影片地址:www.bilibili.com/video/av78062009/
相關原始碼:github.com/anonymousGiga/Rust-link...
本節我們為連結串列實現IterMut,既可以對元素進行可變引用的迭代器。
實現的程式碼如下:
//實現IterMut
pub struct IterMut<'a, T> {
next: Option<&'a mut Node<T>>,
}
impl<T> List<T> {
pub fn iter_mut(&mut self) -> IterMut<T> {
IterMut { next: self.head.as_deref_mut() }
}
}
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_deref_mut();
&mut node.elem
})
}
}
pub struct List<T> {
head: Link<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 }
}
pub fn push(&mut self, elem: T) {
let node = Box::new(Node{
elem: elem,
next: self.head.take(),
});
self.head = Some(node);
}
pub fn pop(&mut self) -> Option<T> {
self.head.take().map(|node| {
self.head = node.next;
node.elem
})
}
pub fn peek(&self) -> Option<&T> {
//self.head.map(|node| {
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
})
}
}
//實現IntoIter
pub struct IntoIter<T>(List<T>);
impl<T> List<T> {
pub fn into_iter(self) -> IntoIter<T> {
IntoIter(self)
}
}
impl<T> Iterator for IntoIter<T> {
type Item = T;
fn next(&mut self) -> Option<Self::Item> {
self.0.pop()
}
}
//實現Iter
pub struct Iter<'a, T> {
next: Option<&'a Node<T>>,
}
impl<T> List<T> {
pub fn iter(&self) -> Iter<T> {
Iter { next: self.head.as_deref() }
}
}
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_deref();
&node.elem
})
}
}
//實現IterMut
pub struct IterMut<'a, T> {
next: Option<&'a mut Node<T>>,
}
impl<T> List<T> {
pub fn iter_mut(&mut self) -> IterMut<T> {
IterMut { next: self.head.as_deref_mut() }
}
}
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_deref_mut();
&mut node.elem
})
}
}
#[cfg(test)]
mod tests {
use super::List;
#[test]
fn basics() {
let mut list = List::new();
assert_eq!(list.pop(), None);
list.push(1);
list.push(2);
list.push(3);
assert_eq!(list.pop(), Some(3));
assert_eq!(list.pop(), Some(2));
list.push(4);
list.push(5);
assert_eq!(list.pop(), Some(5));
assert_eq!(list.pop(), Some(4));
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));
list.peek_mut().map(|value| {
*value = 32
});
assert_eq!(list.peek(), Some(&32));
assert_eq!(list.pop(), Some(32));
}
#[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));
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(&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_mut = list.iter_mut();
assert_eq!(iter_mut.next(), Some(&mut 3));
assert_eq!(iter_mut.next(), Some(&mut 2));
assert_eq!(iter_mut.next(), Some(&mut 1));
}
}
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