You haven't shown what you've already tried. The following one-liner produces the output:

>perl -lne "$l=1;while (/([-.]*([\w])\2*[-.]*(\2+[-.]*)*)/g){ print sp
+rintf '%d-%d:s',$l,pos,$2;$l=pos()+1}"
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See perlre for the regular expression.

You might want to specify what output should be produced for:

XXX---YYY
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