Move some heavy templates into cpp

[Altren]

This PR based on the #202 changes.
Cuts tests build time by 10% on my machine, no hacks or workarounds, just some simple moves to .cpp

[liuzicheng1987]

Sounds great!

[liuzicheng1987]

@Altren , I think this is a great initiative that makes a lot of sense.

I think a couple of minor changes are still necessary, though:

If we are going to place the JSON code into a source file, we should do the same for all supported formats.

Moreover, we should then determine in the CMakeLists.txt whether we want to compile the source file for a particular format. JSON support is activated by default, but it can be turned off, so we mustn't assume that JSON can be installed.

So I think there should be a source file called reflectcpp_json.cpp, reflectcpp_yaml.cpp, etc

And if the flag for the format is set, the source file will be compiled.

Do you understand what I mean?

[liuzicheng1987]

If you don't want to do this, I can do it myself.

[Altren]

If we are going to place the JSON code into a source file, we should do the same for all supported formats.

I agree, I wanted to suggest this change as a next step, since this require more complex changes. But I'm fine doing that in the current PR and will do that.

Moreover, we should then determine in the CMakeLists.txt whether we want to compile the source file for a particular format. JSON support is activated by default, but it can be turned off, so we mustn't assume that JSON can be installed.
So I think there should be a source file called reflectcpp_json.cpp, reflectcpp_yaml.cpp, etc

This would break the idea of having single source file to compile. But I guess we can keep it simple like:
"If you want to compile reflectcpp with yaml support add reflectcpp.cpp and reflectcpp_yaml.cpp into your build"

I'll do some initial implementation that looks good to me, then we can discuss if it have any disadvantages

[Altren]

I've added json.cpp implementation. Please review and if everything looks ok for you I'll continue with other formats

[Altren]

Also I feel like reflectcpp_json.cpp and reflectcpp.cpp should not be in the same directory where other source files are, but don't know how to organize this.
The motivation here is that it might be confusing which are "real" source files and whilch are used for users and build system convenience.

[liuzicheng1987]

@Altren , looks really great.

One minor thing:

if (REFLECTCPP_JSON)
    list(APPEND REFLECT_CPP_SOURCES
        src/reflectcpp_json.cpp
    )
    if (REFLECTCPP_USE_BUNDLED_DEPENDENCIES)
       ....
    else ()
        find_package(ctre CONFIG REQUIRED)
        ...
    endif ()
endif ()

CTRE is required regardless of whether we need JSON. So this should be outside the condition if (REFLECTCPP_JSON):

  if (REFLECTCPP_USE_BUNDLED_DEPENDENCIES)
      target_include_directories(
          reflectcpp PUBLIC
          $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include/rfl/thirdparty>)
  else ()
      find_package(ctre CONFIG REQUIRED)
  endif ()

if (REFLECTCPP_JSON)
   ...
endif()

[Altren]

There are only two new commits above (XML to cpp) and squashed changes about ctre

[Altren]

Should I continue with other formats in this PR or better do them in a separate on to avoid too big PR?

[Altren]

^ rebased onto main to resolve conflicts

[Altren]

Just in case, now this is totally complete, unless there are more review comments

[liuzicheng1987]

@Altren , merged. Thank you for your contribution.