1 files changed, 69 insertions, 0 deletions
diff --git a/lib/Carton/Tree.pm b/lib/Carton/Tree.pm
new file mode 100644
index 0000000..6ce22a1
--- /dev/null
+++ b/lib/Carton/Tree.pm
@@ -0,0 +1,69 @@
+package Carton::Tree;
+use strict;
+use Carton::Dependency;
+
+use Class::Tiny qw( cpanfile snapshot );
+
+use constant STOP => -1;
+
+sub walk_down {
+    my($self, $cb) = @_;
+
+    my $dumper; $dumper = sub {
+        my($dependency, $reqs, $level, $parent) = @_;
+
+        my $ret = $cb->($dependency, $reqs, $level);
+        return if $ret && $ret == STOP;
+
+        local $parent->{$dependency->distname} = 1 if $dependency;
+
+        for my $module (sort $reqs->required_modules) {
+            my $dependency = $self->dependency_for($module, $reqs);
+            if ($dependency->dist) {
+                next if $parent->{$dependency->distname};
+                $dumper->($dependency, $dependency->requirements, $level + 1, $parent);
+            } else {
+                # no dist found in lock
+            }
+        }
+    };
+
+    $dumper->(undef, $self->cpanfile->requirements, 0, {});
+    undef $dumper;
+}
+
+sub dependency_for {
+    my($self, $module, $reqs) = @_;
+
+    my $requirement = $reqs->requirements_for_module($module);
+
+    my $dep = Carton::Dependency->new;
+    $dep->module($module);
+    $dep->requirement($requirement);
+
+    if (my $dist = $self->snapshot->find_or_core($module)) {
+        $dep->dist($dist);
+    }
+
+    return $dep;
+}
+
+sub merged_requirements {
+    my $self = shift;
+
+    my $merged_reqs = CPAN::Meta::Requirements->new;
+
+    my %seen;
+    $self->walk_down(sub {
+        my($dependency, $reqs, $level) = @_;
+        return Carton::Tree::STOP if $dependency && $seen{$dependency->distname}++;
+        $merged_reqs->add_requirements($reqs);
+    });
+
+    $merged_reqs->clear_requirement('perl');
+    $merged_reqs->finalize;
+
+    $merged_reqs;
+}
+
+1;