Combining with other `<CR>` mappings

[Federico Ramirez]

Hi, first of all thanks for the hard work in all of your Vim plugins! They are great and I use several of your plugins in my daily vimming.

I wrote a little plugin I use for autocompleting pairs (eg: adding ] after I type [). It does have some functionality to indent when pressing CR.

To make that compatible with vim-endwise (and maybe other similar plugins which use the <CR> mapping) I saved the old mapping and restored it, doing something like this:

function! s:CarriageReturn() abort
  if some_condition
    " ... the plugin will handle the <CR> mapping
  else
    " ... restore previous <CR> behavior
    return "\<CR>\<Plug>(smartpairs-old-cr)"
  endif
endfunction

let s:old_cr_mapping = maparg('<CR>', 'i', 0, 1)
if s:old_cr_mapping != {}
  let s:old_cr = s:old_cr_mapping.rhs
  let s:old_cr = substitute(s:old_cr, '^<CR>', '', 'g')
  let s:old_cr = substitute(s:old_cr, '<SID>', '<SNR>' . s:old_cr_mapping.sid . '_', 'g')
  let s:old_cr = substitute(s:old_cr, '<Plug>', '<SNR>' . s:old_cr_mapping.sid . '_', 'g')
  execute 'imap <buffer> <Plug>(smartpairs-old-cr) ' . s:old_cr
else
  execute 'inoremap <buffer> <Plug>(smartpairs-old-cr) <Nop>'
endif

imap <expr> <buffer> <CR> <SID>CarriageReturn()

When I'm in a file that uses vim-endwise, like a Ruby file, it still works, but when I'm in another file type, like a regular text file, it inserts EndwiseAppend(<SNR>45_CarriageReturn()) whenever I press enter.

I see in the version notes, it includes:

• Better support for automatically combining with other maps.
• Better support for manually creating combined maps.

I could try and hack something to make my plugin work, but seeing the patch notes I wonder: What's the preferred way to combine my own mappings with vim-endwise's <CR> mappings?

[Tim Pope]

Since you're using <buffer>, I take it you're triggering on an event like FileType or BufReadPost. What happens when that event triggers a second time? My guess would be <Plug>(smartpairs-old-cr) would end up mapped to <SNR>45_CarriageReturn(), and you'd get <SNR>45_CarriageReturn() inserted directly into the buffer. With that inherent instability in the mix, I don't know that it is even possible to layer in delegating to another map.

If you don't mind hard-coding an Endwise reference, this gets much easier to solve:

function! s:CarriageReturn() abort
  if some_condition
    " ... the plugin will handle the <CR> mapping
  else
    return "\<CR>"
  endif
endfunction

if exists('*EndwiseAppend')
  imap <script><expr><buffer> <CR> EndwiseAppend(<SID>CarriageReturn())
else
  imap <script><expr><buffer> <CR> <SID>CarriageReturn()
endif

Now it's idempotent. You'll get the same result even if the map is defined a second time.

I can maybe offer more specific advice if I see a complete working solution, one that doesn't have the "second time" problem.

[Federico Ramirez]

Ohh I see! EndwiseAppend works great!

I'd like advice in a more complete solution though :) I'm using the BufEnter event:

function! SmartPairsInitialize() abort
  if get(b:, 'smartpairs_mappings_initialize', 0) == 0
    let b:smartpairs_mappings_initialize = 1
    let b:smartpairs_pairs = has_key(g:smartpairs_pairs, &filetype) ? g:smartpairs_pairs[&filetype] : g:smartpairs_default_pairs
    call s:SetUpMappings()
  end
endfunction

autocmd BufEnter * :call SmartPairsInitialize()

The full source can be seen here. The mappings are defined in s:SetUpMappings().

Thanks for your help :D

[Tim Pope]

I would strongly consider mapping globally. If you're going to map in every single buffer anyways, the only thing a buffer local map adds is extra complexity. That same solution I gave you should work if you drop the <buffer>. I see from the full source you probably can't do that easily for everything, but it should work for <CR> itself.

BufEnter also fires on basically everything, including mundane events like switching window focus. That does make it a popular hammer to use when you can't figure out the "right" way. Since you're keying off the file type, you probably want the FileType event.

[Federico Ramirez]

Makes sense. Thanks for the advice! 🙏