Hey there fellow Monks, at my work, we've got a whole long list of regexes for parsing and organizing various information. These regexes are in the dozens, and are scattered across several scripts and libraries. What I'd like to do is store all of these regexes along with their mapping data in a database, so that review and maintenance of these mappings is easier.

My question is whether this is safe to do or not. If so, could you please share any potential unsafe examples?

I've drummed up a quick test scenario to ensure the building of regexes from strings gathered externally does seem to work ok:

String regex file:

a.*z
^\d+$
^\d{4}[AZ]\d$

[download]

Test script:

use warnings;
use strict;

use Test::More;

# Retrieve regexes from a text file (or database) as strings, regexify
+ them,
# then use them in code

my $re_file = 'regexes.txt';

open my $fh, '<', $re_file or die "Can't open $re_file: $!";

my $strings = strings();

my $i = 1;

while (my $str_re = <$fh>) {
    chomp $str_re;

    my $re = qr/$str_re/;

    for (@{ $strings->{$i}{match} }) {
        is $_ =~ $re, 1, "$_ matches $str_re ok";
    }
    for (@{ $strings->{$i}{nomatch} }) {
        is $_ =~ $re, '', "$_ doesn't match $str_re ok";
    }

    $i++;
}

done_testing;

sub strings {
    return {
        1 => {
            match   => [
                qw(
                    a123z
                    az
                    a!$@Zz
                ),
            ],
            nomatch => [
                qw(
                    Az
                    aZ
                    a213Z
                    99
                )
            ],
        },
        2 => {
            match   => [
                qw(
                    1
                    9999
                    6472323432
                ),
            ],
            nomatch => [
                qw(
                    a1
                    1a
                    1!
                    aaaa
                )
            ],
        },
        3 => {
            match   => [
                qw(
                    2021Z1
                    2021A1
                ),
            ],
            nomatch => [
                qw(
                    A9
                    123A9
                    1234a9
                    12349
                    1234A99999999
                    1234AZ9
                )
            ],
        },
    };
}

[download]

In reply to Is it safe to use external strings for regexes? by stevieb

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