Toggle the quickfix and location-list windows and resize the quickfix window automatically

quickfix-toggle.vim

" Open/close/toggle the quickfix and location-list windows

" ------------------------------------------------------------------------------
" File: autoload/qf/window.vim
" ------------------------------------------------------------------------------

" Toggle quickfix or location-list window
function! qf#window#toggle(loclist = 0)
    " Check if quickfix window is open in current tabpage, or if current
    " window's location-list window is open
    let is_open = getwininfo()
            \ ->filter('v:val.tabnr == tabpagenr()')
            \ ->filter({_,info -> a:loclist
            \     ? info.loclist && info.winid == getloclist(0, {'winid': 1}).winid
            \     : !info.loclist && info.quickfix
            \   })
            \ ->len()

    if is_open
        execute a:loclist ? 'lclose' : 'cclose' .. (&filetype ==# 'qf' ? '| wincmd p' : '')
    else
        let size = a:loclist ? getloclist(0, {'size': 1}).size : getqflist({'size': 1}).size
        if size
            " See https://github.com/vim/vim/issues/5037
            execute a:loclist ? 'lopen 1' : 'botright copen 1'
            execute 'resize' min([10, size])
        endif
    endif
endfunction

" Same as :cwindow and :lwindow but resize the quickfix window automatically
function! qf#window#open(loclist = 0)
    let size = a:loclist ? getloclist(0, {'size': 1}).size : getqflist({'size': 1}).size

    if !size
        execute a:loclist ? 'lclose' : 'cclose'
    else
        execute a:loclist ? 'lopen 1' : 'botright copen 1'
        execute 'resize' min([10, size])
    endif
endfunction

function! qf#window#close()
    if getwininfo(win_getid())[0].loclist
        lclose
    else
        cclose
        " Required only after cclose
        wincmd p
    endif
endfunction


" ------------------------------------------------------------------------------
" File: vimrc
" ------------------------------------------------------------------------------

" Don't scroll windows when opening new horizontal splits
set splitkeep=topline

" Toggle quickfix and location-list windows
nnoremap <silent> goc :<c-u>call qf#window#toggle(0)<cr>
nnoremap <silent> gol :<c-u>call qf#window#toggle(1)<cr>

augroup quickfix
    autocmd!
    autocmd QuickFixCmdPost [^l]* ++nested call qf#window#open(0)
    autocmd QuickFixCmdPost    l* ++nested call qf#window#open(1)
    autocmd VimEnter            * ++nested call qf#window#open(0)
augroup END


" ------------------------------------------------------------------------------
" File: after/ftplugin/qf.vim
" ------------------------------------------------------------------------------

" Close quickfix window
nnoremap <silent> <buffer> gq :<c-u>call qf#window#close()<cr>

Nice. You could also add v:throwpoint to your echomsg, then you know where the exception was thrown in one line. This gives you something like:

function qf#window#Toggle, line 16: Vim(lopen):E776: No location list

I just noticed that Vim only throws an error when there's no location list (E776), but when there's no quickfix list, it will just open an empty quickfix window after :copen.

Yes, I don't understand the logic; do you think a simple message would be more appropriate as well:

            if a:loclist
                lopen 1
            elseif empty(getqflist())
                echomsg 'Quickfix list is empty'
            else
                botright copen 1
            endif

How about updating the gist as a whole (including dispensing with the s:windos)?

I don't know if this is a bug or desired behavior. It looks inconsistent to me. Anyway, I have removed all the redundant s:windo() invocations in the gist.

And one more note, using getqflist({'size': 1}).size == 0 is more efficient than empty(getqflist()), since in the latter case the entire list is returned.

It looks inconsistent to me.

Yes, it is.

using getqflist({'size': 1}).size == 0 is more efficient than empty(getqflist())

I did not know, I rarely looked at the source code. Since empty() requests little information, I hoped that Vim wouldn't bother returning redundant information. Do you have a pointer?

Good to know!

When you call getqflist(), Vim needs to iterate through the entire list and return a copy of it. This takes a lot more time than just returning a dict containing one element as with getqflist({'size': 1}). You can benchmark it with a larger list.

In the source code take a look at get_errorlist() (called for getqflist()) and qf_get_properties() (called for getqflist({'size': 1})).

Interesting. Surely size is there for a reason, maybe this reason. I wonder about how common it is in other framewords or programming languages to generally supply a size attribute. Here the Vimscript compiler would still have to be smart about getqflist() only being called to read size though.

get_qf_loc_list() is the C function that is invoked when getqflist() is called. As you can see it checks if any arguments have been passed and if so, either of the above functions are invoked, one will return an entire list (which needs to be generated), whereas the other one just returns the properties that have been passed to getqflist(). There's really no magic going on here.

Not at all. I wonder how much one can count on such magic in other languages such as Lua, Python, Go, ...