How to set nowrapscan when formatting text with gq

Question

When I was editing a fairly large text, I accidentally hit gq* instead of gq} and then vim apparently seemed to freeze a moment with the message search hit BOTTOM, continuing at TOP displayed in the command line. I found out it was because the wrapscan option was enabled by default and when the word under cursor was not found between the cursor position and the end of the file, the search continued from the top.

But I should say this is not what we normally expect when formatting text. Besides, the gq command behaves rather weirdly when search wraps round. So I'm trying to figure out how to set the nowrapscan option when formatting text with gq. Though I barely know anything about scripting, I managed to write the following function after reading a couple of topics in help:

nnoremap <F4> :set opfunc=GqNoWrapscan<CR>g@

function! GqNoWrapscan(type)
    let s:wrapscan = &wrapscan
    set nowrapscan
    silent exe "normal! '[gq']"
    let &wrapscan = s:wrapscan
    unlet! s:wrapscan
endfunction

Unfortunately, this function does not work as expected. I still get the same message and the nowrapscan option is apparently not set when I hit <F4>*. Could anyone help?

Answer 1

g@ works like this: vim waits for a motion, does the motion, stuffs the beginning and end cursor positions into the [ and ] marks, then calls your opfunc. So, by the time GqNoWrapscan is entered, the * search has already been done, and wrapscan was on. You would need to set nowrapscan before the g@. Unfortunately, what you are trying to accomplish is non-trivial, since if you provide an invalid motion (or press escape), you will wind up with wrapscan changed with no way to change it back.

One alternative approach (just for illustration) would be to remap * in operator-pending mode so that if it comes after a gq, it does not use wrapscan.

function! StarNoWrap()
    let l:wrapscan = &wrapscan
    if v:operator ==# 'gq'
        set nowrapscan
    endif
    try
        exe 'normal! '.v:count.'*'
    catch /^Vim\%((\a\+)\)\=:E385/
        " search hit BOTTOM without match
        " ought to print an error message here
    endtry
    let &wrapscan = l:wrapscan
endfunction

onoremap * :<c-u>call StarNoWrap()<cr>

An even simpler and more practical approach would be to just do

function! GqNoWrap()
    let l:wrapscan = &wrapscan
    set nowrapscan
    normal! gq*
    let &wrapscan = l:wrapscan
endfunction

nnoremap gq* :<c-u>call GqNoWrapScan()<cr>

" only if you don't want to override regular gq:
nnoremap <F4> gq
nnoremap <F4>* :<c-u>call GqNoWrapScan()<cr>

You will also have to handle # and possibly n, N and a few other commands.