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# vim:set ts=4 sw=4 sts=4 et ai wm=0 nu:
#=============================================================================
# CommonBaseString.pm
#=============================================================================
# Copyright (c) 2020, Bob Lied
#=============================================================================
# Description:
#=============================================================================
package CommonBaseString;
use strict;
use warnings;
use v5.30;
use feature qw/ signatures /;
no warnings qw/ experimental::signatures /;
require Exporter;
our @ISA = qw(Exporter);
our @EXPORT = qw();
our @EXPORT_OK = qw(commonPrefix);
sub new($class, $a, $b)
{
$class = ref($class) || $class;
my $self = {
_a => $a,
_b => $b,
};
bless $self, $class;
return $self;
}
#
sub commonPrefix($s, $t)
{
my @s1 = split("", $s);
my @s2 = split("", $t);
my $prefix = "";
my @possiblePrefixes = ();
while ( @s1 && @s2 && ($s = shift @s1) eq ($t = shift @s2) )
{
$prefix .= $s;
push @possiblePrefixes, $prefix;
}
return \@possiblePrefixes;
}
sub run($self)
{
my ($A, $B) = @{$self}{qw(_a _b)};
my ($lenA, $lenB) = ( length($A), length($B) );
my @thisWorks = ();
my $prefixes = commonPrefix($A, $B);
for my $prefix ( @$prefixes )
{
my $lenP = length($prefix);
# Only prefixes that can be repeated to the length of both strings
# are candidates.
next unless $lenA % $lenP == 0;
next unless $lenB % $lenP == 0;
# Number of repetitions required for each string.
my $repA = $lenA / $lenP;
my $repB = $lenB / $lenP;
my $buildsA = ( ($prefix x $repA) eq $A );
my $buildsB = ( ($prefix x $repB) eq $B );
push @thisWorks, $prefix if ( $buildsA && $buildsB );
}
return \@thisWorks;
}
1;
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