[vim] What Vim command(s) can be used to quote/unquote words?

I wrote a script that does this:

function! WrapSelect (front)
    "puts characters around the selected text.
    let l:front = a:front
    if (a:front == '[')
        let l:back = ']'
    elseif (a:front == '(')
        let l:back = ')'
    elseif (a:front == '{')
        let l:back = '}'
    elseif (a:front == '<')
        let l:back = '>'
    elseif (a:front =~ " ")
        let l:split = split(a:front)
        let l:back = l:split[1]
        let l:front = l:split[0]
    else
        let l:back = a:front
    endif
    "execute: concat all these strings. '.' means "concat without spaces"
    "norm means "run in normal mode and also be able to use \<C-x> characters"
    "gv means "get the previous visual selection back up"
    "c means "cut visual selection and go to insert mode"
    "\<C-R> means "insert the contents of a register. in this case, the
    "default register"
    execute 'norm! gvc' . l:front. "\<C-R>\""  . l:back
endfunction
vnoremap <C-l> :<C-u>call WrapSelect(input('Wrapping? Give both (space separated) or just the first one: '))<cr>

To use, just highlight something, hit control l, and then type a character. If it's one of the characters the function knows about, it'll provide the correct terminating character. If it's not, it'll use the same character to insert on both sides.

Surround.vim can do more than just this, but this was sufficient for my needs.