| //! A doubly-linked list with owned nodes. |
| //! |
| //! The `LinkedList` allows pushing and popping elements at either end |
| //! in constant time. |
| //! |
| //! NOTE: It is almost always better to use [`Vec`] or [`VecDeque`] because |
| //! array-based containers are generally faster, |
| //! more memory efficient, and make better use of CPU cache. |
| //! |
| //! [`Vec`]: ../../vec/struct.Vec.html |
| //! [`VecDeque`]: ../vec_deque/struct.VecDeque.html |
| |
| #![stable(feature = "rust1", since = "1.0.0")] |
| |
| use core::cmp::Ordering; |
| use core::fmt; |
| use core::hash::{Hash, Hasher}; |
| use core::iter::{FromIterator, FusedIterator}; |
| use core::marker::PhantomData; |
| use core::mem; |
| use core::ptr::NonNull; |
| |
| use super::SpecExtend; |
| use crate::boxed::Box; |
| |
| #[cfg(test)] |
| mod tests; |
| |
| /// A doubly-linked list with owned nodes. |
| /// |
| /// The `LinkedList` allows pushing and popping elements at either end |
| /// in constant time. |
| /// |
| /// NOTE: It is almost always better to use `Vec` or `VecDeque` because |
| /// array-based containers are generally faster, |
| /// more memory efficient, and make better use of CPU cache. |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct LinkedList<T> { |
| head: Option<NonNull<Node<T>>>, |
| tail: Option<NonNull<Node<T>>>, |
| len: usize, |
| marker: PhantomData<Box<Node<T>>>, |
| } |
| |
| struct Node<T> { |
| next: Option<NonNull<Node<T>>>, |
| prev: Option<NonNull<Node<T>>>, |
| element: T, |
| } |
| |
| /// An iterator over the elements of a `LinkedList`. |
| /// |
| /// This `struct` is created by the [`iter`] method on [`LinkedList`]. See its |
| /// documentation for more. |
| /// |
| /// [`iter`]: struct.LinkedList.html#method.iter |
| /// [`LinkedList`]: struct.LinkedList.html |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct Iter<'a, T: 'a> { |
| head: Option<NonNull<Node<T>>>, |
| tail: Option<NonNull<Node<T>>>, |
| len: usize, |
| marker: PhantomData<&'a Node<T>>, |
| } |
| |
| #[stable(feature = "collection_debug", since = "1.17.0")] |
| impl<T: fmt::Debug> fmt::Debug for Iter<'_, T> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_tuple("Iter").field(&self.len).finish() |
| } |
| } |
| |
| // FIXME(#26925) Remove in favor of `#[derive(Clone)]` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> Clone for Iter<'_, T> { |
| fn clone(&self) -> Self { |
| Iter { ..*self } |
| } |
| } |
| |
| /// A mutable iterator over the elements of a `LinkedList`. |
| /// |
| /// This `struct` is created by the [`iter_mut`] method on [`LinkedList`]. See its |
| /// documentation for more. |
| /// |
| /// [`iter_mut`]: struct.LinkedList.html#method.iter_mut |
| /// [`LinkedList`]: struct.LinkedList.html |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct IterMut<'a, T: 'a> { |
| // We do *not* exclusively own the entire list here, references to node's `element` |
| // have been handed out by the iterator! So be careful when using this; the methods |
| // called must be aware that there can be aliasing pointers to `element`. |
| list: &'a mut LinkedList<T>, |
| head: Option<NonNull<Node<T>>>, |
| tail: Option<NonNull<Node<T>>>, |
| len: usize, |
| } |
| |
| #[stable(feature = "collection_debug", since = "1.17.0")] |
| impl<T: fmt::Debug> fmt::Debug for IterMut<'_, T> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_tuple("IterMut").field(&self.list).field(&self.len).finish() |
| } |
| } |
| |
| /// An owning iterator over the elements of a `LinkedList`. |
| /// |
| /// This `struct` is created by the [`into_iter`] method on [`LinkedList`] |
| /// (provided by the `IntoIterator` trait). See its documentation for more. |
| /// |
| /// [`into_iter`]: struct.LinkedList.html#method.into_iter |
| /// [`LinkedList`]: struct.LinkedList.html |
| #[derive(Clone)] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct IntoIter<T> { |
| list: LinkedList<T>, |
| } |
| |
| #[stable(feature = "collection_debug", since = "1.17.0")] |
| impl<T: fmt::Debug> fmt::Debug for IntoIter<T> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_tuple("IntoIter").field(&self.list).finish() |
