Start porting rosidl_typesupport_fastrtps_cpp to new IDL pipeline

[sloretz]

FYI @dirk-thomas I spent a little time looking at how much work it was to convert a generator by starting to convert rosidl_typesupport_fastrtps_cpp. The cmake portion and python code changes seem like they're at a reasonable state, but the templates themselves have not been updated.

The remaining work looks like the templates will need to use the new rosidl_parser.definition types, and some functions __cdr_deserialize as well as some static structs (handle, callbacks) will need the message name prefix.

In the olde pipeline the generator would generated files

msg/dds_fastrtps/<msg>__type_support.cpp
msg/<msg>__rosidl_typesupport_fastrtps_cpp.hpp

and

srv/dds_fastrtps/<srv>__request__type_support.cpp
srv/dds_fastrtps/<srv>__response__type_support.cpp
srv/dds_fastrtps/<srv>__type_support.cpp
srv/<srv>__request__rosidl_typesupport_fastrtps_cpp.hpp
srv/<srv>__response__rosidl_typesupport_fastrtps_cpp.hpp
srv/<srv>__rosidl_typesupport_fastrtps_cpp.hpp

If I understand correctly, after conversion to the new IDL pipeline it should generate just two files for any .idl file

<parent_folder>/dds_fastrtps/<name>__type_support.cpp
<parent_folder>/<name>__rosidl_typesupport_cpp.hpp

[dirk-thomas]

The approach looks fine on a first look. (I haven't looked at the details yet though.) Are you planning to continue and update the templates?

[sloretz]

Are you planning to continue and update the templates?

I am not planning on continuing. I opened this in the hope that someone might find it useful.

[dirk-thomas]

Adding fastcdr here instead of the target_link_libraries below doesn't work since it changes the library link order. fastcdr must be linked after all the other libraries.

[dirk-thomas]

I cherry-picked this commit into #14 and completed the transformation of rosidl_typesupport_fastrtps_cpp. Closing this one.