358 lines
8.9 KiB
Rust
358 lines
8.9 KiB
Rust
//! Data structure and definition of a genericsingle-linked LIFO list.
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use std::ptr;
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#[derive(PartialEq)]
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pub struct List<T: PartialEq> {
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head: Link<T>,
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tail: *mut Node<T>,
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}
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type Link<T> = *mut Node<T>;
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#[derive(PartialEq)]
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struct Node<T> {
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elem: T,
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next: Link<T>,
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}
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/// Iterator structure for use in a for loop, pop elements before returning it
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pub struct IntoIter<T: PartialEq>(List<T>);
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/// Iterator structure for use in a for loop, dereference before returning it
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pub struct Iter<'a, T> {
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next: Option<&'a Node<T>>,
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}
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/// Same as Iter structure, returned item are mutable
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pub struct IterMut<'a, T> {
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next: Option<&'a mut Node<T>>,
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}
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impl<T: PartialEq> List<T> {
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/// Push an item at the end of the list
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pub fn push(&mut self, elem: T) {
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unsafe {
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let new_tail = Box::into_raw(Box::new(Node {
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elem,
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next: ptr::null_mut(),
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}));
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if !self.tail.is_null() {
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(*self.tail).next = new_tail;
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} else {
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self.head = new_tail;
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}
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self.tail = new_tail;
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}
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}
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/// Retrieve and remove the item at the head of the list.
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///
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/// Return None if list is empty
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pub fn pop(&mut self) -> Option<T> {
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unsafe {
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if self.head.is_null() {
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None
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} else {
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let head = Box::from_raw(self.head);
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self.head = head.next;
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if self.head.is_null() {
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self.tail = ptr::null_mut();
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}
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Some(head.elem)
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}
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}
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}
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/// Retrieve without removing the item at the head of the list
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///
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/// Return None if list is empty
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pub fn peek(&self) -> Option<&T> {
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unsafe {
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self.head.as_ref().map(|node| &node.elem)
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}
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}
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/// Retrieve without removing the item at the head of the list as mutable
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///
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/// Return None if lsit is empty
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pub fn peek_mut(&mut self) -> Option<&mut T> {
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unsafe {
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self.head.as_mut().map(|node| &mut node.elem)
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}
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}
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/// Search for an element in the list
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///
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/// Return **bool** true if the list contains the element, false otherwise
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///
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/// Worst case complexity of this function is O(n)
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pub fn contains(&self, elem: &T) -> bool {
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let mut iter = self.iter();
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let mut element = iter.next();
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while element.is_some() {
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if element.unwrap() == elem {
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return true;
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} else {
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element = iter.next();
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}
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}
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false
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}
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/// Remove the item from the list
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///
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/// Return true if the item has been found, otherwise return false
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///
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/// Worst-case complexity is O(n)
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pub fn remove(&mut self, item: T)-> bool {
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unsafe {
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let mut current: *mut Node<T> = self.head;
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let mut previous: *mut Node<T> = ptr::null_mut();
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while !current.is_null() {
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if (*current).elem == item {
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(*previous).next = (*current).next;
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drop(Box::from_raw(current).elem);
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return true;
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} else {
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previous = current;
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current = (*current).next;
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}
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}
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}
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false
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}
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/// Return true if the list is empty, false otherwise
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pub fn is_empty(&self) -> bool {
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self.head.is_null()
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}
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/// Turn the list into an iterator for use in a for loop per example.
