it begins

src/calc.rs

@@ -0,0 +1,36 @@
+struct calcNode {
+    item: Item,
+    left: Option<Box<calcNode>>,
+    right: Option<Box<calcNode>>,
+}
+impl Default for calcNode {
+    fn default() -> Self {
+        Self {
+            item: Item::Num(1),
+            left: None,
+            right: None,
+        }
+    }
+}
+
+impl calcNode {
+    pub fn new(item: Item, left: Option<Box<calcNode>>, right: Option<Box<calcNode>>) -> Self {
+        Self { item, left, right }
+    }
+}
+pub enum Item {
+    Num(i32),
+    Oper(Operation),
+}
+pub enum Operation {
+    Add,
+    Sub,
+    Div,
+    Mult,
+}
+#[derive(Default)]
+pub struct calcTree {
+    root: calcNode,
+}
+
+impl calcTree {}