list/
lib.rs

1pub struct List<T> {
2    head: Link<T>,
3}
4
5type Link<T> = Option<Box<Node<T>>>;
6
7struct Node<T> {
8    elem: T,
9    next: Link<T>,
10}
11
12pub struct IntoIter<T>(List<T>);
13
14pub struct Iter<'a, T: 'a> {
15    next: Option<&'a Node<T>>,
16}
17
18pub struct IterMut<'a, T: 'a> {
19    next: Option<&'a mut Node<T>>,
20}
21
22impl<T> List<T> {
23
24    pub fn new() -> Self {
25        List { head: None }
26    }
27
28    pub fn push(&mut self, elem: T) {
29        let new_node = Box::new(Node {
30            elem: elem,
31            next: self.head.take(),
32        });
33
34        self.head = Some(new_node);
35    }
36
37    pub fn pop(&mut self) -> Option<T> {
38        self.head.take().map(|node| {
39            let node = *node;
40            self.head = node.next;
41            node.elem
42        })
43    }
44
45    pub fn peek(&self) -> Option<&T> {
46        self.head.as_ref().map(|node| {
47            &node.elem
48        })
49    }
50
51    pub fn peek_mut(&mut self) -> Option<&mut T> {
52        self.head.as_mut().map(|node| {
53            &mut node.elem
54        })
55    }
56
57    pub fn into_iter(self) -> IntoIter<T> {
58        IntoIter(self)
59    }
60
61    pub fn iter(&self) -> Iter<T> {
62        Iter { next: self.head.as_ref().map(|node| &**node) }
63    }
64
65    pub fn iter_mut(&mut self) -> IterMut<T> {
66        IterMut { next: self.head.as_mut().map(|node| &mut **node) }
67    }
68}
69
70impl<T> Drop for List<T> {
71    fn drop(&mut self) {
72        let mut cur_link = self.head.take();
73        while let Some(mut boxed_node) = cur_link {
74            cur_link = boxed_node.next.take();
75        }
76    }
77}
78
79impl<T> Iterator for IntoIter<T> {
80    type Item = T;
81    fn next(&mut self) -> Option<Self::Item> {
82        self.0.pop()
83    }
84}
85
86impl<'a, T> Iterator for Iter<'a, T> {
87    type Item = &'a T;
88
89    fn next(&mut self) -> Option<Self::Item> {
90        self.next.map(|node| {
91            self.next = node.next.as_ref().map(|node| &**node);
92            &node.elem
93        })
94    }
95}
96
97impl<'a, T> Iterator for IterMut<'a, T> {
98    type Item = &'a mut T;
99
100    fn next(&mut self) -> Option<Self::Item> {
101        self.next.take().map(|node| {
102            self.next = node.next.as_mut().map(|node| &mut **node);
103            &mut node.elem
104        })
105    }
106}
107
108
109#[cfg(test)]
110mod test {
111    use super::List;
112
113    #[test]
114    fn basics() {
115        let mut list = List::new();
116
117        // Check empty list behaves right
118        assert_eq!(list.pop(), None);
119
120        // Populate list
121        list.push(1);
122        list.push(2);
123        list.push(3);
124
125        // Check normal removal
126        assert_eq!(list.pop(), Some(3));
127        assert_eq!(list.pop(), Some(2));
128
129        // Push some more just to make sure nothing's corrupted
130        list.push(4);
131        list.push(5);
132
133        // Check normal removal
134        assert_eq!(list.pop(), Some(5));
135        assert_eq!(list.pop(), Some(4));
136
137        // Check exhaustion
138        assert_eq!(list.pop(), Some(1));
139        assert_eq!(list.pop(), None);
140    }
141
142    #[test]
143    fn peek() {
144        let mut list = List::new();
145        assert_eq!(list.peek(), None);
146        assert_eq!(list.peek_mut(), None);
147        list.push(1); list.push(2); list.push(3);
148
149        assert_eq!(list.peek(), Some(&3));
150        assert_eq!(list.peek_mut(), Some(&mut 3));
151    }
152
153    #[test]
154    fn into_iter() {
155        let mut list = List::new();
156        list.push(1); list.push(2); list.push(3);
157
158        let mut iter = list.into_iter();
159        assert_eq!(iter.next(), Some(3));
160        assert_eq!(iter.next(), Some(2));
161        assert_eq!(iter.next(), Some(1));
162    }
163
164    #[test]
165    fn iter() {
166        let mut list = List::new();
167        list.push(1); list.push(2); list.push(3);
168
169        let mut iter = list.iter();
170        assert_eq!(iter.next(), Some(&3));
171        assert_eq!(iter.next(), Some(&2));
172        assert_eq!(iter.next(), Some(&1));
173    }
174
175    #[test]
176    fn iter_mut() {
177        let mut list = List::new();
178        list.push(1); list.push(2); list.push(3);
179
180        let mut iter = list.iter_mut();
181        assert_eq!(iter.next(), Some(&mut 3));
182        assert_eq!(iter.next(), Some(&mut 2));
183        assert_eq!(iter.next(), Some(&mut 1));
184    }
185}
list/lib.rs

list/
lib.rs
