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| use std::ptr;
pub struct List<T> {
head: Link<T>,
tail: *mut Node<T>,
}
type Link<T> = *mut Node<T>;
struct Node<T> {
elem: T,
next: Link<T>,
}
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> List<T> {
pub fn new() -> Self {
List { head: ptr::null_mut(), tail: ptr::null_mut() }
}
pub fn push(&mut self, elem: T) {
unsafe {
let new_tail = Box::into_raw(Box::new(Node {
elem: elem,
next: ptr::null_mut(),
}));
if !self.tail.is_null() {
(*self.tail).next = new_tail;
} else {
self.head = new_tail;
}
self.tail = new_tail;
}
}
pub fn pop(&mut self) -> Option<T> {
unsafe {
if self.head.is_null() {
None
} else {
let head = Box::from_raw(self.head);
self.head = head.next;
if self.head.is_null() {
self.tail = ptr::null_mut();
}
Some(head.elem)
}
}
}
pub fn peek(&self) -> Option<&T> {
unsafe {
self.head.as_ref().map(|node| &node.elem)
}
}
pub fn peek_mut(&mut self) -> Option<&mut T> {
unsafe {
self.head.as_mut().map(|node| &mut node.elem)
}
}
pub fn into_iter(self) -> IntoIter<T> {
IntoIter(self)
}
pub fn iter(&self) -> Iter<'_, T> {
unsafe {
Iter { next: self.head.as_ref() }
}
}
pub fn iter_mut(&mut self) -> IterMut<'_, T> {
unsafe {
IterMut { next: self.head.as_mut() }
}
}
}
impl<T> Drop for List<T> {
fn drop(&mut self) {
while let Some(_) = self.pop() { }
}
}
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> {
unsafe {
self.next.map(|node| {
self.next = node.next.as_ref();
&node.elem
})
}
}
}
impl<'a, T> Iterator for IterMut<'a, T> {
type Item = &'a mut T;
fn next(&mut self) -> Option<Self::Item> {
unsafe {
self.next.take().map(|node| {
self.next = node.next.as_mut();
&mut node.elem
})
}
}
}
#[cfg(test)]
mod test {
use super::List;
#[test]
fn basics() {
let mut list = List::new();
// 检查空链表行为正确
assert_eq!(list.pop(), None);
// 填充链表
list.push(1);
list.push(2);
list.push(3);
// 检查正常移除
assert_eq!(list.pop(), Some(1));
assert_eq!(list.pop(), Some(2));
// 再压入一些，确保没有损坏
list.push(4);
list.push(5);
// 检查正常移除
assert_eq!(list.pop(), Some(3));
assert_eq!(list.pop(), Some(4));
// 检查耗尽
assert_eq!(list.pop(), Some(5));
assert_eq!(list.pop(), None);
// 检查耗尽情况正确修复了指针
list.push(6);
list.push(7);
// 检查正常移除
assert_eq!(list.pop(), Some(6));
assert_eq!(list.pop(), Some(7));
assert_eq!(list.pop(), None);
}
#[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(1));
assert_eq!(iter.next(), Some(2));
assert_eq!(iter.next(), Some(3));
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(&1));
assert_eq!(iter.next(), Some(&2));
assert_eq!(iter.next(), Some(&3));
assert_eq!(iter.next(), None);
}
#[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 1));
assert_eq!(iter.next(), Some(&mut 2));
assert_eq!(iter.next(), Some(&mut 3));
assert_eq!(iter.next(), None);
}
#[test]
fn miri_food() {
let mut list = List::new();
list.push(1);
list.push(2);
list.push(3);
assert!(list.pop() == Some(1));
list.push(4);
assert!(list.pop() == Some(2));
list.push(5);
assert!(list.peek() == Some(&3));
list.push(6);
list.peek_mut().map(|x| *x *= 10);
assert!(list.peek() == Some(&30));
assert!(list.pop() == Some(30));
for elem in list.iter_mut() {
*elem *= 100;
}
let mut iter = list.iter();
assert_eq!(iter.next(), Some(&400));
assert_eq!(iter.next(), Some(&500));
assert_eq!(iter.next(), Some(&600));
assert_eq!(iter.next(), None);
assert_eq!(iter.next(), None);
assert!(list.pop() == Some(400));
list.peek_mut().map(|x| *x *= 10);
assert!(list.peek() == Some(&5000));
list.push(7);
// 扔在地上让析构函数自己锻炼
}
}
|