Add optional ament packaging

Detect ament during ROS2 builds and export targets so reactor-cpp is discoverable by ament_target_dependencies.

Author: lsk567

CMakeLists.txt

@@ -9,6 +9,13 @@ endif()
 
 project(${LIB_TARGET} LANGUAGES CXX VERSION 0.0.1)
 
+if (NOT DEFINED LF_REACTOR_CPP_SUFFIX)
+  find_package(ament_cmake QUIET)
+  if(ament_cmake_FOUND)
+    set(REACTOR_CPP_USE_AMENT ON)
+  endif()
+endif()
+
 # require C++17
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
@@ -71,3 +78,9 @@ if (DEFINED LF_REACTOR_CPP_SUFFIX)
 else()
   install(DIRECTORY include/ DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
 endif()
+
+if (REACTOR_CPP_USE_AMENT)
+  ament_export_targets(${LIB_TARGET}Config HAS_LIBRARY_TARGET)
+  ament_export_include_directories(include)
+  ament_package()
+endif()

package.xml

@@ -6,7 +6,8 @@
  <description>A C++ reactor runtime</description>
  <maintainer email="[email protected]">user</maintainer>
  <license>ISC License</license>
+ <buildtool_depend>ament_cmake</buildtool_depend>
  <export>
-   <build_type>cmake</build_type>
+   <build_type>ament_cmake</build_type>
  </export>
 </package>