sempr-lsp is a utility tool which can be used to parse text files and report diagnostic information. It uses the "language server protocol" which makes it usable in many different editors (vscode, vim, atom, ...).

NOTE: By now, this package also provides syntax highlighting in vscode - and probably other editors which support textmate grammars. I just did not update the above images, but have a look below. :)

- pygls for the language server:
    pip install pygls

- pybind11 to create python bindings to the c++ code
    pip install pybind11

- a recent version of sempr and rete

cd lib
mkdir build
cd build
pybind11_DIR=<path to site-pakages/pybind11/share/cmake/pybind11> cmake ..
make -j8

This created a custom python module, called something like semprlsp.cpython-36m-x86_64-linux-gnu.so.

The actual language server is server.py. When started, it listens on port 8066. Make sure the previously compiled python module can be found, e.g. by specifying it on the PYTHONPATH:

# run from the build folder
PYTHONPATH=. ../../server.py

Many editors support custom language servers that support the language server protocol (lsp).

.vimrc:

" enable custom language server for ycmd
let g:ycm_language_server =
            \ [
            \   {
            \       'name' : 'rules',
            \       'port' : '8066',
            \       'filetypes' : ['rules'],
            \   },
            \ ]

Note: The connection via TCP is preferred during development -- it makes debugging a bit easier for me. But ycm stops the language server when it is no longer needed, and can't restart it like this. This can be changed by providing a 'cmdline' : '<call to start server.py>' entry.

To automatically set the filetype to rules:

.vim/filetype.vim

" custom filetypes
if exists("did_load_filetypes")
    finish
endif

augroup filetypedetect
    au! BufRead,BufNewFile *.rules      setfiletype rules
augroup END

cp -r sempr-lsp-vscode ~/.vscode/extensions
cd ~/.vscode/extensions/sempr-lsp-vscode
npm install
npm run compile

Make sure to start the server.py before running vscode! I have not yet figured out how to spawn the server from the vscode extension, and the client will only try to connect to the server a few times.