nvim: Refactor and update settings for completion-nvim

Use of trigger keys has been updated upstream. Also disable auto
completion.

nvim/.config/nvim/after/plugin/completion.vim

@@ -1,14 +1,49 @@
-" For nvim-completion
+let g:completion_enable_auto_popup = 0
+let g:completion_auto_change_source = 1
+let g:completion_trigger_on_delete = 1
+let g:completion_matching_ignore_case = 0
+let g:completion_matching_strategy_list = ['exact', 'substring']
+
+let g:completion_chain_complete_list = {
+  \ 'c': [
+  \    {'complete_items': ['buffers']},
+  \    {'mode': 'tags'},
+  \    {'mode': 'keyn'},
+  \    {'mode': '<c-p>'},
+  \    {'mode': '<c-n>'}
+  \],
+  \ 'haskell': [
+  \    {'complete_items': ['lsp']},
+  \    {'complete_items': ['buffers']},
+  \    {'mode': 'keyn'},
+  \    {'mode': '<c-p>'},
+  \    {'mode': '<c-n>'},
+  \],
+  \ 'rust': [
+  \    {'complete_items': ['lsp']},
+  \    {'complete_items': ['buffers']},
+  \    {'mode': 'keyn'}
+  \],
+  \ 'purescript': [
+  \    {'complete_items': ['lsp']},
+  \    {'complete_items': ['buffers']},
+  \    {'mode': 'keyn'},
+  \    {'mode': '<c-p>'},
+  \    {'mode': '<c-n>'}
+  \],
+  \ 'default': [
+  \    {'complete_items': ['buffers']},
+  \    {'mode': 'keyn'},
+  \    {'mode': '<c-p>'},
+  \    {'mode': '<c-n>'},
+  \],
+  \}
+
+inoremap <expr> <Tab>   pumvisible() ? "\<C-n>" : "\<Tab>"
+inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"
+imap <Tab> <Plug>(completion_smart_tab)
 imap <C-j> <Plug>(completion_next_source)
 imap <C-k> <Plug>(completion_prev_source)
 
-" Tab completion. Taken from nvim-completion README.
-function! s:check_back_space() abort
-  let col = col('.') - 1
-  return !col || getline('.')[col - 1] =~ '\s'
-endfunction
-
-inoremap <silent><expr> <TAB>
-  \ pumvisible() ? "\<C-n>" :
-  \ <SID>check_back_space() ? "\<TAB>" :
-  \ completion#trigger_completion()
+" Use completion-nvim in every buffer
+autocmd BufEnter * lua require'completion'.on_attach()

nvim/.config/nvim/autocmd.vim

@@ -28,9 +28,6 @@ augroup UserStatusline
   autocmd ColorScheme * hi User8 guifg=DarkYellow guibg=Black
 augroup END
 
-" Use completion-nvim in every buffer
-autocmd BufEnter * lua require'completion'.on_attach()
-
 augroup LuaHighlight
   autocmd!
   autocmd TextYankPost * silent! lua require'vim.highlight'.on_yank("IncSearch", 2000)

nvim/.config/nvim/plugin_settings.vim

@@ -56,43 +56,5 @@ let g:diagnostic_show_sign = 1
 let g:diagnostic_auto_popup_while_jump = 1
 let g:diagnostic_insert_delay = 1
 
-" For nvim-completion
-let g:completion_enable_auto_popup = 1
-let g:completion_auto_change_source = 1
-let g:completion_chain_complete_list = {
-  \ 'c': [
-  \    {'complete_items': ['buffers']},
-  \    {'mode': 'keyn'},
-  \    {'mode': 'tags'},
-  \    {'mode': '<c-p>'},
-  \    {'mode': '<c-n>'}
-  \],
-  \ 'haskell': [
-  \    {'complete_items': ['lsp']},
-  \    {'complete_items': ['buffers']},
-  \    {'mode': 'keyn'},
-  \    {'mode': '<c-p>'},
-  \    {'mode': '<c-n>'},
-  \],
-  \ 'rust': [
-  \    {'complete_items': ['lsp']},
-  \    {'complete_items': ['buffers']},
-  \    {'mode': 'keyn'}
-  \],
-  \ 'purescript': [
-  \    {'complete_items': ['lsp']},
-  \    {'complete_items': ['buffers']},
-  \    {'mode': 'keyn'},
-  \    {'mode': '<c-p>'},
-  \    {'mode': '<c-n>'}
-  \],
-  \ 'default': [
-  \    {'complete_items': ['buffers']},
-  \    {'mode': 'keyn'},
-  \    {'mode': '<c-p>'},
-  \    {'mode': '<c-n>'},
-  \],
-  \}
-
 lua require 'lsp'
 lua require 'treesitter'