Re: RegEx for users who dont know RegEx

[The Mad Hatter]

One solution is to strip out all characters in the user-supplied data that aren't explicitly allowed and then generate your regex based off of that.

Update -- Try this sample code:

#!/usr/bin/perl
use warnings;
use strict;

my $query = shift;

die "usage: $0 query-string\n"
    if not $query;

print "Original query: '$query'\n";

$query =~ s/[^\w\*]//g;
print "Safe query: '$query'\n";

$query =~ s/\*/\\w\*/g;
print "Parsed query: '$query'\n";

while (<DATA>) {
    print "match: $_"
        if /$query/i;
}

__DATA__
invitation
information
Isolation
InFlaTiOn
IATION
In our nation
it requires concentration
at ionizing radiation

Note that "at ionizing radiation" matches because the iation in radiation matches. Did you just miss that, or should it not match?

[ikegami]

Why strip out the unsafe characters instead of escaping them, as I did below? Using your approach to search for "can't" will fail, for example.

[The Mad Hatter]

*shrugs* Stripping out unsafe characters just seems like a better idea; you know exactly what you're left with. If you want to allow single ticks or other characters, modifying the regex of allowed chars is easy. The code above is just an example, not a final product.