This PR adds Dart language support to Apache Fory™, implementing a comprehensive serialization solution for Dart and Flutter applications. Apache Fory™ Dart consists of approximately 15,000 lines of code and provides an efficient serialization mechanism that works within Flutter's reflection limitations.

Dart supports reflection, but Flutter explicitly prohibits it. To address this constraint, Apache Fory™ Dart uses a combination of:

1. Core serialization/deserialization logic
2. Static code generation for type handling

This approach ensures compatibility with Flutter while maintaining the performance and flexibility expected from Apache Fory™.

• XLANG mode support for cross-language serialization
• Reference tracking for handling object graphs
• Support for primitive types, collections, and custom classes
• Serializer registration system
• Code generation for class and enum serialization
• Support for nested collections with automatic generic type conversion
• Custom serializer registration
• Support for using ByteWriter/ByteReader as serialization sources

import 'package:fory/fory.dart';

part 'example.g.dart';

@foryClass
class SomeClass with _$SomeClassFory {
  late int id;
  late String name;
  late Map<String, double> map;

  SomeClass(this.id, this.name, this.map);

  SomeClass.noArgs();
}

After annotating your class with @foryClass, run:

dart run build_runner build

This generates the necessary code in example.g.dart and creates the _$SomeClassFory mixin.

Fory fory = Fory(
  refTracking: true,
);
fory.register($SomeClass, "example.SomeClass");
SomeClass obj = SomeClass(1, 'SomeClass', {'a': 1.0});

// Serialize
Uint8List bytes = fory.toFory(obj);

// Deserialize
obj = fory.fromFory(bytes) as SomeClass;

import 'package:fory/fory.dart';

part 'example.g.dart';

@foryEnum
enum EnumFoo {
  A,
  B
}

Registration is similar to classes:

fory.register($EnumFoo, "example.EnumFoo");

Apache Fory™ Dart currently supports the following type mappings in XLANG mode:

The implementation is organized into three main components:

1. Codegen: Located at dart/packages/fory/lib/src/codegen Handles static code generation for serialization/deserialization.

2. ForyCore: Located at dart/packages/fory/lib/src Contains the core serialization and deserialization logic.

3. ForyTest: Located at dart/fory-test Comprehensive test suite for Apache Fory™ Dart functionality.

The test suite is inspired by Apache Fory™ Java's testing approach and includes:

• Data Type Tests: Validates custom data types implemented for Dart
• Code Generation Tests: Ensures correctness of the generated static code
• Buffer Tests: Validates correct memory handling for primitive types
• Cross-Language Tests: Tests functionality against other Apache Fory™ implementations
• Performance Tests: Simple benchmarks for serialization/deserialization performance

Tests use the standard dart test framework.

To run tests:

# First, generate necessary code
cd fory-test
dart run build_runner build

# Run all tests
dart test

# For more options (skipping tests, platform-specific tests, etc.)
# See: https://github.com/dart-lang/test/blob/master/pkgs/test/README.md

Inside the fory-test/test_config directory you will find YAML configuration files required by certain tests (for example, the cross_language tests). Before executing those tests, please review and adjust the configs in fory-test/test_config (or provide your own) so that they match your environment.

Apache Fory™ Dart maintains high code quality standards. You can verify this using:

dart analyze
dart fix --dry-run
dart fix --apply

• Only supports XLANG mode (priority was given to cross-language compatibility)
• No out-of-band buffer functionality
• No data type compression (e.g., String compression)
• Generic parameters in user-defined types can be serialized but require manual type conversion after deserialization

• Dart SDK: 3.6.1

analyzer: '>=6.5.0 <8.0.0'
build: ^2.4.1
build_config: ^1.1.0
collection: ^1.19.1
meta: ^1.14.0
source_gen: ^2.0.0
glob: ^2.1.3
decimal: ^3.2.1
lints: ^5.0.0
build_runner: ^2.4.6

path: ^1.9.1
yaml: ^3.1.3
lints: ^5.0.0
build: ^2.4.2
build_runner: ^2.4.15
test: ^1.24.0
checks: ^0.3.0
build_test: ^2.2.3
analyzer: '>=6.5.0 <8.0.0'
collection: ^1.19.1