| } |
| } |
| |
| impl<T> Node<T> { |
| fn new(element: T) -> Self { |
| Node { next: None, prev: None, element } |
| } |
| |
| fn into_element(self: Box<Self>) -> T { |
| self.element |
| } |
| } |
| |
| // private methods |
| impl<T> LinkedList<T> { |
| /// Adds the given node to the front of the list. |
| #[inline] |
| fn push_front_node(&mut self, mut node: Box<Node<T>>) { |
| // This method takes care not to create mutable references to whole nodes, |
| // to maintain validity of aliasing pointers into `element`. |
| unsafe { |
| node.next = self.head; |
| node.prev = None; |
| let node = Some(Box::into_raw_non_null(node)); |
| |
| match self.head { |
| None => self.tail = node, |
| // Not creating new mutable (unique!) references overlapping `element`. |
| Some(head) => (*head.as_ptr()).prev = node, |
| } |
| |
| self.head = node; |
| self.len += 1; |
| } |
| } |
| |
| /// Removes and returns the node at the front of the list. |
| #[inline] |
| fn pop_front_node(&mut self) -> Option<Box<Node<T>>> { |
| // This method takes care not to create mutable references to whole nodes, |
| // to maintain validity of aliasing pointers into `element`. |
| self.head.map(|node| unsafe { |
| let node = Box::from_raw(node.as_ptr()); |
| self.head = node.next; |
| |
| match self.head { |
| None => self.tail = None, |
| // Not creating new mutable (unique!) references overlapping `element`. |
| Some(head) => (*head.as_ptr()).prev = None, |
| } |
| |
| self.len -= 1; |
| node |
| }) |
| } |
| |
| /// Adds the given node to the back of the list. |
| #[inline] |
| fn push_back_node(&mut self, mut node: Box<Node<T>>) { |
| // This method takes care not to create mutable references to whole nodes, |
| // to maintain validity of aliasing pointers into `element`. |
| unsafe { |
| node.next = None; |
| node.prev = self.tail; |
| let node = Some(Box::into_raw_non_null(node)); |
| |
| match self.tail { |
| None => self.head = node, |
| // Not creating new mutable (unique!) references overlapping `element`. |
| Some(tail) => (*tail.as_ptr()).next = node, |
| } |
| |
| self.tail = node; |
| self.len += 1; |
| } |
| } |
| |
| /// Removes and returns the node at the back of the list. |
| #[inline] |
| fn pop_back_node(&mut self) -> Option<Box<Node<T>>> { |
| // This method takes care not to create mutable references to whole nodes, |
| // to maintain validity of aliasing pointers into `element`. |
| self.tail.map(|node| unsafe { |
| let node = Box::from_raw(node.as_ptr()); |
| self.tail = node.prev; |
| |
| match self.tail { |
| None => self.head = None, |
| // Not creating new mutable (unique!) references overlapping `element`. |
| Some(tail) => (*tail.as_ptr()).next = None, |
| } |
| |
| self.len -= 1; |
| node |
| }) |
| } |
| |
| /// Unlinks the specified node from the current list. |
| /// |
| /// Warning: this will not check that the provided node belongs to the current list. |
| /// |
| /// This method takes care not to create mutable references to `element`, to |
| /// maintain validity of aliasing pointers. |
| #[inline] |
| unsafe fn unlink_node(&mut self, mut node: NonNull<Node<T>>) { |
| let node = node.as_mut(); // this one is ours now, we can create an &mut. |
| |
| // Not creating new mutable (unique!) references overlapping `element`. |
| match node.prev { |
| Some(prev) => (*prev.as_ptr()).next = node.next, |
| // this node is the head node |
| None => self.head = node.next, |
| }; |
| |
| match node.next { |
| Some(next) => (*next.as_ptr()).prev = node.prev, |
| // this node is the tail node |
| None => self.tail = node.prev, |
| }; |
| |
| self.len -= 1; |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> Default for LinkedList<T> { |
| /// Creates an empty `LinkedList<T>`. |
| #[inline] |
| fn default() -> Self { |
| Self::new() |
| } |
| } |
| |
| impl<T> LinkedList<T> { |
| /// Creates an empty `LinkedList`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let list: LinkedList<u32> = LinkedList::new(); |
| /// ``` |
| #[inline] |
