my $format = ...;
my $printfStr;
my $regexStr;
my $paramCount;

while ($format)
  {
  my ($chunk) = $format =~ s/^(.*?|\[.*?])(?:\[|$)//g;
  if ($chunk =~ /^\[int]/)
    {# match an int
    $printfStr .= "%d";
    $regexStr .= "(\\d+)";
    ++$paramCount;
    }
  elsif ...
  else
    {# match the text
    $printfStr .= $chunk;
    $regexStr .= "\Q$chunk\E";
    }
  }