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///
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/// When you iter using into_iter, elements are remove from the list
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pub fn into_iter(self) -> IntoIter<T> {
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IntoIter(self)
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}
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/// Turn the list into an iterator for use in a for loop
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///
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/// When you iter using this method, elements are dereferenced
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pub fn iter(&self) -> Iter<'_, T> {
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unsafe {
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Iter { next: self.head.as_ref() }
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}
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}
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/// Same as iter but make the iterator mutable
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pub fn iter_mut(&mut self) -> IterMut<'_, T> {
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unsafe {
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IterMut { next: self.head.as_mut() }
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}
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}
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}
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impl<T: PartialEq> Default for List<T> {
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/// Create an empty list
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fn default() -> Self {
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Self { head: ptr::null_mut(), tail: ptr::null_mut() }
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}
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}
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impl<T: PartialEq> Drop for List<T> {
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fn drop(&mut self) {
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while self.pop().is_some() {} // removing every item from list (necessary as we using unsafe function)
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}
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}
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impl<T: PartialEq> Iterator for IntoIter<T> {
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type Item = T;
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fn next(&mut self) -> Option<Self::Item> {
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// access fields of a tuple struct numerically
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self.0.pop()
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}
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}
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impl<'a, T> Iterator for Iter<'a, T> {
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type Item = &'a T;
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fn next(&mut self) -> Option<Self::Item> {
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unsafe {
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self.next.map(|node| {
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self.next = node.next.as_ref();
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&node.elem
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})
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}
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}
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}
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impl<'a, T> Iterator for IterMut<'a, T> {
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type Item = &'a mut T;
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fn next(&mut self) -> Option<Self::Item> {
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unsafe {
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self.next.take().map(|node| {
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self.next = node.next.as_mut();
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&mut node.elem
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})
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}
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}
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}
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#[cfg(test)]
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mod test {
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use super::List;
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#[test]
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fn basics() {
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let mut list = List::default();
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// Check empty list behaves right
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assert_eq!(list.pop(), None);
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// Populate list
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list.push(1);
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list.push(2);
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list.push(3);
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// Check normal removal
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assert_eq!(list.pop(), Some(1));
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assert_eq!(list.pop(), Some(2));
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// Push some more just to make sure nothing's corrupted
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list.push(4);
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list.push(5);
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// Check normal removal
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assert_eq!(list.pop(), Some(3));
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assert_eq!(list.pop(), Some(4));
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// Check exhaustion
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assert_eq!(list.pop(), Some(5));
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assert_eq!(list.pop(), None);
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}
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#[test]
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fn peek() {
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let mut list = List::default();
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assert_eq!(list.peek(), None);
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assert_eq!(list.peek_mut(), None);
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list.push(1);
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list.push(2);
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list.push(3);
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assert_eq!(list.peek(), Some(&1));
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assert_eq!(list.peek_mut(), Some(&mut 1));
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}
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#[test]
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fn into_iter() {
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let mut list = List::default();
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list.push(1);
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list.push(2);
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list.push(3);
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let mut iter = list.into_iter();
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assert_eq!(iter.next(), Some(1));
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assert_eq!(iter.next(), Some(2));
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assert_eq!(iter.next(), Some(3));
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assert_eq!(iter.next(), None);
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}
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#[test]
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fn iter() {
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let mut list = List::default();
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list.push(1);
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list.push(2);
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list.push(3);
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let mut iter = list.iter();
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assert_eq!(iter.next(), Some(&1));
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assert_eq!(iter.next(), Some(&2));
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assert_eq!(iter.next(), Some(&3));
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}
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#[test]
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fn iter_mut() {
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let mut list = List::default();
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list.push(1);
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list.push(2);
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list.push(3);
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let mut iter = list.iter_mut();
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assert_eq!(iter.next(), Some(&mut 1));
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assert_eq!(iter.next(), Some(&mut 2));
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assert_eq!(iter.next(), Some(&mut 3));
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}
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#[test]
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fn contains_test() {
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let mut list = List::default();
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assert_eq!(list.peek(), None);
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list.push(1);
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list.push(2);
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list.push(3);
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assert_eq!(list.contains(&1), true);
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assert_eq!(list.contains(&4), false);
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}
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#[test]
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fn remove_test() {
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let mut list = List::default();
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assert_eq!(list.peek(), None);
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list.push(1);
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list.push(2);
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list.push(3);
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assert_eq!(list.contains(&2), true);
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list.remove(2);
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assert_eq!(list.contains(&2), false);
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assert_eq!(list.pop(), Option::Some(1));
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assert_eq!(list.pop(), Option::Some(3));
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assert_eq!(list.peek(), Option::None);
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}
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#[test]
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fn miri_test() {
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let mut list = List::default();
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list.push(1);
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list.push(2);
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list.push(3);
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assert!(list.pop() == Some(1));
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list.push(4);
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assert!(list.pop() == Some(2));
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list.push(5);
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assert!(list.peek() == Some(&3));
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list.push(6);
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list.peek_mut().map(|x| *x *= 10);
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assert!(list.peek() == Some(&30));
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assert!(list.pop() == Some(30));
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for elem in list.iter_mut() {
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*elem *= 100;
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}
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let mut iter = list.iter();
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assert_eq!(iter.next(), Some(&400));
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assert_eq!(iter.next(), Some(&500));
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assert_eq!(iter.next(), Some(&600));
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assert_eq!(iter.next(), None);
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assert_eq!(iter.next(), None);
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assert!(list.pop() == Some(400));
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list.peek_mut().map(|x| *x *= 10);
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assert!(list.peek() == Some(&5000));
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list.push(7);
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}
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} |