1967 lines
63 KiB
Rust
1967 lines
63 KiB
Rust
//! A doubly-linked list with owned nodes.
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//!
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//! The `LinkedList` allows pushing and popping elements at either end
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//! in constant time.
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//!
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//! NOTE: It is almost always better to use [`Vec`] or [`VecDeque`] because
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//! array-based containers are generally faster,
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//! more memory efficient, and make better use of CPU cache.
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//!
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//! [`Vec`]: crate::vec::Vec
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//! [`VecDeque`]: super::vec_deque::VecDeque
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#![stable(feature = "rust1", since = "1.0.0")]
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use core::cmp::Ordering;
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use core::fmt;
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use core::hash::{Hash, Hasher};
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use core::iter::{FromIterator, FusedIterator};
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use core::marker::PhantomData;
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use core::mem;
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use core::ptr::NonNull;
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use super::SpecExtend;
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use crate::boxed::Box;
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#[cfg(test)]
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mod tests;
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/// A doubly-linked list with owned nodes.
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///
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/// The `LinkedList` allows pushing and popping elements at either end
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/// in constant time.
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///
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/// A `LinkedList` with a known list of items can be initialized from an array:
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/// ```
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/// use std::collections::LinkedList;
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///
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/// let list = LinkedList::from([1, 2, 3]);
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/// ```
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///
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/// NOTE: It is almost always better to use `Vec` or `VecDeque` because
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/// array-based containers are generally faster,
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/// more memory efficient, and make better use of CPU cache.
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#[stable(feature = "rust1", since = "1.0.0")]
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#[cfg_attr(not(test), rustc_diagnostic_item = "LinkedList")]
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pub struct LinkedList<T> {
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head: Option<NonNull<Node<T>>>,
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tail: Option<NonNull<Node<T>>>,
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len: usize,
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marker: PhantomData<Box<Node<T>>>,
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}
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struct Node<T> {
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next: Option<NonNull<Node<T>>>,
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prev: Option<NonNull<Node<T>>>,
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element: T,
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}
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/// An iterator over the elements of a `LinkedList`.
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///
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/// This `struct` is created by [`LinkedList::iter()`]. See its
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/// documentation for more.
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct Iter<'a, T: 'a> {
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head: Option<NonNull<Node<T>>>,
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tail: Option<NonNull<Node<T>>>,
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len: usize,
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marker: PhantomData<&'a Node<T>>,
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}
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#[stable(feature = "collection_debug", since = "1.17.0")]
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impl<T: fmt::Debug> fmt::Debug for Iter<'_, T> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_tuple("Iter")
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.field(&*mem::ManuallyDrop::new(LinkedList {
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head: self.head,
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tail: self.tail,
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len: self.len,
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marker: PhantomData,
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}))
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.field(&self.len)
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.finish()
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}
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}
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// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<T> Clone for Iter<'_, T> {
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fn clone(&self) -> Self {
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Iter { ..*self }
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}
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}
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/// A mutable iterator over the elements of a `LinkedList`.
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///
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/// This `struct` is created by [`LinkedList::iter_mut()`]. See its
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/// documentation for more.
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct IterMut<'a, T: 'a> {
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head: Option<NonNull<Node<T>>>,
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tail: Option<NonNull<Node<T>>>,
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len: usize,
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marker: PhantomData<&'a mut Node<T>>,
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}
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#[stable(feature = "collection_debug", since = "1.17.0")]
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impl<T: fmt::Debug> fmt::Debug for IterMut<'_, T> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_tuple("IterMut")
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.field(&*mem::ManuallyDrop::new(LinkedList {
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head: self.head,
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tail: self.tail,
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len: self.len,
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marker: PhantomData,
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}))
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.field(&self.len)
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.finish()
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}
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}
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/// An owning iterator over the elements of a `LinkedList`.
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///
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/// This `struct` is created by the [`into_iter`] method on [`LinkedList`]
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/// (provided by the `IntoIterator` trait). See its documentation for more.
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///
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/// [`into_iter`]: LinkedList::into_iter
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#[derive(Clone)]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct IntoIter<T> {
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list: LinkedList<T>,
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}
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#[stable(feature = "collection_debug", since = "1.17.0")]
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impl<T: fmt::Debug> fmt::Debug for IntoIter<T> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_tuple("IntoIter").field(&self.list).finish()
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}
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}
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impl<T> Node<T> {
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fn new(element: T) -> Self {
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Node { next: None, prev: None, element }
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}
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fn into_element(self: Box<Self>) -> T {
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self.element
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}
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}
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// private methods
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impl<T> LinkedList<T> {
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/// Adds the given node to the front of the list.
