Beefy Boxes and Bandwidth Generously Provided by pair Networks
go ahead... be a heretic
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

There are a number of aspects here. First, your initial problem: the \s. Try escaping the \:

my $regexp = "/^STOR\\s[^\n]{100}/smi";
However, then you need to still use the qr operator:
my $r = Parse::RandGen::Regexp->new(qr/$regexp/);
But even that won't work the way you think it will because the leading and trailing delimiters will be treated literally - so the regular expression will match something that has a slash, then a beginning-of-line zero-width assertion, and has a trailing "/smi", literally. You could do something like:
my $r = Parse::RandGen::Regexp->new(eval "qr$regexp");
but that's unsafe if you get your regexp from an unsafe source. Then again, if you're getting regexp's from unsafe sources, I'm not sure how easy it is to strip out unsafe aspects of regular expressions which could execute arbitrary perl code during a match.

To remove the eval, you would also have to limit your input to not include the leading/trailing delimiters. Nor would the smi flags be allowed (or they're mandatory). However, even then, the input can still control these flags inside a regular expression:

(?smi)^STOR\s[^\n]{100}
Note how the \'s aren't escaped here. Because this is data, and not interpreted by perl (until we get to the regular expression handler), we don't need to escape here. Nothing is escapable because nothing is treated as special. Once you've read this in, you can go back to using qr/$regexp/ in your call to the P::RG::R constructor.

Hope this helps.


In reply to Re: Parse::RandGen::Regexp by Tanktalus
in thread Parse::RandGen::Regexp by paulski

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others contemplating the Monastery: (8)
As of 2021-06-21 10:44 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    What does the "s" stand for in "perls"? (Whence perls)












    Results (98 votes). Check out past polls.

    Notices?