Re: match and matchend with a negative lookbehind

On Friday, April 6, 2012 5:04:19 PM UTC+2, Ben Fritz wrote:
> On Thursday, April 5, 2012 10:13:55 PM UTC-5, John Little wrote:
> > On Friday, April 6, 2012 10:02:48 AM UTC+12, Ben Fritz wrote:
> > > Please give the EXACT command you ran...
> >
> > Perhaps this script will illustrate:
> >
> > let s = '-2 3-4-5-6-7-8'
> > let p = '\([0-9-]\@<!-\)\?\d[0-9]*'
> > let [start, end] = [0, 0]
> > while 1
> > let start = match(s, p, end)
> > let end = matchend(s, p, end)
> > if start == -1
> > break
> > endif
> > echo s[start : end-1]
> > endwhile
> >
> > I get:
> >
> > -2
> > 3
> > -4
> > -5
> > -6
> > -7
> > -8
> >
> > It would appear that using the third parameter to match() and matchend(), the match is done as if on a substring starting at the parameter, so the look behind assertion does not see what's there in the original string.
> >
> > This is unlike searching in a buffer; the look behind assertion does look behind the start position of the search. Rameo, is this what you're getting at?
> >
>
> I think you've analyzed it perfectly! Looking closer at the help for match(), I see:
>
> For a String, if {start} > 0 then it is like the string starts
> {start} bytes later, thus "^" will match at {start}. Except
> when {count} is given, then it's like matches before the
> {start} byte are ignored
>
> So with only 3 arguments, from this help text, I would expect exactly the results given, for the reason given.
>
> However, this gave me a hint to fix the problem. With a minor tweak:
>
> let s = '-2 3-4-5-6-7-8'
> let p = '\([0-9-]\@<!-\)\?\d[0-9]*'
> let [start, end] = [0, 0]
> while 1
> " count=1 to ignore previous matches rather than making the string
> " start at a new place
> let start = match(s, p, end, 1)
> let end = matchend(s, p, end, 1)
> if start == -1
> break
> endif
> echo s[start : end-1]
> endwhile
>
> It works as intended. With this script, I get:
>
> -2
> 3
> 4
> 5
> 6
> 7
> 8

Works great!
I adapted it in the function copymatches which I once found on wikia.com
http://vim.wikia.com/wiki/Copy_the_search_results_into_clipboard
and it works.
Hope it will work in all documents ;)

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