foldcolumnの値を自動で決定したい。

autofoldcolumn.vim

function! s:AutoFoldColumn() abort
    let l:foldcolumn = auto_origami#Foldcolumn()
    if l:foldcolumn > 0
        let l:maxfoldcolumn = s:GetMaxFoldColumn()
        if l:foldcolumn < l:maxfoldcolumn
            let l:foldcolumn = l:maxfoldcolumn
        endif
    endif
    let &l:foldcolumn = l:foldcolumn
endfunction

function! s:GetMaxFoldColumn() abort
    let l:save_scrolloff = &l:scrolloff
    let &l:scrolloff = 0
    let l:save = winsaveview()
    
    normal Lkj
    let l:last_line = line('.')
    let l:max_level = 0
    normal H
    while line('.') < l:last_line
        let l:level = foldlevel(line('.'))
        if l:level > l:max_level
            let l:max_level = l:level
        endif
        normal j
    endwhile
    
    call winrestview(l:save)
    let &l:scrolloff = l:save_scrolloff
    if l:max_level == 0
        return 0
    else
        return l:max_level + 1
    endif
endfunction
command! AutoFoldColumn call s:AutoFoldColumn()
augroup autofoldcolumn
    au!
    au CursorHold,BufWinEnter,WinEnter * AutoFoldColumn
augroup END
nmap zA zA:AutoFoldColumn<CR>

auto_origamiをforkして機能追加する方向にしてみよう。