dart_cpp_bridge

Dart/Flutter ↔ C++20 binding generator, inspired by flutter_rust_bridge.

Write normal C++ code and call it from Dart/Flutter, with sync, async, stream, and Dart-closure reverse calls.

What's this?

Write plain C++20 functions and classes — no hand-written FFI boilerplate
Codegen generates Dart API + C++ wire dispatch from annotated headers
Built-in runtime based on Asio + stdexec senders and coroutines
Supports Android, iOS, Windows, Linux, and macOS

Runtime model and compatibility

The package uses the stdexec-based runtime. It contains a broad C++ async/concurrency migration from the legacy async-simple model. The Dart API, C ABI, wire protocol, generated file layout, and method-ID contracts remain stable, but C++ async business code is not source-compatible with the legacy runtime. See the version guide before copying C++ async examples or migrating existing code.

When migrating from the legacy runtime:

Use stdexec::task<T> or another stdexec sender instead of async_simple::coro::Lazy<T>.
Migrate Executor / .via(...) and Signal / Slot to stdexec schedulers, current sender operations, and stop tokens.
Regenerate bindings with the matching dcb_gen_tool release; do not mix legacy generated native code with current runtime headers or tooling.
Build native code as C++20 and link the vendored stdexec target. Keep blocking work off the single-threaded I/O scheduler.

Quickstart

See the documentation for a complete quickstart:

Show me the code

C++

#include <dart_cpp_bridge/annotate.h>
#include <stdexec/execution.hpp>
#include <string>

BRIDGE_SYNC int32_t add(int32_t a, int32_t b) { return a + b; }

BRIDGE_ASYNC
stdexec::task<std::string> greet(std::string name) {
  co_return "Hello, " + name;
}

Dart

import 'package:my_app/src/native_gen/api/api_fn.dart';

void main() async {
  await DcbLib.init();

  print(add(a: 1, b: 2));            // 3
  print(await greet(name: 'World')); // Hello, World
}

Documentation

Homepage: deretame.github.io/dart_cpp_bridge/
Quickstart: deretame.github.io/dart_cpp_bridge/getting-started/
GitHub: github.com/deretame/dart_cpp_bridge

Acknowledgments

Flutter Rust Bridge — architecture and product shape inspiration
Asio — event loop and asynchronous I/O
stdexec — sender/receiver and scheduler foundation
MPMCQueue — lock-free bounded MPMC queue (strict FIFO), the buffer of co::mpsc::bounded channels
Dart / Flutter team — FFI, Isolate, NativeFinalizer, and the broader Dart native ecosystem

License

MIT — see LICENSE.