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);
    }
}