| #[rustc_const_stable(feature = "const_linked_list_new", since = "1.32.0")] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub const fn new() -> Self { |
| LinkedList { head: None, tail: None, len: 0, marker: PhantomData } |
| } |
| |
| /// Moves all elements from `other` to the end of the list. |
| /// |
| /// This reuses all the nodes from `other` and moves them into `self`. After |
| /// this operation, `other` becomes empty. |
| /// |
| /// This operation should compute in O(1) time and O(1) memory. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut list1 = LinkedList::new(); |
| /// list1.push_back('a'); |
| /// |
| /// let mut list2 = LinkedList::new(); |
| /// list2.push_back('b'); |
| /// list2.push_back('c'); |
| /// |
| /// list1.append(&mut list2); |
| /// |
| /// let mut iter = list1.iter(); |
| /// assert_eq!(iter.next(), Some(&'a')); |
| /// assert_eq!(iter.next(), Some(&'b')); |
| /// assert_eq!(iter.next(), Some(&'c')); |
| /// assert!(iter.next().is_none()); |
| /// |
| /// assert!(list2.is_empty()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn append(&mut self, other: &mut Self) { |
| match self.tail { |
| None => mem::swap(self, other), |
| Some(mut tail) => { |
| // `as_mut` is okay here because we have exclusive access to the entirety |
| // of both lists. |
| if let Some(mut other_head) = other.head.take() { |
| unsafe { |
| tail.as_mut().next = Some(other_head); |
| other_head.as_mut().prev = Some(tail); |
| } |
| |
| self.tail = other.tail.take(); |
| self.len += mem::replace(&mut other.len, 0); |
| } |
| } |
| } |
| } |
| |
| /// Provides a forward iterator. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut list: LinkedList<u32> = LinkedList::new(); |
| /// |
| /// list.push_back(0); |
| /// list.push_back(1); |
| /// list.push_back(2); |
| /// |
| /// let mut iter = list.iter(); |
| /// assert_eq!(iter.next(), Some(&0)); |
| /// assert_eq!(iter.next(), Some(&1)); |
| /// assert_eq!(iter.next(), Some(&2)); |
| /// assert_eq!(iter.next(), None); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn iter(&self) -> Iter<'_, T> { |
| Iter { head: self.head, tail: self.tail, len: self.len, marker: PhantomData } |
| } |
| |
| /// Provides a forward iterator with mutable references. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut list: LinkedList<u32> = LinkedList::new(); |
| /// |
| /// list.push_back(0); |
| /// list.push_back(1); |
| /// list.push_back(2); |
| /// |
| /// for element in list.iter_mut() { |
| /// *element += 10; |
| /// } |
| /// |
| /// let mut iter = list.iter(); |
| /// assert_eq!(iter.next(), Some(&10)); |
| /// assert_eq!(iter.next(), Some(&11)); |
| /// assert_eq!(iter.next(), Some(&12)); |
| /// assert_eq!(iter.next(), None); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn iter_mut(&mut self) -> IterMut<'_, T> { |
| IterMut { head: self.head, tail: self.tail, len: self.len, list: self } |
| } |
| |
| /// Returns `true` if the `LinkedList` is empty. |
| /// |
| /// This operation should compute in O(1) time. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut dl = LinkedList::new(); |
| /// assert!(dl.is_empty()); |
| /// |
| /// dl.push_front("foo"); |
| /// assert!(!dl.is_empty()); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn is_empty(&self) -> bool { |
| self.head.is_none() |
| } |
| |
| /// Returns the length of the `LinkedList`. |
| /// |
| /// This operation should compute in O(1) time. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut dl = LinkedList::new(); |
| /// |
| /// dl.push_front(2); |
| /// assert_eq!(dl.len(), 1); |
| /// |
| /// dl.push_front(1); |
| /// assert_eq!(dl.len(), 2); |
| /// |
| /// dl.push_back(3); |
| /// assert_eq!(dl.len(), 3); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn len(&self) -> usize { |
| self.len |
| } |
| |
| /// Removes all elements from the `LinkedList`. |
| /// |
| /// This operation should compute in O(n) time. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut dl = LinkedList::new(); |
| /// |
| /// dl.push_front(2); |
| /// dl.push_front(1); |
| /// assert_eq!(dl.len(), 2); |
| /// assert_eq!(dl.front(), Some(&1)); |
