Simple LSPClient for Python

lspclient.py

import os

# Define the path to the Python script you want to analyze
# path of this file
my_path = os.path.dirname(os.path.realpath(__file__))
file_path = os.path.join(my_path, 'main.py')
import subprocess
import json

class LSPClient:
    def __init__(self, server_command):
        # Start the LSP server process
        self.process = subprocess.Popen(server_command, 
                                        stdin=subprocess.PIPE, 
                                        stdout=subprocess.PIPE, 
                                        stderr=subprocess.PIPE, 
                                        bufsize=0,  # unbuffered
                                        text=True)

    def send_request(self, method, params):
        # Prepare LSP request payload
        request = {
            "jsonrpc": "2.0",
            "id": 1,  # Unique identifier
            "method": method,
            "params": params
        }
        request_str = json.dumps(request)

        # Construct header
        content_length = len(request_str.encode('utf-8'))
        header = f"Content-Length: {content_length}\r\n\r\n"

        # Send the request to the server's stdin
        self.process.stdin.write(header + request_str)
        self.process.stdin.flush()

    def read_response(self):
        # Read the header
        header1 = self.process.stdout.readline()

        # Extract Content-Length
        content_length = int(header1.split(":")[1].strip()) + 1 # +1 for the newline
        header2 = self.process.stdout.readline()
        # Extract Content-Type
        content_type = header2.split(":")[1].strip()
        print("Got: ", content_type, f"(length: {content_length})")
        
        # Read the content based on Content-Length
        response_str = self.process.stdout.read(content_length).strip()
        return json.loads(response_str)

    def close(self):
        # Close the subprocess
        self.process.terminate()


# Example Usage
from pprint import pprint
if __name__ == "__main__":
    # Replace with the actual command to start your LSP server
    lsp_server_command = ["jedi-language-server"]

    client = LSPClient(lsp_server_command)

    # Example: Sending an 'initialize' request
    init_params = {
        "processId": None,
        "rootUri": "file:///" + my_path,
        "capabilities": { # Client capabilities
        },  
    }
    
    
    
    client.send_request("initialize", init_params)
    pprint(client.read_response())
    
    client.send_request("textDocument/didOpen", {
        "textDocument": {
            "uri": "file://" + file_path,
            "languageId": "python",
            "version": 1,
            "text": open(file_path).read()
        }
    })
    pprint(client.read_response())

    client.close()