This README is the one indexed from the repository at its latest ref, not from the tag for this version.

lsp

An implementation of the Language Server Protocol written in Crystal.

This shard is a partial implementation of the Language Server Protocol. It contains json mappings to the data structures and messages as well as a fully working server implementation.

The code has originally been written for the crystalline tool and is now extracted here.

Installation

1. Add the dependency to your shard.yml:

   dependencies:
     lsp:
       github: elbywan/crystal-lsp

2. Run shards install

Usage

require "lsp/server"

# Declare the server capabilities
# See: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#capabilities
server_capabilities = LSP::ServerCapabilities.new(
  # ...
)

# STDIN and STDOUT are used by default, but you can pass any IO.
server = LSP::Server.new(STDIN, STDOUT, server_capabilities)
# A Controller is a class or struct that responds to client events.
# Example: https://github.com/elbywan/crystalline/blob/master/src/crystalline/controller.cr
server.start(Controller.new)

struct Controller
  # Called just after receiving the "initialize" request
  def on_init(init_params : LSP::InitializeParams) : Nil
    # …
  end

  # Called after the handshake is complete and before listening for requests and notifications
  def when_ready : Nil
    # …
  end

  # Called when the client sends a request (https://microsoft.github.io/language-server-protocol/specifications/specification-3-16/#requestMessage)
  def on_request(message : LSP::RequestMessage)
    # …
  end

  # Called when the client sends a notification (https://microsoft.github.io/language-server-protocol/specifications/specification-3-16/#notificationMessage)
  def on_notification(message : LSP::NotificationMessage) : Nil
    # …
  end

  # Called when the client sends a response (https://microsoft.github.io/language-server-protocol/specifications/specification-3-16/#responseMessage)
  def on_response(message : LSP::ResponseMessage, original_message : LSP::RequestMessage?) : Nil
    # …
  end
end

Contributing

1. Fork it (https://github.com/elbywan/lsp/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• Julien Elbaz - creator and maintainer