| /// |
| /// dl.clear(); |
| /// assert_eq!(dl.len(), 0); |
| /// assert_eq!(dl.front(), None); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn clear(&mut self) { |
| *self = Self::new(); |
| } |
| |
| /// Returns `true` if the `LinkedList` contains an element equal to the |
| /// given value. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut list: LinkedList<u32> = LinkedList::new(); |
| /// |
| /// list.push_back(0); |
| /// list.push_back(1); |
| /// list.push_back(2); |
| /// |
| /// assert_eq!(list.contains(&0), true); |
| /// assert_eq!(list.contains(&10), false); |
| /// ``` |
| #[stable(feature = "linked_list_contains", since = "1.12.0")] |
| pub fn contains(&self, x: &T) -> bool |
| where |
| T: PartialEq<T>, |
| { |
| self.iter().any(|e| e == x) |
| } |
| |
| /// Provides a reference to the front element, or `None` if the list is |
| /// empty. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut dl = LinkedList::new(); |
| /// assert_eq!(dl.front(), None); |
| /// |
| /// dl.push_front(1); |
| /// assert_eq!(dl.front(), Some(&1)); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn front(&self) -> Option<&T> { |
| unsafe { self.head.as_ref().map(|node| &node.as_ref().element) } |
| } |
| |
| /// Provides a mutable reference to the front element, or `None` if the list |
| /// is empty. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut dl = LinkedList::new(); |
| /// assert_eq!(dl.front(), None); |
| /// |
| /// dl.push_front(1); |
| /// assert_eq!(dl.front(), Some(&1)); |
| /// |
| /// match dl.front_mut() { |
| /// None => {}, |
| /// Some(x) => *x = 5, |
| /// } |
| /// assert_eq!(dl.front(), Some(&5)); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn front_mut(&mut self) -> Option<&mut T> { |
| unsafe { self.head.as_mut().map(|node| &mut node.as_mut().element) } |
| } |
| |
| /// Provides a reference to the back element, or `None` if the list is |
| /// empty. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut dl = LinkedList::new(); |
| /// assert_eq!(dl.back(), None); |
| /// |
| /// dl.push_back(1); |
| /// assert_eq!(dl.back(), Some(&1)); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn back(&self) -> Option<&T> { |
| unsafe { self.tail.as_ref().map(|node| &node.as_ref().element) } |
| } |
| |
| /// Provides a mutable reference to the back element, or `None` if the list |
| /// is empty. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut dl = LinkedList::new(); |
| /// assert_eq!(dl.back(), None); |
| /// |
| /// dl.push_back(1); |
| /// assert_eq!(dl.back(), Some(&1)); |
| /// |
| /// match dl.back_mut() { |
| /// None => {}, |
| /// Some(x) => *x = 5, |
| /// } |
| /// assert_eq!(dl.back(), Some(&5)); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn back_mut(&mut self) -> Option<&mut T> { |
| unsafe { self.tail.as_mut().map(|node| &mut node.as_mut().element) } |
| } |
| |
| /// Adds an element first in the list. |
| /// |
| /// This operation should compute in O(1) time. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut dl = LinkedList::new(); |
| /// |
| /// dl.push_front(2); |
| /// assert_eq!(dl.front().unwrap(), &2); |
| /// |
| /// dl.push_front(1); |
| /// assert_eq!(dl.front().unwrap(), &1); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn push_front(&mut self, elt: T) { |
| self.push_front_node(box Node::new(elt)); |
| } |
| |
| /// Removes the first element and returns it, or `None` if the list is |
| /// empty. |
| /// |
| /// This operation should compute in O(1) time. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut d = LinkedList::new(); |
| /// assert_eq!(d.pop_front(), None); |
| /// |
| /// d.push_front(1); |
| /// d.push_front(3); |
| /// assert_eq!(d.pop_front(), Some(3)); |
| /// assert_eq!(d.pop_front(), Some(1)); |
| /// assert_eq!(d.pop_front(), None); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn pop_front(&mut self) -> Option<T> { |
| self.pop_front_node().map(Node::into_element) |
| } |
| |
| /// Appends an element to the back of a list. |
| /// |
| /// This operation should compute in O(1) time. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut d = LinkedList::new(); |
