C++20 Coroutines support (#218)

Author: kunitoki

Benchmarks/CMakeLists.txt

@@ -1,4 +1,5 @@
 cmake_minimum_required(VERSION 3.10)
+cmake_policy (SET CMP0169 OLD)
 
 include(FetchContent)
 

Benchmarks/requirements.txt

@@ -0,0 +1,2 @@
+matplotlib
+numpy

CHANGES.md

@@ -1,5 +1,3 @@
-## Master
-
 ## Version 3.0
 
 * Moved to C++17 as minimum supported standard C++ version.
@@ -17,6 +15,11 @@
 * Allow specifying a non virtual base class method when declaring class members (functions or variables) not exposed in the inherited class.
 * Allow using capturing lambdas in `Namespace::addFunction`, `Namespace::addProperty`, `Class<T>::addFunction`, `Class<T>::addStaticFunction`, `Class<T>::addProperty` and `Class<T>::addStaticProperty`.
 * Added multiple inheritance support: `deriveClass` now accepts more than one registered base class (e.g. `deriveClass<D, A, B>`).
+* Added C++20 coroutine integration: `CppCoroutine<R>` type that can be registered via `Namespace::addCoroutine()` to expose C++ generators to Lua using `co_yield` and `co_return`.
+* Added `LuaCoroutine` awaitable to resume a child Lua thread synchronously from inside a `CppCoroutine` body using `co_await`.
+* Added `lua_resume_x` and `lua_isyieldable_x` portable helpers in `LuaBridge/detail/LuaHelpers.h`.
+* Added `LUABRIDGE_HAS_CXX20_COROUTINES` feature-detection macro; opt out with `LUABRIDGE_DISABLE_CXX20_COROUTINES`.
+* Added `ErrorCode::CoroutineYieldFromNonCoroutine` and `ErrorCode::CoroutineAlreadyDone` error codes.
 * Added `Namespace::addVariable` to allow adding a modifiable value by copy into the namespace without incurring in function calls or metatables generation.
 * Added `luabridge::callWithHandler` free function and `LuaRef::callWithHandler` member to provide a custom Lua message handler during `lua_pcall`.
 * Added `luabridge::newFunction` free function and `LuaRef::newFunction` static method to wrap any C++ callable into a Lua function exposed as a `LuaRef`.

CMakeLists.txt

@@ -4,7 +4,7 @@ project (LuaBridge)
 
 include (CMakeDependentOption)
 
-set (CMAKE_CXX_STANDARD 17)
+set (CMAKE_CXX_STANDARD 20)
 set (CMAKE_CXX_STANDARD_REQUIRED ON)
 set (CMAKE_CXX_EXTENSIONS OFF)
 

Images/benchmarks.png

@@ -35,8 +35,11 @@
 [LuaBridge3](https://github.com/kunitoki/LuaBridge3) is a lightweight and dependency-free library for mapping data,
 functions, and classes back and forth between C++ and [Lua](http://wwww.lua.org) (a powerful,
 fast, lightweight, embeddable scripting language). LuaBridge has been tested
-and works with Lua 5.1.5, 5.2.4, 5.3.6, 5.4.8 and 5.5.0 as well as [LuaJit](https://luajit.org/) 2.1 onwards
-and for the first time also with [Luau](https://luau-lang.org/) 0.713 onwards and [Ravi](https://github.com/dibyendumajumdar/ravi) 1.0-beta11.
+and works with:
+* [PUC-Lua](https://lua.org) 5.1.5, 5.2.4, 5.3.6, 5.4.8 and 5.5.0
+* [LuaJit](https://luajit.org/) 2.1
+* [Luau](https://luau-lang.org/) 0.713
+* [Ravi](https://github.com/dibyendumajumdar/ravi) 1.0-beta11
 
 ## Features
 
@@ -87,6 +90,7 @@ LuaBridge3 offers a set of improvements compared to vanilla LuaBridge:
 * Consistent numeric handling and conversions (signed, unsigned and floats) across all lua versions.
 * NaN and Inf values pass through floating-point stack conversions without error.
 * Simplified registration of enum types via the `luabridge::Enum` stack wrapper.
+* C++20 coroutine integration via `addCoroutine()` and `CppCoroutine<R>`; await Lua threads from C++ with `LuaCoroutine`.
 * Opt-out handling of safe stack space checks (automatically avoids exhausting lua stack space when pushing values!).
 * Optional strict stack conversions via `LUABRIDGE_STRICT_STACK_CONVERSIONS` (e.g. `bool` requires an actual boolean, not any truthy value).
 * Error handler support in Lua calls via `LuaRef::callWithHandler` and `luabridge::callWithHandler`.

