Add menu tree

src/menu.rs

@@ -0,0 +1,63 @@
+use Cursive;
+use std::rc::Rc;
+use event::Callback;
+
+#[derive(Default)]
+pub struct MenuTree {
+    pub children: Vec<MenuItem>,
+}
+
+pub enum MenuItem {
+    Leaf(String, Rc<Callback>),
+    Subtree(String, Box<MenuTree>),
+    Delimiter,
+}
+
+impl MenuTree {
+
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn clear(&mut self) {
+        self.children.clear();
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.children.is_empty()
+    }
+
+    pub fn add_delimiter(&mut self) {
+        self.children.push(MenuItem::Delimiter);
+    }
+
+    pub fn delimiter(mut self) -> Self {
+        self.add_delimiter();
+        self
+    }
+
+    pub fn leaf<F: 'static + Fn(&mut Cursive)>(&mut self, title: &str, cb: F)
+                                               -> &mut Self {
+        self.children.push(MenuItem::Leaf(title.to_string(), Rc::new(Box::new(cb))));
+        self
+    }
+
+    pub fn add_subtree(&mut self, title: &str, tree: MenuTree) -> &mut Self {
+        self.children
+            .push(MenuItem::Subtree(title.to_string(), Box::new(tree)));
+        self
+    }
+
+    pub fn new_subtree(&mut self, title: &str) -> &mut Box<MenuTree> {
+        self.add_subtree(title, MenuTree::new());
+        match self.children.last_mut().unwrap() {
+            &mut MenuItem::Subtree(_, ref mut tree) => tree,
+            _ => panic!("??"),
+        }
+    }
+
+    pub fn subtree(mut self, title: &str, tree: MenuTree) -> Self {
+        self.add_subtree(title, tree);
+        self
+    }
+}