024 通过链表学Rust之非安全方式实现链表2

介绍

视频地址：https://www.bilibili.com/video/av78062009/
相关源码：https://github.com/anonymousGiga/Rust-link-list

详细内容

本节实现剩余的迭代器、Drop等。

IntoIter

实现代码如下：

//实现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()	
	}
}

Iter

代码如下：

//实现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
		})	
	}
}

IterMut

实现代码如下：

//实现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
		})	
	}
}

测试代码

	#[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);
    }

完整代码

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: 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
		})
	}
}

//实现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()	
	}
}

//实现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
		})	
	}
}

//实现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(1));
		assert_eq!(list.pop(), Some(2));
		list.push(4);
		assert_eq!(list.pop(), Some(3));
		assert_eq!(list.pop(), Some(4));
		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);
    }
}