Client for communicating with the language server

[nerdondon]

Hi,

I'm looking to make a vscode extension and it would be nice if it could communicate with the rust-analyzer language server and use it's functionality. i see that i could probably just create a language client in the same way as the rust-analyzer vscode extension:

const client = new lc.LanguageClient(
        'rust-analyzer',
        'Rust Analyzer Language Server',
        serverOptions,
        clientOptions,
);

but is there a more supported way? is there an official client interface (node package) that i could add as a dependency of my own project?

if such a thing does not exist, i guess this becomes a sort of feature request for official client specs. it seems that this sort of thing can be generated via protobuff or thrift.

[lnicola]

Do you want to write a replacement for the rust-analyzer Code extension or something that runs along it? Making another LSP client might start a new server instance of both are installed, which would not be ideal.

If you want a replacement, then LSP is the official and supported protocol, and Protobuf or Thrift are not involved in any way. The specs are here, with some extensions here.

If it's something that runs alongside it, there's no API but it would be interesting to hear what use case you have in mind.

[nerdondon]

I am writing something that would just communicate with the existing server instance. AFAIK, it seems like a new client should be able to re-use the existing instance. it seems strange for the server to run out of band just for new clients to spawn new instances but im still new to this.

I'm not trying to replace the LSP protocol, i was just curious if even with the protocol a client could be generated instead of needing to rely on the documentation. i am writing a vscode test explorer extension and would like to see about retrieving test information from the LSP server. Specifically, cargo test -- --list does not return any line numbers for the listed tests and it seems like the Runnable object that one of the LSP extensions provides would be helpful for this information.

[lnicola]

AFAIK, it seems like a new client should be able to re-use the existing instance.

Calling start() on a new LanguageClient spawns another server process.

For a test explorer, see also #5765 (if you haven't already).

[nerdondon]

welp thats good to know. thanks for the pointer. i guess i'll look forward to the official testing explorer support.