| /// d.push_back(1); |
| /// d.push_back(3); |
| /// assert_eq!(3, *d.back().unwrap()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn push_back(&mut self, elt: T) { |
| self.push_back_node(box Node::new(elt)); |
| } |
| |
| /// Removes the last element from a list and returns it, or `None` if |
| /// it is empty. |
| /// |
| /// This operation should compute in O(1) time. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut d = LinkedList::new(); |
| /// assert_eq!(d.pop_back(), None); |
| /// d.push_back(1); |
| /// d.push_back(3); |
| /// assert_eq!(d.pop_back(), Some(3)); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn pop_back(&mut self) -> Option<T> { |
| self.pop_back_node().map(Node::into_element) |
| } |
| |
| /// Splits the list into two at the given index. Returns everything after the given index, |
| /// including the index. |
| /// |
| /// This operation should compute in O(n) time. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `at > len`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut d = LinkedList::new(); |
| /// |
| /// d.push_front(1); |
| /// d.push_front(2); |
| /// d.push_front(3); |
| /// |
| /// let mut splitted = d.split_off(2); |
| /// |
| /// assert_eq!(splitted.pop_front(), Some(1)); |
| /// assert_eq!(splitted.pop_front(), None); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn split_off(&mut self, at: usize) -> LinkedList<T> { |
| let len = self.len(); |
| assert!(at <= len, "Cannot split off at a nonexistent index"); |
| if at == 0 { |
| return mem::take(self); |
| } else if at == len { |
| return Self::new(); |
| } |
| |
| // Below, we iterate towards the `i-1`th node, either from the start or the end, |
| // depending on which would be faster. |
| let split_node = if at - 1 <= len - 1 - (at - 1) { |
| let mut iter = self.iter_mut(); |
| // instead of skipping using .skip() (which creates a new struct), |
| // we skip manually so we can access the head field without |
| // depending on implementation details of Skip |
| for _ in 0..at - 1 { |
| iter.next(); |
| } |
| iter.head |
| } else { |
| // better off starting from the end |
| let mut iter = self.iter_mut(); |
| for _ in 0..len - 1 - (at - 1) { |
| iter.next_back(); |
| } |
| iter.tail |
| }; |
| |
| // The split node is the new tail node of the first part and owns |
| // the head of the second part. |
| let second_part_head; |
| |
| unsafe { |
| second_part_head = split_node.unwrap().as_mut().next.take(); |
| if let Some(mut head) = second_part_head { |
| head.as_mut().prev = None; |
| } |
| } |
| |
| let second_part = LinkedList { |
| head: second_part_head, |
| tail: self.tail, |
| len: len - at, |
| marker: PhantomData, |
| }; |
| |
| // Fix the tail ptr of the first part |
| self.tail = split_node; |
| self.len = at; |
| |
| second_part |
| } |
| |
| /// Creates an iterator which uses a closure to determine if an element should be removed. |
| /// |
| /// If the closure returns true, then the element is removed and yielded. |
| /// If the closure returns false, the element will remain in the list and will not be yielded |
| /// by the iterator. |
| /// |
| /// Note that `drain_filter` lets you mutate every element in the filter closure, regardless of |
| /// whether you choose to keep or remove it. |
| /// |
| /// # Examples |
| /// |
| /// Splitting a list into evens and odds, reusing the original list: |
| /// |
| /// ``` |
| /// #![feature(drain_filter)] |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut numbers: LinkedList<u32> = LinkedList::new(); |
| /// numbers.extend(&[1, 2, 3, 4, 5, 6, 8, 9, 11, 13, 14, 15]); |
| /// |
| /// let evens = numbers.drain_filter(|x| *x % 2 == 0).collect::<LinkedList<_>>(); |
| /// let odds = numbers; |
| /// |
| /// assert_eq!(evens.into_iter().collect::<Vec<_>>(), vec![2, 4, 6, 8, 14]); |
| /// assert_eq!(odds.into_iter().collect::<Vec<_>>(), vec![1, 3, 5, 9, 11, 13, 15]); |
| /// ``` |
| #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] |
| pub fn drain_filter<F>(&mut self, filter: F) -> DrainFilter<'_, T, F> |
