Why is the question on hold at SO? Looks like someones homework alright, but to reverse tree visualisation is a valid problem and potentially useful to someone. Anyway, I hoped there would be some extra neat solution, then spent ten minutes correcting one silly mistake after another. Almost a one-liner:

#! /usr/bin/perl -ln
/\|\s*$/ or /.*?--(-?)|/, splice(@a,$+[0]/3), $1 ? print join "\t", @a
+[0..2], $' : push @a, $';
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