Perl - Generate All Matching String To A Regex

Question

I am kinda new in perl, i wanted to know if there is a way for generating all the combinations that matches a regex.

how is the best way to generate all the matching strings to :

05[0,2,4,7][\d]{7}

thanks in advance.

Answer 1

No there is no way to generate all matches for a certain regex. Consider this one:

a+

There is an infinite number of matches for that regex, thus you cannot list them all.

By the way, I think you want your regex to look like this:

05[0247]\d{7}

Answer 2

While you cannot just take any regex and produce any strings it might fit, in this case you can easily adapt and overcome.

You can use glob to generate combinations:

perl -lwe "print for glob '05{0,2,4,7}'"
050
052
054
057

However, I should not have to tell you that \d{7} actually means quite a few million combinations, right? Generating a list of numbers is trivial, formatting them can be done with sprintf:

my @nums = map sprintf("%07d", $_), 0 .. 9_999_999;

That is assuming you are only looking for 0-9 numericals.

Take those nums and combine them with the globbed ones: Tada.

Answer 3

2012 answer

• String::Random
• Regexp::Genex - generates random strings that match the regexp; not all the possible strings, even for finite patterns like [class]
• Parse::RandGen
• §6.5 regex string generation in HOP

Answer 4

Then there is a way to generate all (four billion of) the matches for this certain regex, viz., 05[0247]\d{7}:

use Modern::Perl;

for my $x (qw{0 2 4 7}) {
    say "05$x" . sprintf '%07d', $_ for 0 .. 9999999;
}