Use virtualtext on nvim to display results (#21)

![](https://i.imgur.com/2rbeRZm.png)


With this PR (neovim/neovim#8180) neovim has support to display text that is not part of the file in a buffer. Using this instead of opening a new split will be a better way to display the size.

> Docs need to be added.


### Two new variables
`g:import_cost_virtualtext_hl_group` : set highlight group (default LineNr)
`g:import_cost_virtualtext_prefix`: prefix for virtualtext ( default > )

autoload/import_cost.vim

@@ -41,6 +41,11 @@ function! s:EchoError(msg)
   echohl None
 endfunction
 
+" Check if virtualtext is supported
+function! import_cost#IsVirtualTextSupported()
+    return has('nvim-0.3.2')
+endfunction
+
 " Pretty format a size in bytes
 function! s:PrettyFormatSize(size)
   let l:pretty_size = a:size / 1000.0
@@ -154,7 +159,7 @@ function! s:FillScratchBuffer(imports, start_line, num_lines)
 
   " Appending the imports
   for import in a:imports
-    call append(import['line'] + a:start_line - 1, s:CreateImportString(import))
+    call append(import['line'] + a:start_line - 1, s:CreateImportString(import, 0))
   endfor
 
   " Clear extra blank lines
@@ -190,11 +195,15 @@ function! s:ParseSingleImport(key, val)
 endfunction
 
 " Create an import string from an import data
-function! s:CreateImportString(import)
+function! s:CreateImportString(import, mini)
   let l:raw_size = s:PrettyFormatSize(a:import['size'])
   let l:gzipped_size = s:PrettyFormatSize(a:import['gzip'])
 
-  let l:str = a:import['name'] . ': ' . l:raw_size
+  if a:mini
+    let l:str = l:raw_size
+  else
+    let l:str = a:import['name'] . ': ' . l:raw_size
+  endif
 
   if g:import_cost_show_gzipped == 1
     let l:str .= ' (gzipped: ' . l:gzipped_size . ')'
@@ -203,6 +212,7 @@ function! s:CreateImportString(import)
   return l:str
 endfunction
 
+
 " This function takes the imports data and returns a string containing data
 " about the total size
 function! s:CreateTotalSizeString(imports)
@@ -218,14 +228,34 @@ function! s:CreateTotalSizeString(imports)
         \ 'name': 'Total size',
         \ 'size': l:size,
         \ 'gzip': l:gzip,
-        \ })
+        \ }, 0)
+endfunction
+
+
+function! s:ShowVirtualTextMessage(imports, range_start_line, buffer_lines) abort
+  let l:hl_group =  get(g:, 'import_cost_virtualtext_hl_group', 'LineNr')
+  let l:prefix = get(g:, 'import_cost_virtualtext_prefix', ' > ')
+
+  let l:buffer = bufnr('')
+  call nvim_buf_clear_highlight(l:buffer, 1000, 0, -1)
+
+  for import in a:imports
+    let l:message = s:CreateImportString(import, 1)
+    let l:line = import['line'] + a:range_start_line - 1
+    call nvim_buf_set_virtual_text(l:buffer, 1000, l:line, [[l:prefix.l:message, l:hl_group]], {})
+  endfor
 endfunction
 
 function! s:OnScriptFinish()
 
   " Check for errors
   if len(s:import_cost_stderr)
-    call s:EchoError(s:import_cost_stderr)
+    if !(import_cost#IsVirtualTextSupported() && g:import_cost_virtualtext)
+      call s:EchoError(s:import_cost_stderr)
+    else
+      let l:buffer = bufnr('')
+      call nvim_buf_clear_highlight(l:buffer, 1000, 0, -1)
+    endif
     return
   endif
 
@@ -243,28 +273,35 @@ function! s:OnScriptFinish()
   " If we've got a single import, echo it instead of creating a new scratch
   " buffer (if needed)
   if l:imports_length == 1 && g:import_cost_always_open_split != 1
-    echom s:CreateImportString(l:imports[0])
+    echom s:CreateImportString(l:imports[0], 0)
     return
   endif
 
