How to define a new Vim operator with a parameter?

Question

I have been looking to map a new operator in Vim that takes an extra parameter.

For example, we know that ciw will “cut inside word” and will put you int

Answer 1

The title of the question might cause misunderstanding. What you want to do is to define a new operator like y, d and c, neither motions nor text objects, isn't it? :help :map-operator describes how to define a new operator. To take a parameter like the surround plugin, use getchar() in your 'operatorfunc'.

Though :help :map-operator describes the basics, it's a bit troublesome to deal with arguments passed to 'operatorfunc'. You can use vim-operator-user to simplify the handling of arguments. With this plugin, surround-like operator can be written as follows:

function! OperatorSurround(motion_wise)
  let _c = getchar()
  let c = type(_c) == type(0) ? nr2char(_c) : _c
  if c ==# "\<Esc>" || c == "\<C-c>"
    return
  endif

  let bp = getpos("'[")
  let ep = getpos("']")
  if a:motion_wise ==# 'char'
    call setpos('.', ep)
    execute "normal! \"=c\<Return>p"
    call setpos('.', bp)
    execute "normal! \"=c\<Return>P"
  elseif a:motion_wise ==# 'line'
    let indent = matchstr(getline('.'), '^\s*')
    call append(ep[1], indent . c)
    call append(bp[1] - 1, indent . c)
  elseif a:motion_wise ==# 'block'
    execute bp[1].','.ep[1].'substitute/\%'.ep[2].'c.\zs/\=c/'
    execute bp[1].','.ep[1].'substitute/\%'.bp[2].'c\zs/\=c/'
    call setpos('.', bp)
  else
  endif
endfunction
call operator#user#define('surround', 'OperatorSurround')
map s  <Plug>(operator-surround)

If you really want to define your own text objects, please consider vim-textobj-user.

Answer 2

Consider one of the plugins for writing custom text objects. For example: https://github.com/kana/vim-textobj-user

Answer 3

Here is an example implementation of the command described in the question, for illustrative purposes.

nnoremap <silent> s :set opfunc=Surround<cr>g@
vnoremap <silent> s :<c-u>call Surround(visualmode(), 1)<cr>

function! Surround(vt, ...)
    let s = InputChar()
    if s =~ "\<esc>" || s =~ "\<c-c>"
        return
    endif
    let [sl, sc] = getpos(a:0 ? "'<" : "'[")[1:2]
    let [el, ec] = getpos(a:0 ? "'>" : "']")[1:2]
    if a:vt == 'line' || a:vt == 'V'
        call append(el, s)
        call append(sl-1, s)
    elseif a:vt == 'block' || a:vt == "\<c-v>"
        exe sl.','.el 's/\%'.sc.'c\|\%'.ec.'c.\zs/\=s/g|norm!``'
    else
        exe el 's/\%'.ec.'c.\zs/\=s/|norm!``'
        exe sl 's/\%'.sc.'c/\=s/|norm!``'
    endif
endfunction

To get user input, the function InputChar() is used, assuming that the required argument is a single character.

function! InputChar()
    let c = getchar()
    return type(c) == type(0) ? nr2char(c) : c
endfunction

If it is necessary to accept a string argument, change the call to InputChar() in Surround() to the call to input(), instead.