Manual.md

@@ -15,6 +15,7 @@ set (LUABRIDGE_DETAIL_HEADERS
   ${CMAKE_CURRENT_SOURCE_DIR}/LuaBridge/detail/CFunctions.h
   ${CMAKE_CURRENT_SOURCE_DIR}/LuaBridge/detail/ClassInfo.h
   ${CMAKE_CURRENT_SOURCE_DIR}/LuaBridge/detail/Config.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/LuaBridge/detail/Coroutine.h
   ${CMAKE_CURRENT_SOURCE_DIR}/LuaBridge/detail/Enum.h
   ${CMAKE_CURRENT_SOURCE_DIR}/LuaBridge/detail/Errors.h
   ${CMAKE_CURRENT_SOURCE_DIR}/LuaBridge/detail/Expected.h

README.md

@@ -18,6 +18,7 @@
 
 #include "detail/CFunctions.h"
 #include "detail/ClassInfo.h"
+#include "detail/Coroutine.h"
 #include "detail/Enum.h"
 #include "detail/Errors.h"
 #include "detail/Expected.h"

Source/CMakeLists.txt

@@ -12,6 +12,32 @@
 #error LuaBridge 3 requires a compliant C++17 compiler, or C++17 has not been enabled !
 #endif
 
+#if defined(LUAU_FASTMATH_BEGIN)
+#define LUABRIDGE_ON_LUAU 1
+#elif defined(LUAJIT_VERSION)
+#define LUABRIDGE_ON_LUAJIT 1
+#elif defined(RAVI_OPTION_STRING2)
+#define LUABRIDGE_ON_RAVI 1
+#elif defined(LUA_VERSION_NUM)
+#define LUABRIDGE_ON_LUA 1
+#else
+#error "Lua headers must be included prior to LuaBridge ones"
+#endif
+
+/**
+ * @brief Enable C++20 coroutine integration with Lua coroutines.
+ *
+ * Requires C++20 and Lua 5.2+ (lua_yieldk). Not supported on Lua 5.1, LuaJIT, or Luau.
+ * Define LUABRIDGE_DISABLE_CXX20_COROUTINES to force-disable even when C++20 is available.
+ */
+#if !defined(LUABRIDGE_HAS_CXX20_COROUTINES)
+#if !defined(LUABRIDGE_DISABLE_CXX20_COROUTINES) && (__cplusplus >= 202002L || (defined(_MSC_VER) && _HAS_CXX20)) && !(LUABRIDGE_ON_LUAU || LUABRIDGE_ON_LUAJIT || LUABRIDGE_ON_RAVI || LUA_VERSION_NUM < 502)
+#define LUABRIDGE_HAS_CXX20_COROUTINES 1
+#else
+#define LUABRIDGE_HAS_CXX20_COROUTINES 0
+#endif
+#endif
+
 #if !defined(LUABRIDGE_HAS_EXCEPTIONS)
 #if defined(_MSC_VER)
 #if _CPPUNWIND || _HAS_EXCEPTIONS
@@ -48,18 +74,6 @@
 #define LUABRIDGE_NO_SANITIZE(x)
 #endif
 
-#if defined(LUAU_FASTMATH_BEGIN)
-#define LUABRIDGE_ON_LUAU 1
-#elif defined(LUAJIT_VERSION)
-#define LUABRIDGE_ON_LUAJIT 1
-#elif defined(RAVI_OPTION_STRING2)
-#define LUABRIDGE_ON_RAVI 1
-#elif defined(LUA_VERSION_NUM)
-#define LUABRIDGE_ON_LUA 1
-#else
-#error "Lua headers must be included prior to LuaBridge ones"
-#endif
-
 #if defined(__OBJC__)
 #define LUABRIDGE_ON_OBJECTIVE_C 1
 #endif