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#[inline]
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fn push_front_node(&mut self, mut node: Box<Node<T>>) {
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// This method takes care not to create mutable references to whole nodes,
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// to maintain validity of aliasing pointers into `element`.
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unsafe {
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node.next = self.head;
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node.prev = None;
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let node = Some(Box::leak(node).into());
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match self.head {
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None => self.tail = node,
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// Not creating new mutable (unique!) references overlapping `element`.
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Some(head) => (*head.as_ptr()).prev = node,
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}
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self.head = node;
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self.len += 1;
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}
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}
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/// Removes and returns the node at the front of the list.
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#[inline]
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fn pop_front_node(&mut self) -> Option<Box<Node<T>>> {
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// This method takes care not to create mutable references to whole nodes,
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// to maintain validity of aliasing pointers into `element`.
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self.head.map(|node| unsafe {
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let node = Box::from_raw(node.as_ptr());
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self.head = node.next;
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match self.head {
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None => self.tail = None,
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// Not creating new mutable (unique!) references overlapping `element`.
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Some(head) => (*head.as_ptr()).prev = None,
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}
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self.len -= 1;
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node
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})
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}
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/// Adds the given node to the back of the list.
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#[inline]
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fn push_back_node(&mut self, mut node: Box<Node<T>>) {
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// This method takes care not to create mutable references to whole nodes,
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// to maintain validity of aliasing pointers into `element`.
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unsafe {
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node.next = None;
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node.prev = self.tail;
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let node = Some(Box::leak(node).into());
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match self.tail {
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None => self.head = node,
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// Not creating new mutable (unique!) references overlapping `element`.
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Some(tail) => (*tail.as_ptr()).next = node,
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}
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self.tail = node;
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self.len += 1;
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}
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}
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/// Removes and returns the node at the back of the list.
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#[inline]
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fn pop_back_node(&mut self) -> Option<Box<Node<T>>> {
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// This method takes care not to create mutable references to whole nodes,
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// to maintain validity of aliasing pointers into `element`.
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self.tail.map(|node| unsafe {
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let node = Box::from_raw(node.as_ptr());
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self.tail = node.prev;
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match self.tail {
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None => self.head = None,
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// Not creating new mutable (unique!) references overlapping `element`.
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Some(tail) => (*tail.as_ptr()).next = None,
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}
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self.len -= 1;
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node
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})
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}
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/// Unlinks the specified node from the current list.
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///
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/// Warning: this will not check that the provided node belongs to the current list.
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///
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/// This method takes care not to create mutable references to `element`, to
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/// maintain validity of aliasing pointers.
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#[inline]
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unsafe fn unlink_node(&mut self, mut node: NonNull<Node<T>>) {
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let node = unsafe { node.as_mut() }; // this one is ours now, we can create an &mut.
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// Not creating new mutable (unique!) references overlapping `element`.
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match node.prev {
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Some(prev) => unsafe { (*prev.as_ptr()).next = node.next },
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// this node is the head node
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None => self.head = node.next,
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};
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match node.next {
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Some(next) => unsafe { (*next.as_ptr()).prev = node.prev },
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// this node is the tail node
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None => self.tail = node.prev,
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};
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self.len -= 1;
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}
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/// Splices a series of nodes between two existing nodes.
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///
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/// Warning: this will not check that the provided node belongs to the two existing lists.
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#[inline]
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unsafe fn splice_nodes(
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&mut self,
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existing_prev: Option<NonNull<Node<T>>>,
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existing_next: Option<NonNull<Node<T>>>,
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mut splice_start: NonNull<Node<T>>,
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mut splice_end: NonNull<Node<T>>,
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splice_length: usize,
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) {
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// This method takes care not to create multiple mutable references to whole nodes at the same time,
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// to maintain validity of aliasing pointers into `element`.
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if let Some(mut existing_prev) = existing_prev {
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unsafe {
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existing_prev.as_mut().next = Some(splice_start);
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}
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} else {
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self.head = Some(splice_start);
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}
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if let Some(mut existing_next) = existing_next {
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unsafe {
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existing_next.as_mut().prev = Some(splice_end);
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}
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} else {
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self.tail = Some(splice_end);
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}
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unsafe {
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splice_start.as_mut().prev = existing_prev;
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splice_end.as_mut().next = existing_next;
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}
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self.len += splice_length;
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}
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/// Detaches all nodes from a linked list as a series of nodes.
