Update for new coc.nvim

init.vim

@@ -358,13 +358,23 @@ set shortmess+=c
 " always show signcolumns
 set signcolumn=yes
 
-" Use tab for trigger completion with characters ahead and navigate.
-" Use command ':verbose imap <tab>' to make sure tab is not mapped by other plugin.
+" {{{ coc completion
+"Use <tab> and <S-tab> to navigate completion list:  
+
+function! CheckBackSpace() abort
+    let col = col('.') - 1
+    return !col || getline('.')[col - 1]  =~ '\s'
+endfunction
+inoremap <silent><expr> <CR> coc#pum#visible() ? coc#_select_confirm()
+            \: "\<C-g>u\<CR>\<c-r>=coc#on_enter()\<CR>"
+
+" Insert <tab> when previous text is space, refresh completion if not.
 inoremap <silent><expr> <TAB>
-      \ pumvisible() ? "\<C-n>" :
-      \ <SID>check_back_space() ? "\<TAB>" :
+            \ coc#pum#visible() ? coc#pum#next(1):
+            \ CheckBackSpace() ? "\<Tab>" :
             \ coc#refresh()
-inoremap <expr><S-TAB> pumvisible() ? "\<C-p>" : "\<C-h>"
+inoremap <expr><S-TAB> coc#pum#visible() ? coc#pum#prev(1) : "\<C-h>"
+"}}}
 
 function! s:check_back_space() abort
   let col = col('.') - 1
@@ -374,10 +384,6 @@ endfunction
 " Use <c-space> to trigger completion.
 inoremap <silent><expr> <c-space> coc#refresh()
 
-" Use <cr> to confirm completion, `<C-g>u` means break undo chain at current position.
-" Coc only does snippet and additional edit on confirm.
-inoremap <expr> <cr> pumvisible() ? "\<C-y>" : "\<C-g>u\<CR>"
-
 " Use `[c` and `]c` to navigate diagnostics
 nmap <silent> [c <Plug>(coc-diagnostic-prev)
 nmap <silent> ]c <Plug>(coc-diagnostic-next)