parkovski / wscoro

Minimal C++20 coroutine library.

wscoro - Bare bones C++20 coroutine library

This is an early alpha and the current API should not be considered stable.

Currently supported compilers: MSVC, GCC.

wscoro implements only the essentials needed to use C++20 coroutines. There are no thread pools or executors; instead wscoro provides types for chaining coroutines. C++20's coroutine support features are very low-level and wscoro does not cover all possible cases, however it does support many common scenarios.

Usage

wscoro provides several different task type templates separated by feature support:

Type	Awaitable	Auto-start	co_await	co_yield	co_return
Immediate	✅	✅	❌	❌	✅
Lazy	✅	❌	❌	❌	✅
Task	✅	✅	✅	❌	✅
DelayTask	✅	❌	✅	❌	✅
Generator	✅	❌	❌	✅	❌
AsyncGenerator	✅	❌	✅	✅	❌
FireAndForget	❌	✅	✅	❌	❌

• Awaitable: The resulting task can be awaited with co_await.
• Auto-start: The resulting task begins automatically when created. Types not marked auto-start must be started with a call to coroutine.resume().
• co_await: The type supports the co_await operator to await another coroutine.
• co_yield: The coroutine can "return" multiple values with co_yield. Calling co_await on these types gives an std::optional, where std::nullopt represents that the generator is finished.
• co_return: The coroutine can return a value when finished. Types without this feature can only use the void form of co_return (co_return;).

Outside of a coroutine body where co_await is supported, the result of a coroutine must be fetched with await_resume().