Add default coc.nvim extensions & update autocomplete function

nvim/init.vim

@@ -97,24 +97,37 @@ highlight CursorLine cterm=NONE
 set laststatus=2
 set statusline=\ %F\ %m%r%w\ %=\ %{hostname()}\ \ \ %{strlen(&ft)?&ft:'none'}\ %{(&bomb?\",BOM\":\"\")}\ %{&ff}\ \ %l/%L\ \ %c\ %P
 
-" tab autocompletion
-function! Tab_Or_Complete()
-  if col('.')>1 && strpart( getline('.'), col('.')-2, 3 ) =~ '^\w'
-    return "\<C-N>"
-  else
-    return "\<Tab>"
-  endif
+" use <tab> for trigger completion and navigate to the next complete item
+function! s:check_back_space() abort
+  let col = col('.') - 1
+  return !col || getline('.')[col - 1]  =~ '\s'
 endfunction
 
+" tab completion
+inoremap <silent><expr> <Tab>
+      \ pumvisible() ? "\<C-n>" :
+      \ <SID>check_back_space() ? "\<Tab>" :
+      \ coc#refresh()
+
 " open nerdtree browser
 map <silent> <C-E> :NERDTreeToggle <CR>
 
-" tab for completion
-inoremap <Tab> <C-R>=Tab_Or_Complete()<CR>
-
 " set default coc environment path
 let g:python3_host_prog = '~/.local/lib/coc/.venv/bin/python'
 
+" default coc extensions
+" see https://github.com/neoclide/coc.nvim/wiki/Using-coc-extensions#install-extensions
+" installed if not detected to ~/.config/coc/extensions
+let g:coc_global_extensions = [\
+  'coc-pyright',\
+  'coc-html',\
+  'coc-htmldjango',\
+  'coc-css',\
+  'coc-tsserver',\
+  'coc-git',\
+  'coc-json'\
+]
+
 if filereadable(expand('~/.config/nvim/override.vim'))
   source ~/.config/nvim/override.vim
 endif