Add rmw_*_event_init() functions (#397)

Signed-off-by: Miaofei <miaofei@amazon.com>

rmw_connext_cpp/src/rmw_event.cpp

@@ -20,15 +20,34 @@
 
 extern "C"
 {
-/// Take an event from the event handle.
-/**
- * \param event_handle event object to take from
- * \param event_info event info object to write taken data into
- * \param taken boolean flag indicating if an event was taken or not
- * \return `RMW_RET_OK` if successful, or
- * \return `RMW_RET_BAD_ALLOC` if memory allocation failed, or
- * \return `RMW_RET_ERROR` if an unexpected error occurs.
- */
+rmw_ret_t
+rmw_publisher_event_init(
+  rmw_event_t * rmw_event,
+  const rmw_publisher_t * publisher,
+  rmw_event_type_t event_type)
+{
+  return __rmw_init_event(
+    rti_connext_identifier,
+    rmw_event,
+    publisher->implementation_identifier,
+    publisher->data,
+    event_type);
+}
+
+rmw_ret_t
+rmw_subscription_event_init(
+  rmw_event_t * rmw_event,
+  const rmw_subscription_t * subscription,
+  rmw_event_type_t event_type)
+{
+  return __rmw_init_event(
+    rti_connext_identifier,
+    rmw_event,
+    subscription->implementation_identifier,
+    subscription->data,
+    event_type);
+}
+
 rmw_ret_t
 rmw_take_event(
   const rmw_event_t * event_handle,

rmw_connext_shared_cpp/include/rmw_connext_shared_cpp/event.hpp

@@ -22,6 +22,26 @@
 
 #include "rmw_connext_shared_cpp/visibility_control.h"
 
+/// Initialize a rmw_event_t.
+/**
+ * \param[in|out] rmw_event to initialize
+ * \param topic_endpoint_impl_identifier implementation identifier of event's parent topic endpoint
+ * \param data to initialize with
+ * \param event_type for the event to handle
+ * \return `RMW_RET_OK` if successful, or
+ * \return `RMW_RET_INVALID_ARGUMENT` if invalid argument, or
+ * \return `RMW_RET_UNSUPPORTED` if event_type is not supported, or
+ * \return `RMW_RET_ERROR` if an unexpected error occurs.
+ */
+RMW_CONNEXT_SHARED_CPP_PUBLIC
+rmw_ret_t
+__rmw_init_event(
+  const char * identifier,
+  rmw_event_t * rmw_event,
+  const char * topic_endpoint_impl_identifier,
+  void * data,
+  rmw_event_type_t event_type);
+
 /// Take an event from the event handle.
 /**
  *

rmw_connext_shared_cpp/src/event.cpp

@@ -20,6 +20,35 @@
 #include "rmw_connext_shared_cpp/event_converter.hpp"
 #include "rmw_connext_shared_cpp/types.hpp"
 
+rmw_ret_t
+__rmw_init_event(
+  const char * identifier,
+  rmw_event_t * rmw_event,
+  const char * topic_endpoint_impl_identifier,
+  void * data,
+  rmw_event_type_t event_type)
+{
+  RMW_CHECK_ARGUMENT_FOR_NULL(identifier, RMW_RET_INVALID_ARGUMENT);
+  RMW_CHECK_ARGUMENT_FOR_NULL(rmw_event, RMW_RET_INVALID_ARGUMENT);
+  RMW_CHECK_ARGUMENT_FOR_NULL(topic_endpoint_impl_identifier, RMW_RET_INVALID_ARGUMENT);
+  RMW_CHECK_ARGUMENT_FOR_NULL(data, RMW_RET_INVALID_ARGUMENT);
+  RMW_CHECK_TYPE_IDENTIFIERS_MATCH(
+    topic endpoint,
+    topic_endpoint_impl_identifier,
+    identifier,
+    return RMW_RET_INCORRECT_RMW_IMPLEMENTATION);
+  if (!is_event_supported(event_type)) {
+    RMW_SET_ERROR_MSG("provided event_type is not supported by rmw_fastrtps_cpp");
+    return RMW_RET_UNSUPPORTED;
+  }
+
+  rmw_event->implementation_identifier = topic_endpoint_impl_identifier;
+  rmw_event->data = data;
+  rmw_event->event_type = event_type;
+
+  return RMW_RET_OK;
+}
+
 rmw_ret_t
 __rmw_take_event(
   const char * implementation_identifier,