Add support for C++20 modules

CMakeLists.txt

@@ -65,6 +65,10 @@ if (HAVE_GETTIMEOFDAY)
     add_definitions(-DHAVE_GETTIMEOFDAY)
 endif ()
 
+# Module options
+option(RTAUDIO_BUILD_MODULES "Build C++ modules for RtAudio" OFF)
+option(RTAUDIO_USE_NAMESPACE "Force usage of namespace rt::audio for modules" ON)
+
 # Add -Wall if possible
 if (CMAKE_COMPILER_IS_GNUCXX)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
@@ -279,6 +283,15 @@ target_compile_definitions(rtaudio PRIVATE ${API_DEFS})
 target_compile_definitions(rtaudio PRIVATE RTAUDIO_EXPORT)
 target_link_libraries(rtaudio ${LINKLIBS})
 
+if(RTAUDIO_BUILD_MODULES)
+  if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.28)
+    message(STATUS "Building rtaudio C++ module")
+    add_subdirectory(modules)
+  else()
+    message(WARNING "Skipping rtaudio C++ module (requires CMake 3.28+, found ${CMAKE_VERSION})")
+  endif()
+endif()
+
 # Subdirs
 
 if (NOT DEFINED RTAUDIO_BUILD_TESTING OR RTAUDIO_BUILD_TESTING STREQUAL "")

README.md

@@ -28,6 +28,8 @@ RtAudio is a set of C++ classes that provides a common API (Application Programm
 
 RtAudio incorporates the concept of audio streams, which represent audio output (playback) and/or input (recording).  Available audio devices and their capabilities can be enumerated and then specified when opening a stream.  Where applicable, multiple API support can be compiled and a particular API specified when creating an RtAudio instance.  See the \ref apinotes section for information specific to each of the supported audio APIs.
 
+RtAudio is also offered as a module, which is enabled with `RTAUDIO_BUILD_MODULES`, and is accessed with `import rt.audio;`. Namespaces are inlined, so classes can be accessed through namespace `rt::audio` or through the global namespace (for example, `rt::audio::RtApi` and `::RtApi` are both valid).
+
 ## Building
 
 Several build systems are available.  These are:

RtAudio.h

@@ -85,6 +85,9 @@
 #include <functional>
 #include <memory>
 
+inline namespace rt {
+inline namespace audio {
+
 /*! \typedef typedef unsigned long RtAudioFormat;
     \brief RtAudio data format type.
 
@@ -648,6 +651,9 @@ class RTAUDIO_DLL_PUBLIC RtAudio
   std::shared_ptr<RtApi> rtapi_;
 };
 
+}
+}
+
 // Operating system dependent thread functionality.
 #if defined(_MSC_VER)
 
@@ -658,16 +664,24 @@ class RTAUDIO_DLL_PUBLIC RtAudio
   #include <process.h>
   #include <stdint.h>
 
+inline namespace rt {
+inline namespace audio {
   typedef uintptr_t ThreadHandle;
   typedef CRITICAL_SECTION StreamMutex;
+}
+}
 
 #else
 
   // Using pthread library for various flavors of unix.
   #include <pthread.h>
 
+inline namespace rt {
+inline namespace audio {
   typedef pthread_t ThreadHandle;
   typedef pthread_mutex_t StreamMutex;
+}
+}
 
 #endif
 
@@ -680,6 +694,9 @@ class RTAUDIO_DLL_PUBLIC RtAudio
 
 #endif
 
+inline namespace rt {
+inline namespace audio {
+
 // This global structure type is used to pass callback information
 // between the private RtAudio stream structure and global callback
 // handling functions.
@@ -738,12 +755,18 @@ class S24 {
 };
 #pragma pack(pop)
 
+}
+}
+
 #if defined( HAVE_GETTIMEOFDAY )
   #include <sys/time.h>
 #endif
 
 #include <sstream>
 
+inline namespace rt {
+inline namespace audio {
+
 class RTAUDIO_DLL_PUBLIC RtApi
 {
 public:
@@ -931,6 +954,9 @@ inline void RtAudio :: showWarnings( bool value ) { rtapi_->showWarnings( value
 
 #endif
 
+}
+}
+
 // Indentation settings for Vim and Emacs
 //
 // Local Variables:

modules/CMakeLists.txt

@@ -0,0 +1,32 @@
+cmake_minimum_required(VERSION 3.28)
+
+add_library(rtaudio_modules)
+
+set(RTAUDIO_MODULES
+    RtAudio.cppm
+)
+
+
+if(NOT COMMAND configure_cpp_module_target)
+    function(configure_cpp_module_target target)
+        target_sources(${target} PUBLIC FILE_SET CXX_MODULES FILES ${RTAUDIO_MODULES})
+    endfunction()
+endif()
+
+if(RTAUDIO_USE_NAMESPACE)
+    target_compile_definitions(rtaudio_modules PRIVATE RTAUDIO_USE_NAMESPACE)
+endif()
+
+configure_cpp_module_target(rtaudio_modules)
+
+target_link_libraries(rtaudio_modules
+    PUBLIC
+    rtaudio
+)
+
+target_include_directories(rtaudio_modules
+    PRIVATE
+    ${PROJECT_SOURCE_DIR}
+)
+
+target_compile_features(rtaudio_modules PUBLIC cxx_std_20)

modules/RtAudio.cppm

@@ -0,0 +1,29 @@
+module;
+
+#include "RtAudio.h"
+
+export module rt.audio;
+
+export
+#ifdef RTAUDIO_USE_NAMESPACE
+inline namespace rt {
+inline namespace audio {
+#else
+namespace rt::audio {
+#endif
+    using rt::audio::RtAudioFormat;
+    using rt::audio::RtAudioStreamFlags;
+    using rt::audio::RtAudioStreamStatus;
+    using rt::audio::RtAudioCallback;
+    using rt::audio::RtAudioErrorType;
+    using rt::audio::RtAudioErrorCallback;
+    using rt::audio::RtApi;
+    using rt::audio::RtAudio;
+    using rt::audio::ThreadHandle;
+    using rt::audio::StreamMutex;
+    using rt::audio::CallbackInfo;
+    using rt::audio::S24;
+}
+#ifdef RTAUDIO_USE_NAMESPACE
+}
+#endif