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#[inline]
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fn detach_all_nodes(mut self) -> Option<(NonNull<Node<T>>, NonNull<Node<T>>, usize)> {
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let head = self.head.take();
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let tail = self.tail.take();
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let len = mem::replace(&mut self.len, 0);
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if let Some(head) = head {
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let tail = unsafe { tail.unwrap_unchecked() };
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Some((head, tail, len))
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} else {
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None
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}
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}
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#[inline]
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unsafe fn split_off_before_node(
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&mut self,
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split_node: Option<NonNull<Node<T>>>,
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at: usize,
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) -> Self {
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// The split node is the new head node of the second part
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if let Some(mut split_node) = split_node {
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let first_part_head;
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let first_part_tail;
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unsafe {
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first_part_tail = split_node.as_mut().prev.take();
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}
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if let Some(mut tail) = first_part_tail {
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unsafe {
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tail.as_mut().next = None;
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}
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first_part_head = self.head;
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} else {
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first_part_head = None;
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}
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let first_part = LinkedList {
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head: first_part_head,
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tail: first_part_tail,
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len: at,
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marker: PhantomData,
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};
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// Fix the head ptr of the second part
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self.head = Some(split_node);
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self.len = self.len - at;
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first_part
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} else {
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mem::replace(self, LinkedList::new())
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}
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}
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#[inline]
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unsafe fn split_off_after_node(
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&mut self,
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split_node: Option<NonNull<Node<T>>>,
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at: usize,
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) -> Self {
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// The split node is the new tail node of the first part and owns
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// the head of the second part.
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if let Some(mut split_node) = split_node {
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let second_part_head;
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let second_part_tail;
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unsafe {
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second_part_head = split_node.as_mut().next.take();
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}
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if let Some(mut head) = second_part_head {
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unsafe {
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head.as_mut().prev = None;
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}
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second_part_tail = self.tail;
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} else {
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second_part_tail = None;
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}
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let second_part = LinkedList {
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head: second_part_head,
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tail: second_part_tail,
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len: self.len - at,
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marker: PhantomData,
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};
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// Fix the tail ptr of the first part
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self.tail = Some(split_node);
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self.len = at;
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second_part
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} else {
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mem::replace(self, LinkedList::new())
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}
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<T> Default for LinkedList<T> {
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/// Creates an empty `LinkedList<T>`.
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#[inline]
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fn default() -> Self {
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Self::new()
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}
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}
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impl<T> LinkedList<T> {
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/// Creates an empty `LinkedList`.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::LinkedList;
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///
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/// let list: LinkedList<u32> = LinkedList::new();
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/// ```
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#[inline]
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#[rustc_const_stable(feature = "const_linked_list_new", since = "1.32.0")]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub const fn new() -> Self {
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LinkedList { head: None, tail: None, len: 0, marker: PhantomData }
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}
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/// Moves all elements from `other` to the end of the list.
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///
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/// This reuses all the nodes from `other` and moves them into `self`. After
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/// this operation, `other` becomes empty.
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///
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/// This operation should compute in *O*(1) time and *O*(1) memory.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::LinkedList;
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///
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/// let mut list1 = LinkedList::new();
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/// list1.push_back('a');
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///
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/// let mut list2 = LinkedList::new();
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/// list2.push_back('b');
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/// list2.push_back('c');
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///
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/// list1.append(&mut list2);
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///
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/// let mut iter = list1.iter();
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/// assert_eq!(iter.next(), Some(&'a'));
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/// assert_eq!(iter.next(), Some(&'b'));
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/// assert_eq!(iter.next(), Some(&'c'));
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/// assert!(iter.next().is_none());
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///
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/// assert!(list2.is_empty());
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn append(&mut self, other: &mut Self) {
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match self.tail {
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None => mem::swap(self, other),
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Some(mut tail) => {
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// `as_mut` is okay here because we have exclusive access to the entirety
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// of both lists.
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if let Some(mut other_head) = other.head.take() {
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unsafe {
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tail.as_mut().next = Some(other_head);
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other_head.as_mut().prev = Some(tail);
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}
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self.tail = other.tail.take();
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self.len += mem::replace(&mut other.len, 0);
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}
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}
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}
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}
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/// Provides a forward iterator.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::LinkedList;
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///
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/// let mut list: LinkedList<u32> = LinkedList::new();
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///
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/// list.push_back(0);
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/// list.push_back(1);
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/// list.push_back(2);
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///
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/// let mut iter = list.iter();
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/// assert_eq!(iter.next(), Some(&0));
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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(), None);
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/// ```
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#[inline]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn iter(&self) -> Iter<'_, T> {
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Iter { head: self.head, tail: self.tail, len: self.len, marker: PhantomData }
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}
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/// Provides a forward iterator with mutable references.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::LinkedList;
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///
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/// let mut list: LinkedList<u32> = LinkedList::new();
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///
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/// list.push_back(0);
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/// list.push_back(1);
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/// list.push_back(2);
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///
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/// for element in list.iter_mut() {
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/// *element += 10;
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/// }
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///
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/// let mut iter = list.iter();
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/// assert_eq!(iter.next(), Some(&10));
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/// assert_eq!(iter.next(), Some(&11));
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/// assert_eq!(iter.next(), Some(&12));
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/// assert_eq!(iter.next(), None);
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/// ```
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#[inline]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn iter_mut(&mut self) -> IterMut<'_, T> {
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IterMut { head: self.head, tail: self.tail, len: self.len, marker: PhantomData }
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}
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|
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/// Provides a cursor at the front element.
