Exact string match in vim? (Like 'regex-off' mode in less.)

In vim, I often want to search on a string with finicky characters which need escaping. Is there a way I can turn off the meaning of all special characters, kind of like regex-off mode in less, or fgrep?

I am dealing with particularly hairy strings; here's an example:

((N/N)/(N/N))/N

Not having to escape any characters to do a search in vim would be a major timesaver.

\V in Vim helps with some metacharacters, but critically not / or \.

command! -nargs=1 S let @/ = escape('<args>', '\')
nmap <Leader>S :execute(":S " . input('Regex-off: /'))<CR>

Depending on the exact string you're searching, the \V prefix will probably do the trick.
See :help \V:

after:    \v       \m       \M       \V         matches ~
                'magic' 'nomagic'    
          $        $        $        \$         matches end-of-line
          .        .        \.       \.         matches any character
          *        *        \*       \*         any number of the previous atom
          ()       \(\)     \(\)     \(\)       grouping into an atom
          |        \|       \|       \|         separating alternatives
          \a       \a       \a       \a         alphabetic character
          \\       \\       \\       \\         literal backslash
          \.       \.       .        .          literal dot
          \{       {        {        {          literal '{'
          a        a        a        a          literal 'a'

So if I have a string hello.*$world, I can use the command /\V.*$ to find just .*$ -- the only part of the string that should need escaping is another backslash, but you can still do grouping, etc., by escaping the special symbol.

:g #\V((N/N)/(N/N))/N#   

The :g command is a global search, noting that:

:[range]g[lobal]/{pattern}/[cmd]
                        Execute the Ex command [cmd] (default ":p") on the
                        lines within [range] where {pattern} matches.

Instead of the '/' which surrounds the {pattern}, you can use any other
single byte character, but not an alphanumeric character, '\', '"' or '|'.
This is useful if you want to include a '/' in the search pattern or
replacement string.

So where I used a #, you could use a ?, @, or whatever other character meeting the above condition. The catch with that :g command is that it expects a command at the end, so if you do not have a trailing space after the final character, it won't perform the search as you would expect. And again, even though you're using \V, you'll still have to escape backslashes.

If that still doesn't cut it for you, this Nabble post has a suggestion that takes a literal string with embedded backslashes and other special Vim characters, and claims to search for it without a problem; but it requires creating a Vim function, which may or may not be okay in your environment.

Looking at your specific example, probably the easiest way to do this (since \V won't help here) is to use ? instead of /: then you won't have to escape the /s:

?((N/N)/(N/N))/N

This will search backwards instead of forwards, but you can always do 'N' instead of 'n' to search forwards after the first go. Or you can press / followed by the up cursor key to automatically escape the forward slashes.

However, there's nothing you can easily do about escaping backslashes. I guess you could do:

:let @/ = escape(pattern, '\')

and then use n to search, but it's probably not much easier. The best I can come up with is:

:command! -nargs=1 S let @/ = escape('<args>', '\')

Then do:

:S (N)/(N+1)\(N)
n