In this project, we use SWIG to generate 'glue code' to integrate the C++ code into Java.
SWIG is a software development tool that simplifies integrating C and C++ code with a variety of other languages.
You can get more info about SWIG here and the list of supported languages
here.
SWIG uses interface files (with a suffix .i) to specify which classes and functions will be usable from the
langauge we are integrating into.
In our case, the interface is already prepared in the file shortestPathsInterface.i in this directory.
This interface file can be used to to generate 'glue code' for any of the languages supported by SWIG.
To generate 'glue code' for example for Python, we could use:
swig -python -c++ shortestPathsInterface.i`
Here the first argument denotes the programming language we are integrating into.
The second argument is needed to distinguish between C and C++ as the language of the code we are integrating.
This call will generate new shortestPathsInterface_wrap.cxx file that will overwrite the existing one which is
prepared for Java.
The newly generated shortestPathsInterface_wrap.cxx will contain the wrappers for Python.
The file additionally includes Python.h.
Additionally, shortestPaths.py will be generated.
This file needs to be included in the Python project in order to make the library usable from it.
After that, you will have to compile a new library, this means running the shortestPaths target from the
CMakeLists.txt in the root directory of this project again.
This run will use the new shortestPathsInterface_wrap.cxx so it will generate a library usable from the desired
language.
Depending on your chosen language, you might need to change the CMmakeLists.txt file to include new required packages.
For example for Java, find_package(JNI REQUIRED) is necessary.
For other languages, other packages might be needed.
We have described the process on an example of integrating with Python.
With other languages, the process is fairly similar.
You start with swig -[desired_language] -c++ shortestPathsInterface.i.
This will generate shortestPathsInterface_wrap.cxx containing wrappers for the desired language and some additional
source code file in your chosen language (there can be more of them based on the language) that you have to include
in your project.
Since the intention of this document is not to describe the whole process in depth, but only to point the interested reader in the right direction, we refer you to the SWIG documentation and the SWIG tutorial for futher information regarding this topic.