load2graph

use strict;
use Data::Dumper;
use YAML;


my @loads = (
    [ A => "B" ],
    [ A => "C" ],
    [ C => "D" ],
    [ D => "E" ],
    [ C => "F" ],
);

    my @load_graph;
    my @stack = ( \@load_graph );
    my @callers_stack;
    my $prev_caller = "";
    my $prev_callee = "";

    for my $load (@loads) {
        my $caller = $load->[0];
        my $callee = $load->[1];
        print STDERR "* $caller -> $callee -- (@callers_stack)\n";

        if ($caller eq $prev_caller) {
            push @{ $stack[-1] }, [ $callee ];
        }
        elsif ($caller eq $prev_callee) {
            push @{ $stack[-1][-1] }, [ [ $callee ] ];
            push @stack, $stack[-1][-1][-1];
            push @callers_stack, $caller;
        }
        else {
            while (@callers_stack and $callers_stack[-1] ne $caller) {
                print STDERR "--- (@callers_stack)\n";
                pop @callers_stack;
                pop @stack;
            }

            if ($callers_stack[-1] eq $caller) {
                push @{ $stack[-1] }, [ $callee ];
            }
            else {
                push @callers_stack, $caller;
                push @stack, [ [ $callee ] ];
                push @load_graph, [ $caller => $stack[-1] ];
            }
        }
    print Dumper(\@load_graph), $/;

        $prev_caller = $caller;
        $prev_callee = $callee;
    }



    my @expected = (
        [ "A" => [
            [ "B" ],
            [ "C" => [
                [ "D" => [
                    [ "E" ]
                  ]
                ],
                [ "F" ],
              ]
            ],
          ],
        ]
    );


use Test::More;
plan tests => 1;
is_deeply(\@load_graph, \@expected);