Add: coc.nvim integration enhacements (#2415)

* Enhance coc.nvim integration

* Update documentation

autoload/SpaceVim/layers/lsp.vim

@@ -9,7 +9,9 @@
 function! SpaceVim#layers#lsp#plugins() abort
   let plugins = []
 
-  if has('nvim')
+  if SpaceVim#layers#isLoaded("autocomplete") && get(g:, "spacevim_autocomplete_method") ==# 'coc'
+    " nop
+  elseif has('nvim')
     call add(plugins, ['autozimu/LanguageClient-neovim',
           \ { 'merged': 0, 'if': has('python3'), 'build' : 'bash install.sh' }])
   else

autoload/SpaceVim/lsp.vim

@@ -8,7 +8,69 @@
 
 scriptencoding utf-8
 
-if has('nvim')
+
+if SpaceVim#layers#isLoaded("autocomplete") && get(g:, "spacevim_autocomplete_method") ==# 'coc'
+  " use coc.nvim
+  let s:coc_language_servers = {}
+  let s:coc_language_servers_key_id_map = {}
+  function! SpaceVim#lsp#reg_server(ft, cmds) abort
+    " coc.nvim doesn't support key values containing dots
+    " See https://github.com/neoclide/coc.nvim/issues/323
+    " Since a:cmds[0], i.e. the language server command can be a full path,
+    " which can potentially contain dots, we just take it's last part, if any
+    " dots are present.
+    " 
+    " Clearly, with this implementation, an edge case could be the following
+    "
+    " [layers.override_cmd]
+    "   c = ['/home/user/.local/.bin/ccls', '--log-file=/tmp/ccls.log']
+    "   cpp = ['/home/user/local/.bin/ccls', '--log-file=/tmp/ccls.log']
+    "
+    " the last part `bin/ccls` is the same, whereas the commands are not
+    " actually the same.
+    " We need to keep an id to distinguish among conflicting keys.
+    
+    if stridx(a:cmds[0], ".") >= 0 
+      let l:key = split(a:cmds[0], "\\.")[-1]
+    else
+      let l:key = a:cmds[0]
+    endif
+
+    for id in range(get(s:coc_language_servers_key_id_map, l:key, 0))
+      if has_key(s:coc_language_servers, l:key . id) && s:coc_language_servers[l:key . id].command ==# a:cmds[0]
+        call add(s:coc_language_servers[l:key . id].filetypes, a:ft)
+        return
+      endif
+    endfor
+
+    let s:coc_language_servers_key_id_map[l:key] = get(s:coc_language_servers_key_id_map, l:key, 0)
+    let s:coc_language_servers[l:key . s:coc_language_servers_key_id_map[l:key]] = {
+          \'command': a:cmds[0],
+          \'args': a:cmds[1:],
+          \'filetypes': [a:ft]
+          \}
+
+    let s:coc_language_servers_key_id_map[l:key] = s:coc_language_servers_key_id_map[l:key] + 1
+
+    autocmd! User CocNvimInit :call coc#config("languageserver", s:coc_language_servers)
+  endfunction
+
+  function! SpaceVim#lsp#show_doc() abort
+    call CocActionAsync("doHover")
+  endfunction
+
+  function! SpaceVim#lsp#go_to_def() abort
+    call CocActionAsync("jumpDefinition")
+  endfunction
+
+  function! SpaceVim#lsp#rename() abort
+    call CocActionAsync("rename")
+  endfunction
+
+  function! SpaceVim#lsp#references() abort
+    call CocActionAsync("jumpReferences")
+  endfunction
+elseif has('nvim')
   " use LanguageClient-neovim
   function! SpaceVim#lsp#reg_server(ft, cmds) abort
     let g:LanguageClient_serverCommands[a:ft] = copy(a:cmds)

docs/layers/autocomplete.md

@@ -10,6 +10,7 @@ description: "Autocomplete code within SpaceVim, fuzzy find the candidates from
 - [Description](#description)
 - [Install](#install)
 - [Configuration](#configuration)
+  - [Choose which completion engine to be used](#choose-which-completion-engine-to-be-used)
   - [Key bindings](#key-bindings)
   - [Snippets directories](#snippets-directories)
   - [Show snippets in auto-completion popup](#show-snippets-in-auto-completion-popup)
@@ -29,7 +30,10 @@ The following completion engines are supported:
 - [neocomplete](https://github.com/Shougo/neocomplete.vim) - vim with `+lua`
 - [neocomplcache](https://github.com/Shougo/neocomplcache.vim) - vim without `+lua`
 - [deoplete](https://github.com/Shougo/deoplete.nvim) - neovim with `+python3`
+- [coc](https://github.com/neoclide/coc.nvim) - vim >= 8.1 or neovim >= 0.3.1
 - [YouCompleteMe](https://github.com/Valloric/YouCompleteMe) - disabled by default, to enable ycm, see `:h g:spacevim_enable_ycm`
+- [Completor](https://github.com/maralla/completor.vim) - vim8 with `+python` or `+python3`
+- [asyncomplete](https://github.com/prabirshrestha/asyncomplete.vim) - vim8 or neovim with `timers`
 
 Snippets are supported via [neosnippet](https://github.com/Shougo/neosnippet.vim).
 
@@ -44,6 +48,20 @@ To use this configuration layer, add following snippet to your custom configurat
 
 ## Configuration
 
+### Choose which completion engine to be used
+
+You can choose the completion engine (among the supported ones) to be used
+with the following variable:
+
+- `g:spacevim_autocomplete_method`: the possible values are:
+    - `ycm`: for YouCompleteMe
+    - `neocomplcache`
+    - `coc`: **Note** that coc.nvim is also a language server protocol client. 
+See [lsp layer](language-server-protocol.md) for more information.
+    - `deoplete`
+    - `asyncomplete`
+    - `completor`
+
 ### Key bindings
 
 You can customize the user experience of auto-completion with the following layer variables:

docs/layers/language-server-protocol.md

@@ -22,9 +22,12 @@ This layers adds extensive support for [language-server-protocol](https://micros
 This layer is a heavy wallpaper of [LanguageClient-neovim](https://github.com/SpaceVim/LanguageClient-neovim) (an old fork),
 The upstream is rewritten by rust.
 
-we also include [vim-lsp](https://github.com/prabirshrestha/vim-lsp), which is wrote in pure vim script.
+We also include [vim-lsp](https://github.com/prabirshrestha/vim-lsp), which is wrote in pure vim script.
 
-the neovim team is going to implement the build-in LSP support, the
+Note that if `coc` is used as autocomplete method in the `autocomplete` layer,
+it will be used as lsp client.
+
+The neovim team is going to implement the build-in LSP support, the
 PR is [neovim#6856](https://github.com/neovim/neovim/pull/6856). and the author of this PR
 create another plugin [tjdevries/nvim-langserver-shim](https://github.com/tjdevries/nvim-langserver-shim)
 
@@ -33,6 +36,8 @@ SpaceVim should works well in different version of vim/neovim, so in the feature
 ```vim
 if has('nvim')
   " use neovim build-in lsp
+if SpaceVim#layers#isLoaded("autocomplete") && get(g:, "spacevim_autocomplete_method") ==# 'coc'
+  " use coc.nvim
 elseif has('python3')
   " use LanguageClient-neovim
 else