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///
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/// The cursor is pointing to the "ghost" non-element if the list is empty.
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#[inline]
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#[unstable(feature = "linked_list_cursors", issue = "58533")]
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pub fn cursor_front(&self) -> Cursor<'_, T> {
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Cursor { index: 0, current: self.head, list: self }
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}
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|
|
/// Provides a cursor with editing operations at the front element.
|
|
///
|
|
/// The cursor is pointing to the "ghost" non-element if the list is empty.
|
|
#[inline]
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn cursor_front_mut(&mut self) -> CursorMut<'_, T> {
|
|
CursorMut { index: 0, current: self.head, list: self }
|
|
}
|
|
|
|
/// Provides a cursor at the back element.
|
|
///
|
|
/// The cursor is pointing to the "ghost" non-element if the list is empty.
|
|
#[inline]
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn cursor_back(&self) -> Cursor<'_, T> {
|
|
Cursor { index: self.len.checked_sub(1).unwrap_or(0), current: self.tail, list: self }
|
|
}
|
|
|
|
/// Provides a cursor with editing operations at the back element.
|
|
///
|
|
/// The cursor is pointing to the "ghost" non-element if the list is empty.
|
|
#[inline]
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn cursor_back_mut(&mut self) -> CursorMut<'_, T> {
|
|
CursorMut { index: self.len.checked_sub(1).unwrap_or(0), current: self.tail, 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 split = d.split_off(2);
|
|
///
|
|
/// assert_eq!(split.pop_front(), Some(1));
|
|
/// assert_eq!(split.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
|
|
};
|
|
unsafe { self.split_off_after_node(split_node, at) }
|
|
}
|
|
|
|
/// Removes the element at the given index and returns it.
|
|
///
|
|
/// This operation should compute in *O*(*n*) time.
|
|
///
|
|
/// # Panics
|
|
/// Panics if at >= len
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// #![feature(linked_list_remove)]
|
|
/// use std::collections::LinkedList;
|
|
///
|
|
/// let mut d = LinkedList::new();
|
|
///
|
|
/// d.push_front(1);
|
|
/// d.push_front(2);
|
|
/// d.push_front(3);
|
|
///
|
|
/// assert_eq!(d.remove(1), 2);
|
|
/// assert_eq!(d.remove(0), 3);
|
|
/// assert_eq!(d.remove(0), 1);
|
|
/// ```
|
|
#[unstable(feature = "linked_list_remove", issue = "69210")]
|
|
pub fn remove(&mut self, at: usize) -> T {
|
|
let len = self.len();
|
|
assert!(at < len, "Cannot remove at an index outside of the list bounds");
|
|
|
|
// Below, we iterate towards the node at the given index, either from
|
|
// the start or the end, depending on which would be faster.
|
|
let offset_from_end = len - at - 1;
|
|
if at <= offset_from_end {
|
|
let mut cursor = self.cursor_front_mut();
|
|
for _ in 0..at {
|
|
cursor.move_next();
|
|
}
|
|
cursor.remove_current().unwrap()
|
|
} else {
|
|
let mut cursor = self.cursor_back_mut();
|
|
for _ in 0..offset_from_end {
|
|
cursor.move_prev();
|
|
}
|
|
cursor.remove_current().unwrap()
|
|
}
|
|
}
|
|
|
|
/// 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, pred: filter, idx: 0, 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 self.0.pop_front_node().is_some() {}
|
|
}
|
|
}
|
|
|
|
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> {}
|
|
|
|
/// A cursor over a `LinkedList`.
|
|
///
|
|
/// A `Cursor` is like an iterator, except that it can freely seek back-and-forth.
|
|
///
|
|
/// Cursors always rest between two elements in the list, and index in a logically circular way.
|
|
/// To accommodate this, there is a "ghost" non-element that yields `None` between the head and
|
|
/// tail of the list.
