nvim: Improve lsp source chaining

Lsp will by default invoke most of its sources simultaneously (one after
the other if no completions are found for the first), but this is
disabled for pandoc.

In pandoc, only the buffer and lsp sources are invoked (the first
chain), since bibcite will take a while to compile the cite keys.
To invoke bibcite in pandoc, use c-j/c-k when in the completion menu,
and they will be calculated.

This may be removed if a faster compilation for bibtex citekeys is
found.

bootstrap/packages.txt

@@ -9,6 +9,7 @@ aspell-de
 aspell-en
 atool
 barrier
+bash-language-server
 bat
 bc
 biber
@@ -34,6 +35,7 @@ glances
 glow
 gnome-keyring
 go
+gopls
 grub
 hugo
 i3-gaps
@@ -90,6 +92,7 @@ psmisc
 pulsemixer
 python-black
 python-jedi
+python-language-server
 python-pdfminer.six
 python-pipx
 python-pybtex
@@ -115,6 +118,7 @@ surfraw
 sxhkd
 systemd-sysvcompat
 tdrop-git
+texlab
 texlive-bibtexextra
 texlive-fontsextra
 texlive-formatsextra
@@ -138,6 +142,7 @@ usbutils
 vagrant
 vi
 vifm
+vim-language-server
 xcape
 xclip
 xorg-xev

nvim/.config/nvim/init.vim

@@ -53,6 +53,7 @@ Plug 'junegunn/fzf.vim'
 
 Plug 'neovim/nvim-lspconfig'                                                          " some commong language server configurations
 Plug 'nvim-lua/completion-nvim'                                                       " simple completion engine built specifically for nvim and lsp
+Plug 'steelsojka/completion-buffers'                                                  " completion source from words found in current buffers
 Plug 'desmap/ale-sensible' | Plug 'w0rp/ale'                                          " asynchronous linting - might be superseded by lsp or coc.nvim at some point
                                                                                       " statusline
 Plug 'vim-airline/vim-airline'
@@ -189,6 +190,9 @@ set noequalalways
 " make sure there's always *some* context below cursor
 set scrolloff=5
 
+" in .tex files, default to latex over plaintext/context as syntax
+let g:tex_flavor = "latex"
+
 " }}}
 " KEYBINDINGS {{{
 " ================================================================================

nvim/.config/nvim/plugin/completion-nvim.vim

@@ -2,13 +2,12 @@
 autocmd BufEnter * lua require'completion'.on_attach()
 
 "map <c-p> to manually trigger completion
-imap <silent> <c-p> <Plug>(completion_trigger)
-imap <silent> <c-n> <Plug>(completion_trigger)
-
-" Add <Tab> and <S-Tab> to navigate through popup menu
-inoremap <expr> <Tab>   pumvisible() ? "\<C-n>" : "\<Tab>"
-inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"
-
+imap <silent> <c-n> <Plug>(completion_smart_tab)
+imap <silent> <c-p> <Plug>(completion_smart_s_tab)
+" switch between completion sources manually with c-j/c-k
+" only do so if popupmenu is visible, otherwise normal function
+imap <silent> <c-j> <Plug>(completion_next_source)
+imap <silent> <c-k> <Plug>(completion_previous_source)
 
 " Set completeopt to have a better completion experience
 set completeopt=menuone,noinsert,noselect
@@ -22,37 +21,48 @@ let g:completion_matching_strategy_list = ['exact', 'substring', 'fuzzy']
 " even when backtracking enable completion
 let g:completion_trigger_on_delete = 1
 
+" switch between different completion changes when no completions found for
+" current one
+let g:completion_auto_change_source = 1
+
 " register new completion engines
 " (set in rtp/lua/*_complete.lua)
 "
 " pandoc citation key completion
 lua require'completion'.addCompletionSource('bibcite', require'pandoc_complete'.complete_item)
 
-" only call for specified shortcut, or with completion keys
+" in pandoc files, normal completion should only come from buffer sources and
+" bibcite only invoked manually, since it takes long to parse
 augroup pandocCompletion
   autocmd!
   autocmd BufEnter * call SetupPandocCompletion()
 augroup end
 fun! SetupPandocCompletion()
   if &ft =~ 'pandoc'
-        let g:completion_enable_auto_popup = 0
-        let g:completion_trigger_character = ['@\w*']
+    let g:completion_auto_change_source = 1
     return
   endif
-    let g:completion_enable_auto_popup = 1
-    let g:completion_trigger_character = ['.']
+  let g:completion_auto_change_source = 0
 endfun
 
 " the completion chains for different filetypes
 " see https://github.com/nvim-lua/completion-nvim/wiki/chain-complete-support
 let g:completion_chain_complete_list = {
     \ 'pandoc': [
-    \    {'complete_items': ['bibcite', 'lsp', 'snippet']},
+    \    { 'complete_items': ['buffer',  'lsp', 'snippet']},
+    \    { 'complete_items': ['bibcite'] },
+    \    { 'mode': '<c-p>'},
+    \    { 'mode': '<c-n>'}
+    \],
+    \ 'tex': [
+    \    { 'complete_items': ['buffer',  'lsp', 'snippet']},
+    \    { 'complete_items': ['bibcite'] },
     \    { 'mode': '<c-p>'},
     \    { 'mode': '<c-n>'}
     \],
     \ 'default': [
     \    { 'complete_items': ['lsp', 'snippet']},
+    \    { 'complete_items': [ 'buffers' ] },
     \    { 'mode': '<c-p>'},
     \    { 'mode': '<c-n>'}
     \]

nvim/.config/nvim/plugin/nvim-lspconfig.vim

@@ -1,4 +1,9 @@
-
 " enable python language servers
 lua require'nvim_lsp'.pyls.setup{}
 lua require'nvim_lsp'.vimls.setup{}
+lua require'nvim_lsp'.bashls.setup{}
+lua require'nvim_lsp'.gopls.setup{}
+lua require'nvim_lsp'.texlab.setup{}
+
+" requires manual `:LspInstall sumneko_lua`
+lua require'nvim_lsp'.sumneko_lua.setup{}

nvim/.config/nvim/watch.lua

@@ -14,3 +14,4 @@ function watch_file(fname)
 end
 vim.api.nvim_command(
   "command! -nargs=1 Watch call luaeval('watch_file(_A)', expand('<args>'))")
+