Flow type-at-pos in nvim

neovim/init.vim

@@ -236,3 +236,63 @@ let g:gitgutter_map_keys = 0
 map <silent> <leader>g :GitGutterToggle<CR>
 nmap <silent> ]h <Plug>GitGutterNextHunk
 nmap <silent> [h <Plug>GitGutterPrevHunk
+
+" Sligthly adapted from
+" https://github.com/fatih/vim-go/blob/32ae8640716530bd55062379177da51efb37dfd2/autoload/go/doc.vim#L75
+let s:buf_nr = -1
+function! s:FlowType() abort
+    let content = system('npx flow type-at-pos '.fnameescape(expand('%')).' '.line('.').' '.col('.'))
+
+    " botright new
+    " setlocal buftype=nofile bufhidden=wipe nobuflisted noswapfile nowrap
+    " call append(0, split(content, "\n"))
+
+    " reuse existing buffer window if it exists otherwise create a new one
+    let is_visible = bufexists(s:buf_nr) && bufwinnr(s:buf_nr) != -1
+    if !bufexists(s:buf_nr)
+        new
+        sil file `="[Flow]"`
+        let s:buf_nr = bufnr('%')
+    elseif bufwinnr(s:buf_nr) == -1
+        split
+        execute s:buf_nr . 'buffer'
+    elseif bufwinnr(s:buf_nr) != bufwinnr('%')
+        execute bufwinnr(s:buf_nr) . 'wincmd w'
+    endif
+
+    " if window was not visible then resize it
+    if !is_visible
+        " cap window height to 20, but resize it for smaller contents
+        let max_height = go#config#DocMaxHeight()
+        let content_height = len(split(content, "\n"))
+        if content_height > max_height
+            exe 'resize ' . max_height
+        else
+            exe 'resize ' . content_height
+        endif
+    endif
+
+    setlocal filetype=js
+    setlocal bufhidden=delete
+    setlocal buftype=nofile
+    setlocal noswapfile
+    setlocal nobuflisted
+    setlocal nocursorline
+    setlocal nocursorcolumn
+    setlocal iskeyword+=:
+    setlocal iskeyword-=-
+
+    setlocal modifiable
+    %delete _
+    call append(0, split(content, "\n"))
+    sil $delete _
+    setlocal nomodifiable
+    sil normal! gg
+
+    " close easily with <esc> or enter
+    noremap <buffer> <silent> <CR> :<C-U>close<CR>
+    noremap <buffer> <silent> <Esc> :<C-U>close<CR>
+endfunction
+
+command FlowTypeAtPos call s:FlowType()
+autocmd FileType javascript nnoremap <buffer> <silent> K :FlowTypeAtPos<CR>