|
|
///
|
|
/// When created, cursors start at the front of the list, or the "ghost" non-element if the list is empty.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub struct Cursor<'a, T: 'a> {
|
|
index: usize,
|
|
current: Option<NonNull<Node<T>>>,
|
|
list: &'a LinkedList<T>,
|
|
}
|
|
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
impl<T> Clone for Cursor<'_, T> {
|
|
fn clone(&self) -> Self {
|
|
let Cursor { index, current, list } = *self;
|
|
Cursor { index, current, list }
|
|
}
|
|
}
|
|
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
impl<T: fmt::Debug> fmt::Debug for Cursor<'_, T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
f.debug_tuple("Cursor").field(&self.list).field(&self.index()).finish()
|
|
}
|
|
}
|
|
|
|
/// A cursor over a `LinkedList` with editing operations.
|
|
///
|
|
/// A `Cursor` is like an iterator, except that it can freely seek back-and-forth, and can
|
|
/// safely mutate the list during iteration. This is because the lifetime of its yielded
|
|
/// references is tied to its own lifetime, instead of just the underlying list. This means
|
|
/// cursors cannot yield multiple elements at once.
|
|
///
|
|
/// Cursors always rest between two elements in the list, and index in a logically circular way.
|
|
/// To accommodate this, there is a "ghost" non-element that yields `None` between the head and
|
|
/// tail of the list.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub struct CursorMut<'a, T: 'a> {
|
|
index: usize,
|
|
current: Option<NonNull<Node<T>>>,
|
|
list: &'a mut LinkedList<T>,
|
|
}
|
|
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
impl<T: fmt::Debug> fmt::Debug for CursorMut<'_, T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
f.debug_tuple("CursorMut").field(&self.list).field(&self.index()).finish()
|
|
}
|
|
}
|
|
|
|
impl<'a, T> Cursor<'a, T> {
|
|
/// Returns the cursor position index within the `LinkedList`.
|
|
///
|
|
/// This returns `None` if the cursor is currently pointing to the
|
|
/// "ghost" non-element.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn index(&self) -> Option<usize> {
|
|
let _ = self.current?;
|
|
Some(self.index)
|
|
}
|
|
|
|
/// Moves the cursor to the next element of the `LinkedList`.
|
|
///
|
|
/// If the cursor is pointing to the "ghost" non-element then this will move it to
|
|
/// the first element of the `LinkedList`. If it is pointing to the last
|
|
/// element of the `LinkedList` then this will move it to the "ghost" non-element.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn move_next(&mut self) {
|
|
match self.current.take() {
|
|
// We had no current element; the cursor was sitting at the start position
|
|
// Next element should be the head of the list
|
|
None => {
|
|
self.current = self.list.head;
|
|
self.index = 0;
|
|
}
|
|
// We had a previous element, so let's go to its next
|
|
Some(current) => unsafe {
|
|
self.current = current.as_ref().next;
|
|
self.index += 1;
|
|
},
|
|
}
|
|
}
|
|
|
|
/// Moves the cursor to the previous element of the `LinkedList`.
|
|
///
|
|
/// If the cursor is pointing to the "ghost" non-element then this will move it to
|
|
/// the last element of the `LinkedList`. If it is pointing to the first
|
|
/// element of the `LinkedList` then this will move it to the "ghost" non-element.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn move_prev(&mut self) {
|
|
match self.current.take() {
|
|
// No current. We're at the start of the list. Yield None and jump to the end.
|
|
None => {
|
|
self.current = self.list.tail;
|
|
self.index = self.list.len().checked_sub(1).unwrap_or(0);
|
|
}
|
|
// Have a prev. Yield it and go to the previous element.
|
|
Some(current) => unsafe {
|
|
self.current = current.as_ref().prev;
|
|
self.index = self.index.checked_sub(1).unwrap_or_else(|| self.list.len());
|
|
},
|
|
}
|
|
}
|
|
|
|
/// Returns a reference to the element that the cursor is currently
|
|
/// pointing to.
|
|
///
|
|
/// This returns `None` if the cursor is currently pointing to the
|
|
/// "ghost" non-element.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn current(&self) -> Option<&'a T> {
|
|
unsafe { self.current.map(|current| &(*current.as_ptr()).element) }
|
|
}
|
|
|
|
/// Returns a reference to the next element.
|
|
///
|
|
/// If the cursor is pointing to the "ghost" non-element then this returns
|
|
/// the first element of the `LinkedList`. If it is pointing to the last
|
|
/// element of the `LinkedList` then this returns `None`.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn peek_next(&self) -> Option<&'a T> {
|
|
unsafe {
|
|
let next = match self.current {
|
|
None => self.list.head,
|
|
Some(current) => current.as_ref().next,
|
|
};
|
|
next.map(|next| &(*next.as_ptr()).element)
|
|
}
|
|
}
|
|
|
|
/// Returns a reference to the previous element.
