Second list implementation

src/lib.rs

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

src/second.rs

@@ -0,0 +1,199 @@
+pub struct List<T> {
+    head: Link<T>,
+}
+
+type Link<T> = Option<Box<Node<T>>>;
+
+struct Node<T> {
+    elem: T,
+    next: Link<T>,
+}
+
+pub struct Iter<'a, T: 'a> {
+    next: Option<&'a Node<T>>,
+}
+
+pub struct IterMut<'a, T: 'a> {
+    next: Option<&'a mut Node<T>>,
+}
+
+pub struct IntoIter<T>(List<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| {
+            let node = *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
+        })
+    }
+
+    pub fn iter(&self) -> Iter<T> {
+        Iter { next: self.head.as_ref().map(|node| &**node) }
+    }
+
+    pub fn iter_mut(&mut self) -> IterMut<T> {
+        IterMut { next: self.head.as_mut().map(|node| &mut **node) }
+    }
+
+    pub fn into_iter(self) -> IntoIter<T> {
+        IntoIter(self)
+    }
+}
+
+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
+        })
+    }
+}
+
+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
+        })
+    }
+}
+
+impl<T> Iterator for IntoIter<T> {
+    type Item = T;
+    fn next(&mut self) -> Option<Self::Item> {
+        // access fields of a tuple struct numerically
+        self.0.pop()
+    }
+}
+
+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 = boxed_node.next.take();
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::List;
+
+    #[test]
+    fn basics() {
+        let mut list = List::new();
+
+        // Check empty list behaves right
+        assert_eq!(list.pop(), None);
+
+        // Populate list
+        list.push(1);
+        list.push(2);
+        list.push(3);
+
+        // Check normal removal
+        assert_eq!(list.pop(), Some(3));
+        assert_eq!(list.pop(), Some(2));
+
+        // Push some more just to make sure nothing's corrupted
+        list.push(4);
+        list.push(5);
+
+        // Check normal removal
+        assert_eq!(list.pop(), Some(5));
+        assert_eq!(list.pop(), Some(4));
+
+        // Check exhaustion
+        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));
+    }
+
+    #[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));
+    }
+
+    #[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));
+    }
+
+
+}