initial commit

src/linked_list.rs

@@ -0,0 +1,153 @@
+use std::mem;
+use std::ptr;
+
+pub struct List<T> {
+    list_head: Option<Box<Node<T>>>,
+    list_tail: Rawlink<Node<T>>,
+}
+
+struct Rawlink<T> { p: *mut T }
+
+impl<T> Copy for Rawlink<T> {}
+
+impl<T> Clone for Rawlink<T> {
+    fn clone(&self) -> Self { Rawlink { p: self.p } }
+}
+
+pub struct Node<T> {
+    next: Option<Box<Node<T>>>,
+    prev: Rawlink<Node<T>>,
+    value: T,
+}
+
+impl<T> List<T> {
+    pub fn is_empty(&self) -> bool {
+        self.list_head.is_none()
+    }
+
+    pub fn len(&self) -> usize {
+        let mut node = &self.list_head;
+        let mut i = 0;
+        loop {
+            match *node {
+                Some(ref n) => {
+                    i+=1;
+                    node=&n.next;
+                }
+                None => {
+                    return i;
+                }
+            }
+        }
+    }
+    
+    /// Create an empty DList
+    pub fn new() -> List<T> {
+        List{list_head: None, list_tail: Rawlink::none()}
+    }
+
+    pub fn push_front(&mut self, elt: T) {
+        self.push_front_node(Box::new(Node::new(elt)))
+    }
+
+    pub fn push_front_node(&mut self, mut new_head: Box<Node<T>>) {
+        match self.list_head {
+            None => {
+                self.list_tail = Rawlink::some(&mut new_head);
+                new_head.prev = Rawlink::none();
+                self.list_head = Some(new_head);
+            }
+            Some(ref mut head) => {
+                new_head.prev = Rawlink::none();
+                head.prev = Rawlink::some(&mut new_head);
+                mem::swap(head, &mut new_head);
+                head.next = Some(new_head);
+            }
+        }
+    }
+
+    /// Provide a forward iterator
+    #[inline]
+    pub fn iter<'a>(&'a self) -> ListIterator<'a, T> {
+        ListIterator{nelem: self.len(), head: &self.list_head, tail: self.list_tail}
+    }
+}
+
+impl<T> Node<T> {
+    fn new(v: T) -> Node<T> {
+        Node{value: v, next: None, prev: Rawlink::none()}
+    }
+}
+
+/// Rawlink is a type like Option<T> but for holding a raw pointer
+impl<T> Rawlink<T> {
+    /// Like Option::None for Rawlink
+    fn none() -> Rawlink<T> {
+        Rawlink{p: ptr::null_mut()}
+    }
+
+    /// Like Option::Some for Rawlink
+    fn some(n: &mut T) -> Rawlink<T> {
+        Rawlink{p: n as *mut T}
+    }
+
+    /// Convert the `Rawlink` into an Option value
+    fn resolve_immut<'a>(&self) -> Option<&'a T> {
+        unsafe { self.p.as_ref() }
+    }
+
+    /// Convert the `Rawlink` into an Option value
+    fn resolve<'a>(&mut self) -> Option<&'a mut T> {
+        unsafe { self.p.as_mut() }
+    }
+
+    /// Return the `Rawlink` and replace with `Rawlink::none()`
+    fn take(&mut self) -> Rawlink<T> {
+        mem::replace(self, Rawlink::none())
+    }
+}
+
+pub struct ListIterator<'a, T: 'a> {
+    head: &'a Option<Box<Node<T>>>,
+    tail: Rawlink<Node<T>>,
+    nelem: usize,
+}
+
+impl<'a, A> Iterator for ListIterator<'a, A> {
+    type Item = &'a A;
+    
+    #[inline]
+    fn next(&mut self) -> Option<&'a A> {
+        if self.nelem == 0 {
+            return None;
+        }
+        self.head.as_ref().map(|head| {
+            self.nelem -= 1;
+            self.head = &head.next;
+            &head.value
+        })
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.nelem, Some(self.nelem))
+    }
+}
+
+impl<'a, A> DoubleEndedIterator for ListIterator<'a, A> {
+    #[inline]
+    fn next_back(&mut self) -> Option<&'a A> {
+        if self.nelem == 0 {
+            return None;
+        }
+        let tmp = self.tail.resolve_immut();
+        tmp.as_ref().map(|prev| {
+            self.nelem -= 1;
+            self.tail = prev.prev;
+            &prev.value
+        })
+    }
+}
+
+fn main() {
+}