Hmmm... I'm afraid that the recursive 'between'
above there might not work for complex cases.
The non-greedy regexp would make it match the first
start-end pair it found, so if we had:
yadda yadda start this is comment start this is still comment end this
+ should still be comment end yadda yadda
then we should wind up with the whole thing, minus start and end and yadda,
but instead we get:
this is comment start this is still comment
The only way I can think of to get around this
is by keeping external track of the levels. This also
de-recurses it, which makes it less beautiful, but faster (in theory):
sub between {
my ($text) = @_;
my $level = 0;
my @comments = ();
while ( $text =~ m{\G .*? (start|end) (.*?) (?: (?=start|end) | $
+) }gxs ) {
if ( $1 eq 'start') { $level++; }
else { ($level > 0) and $level--; }
$level > 0 and push(@comments, $2);
}
return join('', @comments);
}
This returns:
this is comment this is still comment this should still be comment
So what we're doing here is going through the text
looking for 'start's and 'end's. We keep a counter
indicating how many levels deep we are in 'start's and 'end's.
Every time we hit a 'start', we add one. Every time we hit an
'end', we subtract one, checking first to make sure that our level doesn't go negative. (Otherwise,
somebody could mess us up by starting a file "end end end".)
Afterwards, we look at the patch
of text between the current tag and the next start/end tag.
If our level is greater than 0, we're between a 'start' and
an 'end' tag, so we store that segment. Otherwise, we're
not, so we look for another 'start' or 'end' tag until the end of file.
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