How python swig wrappers were generated without any source files in my case?

I was researching using C++ in Python with SWIG. I came across this repo. I installed as recommended with python -m pip install tesseract-robotics. I expected it to download C++ source code, generate .cpp files from .i files and only then build .dlls. But, it seems it only installed _packageX.pyd, packageX.py and corresponding .dll file for each package.

How this even possible? Doen't SWIG needs the .i and C++ source files to generate the code to build for specific platform? Or, was all this built somewhere on the cloud (maybe even in https://pypi.org/) and pip install did not actually build anything, but just downloaded pre-built platfrom specific .dll and .py files?

As mentioned in user17732522's comment, the tesseract-robotics native components are compiled and packed into Python wheels. These precompiled wheels are available for Windows and recent Linux x64 releases, for Python 3.7 and greater. Compiling everything for this package is extremely complicated, and is not something a user can be expected to accomplish.

The GitHub workflow that does the compilation can be found here if you are interested in seeing how it works: https://github.com/tesseract-robotics/tesseract_python/blob/master/.github/workflows/wheels.yml