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lists/src/fifth.rs

@@ -0,0 +1,124 @@
+use std::ptr;
+
+pub struct List<T> {
+    head: Link<T>,
+    tail: *mut Node<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, tail: ptr::null_mut() }
+    }
+
+    pub fn push(&mut self, elem: T) {
+        let mut new_tail = Box::new(Node {
+            elem,
+            next: None,
+        });
+
+        let raw_tail: *mut _ = &mut *new_tail;
+
+        if !self.tail.is_null() {
+            unsafe {
+                (*self.tail).next = Some(new_tail);
+            }
+        } else {
+            self.head = Some(new_tail);
+        }
+
+        self.tail = raw_tail;
+    }
+
+    pub fn pop(&mut self) -> Option<T> {
+        self.head.take().map(|head| {
+            let head = *head;
+            self.head = head.next;
+
+            if self.head.is_none() {
+                self.tail = ptr::null_mut();
+            }
+
+            head.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 into_iter(self) -> IntoIter<T> {
+        IntoIter(self)
+    }
+
+    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 struct IntoIter<T>(List<T>);
+
+pub struct Iter<'a, T> {
+    next: Option<&'a Node<T>>,
+}
+
+pub struct IterMut<'a, T> {
+    next: Option<&'a mut Node<T>>,
+}
+
+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();
+        }
+    }
+}
+
+impl<T> Iterator for IntoIter<T> {
+    type Item = T;
+    fn next(&mut self) -> Option<Self::Item> {
+        self.0.pop()
+    }
+}
+
+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
+        })
+    }
+}

lists/src/lib.rs

@@ -2,3 +2,4 @@ pub mod first;
 pub mod second;
 pub mod third;
 pub mod fourth;
+pub mod fifth;