|
|
///
|
|
/// If the cursor is pointing to the "ghost" non-element then this returns
|
|
/// the last element of the `LinkedList`. If it is pointing to the first
|
|
/// element of the `LinkedList` then this returns `None`.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn peek_prev(&self) -> Option<&'a T> {
|
|
unsafe {
|
|
let prev = match self.current {
|
|
None => self.list.tail,
|
|
Some(current) => current.as_ref().prev,
|
|
};
|
|
prev.map(|prev| &(*prev.as_ptr()).element)
|
|
}
|
|
}
|
|
|
|
/// Provides a reference to the front element of the cursor's parent list,
|
|
/// or None if the list is empty.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn front(&self) -> Option<&'a T> {
|
|
self.list.front()
|
|
}
|
|
|
|
/// Provides a reference to the back element of the cursor's parent list,
|
|
/// or None if the list is empty.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn back(&self) -> Option<&'a T> {
|
|
self.list.back()
|
|
}
|
|
}
|
|
|
|
impl<'a, T> CursorMut<'a, T> {
|
|
/// Returns the cursor position index within the `LinkedList`.
|
|
///
|
|
/// This returns `None` if the cursor is currently pointing to the
|
|
/// "ghost" non-element.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn index(&self) -> Option<usize> {
|
|
let _ = self.current?;
|
|
Some(self.index)
|
|
}
|
|
|
|
/// Moves the cursor to the next element of the `LinkedList`.
|
|
///
|
|
/// If the cursor is pointing to the "ghost" non-element then this will move it to
|
|
/// the first element of the `LinkedList`. If it is pointing to the last
|
|
/// element of the `LinkedList` then this will move it to the "ghost" non-element.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn move_next(&mut self) {
|
|
match self.current.take() {
|
|
// We had no current element; the cursor was sitting at the start position
|
|
// Next element should be the head of the list
|
|
None => {
|
|
self.current = self.list.head;
|
|
self.index = 0;
|
|
}
|
|
// We had a previous element, so let's go to its next
|
|
Some(current) => unsafe {
|
|
self.current = current.as_ref().next;
|
|
self.index += 1;
|
|
},
|
|
}
|
|
}
|
|
|
|
/// Moves the cursor to the previous element of the `LinkedList`.
|
|
///
|
|
/// If the cursor is pointing to the "ghost" non-element then this will move it to
|
|
/// the last element of the `LinkedList`. If it is pointing to the first
|
|
/// element of the `LinkedList` then this will move it to the "ghost" non-element.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn move_prev(&mut self) {
|
|
match self.current.take() {
|
|
// No current. We're at the start of the list. Yield None and jump to the end.
|
|
None => {
|
|
self.current = self.list.tail;
|
|
self.index = self.list.len().checked_sub(1).unwrap_or(0);
|
|
}
|
|
// Have a prev. Yield it and go to the previous element.
|
|
Some(current) => unsafe {
|
|
self.current = current.as_ref().prev;
|
|
self.index = self.index.checked_sub(1).unwrap_or_else(|| self.list.len());
|
|
},
|
|
}
|
|
}
|
|
|
|
/// Returns a reference to the element that the cursor is currently
|
|
/// pointing to.
|
|
///
|
|
/// This returns `None` if the cursor is currently pointing to the
|
|
/// "ghost" non-element.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn current(&mut self) -> Option<&mut T> {
|
|
unsafe { self.current.map(|current| &mut (*current.as_ptr()).element) }
|
|
}
|
|
|
|
/// Returns a reference to the next element.
|
|
///
|
|
/// If the cursor is pointing to the "ghost" non-element then this returns
|
|
/// the first element of the `LinkedList`. If it is pointing to the last
|
|
/// element of the `LinkedList` then this returns `None`.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn peek_next(&mut self) -> Option<&mut T> {
|
|
unsafe {
|
|
let next = match self.current {
|
|
None => self.list.head,
|
|
Some(current) => current.as_ref().next,
|
|
};
|
|
next.map(|next| &mut (*next.as_ptr()).element)
|
|
}
|
|
}
|
|
|
|
/// Returns a reference to the previous element.
|
|
///
|
|
/// If the cursor is pointing to the "ghost" non-element then this returns
|
|
/// the last element of the `LinkedList`. If it is pointing to the first
|
|
/// element of the `LinkedList` then this returns `None`.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn peek_prev(&mut self) -> Option<&mut T> {
|
|
unsafe {
|
|
let prev = match self.current {
|
|
None => self.list.tail,
|
|
Some(current) => current.as_ref().prev,
|
|
};
|
|
prev.map(|prev| &mut (*prev.as_ptr()).element)
|
|
}
|
|
}
|
|
|
|
/// Returns a read-only cursor pointing to the current element.
