CODEWITHSUNDEEP
visual-studio-codevscode-extensionslanguage-server-protocol
SvenEV
SvenEV

Reputation: 123

Language Server: How to enable "onDidOpenTextDocument" events

I'm developing a language server (and client) for VS Code based on the official "lsp-sample". According to the documentation (Language Server Extension Guide), setting the capability textDocumentSync: TextDocumentSyncKind.Incremental should enable the language server to receive the events onDidOpenTextDocument, onDidChangeTextDocument and onDidCloseTextDocument.

However, VS Code does not appear to send these events to the language server, and breakpoints in the event handlers (e.g. on this line) are not hit (breakpoints in other event handlers are hit, though, so debugging the language server does work).

What could be wrong in the client or server configurations that would prevent VS Code from sending these events?

Upvotes: 1

Views: 658

Answers (1)

SvenEV
SvenEV

Reputation: 123

After lots of debugging of the language client I found the issue: On startup, my language server prints something to stdout to indicate that it's ready. Since the language server is communicating via stdout/stdin, VS Code (correctly) interprets this as a violation of the protocol, causing the whole thing to not even start correctly. Removing the print statement resolved the issue.

Surprisingly, the LSP plugin in Sublime Text apparently ignored this protocol violation and continued to function despite my faulty language server implementation.

Upvotes: 1

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