client-server requst: onEnter

On Enter

Server Capability: { "onEnter": boolean }

This request is send from client to server to handle Enter keypress.

Method: experimental/onEnter

Request:: TextDocumentPositionParams

Response:: SnippetTextEdit[]

Example

fn main() {
    // Some /*cursor here*/ docs
    let x = 92;
}

experimental/onEnter returns the following snippet

fn main() {
    // Some
    // $0 docs
    let x = 92;
}

The primary goal of onEnter is to handle automatic indentation when opening a new line.
This is not yet implemented.
The secondary goal is to handle fixing up syntax, like continuing doc strings and comments, and escaping \n in string literals.

As proper cursor positioning is raison-d'etat for onEnter, it uses SnippetTextEdit.

Unresolved Question

• How to deal with synchronicity of the request?
  One option is to require the client to block until the server returns the response.
  Another option is to do a OT-style merging of edits from client and server.
  A third option is to do a record-replay: client applies heuristic on enter immediatelly, then applies all user's keypresses.
  When the server is ready with the response, the client rollbacks all the changes and applies the recorded actions on top of the correct response.
• How to deal with multiple carets?
• Should we extend this to arbitrary typed events and not just onEnter?
• The name seems wrong.

Start with the experimental/onEnter request proposal and its unresolved questions about synchronicity, multiple carets, scope, and naming. No implementation files or tests are identified in the issue. Done would require settling the protocol design and specifying the request behavior before implementation can begin.