|
|
///
|
|
/// The lifetime of the returned `Cursor` is bound to that of the
|
|
/// `CursorMut`, which means it cannot outlive the `CursorMut` and that the
|
|
/// `CursorMut` is frozen for the lifetime of the `Cursor`.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn as_cursor(&self) -> Cursor<'_, T> {
|
|
Cursor { list: self.list, current: self.current, index: self.index }
|
|
}
|
|
}
|
|
|
|
// Now the list editing operations
|
|
|
|
impl<'a, T> CursorMut<'a, T> {
|
|
/// Inserts a new element into the `LinkedList` after the current one.
|
|
///
|
|
/// If the cursor is pointing at the "ghost" non-element then the new element is
|
|
/// inserted at the front of the `LinkedList`.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn insert_after(&mut self, item: T) {
|
|
unsafe {
|
|
let spliced_node = Box::leak(Box::new(Node::new(item))).into();
|
|
let node_next = match self.current {
|
|
None => self.list.head,
|
|
Some(node) => node.as_ref().next,
|
|
};
|
|
self.list.splice_nodes(self.current, node_next, spliced_node, spliced_node, 1);
|
|
if self.current.is_none() {
|
|
// The "ghost" non-element's index has changed.
|
|
self.index = self.list.len;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Inserts a new element into the `LinkedList` before the current one.
|
|
///
|
|
/// If the cursor is pointing at the "ghost" non-element then the new element is
|
|
/// inserted at the end of the `LinkedList`.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn insert_before(&mut self, item: T) {
|
|
unsafe {
|
|
let spliced_node = Box::leak(Box::new(Node::new(item))).into();
|
|
let node_prev = match self.current {
|
|
None => self.list.tail,
|
|
Some(node) => node.as_ref().prev,
|
|
};
|
|
self.list.splice_nodes(node_prev, self.current, spliced_node, spliced_node, 1);
|
|
self.index += 1;
|
|
}
|
|
}
|
|
|
|
/// Removes the current element from the `LinkedList`.
|
|
///
|
|
/// The element that was removed is returned, and the cursor is
|
|
/// moved to point to the next element in the `LinkedList`.
|
|
///
|
|
/// If the cursor is currently pointing to the "ghost" non-element then no element
|
|
/// is removed and `None` is returned.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn remove_current(&mut self) -> Option<T> {
|
|
let unlinked_node = self.current?;
|
|
unsafe {
|
|
self.current = unlinked_node.as_ref().next;
|
|
self.list.unlink_node(unlinked_node);
|
|
let unlinked_node = Box::from_raw(unlinked_node.as_ptr());
|
|
Some(unlinked_node.element)
|
|
}
|
|
}
|
|
|
|
/// Removes the current element from the `LinkedList` without deallocating the list node.
|
|
///
|
|
/// The node that was removed is returned as a new `LinkedList` containing only this node.
|
|
/// The cursor is moved to point to the next element in the current `LinkedList`.
|
|
///
|
|
/// If the cursor is currently pointing to the "ghost" non-element then no element
|
|
/// is removed and `None` is returned.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn remove_current_as_list(&mut self) -> Option<LinkedList<T>> {
|
|
let mut unlinked_node = self.current?;
|
|
unsafe {
|
|
self.current = unlinked_node.as_ref().next;
|
|
self.list.unlink_node(unlinked_node);
|
|
|
|
unlinked_node.as_mut().prev = None;
|
|
unlinked_node.as_mut().next = None;
|
|
Some(LinkedList {
|
|
head: Some(unlinked_node),
|
|
tail: Some(unlinked_node),
|
|
len: 1,
|
|
marker: PhantomData,
|
|
})
|
|
}
|
|
}
|
|
|
|
/// Inserts the elements from the given `LinkedList` after the current one.
|
|
///
|
|
/// If the cursor is pointing at the "ghost" non-element then the new elements are
|
|
/// inserted at the start of the `LinkedList`.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn splice_after(&mut self, list: LinkedList<T>) {
|
|
unsafe {
|
|
let (splice_head, splice_tail, splice_len) = match list.detach_all_nodes() {
|
|
Some(parts) => parts,
|
|
_ => return,
|
|
};
|
|
let node_next = match self.current {
|
|
None => self.list.head,
|
|
Some(node) => node.as_ref().next,
|
|
};
|
|
self.list.splice_nodes(self.current, node_next, splice_head, splice_tail, splice_len);
|
|
if self.current.is_none() {
|
|
// The "ghost" non-element's index has changed.
