[ILUG] Regex Question

[John Tobin]

On Mon, Sep 27, 2004 at 02:39:15PM +0100, Rory Winston wrote:
> Regex gurus,
> 
> I'm trying to do a simple substitute in Vim. I hav a HTML page with hundreds
> of lines like:
> 
> <div class="foo"></div>
> <div class="foo"></div>
> <div class="foo"></div>
> <div class="foo"></div>
> 
> What I would like to be able to do is replace every n'th element with
> something else. So if n = 3, then the result is:
> 
> <div class="foo"></div>
> <div class="foo"></div>
> <div class="foo">TEST</div>
> <div class="foo"></div>
> <div class="foo"></div>
> <div class="foo">TEST</div>
> 
> Does anybody know how I might achieve this?

You'll need to use sub-replace-special and call a function from it.  Put
this in a file somewhere:

function! My_replace()
        if line ( "." ) % 3 == 0
                return ">TEXT<"
        else
                return "><"
        endif
endfunction

Source it with :source ~/some/file
Then substitute like so:
:%s/></\=My_replace()/

For more information see:
:help sub-replace-special
:help :function
sub-replace-special could use some more documentation.

-- 
John Tobin
"No no no. You're supposed to test with -march=... -fomit-frame-pointer
-ffancy-math -fuse-lots-of-resources-go-very-fast -fsacrifice-more-goats
-fsummon-cthulu-if-that-helps as root at nice -20, preferably in single
user mode and jumps should be aligned on pentagrams, not 8 byte
boundaries.
Definitely not use debugging :-)"
				      Nicholas Clark, in perl6-internals