tapioca.vim

if empty(prop_type_get('tapioca'))
  let s:id = 0
  let s:m = {}
  call prop_type_add('tapioca', {
  \ 'highlight': 'TODO',
  \ 'start_incl': 1,
  \ 'end_incl': 1,
  \})
endif

function! s:Add(...) abort
  let s:id += 1
  call prop_add(line('.'), col('.'), {'length': strlen('●'), 'type': 'tapioca', 'id': s:id})
  let s:m[s:id] = v:char
  let v:char = '●'
endfunction

function! s:TapiocaOn() abort
  augroup Tapioca
    au!
    autocmd InsertCharPre <buffer> call s:Add()
  augroup END
endfunction

function! s:TapiocaOff() abort
  augroup Tapioca
    au!
  augroup END
  for l:l in range(1, line('$'))
    let l:rs = getline(l:l)
    for l:p in prop_list(l:l, {'type': 'tapioca'})
      if l:p.col > 1
        let l:rs = l:rs[: l:p.col-1] . get(s:m, l:p.id, '') . l:rs[l:p.col+l:p.length-1 :]
      else
        let l:rs = get(s:m, l:p.id, '') . l:rs[l:p.col+l:p.length-1 :]
      endif
    endfor
    call setline(l:l, l:rs)
  endfor
endfunction

command TapiocaOn call s:TapiocaOn()
command TapiocaOff call s:TapiocaOff()