linked

src/SUMMARY.md

@@ -12,6 +12,7 @@
   - [RcChars](./exercises/rcchars.md)
   - [Async Fn](./exercises/async_fn.md)
   - [Get Functions](./exercises/get_functions.md)
+  - [Linked](./exercises/linked.md)
 - [Chapter 2](./chapter_2.md)
   - [AnyStr](./exercises/anystr.md)
   - [Mode](./exercises/mode.md)

src/exercises/linked.md

@@ -0,0 +1,68 @@
+# `Linked`
+
+Fix (many) errors to make this compile and pass tests:
+
+```rust
+# #[derive(Clone, Copy)]
+struct Node<'a> {
+    next: Option<&'a Self>,
+    value: &'a str,
+}
+
+struct Linked<'a, F> {
+    node: Node<'a>,
+    callback: &'a mut F,
+}
+
+impl<'a, F: FnMut(String)> Linked<'a, F> {
+# /*
+    fn with(&mut self, value: &str) -> Linked<'_, F> {
+        Self {
+            node: Node {
+                next: Some(self.node),
+# */
+# fn with<'b>(&'b mut self, value: &'b str) -> Linked<'b, F> {
+# Linked {
+# node: Node {
+# next: Some(&self.node),
+                value,
+            },
+            callback: self.callback,
+        }
+    }
+
+    fn call(&mut self) {
+        let mut node = self.node;
+        let mut value = node.value.to_string();
+        while let Some(next) = node.next {
+            value += next.value;
+# /*
+            node = next;
+        }
+        self.callback(value);
+# */
+# node = *next; }
+# (self.callback)(value);
+    }
+}
+
+let mut vec = vec![];
+
+
+let mut linked = Linked {
+    node: Node { next: None, value: "0" },
+    callback: &mut |value| vec.push(value),
+};
+
+// why does removing code below cause the instantiation to fail?
+
+linked.call();
+{
+    let mut linked = linked.with("1");
+    linked.with("2").call();
+    linked.with("3").call();
+}
+linked.with("4").call();
+
+assert_eq!(vec, ["0", "210", "310", "40"]);
+```