--- joost rust <[EMAIL PROTECTED]> wrote:
>
> hi all,
>
> Why is it that my CPU usage goes up to 100% when I use 5 or more ".*?" in my
> regexp? Like this:
>
> (Checking one HTML file!!)
>
> if ($txt =~
> m/<form.*?name.*?=.*?>.*?<input.*?type="image"\ssrc="`imageP.*?>/is)
> {
> print "yeeha";
> }
>
> I don't need workarounds, just why?
>
> Juiced
I don't know why your CPU usage would go up to 100%, but I do know that your regex is
broken and
rather inneficient.
If you want to see the internals of the regex engine, you can use the "re" pragma.
Try the
following snippet and see what pops out:
################################
use strict;
use re 'debug';
my $txt =<<'END_HTML';
<html>
<head>
<title>Someform</title>
</head>
<body bgcolor="#FFFF">
<h1>This is a test of the emergency broadcast system</h1>
<table>
<tr>
<td>
<form name="someform" action="/cgi-bin/somescript.cgi">
<input type="hidden" name="test" value="test">
<input type="image"
src="`imageP">
</form>
</td>
</tr>
</table>
</body>
</html>
END_HTML
if ($txt =~
m/<form.*?name.*?=.*?>.*?<input.*?type="image"\s+src="`imageP.*?>/is)
{
print "yeeha";
}
################################
This will dump a lot of information, but once you trace through it, you can see
*exactly* what
your regular expression is doing. This is extremely useful if you can't figure out
what a
particular regex is matching (or not matching!).
One thing: your /i modifier on the regex makes the regex case insensitive. This will
add a lot
of overhead to your regular expression as it's effectively trying to match twice as
many letters.
Also, you should add a plus (+) after the \s which is before "src". Otherwise, you're
only able
to match one space.
You mentioned that you don't want workarounds so I won't provide one, but I do
recommend that you
read "Death to Dot Star!" (http://www.perlmonks.org/index.pl?node_id=24640). It
details the
problem inherent in using unspecific constructs like .* and .*?.
Cheers,
Curtis "Ovid" Poe
=====
Senior Programmer
Onsite! Technology (http://www.onsitetech.com/)
"Ovid" on http://www.perlmonks.org/
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