How to access adjacent/parent array OR how to access multi dimensional array with dynamic indexes

[wakatana]

Hello monks. I have following structure:

$VAR1 = 'ng1';
$VAR2 = [
          'ng1_1',
          [
            'ng1_1_1',
            [
              'ng1_1_1_u1',
              'ng1_1_1_u2',
              'ng1_1_1_u3'
            ],
            'ng1_1_2',
            'ng1_1_3',
            'ng1_1_4'
          ],
          'ng1_2',
          'ng1_3',
          'ng1_4'
        ];
$VAR3 = 'ng2';
$VAR4 = [
          'ng2_1',
          [
            'ng2_1_u1',
            'ng2_1_u2',
            'ng2_1_u3'
          ],
          'ng2_2',
          'ng2_3',
          'ng2_4'
        ];
$VAR5 = 'ng3';
$VAR6 = [
          'ng3_1',
          'ng3_2',
          'ng3_3',
          'ng3_4'
        ];

Here is the same structure with indexes and indentation for better orientation:

 [0]            ng1
  [1][0]          ng1_1
   [1][1][0]        ng1_1_1
    [1][1][1][0]     ng1_1_1_u1
    [1][1][1][1]     ng1_1_1_u2
    [1][1][1][2]     ng1_1_1_u3
   [1][1][2]        ng1_1_2
   [1][1][3]        ng1_1_3
   [1][1][4]        ng1_1_4
  [1][2]          ng1_2
  [1][3]          ng1_3
  [1][4]          ng1_4
 [2]            ng2
  [3][0]          ng2_1
   [3][1][0]       ng2_1_u1
   [3][1][1]       ng2_1_u2
   [3][1][2]       ng2_1_u3
  [3][2]          ng2_2
  [3][3]          ng2_3
  [3][4]          ng2_4
 [4]            ng3
  [5][0]          ng3_1
  [5][1]          ng3_2
  [5][2]          ng3_3
  [5][3]          ng3_4

I have function which prints indexes of particular element:

# &findElementPosition(\@tree,"ng1_1_1_u3");
#
sub findElementPosition{
  my ($tree,$needle) = @_;
  for my $treeElement (@{$tree}){
    if (ref $treeElement eq "ARRAY"){
      push @position,0;
      &findElementPosition($treeElement,$needle);
      pop @position;
      $position[-1]++;
    }
    else{
      if ($treeElement eq $needle){
        for (@position){ print "[$_]" }
        print " " . $treeElement . "\n";
      }
      $position[-1]++;
    }
  }
}

The code above prints:

[1][1][1][2] ng1_1_1_u3

But, I need a function which is able to print the parent's index. E.g. if I give the input: "ng1_1_1_u3" I want the output: [1][1][0] ng1_1_1
The idea is simple. All that is need before printing is to remove the last element from "@position" array and then decrement the actual last element in this array, something like this:

pop @position;
$position[-1]--;

The question is, how can I print coresponding element to those indexes?

[hdb]

I would carry it around in your recursion. I have also eliminated the global @position:

use strict;
use warnings;

my @tree = ( 'ng1',
                         [ 'ng1_1', 
                             [ 'ng1_1_1', [ 'ng1_1_1_u1', 'ng1_1_1_u2'
+, 'ng1_1_1_u3' ],
                                 'ng1_1_2', 'ng1_1_3', 'ng1_1_4' ],
                             'ng1_2', 'ng1_3', 'ng1_4' ],
                         'ng2', 
                         [ 'ng2_1', [ 'ng2_1_u1', 'ng2_1_u2', 'ng2_1_u
+3' ],
                             'ng2_2', 'ng2_3', 'ng2_4' ],
                         'ng3',
                         [ 'ng3_1', 'ng3_2', 'ng3_3', 'ng3_4' ],
        );

sub findElementPosition{
        my ($tree,$position,$parent,$needle) = @_;
        my $previous;
        my $pos = 0;
        for my $treeElement (@{$tree}){
                if (ref $treeElement eq "ARRAY"){
                        findElementPosition($treeElement,[@$position,$
+pos],$previous,$needle);
                }    else {
                        if ($treeElement eq $needle){
                                print "[$_]" for @$position[0..@$posit
+ion-2];
                                print "[",$position->[-1]-1,"] $parent
+ \n";
                        }
                        $previous = $treeElement;
                }
                $pos++;
        }
}

my @position;

findElementPosition( \@tree, \@position, "", "ng1_1_1_u3" );
findElementPosition( \@tree, \@position, "", "ng3_1" );