeneratorForFunction
• GeneratorForExtension
• GeneratorForEnum
• GeneratorForType
• GeneratorForTopLevelVariable
• GeneratorForAnnotatedElements