nemethf / pyls-bess

Bess plugin for the python-language-server

Bess plugin for pyls

pyls-bess is a simple plugin for pyls.

The Bess scripting/configuration language is basically python with some syntactic sugar and global variables. pyls-bess relies on bess-gen-doc for the global variables (see globals.py and globals.min.json.gz). It uses very simple heuristics to understand the syntactic sugar.

pyls-bess should work with any text editor supporting the language server protocol, however I only tested it with emacs/eglot.

Features

• Documentation help of a bess module

  

• Documentation help for a method argument

  

• Jump to definition / references. In case of multiple references, the default order of the references is "project", "cpp_definition", "mclass", "protobuf", "examples".

  

• Completion of the global variable bess

  

• Completion of a module instance

  

• Type checking with mypy

  

  The mypy plugin detects that Queue().get_status()['dequeue'] is incorrect because the return value of get_status has no key dequeue. Pyls, however, cannot currently complete the possible keys. Moreover, completing Queue().get_status(). incorrectly lists the possible dictionary keys as properties. But at least it helps to find out dequeue should be changed to dequeued.

Installation

Install with pip3 install ..

Configuration

pyls-bess defines three configuration variables.

bess.source_directory sets the location of bess itself. If this varialbe is not set, pyls-bess falls back to the BESS environment variable.

bess.definitions and bess.refereneces define lists of reference types. The server searches for definitions/references considering the lists in order. The possible reference types are project, cpp_definition, mclass, protobuf, and examples.

The bess-specific configuration variables can be append to an existing setup.cfg, tox.ini, or pycodestyle.cfg file. Alternatively, it can be placed in a separate .bessls file at the root of the project, or in a user-level configuration file named bessls in XDG_CONFIG_HOME (usually ~/.config). With the following example, pyls-bess searches the current project (workspace) and then the module_msg.proto file for references. If bessls found references in the proto file it returns the file as /opt/bess/protobuf/module_msg.proto.

[bess]
references = project, protobuf
source_directory = /opt/bess

Configuration of Emacs/eglot

Adding the following lines to the Emacs initialization file is enough.

(setenv "BESS" "/opt/bess")

(define-derived-mode bess-mode python-mode "bess")
(add-to-list 'auto-mode-alist '("\\.bess\\'" . bess-mode))
(with-eval-after-load 'eglot
  (add-to-list 'eglot-server-programs '(bess-mode . ("pyls"))))