| where |
| F: FnMut(&mut T) -> bool, |
| { |
| // avoid borrow issues. |
| let it = self.head; |
| let old_len = self.len; |
| |
| DrainFilter { list: self, it: it, pred: filter, idx: 0, old_len: old_len } |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| unsafe impl<#[may_dangle] T> Drop for LinkedList<T> { |
| fn drop(&mut self) { |
| struct DropGuard<'a, T>(&'a mut LinkedList<T>); |
| |
| impl<'a, T> Drop for DropGuard<'a, T> { |
| fn drop(&mut self) { |
| // Continue the same loop we do below. This only runs when a destructor has |
| // panicked. If another one panics this will abort. |
| while let Some(_) = self.0.pop_front_node() {} |
| } |
| } |
| |
| while let Some(node) = self.pop_front_node() { |
| let guard = DropGuard(self); |
| drop(node); |
| mem::forget(guard); |
| } |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a, T> Iterator for Iter<'a, T> { |
| type Item = &'a T; |
| |
| #[inline] |
| fn next(&mut self) -> Option<&'a T> { |
| if self.len == 0 { |
| None |
| } else { |
| self.head.map(|node| unsafe { |
| // Need an unbound lifetime to get 'a |
| let node = &*node.as_ptr(); |
| self.len -= 1; |
| self.head = node.next; |
| &node.element |
| }) |
| } |
| } |
| |
| #[inline] |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| (self.len, Some(self.len)) |
| } |
| |
| #[inline] |
| fn last(mut self) -> Option<&'a T> { |
| self.next_back() |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a, T> DoubleEndedIterator for Iter<'a, T> { |
| #[inline] |
| fn next_back(&mut self) -> Option<&'a T> { |
| if self.len == 0 { |
| None |
| } else { |
| self.tail.map(|node| unsafe { |
| // Need an unbound lifetime to get 'a |
| let node = &*node.as_ptr(); |
| self.len -= 1; |
| self.tail = node.prev; |
| &node.element |
| }) |
| } |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> ExactSizeIterator for Iter<'_, T> {} |
| |
| #[stable(feature = "fused", since = "1.26.0")] |
| impl<T> FusedIterator for Iter<'_, T> {} |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a, T> Iterator for IterMut<'a, T> { |
| type Item = &'a mut T; |
| |
| #[inline] |
| fn next(&mut self) -> Option<&'a mut T> { |
| if self.len == 0 { |
| None |
| } else { |
| self.head.map(|node| unsafe { |
| // Need an unbound lifetime to get 'a |
| let node = &mut *node.as_ptr(); |
| self.len -= 1; |
| self.head = node.next; |
| &mut node.element |
| }) |
| } |
| } |
| |
| #[inline] |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| (self.len, Some(self.len)) |
| } |
| |
| #[inline] |
| fn last(mut self) -> Option<&'a mut T> { |
| self.next_back() |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a, T> DoubleEndedIterator for IterMut<'a, T> { |
| #[inline] |
| fn next_back(&mut self) -> Option<&'a mut T> { |
| if self.len == 0 { |
| None |
| } else { |
| self.tail.map(|node| unsafe { |
| // Need an unbound lifetime to get 'a |
| let node = &mut *node.as_ptr(); |
| self.len -= 1; |
| self.tail = node.prev; |
| &mut node.element |
| }) |
| } |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> ExactSizeIterator for IterMut<'_, T> {} |
| |
| #[stable(feature = "fused", since = "1.26.0")] |
| impl<T> FusedIterator for IterMut<'_, T> {} |
| |
| impl<T> IterMut<'_, T> { |
| /// Inserts the given element just after the element most recently returned by `.next()`. |
| /// The inserted element does not appear in the iteration. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(linked_list_extras)] |
| /// |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut list: LinkedList<_> = vec![1, 3, 4].into_iter().collect(); |
| /// |
| /// { |
| /// let mut it = list.iter_mut(); |
| /// assert_eq!(it.next().unwrap(), &1); |
| /// // insert `2` after `1` |
| /// it.insert_next(2); |
| /// } |
| /// { |
| /// let vec: Vec<_> = list.into_iter().collect(); |
| /// assert_eq!(vec, [1, 2, 3, 4]); |
| /// } |
| /// ``` |
| #[inline] |
| #[unstable( |
| feature = "linked_list_extras", |
| reason = "this is probably better handled by a cursor type -- we'll see", |
| issue = "27794" |
| )] |
| pub fn insert_next(&mut self, element: T) { |
