#!/usr/bin/perl

# https://perlmonks.org/?node_id=1226425

use strict;
use warnings;

my %hash;
my ($header, @rules) = grep /\w/, <DATA>;
my (undef, @fieldnames) = $header =~ /\w+/g;

findnext(\%hash, 1, 'A', '00');
use Data::Dump 'dd'; dd \%hash;

sub findnext
  {
  my ($refh, $rule, $stage1, $stage2) = @_;
  for my $row (@rules)
    {
    if($row =~ /^\W+(\w+)\W+$rule\W+$stage1\W+$stage2\W+(\w+)\W+(\w+)\W+(\w+)/)
      {
      my ($return, $nextrule, $nextstage1, $nextstage2) = ($1, $2, $3, $4);
      my %values;
      @values{@fieldnames} =
        ($rule, $stage1, $stage2, $nextrule, $nextstage1, $nextstage2);
      $refh->{$return}{ROWDATA} = \%values;
      findnext($refh->{$return}, $nextrule, $nextstage1, $nextstage2);
      }
    }
  }

__DATA__
* return * rule * stage1 * stage2 * next_rule * next_stage1 * next_stage2 *
***************************************************************************
*   ret1 *    1 *     A  *     00 *         2 *           B *          10 *
*   ret2 *    1 *     A  *     00 *         5 *           D *          23 *
*   bob1 *    2 *     B  *     10 *         5 *           D *          23 *
*   bob2 *    2 *     B  *     10 *         6 *           E *          44 *
*   dog1 *    3 *     B  *     10 *         6 *           E *          44 *
*   dog2 *    4 *     C  *     10 *         6 *           E *          44 *
*   cat1 *    5 *     D  *     23 *         7 *           F *          55 *
*   cat2 *    5 *     D  *     23 *         7 *           F *          56 *
*   cat3 *    5 *     D  *     23 *         7 *           F *          57 *
*   hit1 *    6 *     E  *     44 *         7 *           G *          55 *
*   hit1 *    6 *     K  *     14 *         7 *           H *          55 *
*   hit2 *    6 *     E  *     44 *         7 *           G *          56 *
***************************************************************************