Re: Regex Help Needed

[John Deighan]

At 01:26 PM 9/2/2003, Dax T. Games wrote:

I have a list of characters.  I need to get a list of all possble sequences of these characters for example. 
 
I have a string that consists of '-mevqgn' I need to pattern match any combination of 'mevqgn' with a preceding - or --.
 
Right now this is what I am doing but it is very ugly and difficult to come up with the combinations and it makes my brain hurt!:
 
 if ($LS_Val =~ /-{1,2}(mevqgn|
           emvqgn|evmqgn|evqmgn|evqgmn|evqgnm|
           veqgnm|vqegnm|vqgenm|vqgnem|vagnme|
           qvgnme|qgvnme|qgnvme|qgnmve|qgnmev|
           gqmnev|gmqnev|gmnqev|gmneqv|gmnevq|
           mgnevq|mngevq|mnegvq|mnevgq|mnevqg|
           nmevqg|nemvqg|nevmqg|nevqmg|nevqgm|
           envqgm|evnqgm|evqngm|evqgnm|evqgmn|
           )/i)
{
    #Do Something;
}
   
 
A subroutine that takes the string of characters as an argument and then returns 1 on success and undef on fail would be ideal for my purpose.

if ($val =~ /^--?[mevqgn]{6}$/) almost works, but allows, e.g. -megggg, i.e. repetitions.

I would just do:

if (($val =~ /^--?([a-z]+)$/) && (length($1)==6) && check($1, qw(m e v q g n))) {
        ...

sub check { my($str, @chars) = @_;

        foreach my $ch (@chars) {
                return undef if (index($str, $ch)==-1);
        }



Full test program:  -------------------------------------

use strict;

MAIN: {
test('');
test('-');
test('--');
test('-mev');

test('-mevqgn');
test('--mevqgn');
test('--qvgnme');
test('-qgvnme');
test('--qgnvme');
test('--qgnmve');
test('-qgnmev');
}

# ------------------------------------------

sub test { my($str) = @_;

if (($str =~ /^--?([a-z]+)$/)
                && (length($1)==6)
                && check($1, qw(m e v q g n))) {
        print("OK '$str'\n");
        }
else {
        print("no '$str'\n");
        }
} # test

# ------------------------------------------

sub check { my($str, @chars) = @_;

foreach my $ch (@chars) {
        return undef if (index($str, $ch)==-1);
        }
return 1;
} # check

John Deighan

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