| match self.head { |
| // `push_back` is okay with aliasing `element` references |
| None => self.list.push_back(element), |
| Some(head) => unsafe { |
| let prev = match head.as_ref().prev { |
| // `push_front` is okay with aliasing nodes |
| None => return self.list.push_front(element), |
| Some(prev) => prev, |
| }; |
| |
| let node = Some(Box::into_raw_non_null(box Node { |
| next: Some(head), |
| prev: Some(prev), |
| element, |
| })); |
| |
| // Not creating references to entire nodes to not invalidate the |
| // reference to `element` we handed to the user. |
| (*prev.as_ptr()).next = node; |
| (*head.as_ptr()).prev = node; |
| |
| self.list.len += 1; |
| }, |
| } |
| } |
| |
| /// Provides a reference to the next element, without changing the iterator. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(linked_list_extras)] |
| /// |
| /// use std::collections::LinkedList; |
| /// |
| /// let mut list: LinkedList<_> = vec![1, 2, 3].into_iter().collect(); |
| /// |
| /// let mut it = list.iter_mut(); |
| /// assert_eq!(it.next().unwrap(), &1); |
| /// assert_eq!(it.peek_next().unwrap(), &2); |
| /// // We just peeked at 2, so it was not consumed from the iterator. |
| /// assert_eq!(it.next().unwrap(), &2); |
| /// ``` |
| #[inline] |
| #[unstable( |
| feature = "linked_list_extras", |
| reason = "this is probably better handled by a cursor type -- we'll see", |
| issue = "27794" |
| )] |
| pub fn peek_next(&mut self) -> Option<&mut T> { |
| if self.len == 0 { |
| None |
| } else { |
| unsafe { self.head.as_mut().map(|node| &mut node.as_mut().element) } |
| } |
| } |
| } |
| |
| /// An iterator produced by calling `drain_filter` on LinkedList. |
| #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] |
| pub struct DrainFilter<'a, T: 'a, F: 'a> |
| where |
| F: FnMut(&mut T) -> bool, |
| { |
| list: &'a mut LinkedList<T>, |
| it: Option<NonNull<Node<T>>>, |
| pred: F, |
| idx: usize, |
| old_len: usize, |
| } |
| |
| #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] |
| impl<T, F> Iterator for DrainFilter<'_, T, F> |
| where |
| F: FnMut(&mut T) -> bool, |
| { |
| type Item = T; |
| |
| fn next(&mut self) -> Option<T> { |
| while let Some(mut node) = self.it { |
| unsafe { |
| self.it = node.as_ref().next; |
| self.idx += 1; |
| |
| if (self.pred)(&mut node.as_mut().element) { |
| // `unlink_node` is okay with aliasing `element` references. |
| self.list.unlink_node(node); |
| return Some(Box::from_raw(node.as_ptr()).element); |
| } |
| } |
| } |
| |
| None |
| } |
| |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| (0, Some(self.old_len - self.idx)) |
| } |
| } |
| |
| #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] |
| impl<T, F> Drop for DrainFilter<'_, T, F> |
| where |
| F: FnMut(&mut T) -> bool, |
| { |
| fn drop(&mut self) { |
| self.for_each(drop); |
| } |
| } |
| |
| #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] |
| impl<T: fmt::Debug, F> fmt::Debug for DrainFilter<'_, T, F> |
| where |
| F: FnMut(&mut T) -> bool, |
| { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_tuple("DrainFilter").field(&self.list).finish() |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> Iterator for IntoIter<T> { |
| type Item = T; |
| |
| #[inline] |
| fn next(&mut self) -> Option<T> { |
| self.list.pop_front() |
| } |
| |
| #[inline] |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| (self.list.len, Some(self.list.len)) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> DoubleEndedIterator for IntoIter<T> { |
| #[inline] |
| fn next_back(&mut self) -> Option<T> { |
| self.list.pop_back() |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> ExactSizeIterator for IntoIter<T> {} |
| |
| #[stable(feature = "fused", since = "1.26.0")] |
| impl<T> FusedIterator for IntoIter<T> {} |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> FromIterator<T> for LinkedList<T> { |
| fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self { |
| let mut list = Self::new(); |
| list.extend(iter); |
| list |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> IntoIterator for LinkedList<T> { |
