Custom language server: how to get the client to send *all* files to the server, not just those opened/edited by the user?

Question

I'm working on implementing a custom language server and a VSCode language extension. My starting point for the client side is lsp-sample. My server implementation is entirely from scratch, in a different language (not JS).

Currently, I've successfully set up textDocument/didOpen and textDocument/didChange messages to be sent by the client and received by the server. However, I'm having trouble figuring out how to synchronize all files in the VSCode workspace, not just those that the user has opened. I can't find where this is supported in the protocol. The only text document synchronization capabilities I see are for documents opening, closing, and edits. What about all the other documents in the workspace?

For example, in order to handle "goto definition" requests, the server needs to know about definitions in other files, perhaps those that have never been opened or edited by the user.

A hacky solution would be, on the server side, to parse the URI of the workspace and just go load a bunch of files manually. But this seems like something that the LSP should support; perhaps I'm just missing where it's documented. (Also, it feels like I would be violating the spirit of the LSP design to do some covert ops like this behind the scenes, without communicating with the client.)

Answer 1

Perhaps you're looking for

DidChangeWatchedFiles Notification

See Specification

The watched files notification is sent from the client to the server when the client detects changes to files and folders watched by the language client (note although the name suggest that only file events are sent it is about file system events which include folders as well). It is recommended that servers register for these file system events using the registration mechanism. In former implementations clients pushed file events without the server actively asking for it.

Basically the client is responsible of watching the files you require and sends a notification to the server each time something changes on them. At this point the server is capable to load them.