added move_up

src/directory.rs

@@ -220,6 +220,37 @@ impl Directory {
         self.selection += u16::try_from(sibling_len).unwrap_or(u16::MAX);
     }
 
+    fn move_up(&mut self) {
+        let current_depth = self.selected().depth;
+
+        let Some(index) = (0 .. self.selection())
+            .rev()
+            .take_while(|&i| self.dirs[i].depth >= current_depth)
+            .filter(|&i| self.dirs[i].depth == current_depth)
+            .next()
+        else {
+            return
+        };
+
+        let selected_subtree = self.subtree_indices(self.selection());
+        let sibling_subtree = self.subtree_indices(index);
+
+        let select_len = selected_subtree.len();
+        let sibling_len = sibling_subtree.len();
+
+        let selected_copy = self.dirs[selected_subtree].to_owned();
+        let sibling_copy = self.dirs[sibling_subtree].to_owned();
+        let back_to_back = selected_copy.into_iter().chain(sibling_copy);
+
+        let full_range = index .. index+select_len+sibling_len;
+        for (dst, item) in self.dirs[full_range].iter_mut().zip(back_to_back) {
+            *dst = item;
+        }
+
+        self.selection -= u16::try_from(sibling_len).unwrap_or(u16::MAX);
+
+    }
+
     fn selected(&self) -> &Item {
         &self.dirs[self.selection()]
     }
@@ -316,6 +347,9 @@ impl Directory {
             },
             KeyCode::Down => {
                 self.move_down();
+            },
+            KeyCode::Up => {
+                self.move_up();
             }
             _ => (),
         }