#+TITLE: LSP layer

* Table of Contents                      :TOC_4_gh:noexport:
- [[#description][Description]]
  - [[#features][Features:]]
- [[#configuration][Configuration]]

* Description
This layer adds support for basic language server protocol packages speaking
[[https://microsoft.github.io/language-server-protocol/specification][language server protocol]].

** Features:
- Cross references (definitions, references, document symbol, workspace symbol
  search and others)
- Workspace-wide symbol rename
- Symbol highlighting
- Flycheck
- Completion with =company-lsp=
- Signature help with eldoc
- Symbol documentation in a child frame (=lsp-ui-doc=)

Each language server may support the language server protocol in varying degree
and they may also provide extensions, check the language server's website for
details.
=M-x lsp-capabilities= in a LSP buffer to list capabilities of the server.

* Configuration
The LSP ecosystem is based on two packages: [[https://github.com/emacs-lsp/lsp-mode][lsp-mode]] and [[https://github.com/emacs-lsp/lsp-ui][lsp-ui]].
Please check out their documentation.

If you add =lsp-*-enable= to major mode hooks for auto initialization of
language clients, customize =lsp-project-whitelist= =lsp-project-blacklist= to
disable projects you don't want to enable LSP.

If some features doe not work as intended, here is a common check list.

- =M-x lsp-capabilities= If the LSP workspace is initialized correctly
- =M-: xref-backend-functions= should be =(lsp--xref-backend)= for cross
  references
- =M-: completion-at-point-functions= should be =(lsp-completion-at-point)= for
  completion