client->server request: matching brace

[matklad]

Another request from rust-analyzer

Matching Brace

Server Capability: { "matchingBrace": boolean }

This request is send from client to server to handle "Matching Brace" editor action.

Method: experimental/matchingBrace

Request:

interface MatchingBraceParams {
    textDocument: TextDocumentIdentifier,
    /// Position for each cursor
    positions: Position[],
}

Response:

Position[]

Example

fn main() {
    let x: Vec<()>/*cursor here*/ = vec![]
}

experimental/matchingBrace yields the position of <.
In many cases, matching braces can be handled by the editor.
However, some cases (like disambiguating between generics and comparison operations) need a real parser.
Moreover, it would be cool if editors didn't need to implement even basic language parsing

Unresolved Question

• Should we return a a nested brace structure, to allow paredit-like actions of jump out of the current brace pair?
  This is how SelectionRange request works.
• Alternatively, should we perhaps flag certain SelectionRanges as being brace pairs?

[matklad]

This basically documents what rust-analyzer is doing today, but now I lean towards the last alternative for the general protocol -- just stuffing info about braces into SelectionRange request.

[dbaeumer]

@jrieken FYI.

[dbaeumer]

Dups #672.