| type Item = T; |
| type IntoIter = IntoIter<T>; |
| |
| /// Consumes the list into an iterator yielding elements by value. |
| #[inline] |
| fn into_iter(self) -> IntoIter<T> { |
| IntoIter { list: self } |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a, T> IntoIterator for &'a LinkedList<T> { |
| type Item = &'a T; |
| type IntoIter = Iter<'a, T>; |
| |
| fn into_iter(self) -> Iter<'a, T> { |
| self.iter() |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a, T> IntoIterator for &'a mut LinkedList<T> { |
| type Item = &'a mut T; |
| type IntoIter = IterMut<'a, T>; |
| |
| fn into_iter(self) -> IterMut<'a, T> { |
| self.iter_mut() |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> Extend<T> for LinkedList<T> { |
| fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) { |
| <Self as SpecExtend<I>>::spec_extend(self, iter); |
| } |
| } |
| |
| impl<I: IntoIterator> SpecExtend<I> for LinkedList<I::Item> { |
| default fn spec_extend(&mut self, iter: I) { |
| iter.into_iter().for_each(move |elt| self.push_back(elt)); |
| } |
| } |
| |
| impl<T> SpecExtend<LinkedList<T>> for LinkedList<T> { |
| fn spec_extend(&mut self, ref mut other: LinkedList<T>) { |
| self.append(other); |
| } |
| } |
| |
| #[stable(feature = "extend_ref", since = "1.2.0")] |
| impl<'a, T: 'a + Copy> Extend<&'a T> for LinkedList<T> { |
| fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) { |
| self.extend(iter.into_iter().cloned()); |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: PartialEq> PartialEq for LinkedList<T> { |
| fn eq(&self, other: &Self) -> bool { |
| self.len() == other.len() && self.iter().eq(other) |
| } |
| |
| fn ne(&self, other: &Self) -> bool { |
| self.len() != other.len() || self.iter().ne(other) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: Eq> Eq for LinkedList<T> {} |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: PartialOrd> PartialOrd for LinkedList<T> { |
| fn partial_cmp(&self, other: &Self) -> Option<Ordering> { |
| self.iter().partial_cmp(other) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: Ord> Ord for LinkedList<T> { |
| #[inline] |
| fn cmp(&self, other: &Self) -> Ordering { |
| self.iter().cmp(other) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: Clone> Clone for LinkedList<T> { |
| fn clone(&self) -> Self { |
| self.iter().cloned().collect() |
| } |
| |
| fn clone_from(&mut self, other: &Self) { |
| let mut iter_other = other.iter(); |
| if self.len() > other.len() { |
| self.split_off(other.len()); |
| } |
| for (elem, elem_other) in self.iter_mut().zip(&mut iter_other) { |
| elem.clone_from(elem_other); |
| } |
| if !iter_other.is_empty() { |
| self.extend(iter_other.cloned()); |
| } |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: fmt::Debug> fmt::Debug for LinkedList<T> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_list().entries(self).finish() |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: Hash> Hash for LinkedList<T> { |
| fn hash<H: Hasher>(&self, state: &mut H) { |
| self.len().hash(state); |
| for elt in self { |
| elt.hash(state); |
| } |
| } |
| } |
| |
| // Ensure that `LinkedList` and its read-only iterators are covariant in their type parameters. |
| #[allow(dead_code)] |
| fn assert_covariance() { |
| fn a<'a>(x: LinkedList<&'static str>) -> LinkedList<&'a str> { |
| x |
| } |
| fn b<'i, 'a>(x: Iter<'i, &'static str>) -> Iter<'i, &'a str> { |
| x |
| } |
| fn c<'a>(x: IntoIter<&'static str>) -> IntoIter<&'a str> { |
| x |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| unsafe impl<T: Send> Send for LinkedList<T> {} |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| unsafe impl<T: Sync> Sync for LinkedList<T> {} |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| unsafe impl<T: Sync> Send for Iter<'_, T> {} |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| unsafe impl<T: Sync> Sync for Iter<'_, T> {} |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| unsafe impl<T: Send> Send for IterMut<'_, T> {} |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| unsafe impl<T: Sync> Sync for IterMut<'_, T> {} |
