This question I posted on SO (but didn't get any comments) - (link:https://stackoverflow.com/questions/54179876/reorganize-hash-in-specific-format)
Consider the following hash of files:

%files_data = { 
              './GetOpt.pm' => {
                          'pid' => {
                                     '56061' => 1,
                                     '56065' => 1
                                   }
                            },
              'file1' => {
                          'pid' => {
                                     '56061' => 2
                                   }
                        },
              'file2' => {
                         'pid' => {
                                    '56065' => 2
                                  }
                       },
              './src/bin/perl' => {
                            'pid' => {
                                       '56061' => 1,
                                       '56065' => 1
                                     }
                          }
                    };
[download]

Also consider the following hash of process_data:

            
    %process_data = (

              '56061' => {
                           'parent' => 'NA',
                           'name' => 'file1'
                         },
              '56069' => {
                           'parent' => '56065',
                           'name' => 'echo Hello_file1'
                         },
              '56062' => {
                           'parent' => '56061',
                           'name' => 'echo Hello_file2'
                         },
              '56065' => {
                           'parent' => '56061',
                           'name' => 'file2'
                         }
            );
[download]

I would like to iterate through the `$files_data` hash and for each file get the chain of files.
So I'll get the following hash:

    
    %hash = (
            'file1' => {
                '/src/bin/perl' => 1,
                'file2' => { 
                    '/src/bin/perl' => 1,
                    './GetOpt.pm' => 1
                },
                './GetOpt.pm' => 1,
        }
    );
[download]

I need to follow the pid chain up to the main parent ('NA') for each file.
What would be the most efficient way to solve it? I need some guidance on how to implement it.
I'll try to explain how my logic works and show some code. lets take for example `'./GetOpt.pm'` file. It has a pid `56061` so we go to the `%process_data` and see `'file1'` (which is a file). Also we see that the parent of `56061` is `NA` so we stop and get:
file1 => ./GetOpt.pm But `./GetOpt.pm` has another pid - `56065` so we go to `56065` and see `file2` (which is a file). Then we go to `56061` which has `file1` (which is s file). so we get:

    file1 => file2 => ./GetOpt.pm
[download]

Combine it:

    file1 => {
        ./GetOpt.pm,
        file2 => ./GetOpt.pm
    }
[download]

I would like to build a process file chain (only with files). the `%files_data` contains valid files and `%process_data` contains the hierarchy of the process we need to follow.
Some of what I tried to do:

create_proc_tree(\%process_data,\%files_data);

sub create_proc_tree
{
    my ($proc_href,$files_href) = @_;
    my %hash;
    while (my ($file, $procs) = each %{$files_href}) {
        foreach my $pid (keys(%{$procs->{'pid'}})) {
            my $prev_file = $file;
            do {
                my $parent_id = $proc_href->{$pid}{parent};
                my $parent_name = $proc_href->{$pid}{name};
                if ($prev_file eq $parent_name) {
                    $hash{$parent_name} = 1;
                } else {
                    $hash{$parent_name} = { (%{ $hash{$prev_file} // {
+} }, $prev_file) };
                    delete($hash{$prev_file});
                }
                $prev_file = $parent_name;
                my $parent_name = $proc_href->{$parent_id}{name};
            } while(defined($parent_name));
        }
    }
    print Dumper(\%hash); # Printing for debug
}
[download]

It does not quite do what I want. The hierarchy is not valid. I'm not sure what is wrong with the algorithm, it feels like true but the output is not as expected.
I think that its because I counted the data to many times without deleting.
It made me think that this algorithm is not efficient and messy. I have found out that we can use 'eval' in order to convert string to hash:

use Data::Dumper;
$abc = "Mouse=>Jerry, Cat=>Tom, Dog=>Spike";
my %hash = eval( "( $abc )" );
print Dumper(\%hash);
[download]

Maybe a better approach will be to build a string like and then convert it to hash (although I read a comment saying that it is a bad why to use eval).
Also, I though of finding first the Main parent file and the go until I get the current file. How should I solve this issue? What would be the best approach?

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