   " Create a new scratch buffer and fill it
   " Keep the focus on the currently opened buffer
   if l:imports_length > 0
-    let l:current_buffer_name = bufname('%')
-    normal m'
+    if import_cost#IsVirtualTextSupported() && g:import_cost_virtualtext
+      call s:ShowVirtualTextMessage(l:imports, s:range_start_line, s:buffer_lines)
+    else
+      let l:current_buffer_name = bufname('%')
+      normal m'
+
+      call s:CreateScratchBuffer()
+      call s:FillScratchBuffer(l:imports, s:range_start_line, s:buffer_lines)
 
-    call s:CreateScratchBuffer()
-    call s:FillScratchBuffer(l:imports, s:range_start_line, s:buffer_lines)
+      " We'll keep the total size string within the scratch buffer
+      let b:total_size_string = s:CreateTotalSizeString(l:imports)
+      let l:result_message .= ' ' . b:total_size_string
 
-    " We'll keep the total size string within the scratch buffer
-    let b:total_size_string = s:CreateTotalSizeString(l:imports)
-    let l:result_message .= ' ' . b:total_size_string
+      execute bufwinnr(l:current_buffer_name) . 'wincmd w'
+      normal ''
+    endif
 
-    execute bufwinnr(l:current_buffer_name) . 'wincmd w'
-    normal ''
   endif
 
-  echom l:result_message
+  if !(import_cost#IsVirtualTextSupported() && g:import_cost_virtualtext)
+    echom l:result_message
+  endif
 endfunction
 
 " }}}

doc/import_cost.txt

@@ -158,6 +158,44 @@ enabled by default. >
 Value: 0 or 1
 Default: 0 (use asynchronous execution)
 
+------------------------------------------------------------------------------
+g:import_cost_virtualtext                          *g:import_cost_virtualtext*
+
+When this option is on, it will disable the use of virtualtext feature that
+will show the result to the right of the import and instead display the
+result in a split.
+
+If you are running a version without virtualtext, this option is assumed to be
+set to false.
+ >
+
+    let g:import_cost_virtualtext = 0
+<
+Value: 0 or 1
+Default: 1 (use virtualtext insted of split if available)
+
+------------------------------------------------------------------------------
+g:import_cost_virtualtext_hl_group          *g:import_cost_virtualtext_hl_group*
+
+This options control what highlight group will be used to show the info.
+ >
+
+    let g:import_cost_virtualtext_hl_group = "LineNr"
+<
+Value: string
+Default: "LineNr"
+
+------------------------------------------------------------------------------
+g:import_cost_virtualtext_prefix          *g:import_cost_virtualtext_prefix*
+
+This options sets the prefix used to when displaying the import cost info.
+ >
+
+    let g:import_cost_virtualtext_prefix = " :: "
+<
+Value: string
+Default: ">"
+
 ==============================================================================
 LICENSE                                                  *import-cost-license*
 

plugin/import_cost.vim

@@ -35,6 +35,7 @@ let s:default_settings = {
   \ 'split_size': 50,
   \ 'split_pos': 'left',
   \ 'disable_async': 0,
+  \ 'virtualtext': 1,
   \ }
 
 call s:InitSettings(s:default_settings)
@@ -45,6 +46,15 @@ call s:InitSettings(s:default_settings)
 function! s:InitCommands()
   command! -buffer -range=0 ImportCost call import_cost#ImportCost(<count>, <line1>, <line2>)
   command! -buffer          ImportCostSingle call import_cost#ImportCost(1, <line1>, <line1>)
+
+  if import_cost#IsVirtualTextSupported() && g:import_cost_virtualtext && !g:import_cost_disable_async
+    augroup import_cost_auto_run
+      autocmd!
+      autocmd InsertLeave * call import_cost#ImportCost(0, 0 ,0)
+      autocmd BufEnter * call import_cost#ImportCost(0, 0 ,0)
+      autocmd CursorHold * call import_cost#ImportCost(0, 0 ,0)
+    augroup END
+  endif
 endfunction
 
 " }}}