nvim: Switch to nvim-lsp

Enabled lsp within nvim and switched completion engine from deoplete to
completion-nvim.

The completion will be somewhat more barebones for some filetypes until
the language servers are set up, but should then (theoretically) carry a
lot more features than before.

Additionally, we can, over time, add additional code inspection
functionality.

One change concerns the calling of bibtex cite key completion in pandoc
files: Where before the completion would automatically begin after
typing an '@', it will now only start on manual completion invocation
(c-p/c-n) -- since the completion from my current bibtex file takes a
while to load.

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

@@ -0,0 +1,59 @@
+" use completion-nvim for all buffers (not just lsp)
+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>"
+
+
+" Set completeopt to have a better completion experience
+set completeopt=menuone,noinsert,noselect
+
+" Avoid showing message extra message when using completion
+set shortmess+=c
+
+" set loop of strategies in descending order
+let g:completion_matching_strategy_list = ['exact', 'substring', 'fuzzy']
+
+" even when backtracking enable completion
+let g:completion_trigger_on_delete = 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
+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*']
+        return
+    endif
+    let g:completion_enable_auto_popup = 1
+    let g:completion_trigger_character = ['.']
+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']},
+    \    {'mode': '<c-p>'},
+    \    {'mode': '<c-n>'}
+    \],
+    \ 'default': [
+    \    {'complete_items': ['lsp', 'snippet']},
+    \    {'mode': '<c-p>'},
+    \    {'mode': '<c-n>'}
+    \]
+\}

nvim/.config/nvim/plugin/deoplete.vim

@@ -1,20 +0,0 @@
-" PLUGIN: DEOPLETE
-" For async completion
-" enable deoplete at startup
-let g:deoplete#enable_at_startup =1
-
-call deoplete#custom#option( {
-      \ 'camel_case': v:true,
-      \ 'smart_case': v:true,
-      \ 'ignore_case': v:true,
-      \ 'refresh_always': v:true,
-      \ 'max_abbr_width': 0,
-      \ 'max_menu_width': 0
-      \} )
-
-call deoplete#custom#var('omni', 'input_patterns', {
-      \'pandoc': '@\w*',
-      \})
-call deoplete#custom#var('omni', 'functions', {
-      \'pandoc': 'pandoc#completion#Complete',
-      \})

nvim/.config/nvim/plugin/echodoc.vim

@@ -1,7 +0,0 @@
-" PLUGIN: ECHODOC
-let g:echodoc#type="virtual"
-let g:echodoc_enable_at_startup=1
-set splitbelow
-set completeopt+=menu,menuone,noinsert,noselect
-set completeopt-=preview
-autocmd CompleteDone * pclose

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

@@ -0,0 +1,4 @@
+
+" enable python language servers
+lua require'nvim_lsp'.pyls.setup{}
+lua require'nvim_lsp'.vimls.setup{}

nvim/.config/nvim/plugin/vim-polyglot.vim

@@ -1,7 +1,7 @@
 " PLUGIN: vim-polyglot
 "
 " we disable markdown so that every markdown file can be given pandoc type
-let g:polyglot_disabled = ['markdown']
+" let g:polyglot_disabled = ['markdown']
 
 au BufNewFile,BufRead *.{md,mdown,mkd,mkdn,markdown,mdwn} set ft=pandoc
 au BufNewFile,BufRead *.{md,mdown,mkd,mkdn,markdown,mdwn}.{des3,des,bf,bfa,aes,idea,cast,rc2,rc4,rc5,desx} set ft=pandoc