Finished chapter 2

NOTES.md

@@ -0,0 +1,10 @@
+# Lessons from Stack 1
+
+When you need to do the ol' switcheroo with some memory
+mem::replace comes in useful.
+
+# Lessons from Stack 2
+
+take() is handy, read more about this.
+Sometimes you just have to get your hands dirty and do some lifetimes, just a fact of life, get used to it son.
+Revise some of these impl types, to understand better how they function with std library collections.

lists/src/first.rs

@@ -41,7 +41,7 @@ impl Drop for List {
     fn drop(&mut self) {
         let mut cur_link = mem::replace(&mut self.head, Link::Empty);
         while let Link::More(mut boxed_node) = cur_link {
-            cur_link = mem::replace(&mut boxed_node.ndex, Link::Empty);
+            cur_link = mem::replace(&mut boxed_node.next, Link::Empty);
         }
     }
 }

lists/src/lib.rs

@@ -1 +1,2 @@
-pub mod first;
+pub mod first;
+pub mod second;

lists/src/second.rs

@@ -0,0 +1,185 @@
+use std::mem;
+
+pub struct List<T> {
+    head: Link<T>
+}
+
+type Link<T> = Option<Box<Node<T>>>;
+
+struct Node<T> {
+    elem: T,
+    next: Link<T>,
+}
+
+impl<T> List<T> {
+    pub fn new() -> Self {
+        List { head: None }
+    }
+
+    pub fn push(&mut self, elem: T) {
+        let new_node = Box::new(Node {
+            elem,
+            next: self.head.take(), 
+        });
+        self.head = Some(new_node);
+    }
+    pub fn pop(&mut self) -> Option<T> {
+        self.head.take().map(|node| {
+            self.head = node.next;
+            node.elem
+        })
+    }
+    pub fn peek(&self) -> Option<&T> {
+        self.head.as_ref().map(|node| {
+            &node.elem
+        })
+    }
+    pub fn peek_mut(&mut self) -> Option<&mut T> {
+        self.head.as_mut().map(|node| {
+            &mut node.elem
+        })
+    }
+}
+
+impl<T> Drop for List<T> {
+    fn drop(&mut self) {
+        let mut cur_link = self.head.take(); 
+        while let Some(mut boxed_node) = cur_link {
+            cur_link = mem::replace(&mut boxed_node.next, None);
+        }
+    }
+}
+
+pub struct IntoIter<T>(List<T>);
+
+impl<T> List<T> {
+    pub fn into_iter(self) -> IntoIter<T> {
+        IntoIter(self)
+    }
+}
+
+impl<T> Iterator for IntoIter<T> {
+    type Item = T;
+    fn next(&mut self) -> Option<Self::Item> {
+        self.0.pop()
+    }
+}
+
+pub struct Iter<'a, T> {
+    next: Option<&'a Node<T>>,
+}
+
+impl<T> List<T> {
+    pub fn iter<>(&self) -> Iter<T> {
+        Iter { next: self.head.as_ref().map(|node| &**node) }
+    }
+}
+
+impl<'a, T> Iterator for Iter<'a, T> {
+    type Item = &'a T;
+    fn next(&mut self) -> Option<Self::Item> {
+        self.next.map(|node| {
+            self.next = node.next.as_ref().map(|node| &**node);
+            &node.elem
+        })
+    }
+}
+
+pub struct IterMut<'a, T> {
+    next: Option<&'a mut Node<T>>,
+}
+
+impl<T> List<T> {
+    pub fn iter_mut(&mut self) -> IterMut<'_, T> {
+        IterMut { next: self.head.as_mut().map(|node| &mut **node) }
+    }
+}
+
+impl<'a, T> Iterator for IterMut<'a, T> {
+    type Item = &'a mut T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.next.take().map(|node| {
+            self.next = node.next.as_mut().map(|node| &mut **node);
+            &mut node.elem
+        })
+    }
+}
+
+#[cfg(test)]
+mod test {
+
+    use super::List;
+
+    #[test]
+    fn basics() {
+        let mut list = List::new();
+
+        assert_eq!(list.pop(), None);
+
+        list.push(1);
+        list.push(2);
+        list.push(3);
+
+        assert_eq!(list.pop(), Some(3));
+        assert_eq!(list.pop(), Some(2));
+
+        list.push(4);
+        list.push(5);
+
+        assert_eq!(list.pop(), Some(5));
+        assert_eq!(list.pop(), Some(4));
+
+        assert_eq!(list.pop(), Some(1));
+        assert_eq!(list.pop(), None);
+    }
+
+    #[test]
+    fn peek() {
+        let mut list = List::new();
+        assert_eq!(list.peek(), None);
+        assert_eq!(list.peek_mut(), None);
+        list.push(1); list.push(2); list.push(3);
+
+        assert_eq!(list.peek(), Some(&3));
+        assert_eq!(list.peek_mut(), Some(&mut 3));
+        list.peek_mut().map(|value| {
+            *value = 42
+        });
+        assert_eq!(list.peek(), Some(&42));
+        assert_eq!(list.pop(), Some(42));
+    }
+
+    #[test]
+    fn into_iter() {
+        let mut list = List::new();
+        list.push(1); list.push(2); list.push(3);
+
+        let mut iter = list.into_iter();
+        assert_eq!(iter.next(), Some(3));
+        assert_eq!(iter.next(), Some(2));
+        assert_eq!(iter.next(), Some(1));
+        assert_eq!(iter.next(), None);
+    }
+
+    #[test]
+    fn iter() {
+        let mut list = List::new();
+        list.push(1); list.push(2); list.push(3);
+
+        let mut iter = list.iter();
+        assert_eq!(iter.next(), Some(&3));
+        assert_eq!(iter.next(), Some(&2));
+        assert_eq!(iter.next(), Some(&1));
+    }
+    #[test]
+    fn iter_mut() {
+        let mut list = List::new();
+        list.push(1); list.push(2); list.push(3);
+
+        let mut iter = list.iter_mut();
+        assert_eq!(iter.next(), Some(&mut 3));
+        assert_eq!(iter.next(), Some(&mut 2));
+        assert_eq!(iter.next(), Some(&mut 1));
+    }
+}