|
|
self.index = self.list.len;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Inserts the elements from the given `LinkedList` before the current one.
|
|
///
|
|
/// If the cursor is pointing at the "ghost" non-element then the new elements are
|
|
/// inserted at the end of the `LinkedList`.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn splice_before(&mut self, list: LinkedList<T>) {
|
|
unsafe {
|
|
let (splice_head, splice_tail, splice_len) = match list.detach_all_nodes() {
|
|
Some(parts) => parts,
|
|
_ => return,
|
|
};
|
|
let node_prev = match self.current {
|
|
None => self.list.tail,
|
|
Some(node) => node.as_ref().prev,
|
|
};
|
|
self.list.splice_nodes(node_prev, self.current, splice_head, splice_tail, splice_len);
|
|
self.index += splice_len;
|
|
}
|
|
}
|
|
|
|
/// Splits the list into two after the current element. This will return a
|
|
/// new list consisting of everything after the cursor, with the original
|
|
/// list retaining everything before.
|
|
///
|
|
/// If the cursor is pointing at the "ghost" non-element then the entire contents
|
|
/// of the `LinkedList` are moved.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn split_after(&mut self) -> LinkedList<T> {
|
|
let split_off_idx = if self.index == self.list.len { 0 } else { self.index + 1 };
|
|
if self.index == self.list.len {
|
|
// The "ghost" non-element's index has changed to 0.
|
|
self.index = 0;
|
|
}
|
|
unsafe { self.list.split_off_after_node(self.current, split_off_idx) }
|
|
}
|
|
|
|
/// Splits the list into two before the current element. This will return a
|
|
/// new list consisting of everything before the cursor, with the original
|
|
/// list retaining everything after.
|
|
///
|
|
/// If the cursor is pointing at the "ghost" non-element then the entire contents
|
|
/// of the `LinkedList` are moved.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn split_before(&mut self) -> LinkedList<T> {
|
|
let split_off_idx = self.index;
|
|
self.index = 0;
|
|
unsafe { self.list.split_off_before_node(self.current, split_off_idx) }
|
|
}
|
|
|
|
/// Appends an element to the front of the cursor's parent list. The node
|
|
/// that the cursor points to is unchanged, even if it is the "ghost" node.
|
|
///
|
|
/// This operation should compute in O(1) time.
|
|
// `push_front` continues to point to "ghost" when it addes a node to mimic
|
|
// the behavior of `insert_before` on an empty list.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn push_front(&mut self, elt: T) {
|
|
// Safety: We know that `push_front` does not change the position in
|
|
// memory of other nodes. This ensures that `self.current` remains
|
|
// valid.
|
|
self.list.push_front(elt);
|
|
self.index += 1;
|
|
}
|
|
|
|
/// Appends an element to the back of the cursor's parent list. The node
|
|
/// that the cursor points to is unchanged, even if it is the "ghost" node.
|
|
///
|
|
/// This operation should compute in O(1) time.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn push_back(&mut self, elt: T) {
|
|
// Safety: We know that `push_back` does not change the position in
|
|
// memory of other nodes. This ensures that `self.current` remains
|
|
// valid.
|
|
self.list.push_back(elt);
|
|
if self.current().is_none() {
|
|
// The index of "ghost" is the length of the list, so we just need
|
|
// to increment self.index to reflect the new length of the list.
|
|
self.index += 1;
|
|
}
|
|
}
|
|
|
|
/// Removes the first element from the cursor's parent list and returns it,
|
|
/// or None if the list is empty. The element the cursor points to remains
|
|
/// unchanged, unless it was pointing to the front element. In that case, it
|
|
/// points to the new front element.
|
|
///
|
|
/// This operation should compute in O(1) time.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn pop_front(&mut self) -> Option<T> {
|
|
// We can't check if current is empty, we must check the list directly.
|
|
// It is possible for `self.current == None` and the list to be
|
|
// non-empty.
|
|
if self.list.is_empty() {
|
|
None
|
|
} else {
|
|
// We can't point to the node that we pop. Copying the behavior of
|
|
// `remove_current`, we move on the the next node in the sequence.
|
|
// If the list is of length 1 then we end pointing to the "ghost"
|
|
// node at index 0, which is expected.
|
|
if self.list.head == self.current {
|
|
self.move_next();
|
|
} else {
|
|
self.index -= 1;
|
|
}
|
|
self.list.pop_front()
|
|
}
|
|
}
|
|
|
|
/// Removes the last element from the cursor's parent list and returns it,
|
|
/// or None if the list is empty. The element the cursor points to remains
|
|
/// unchanged, unless it was pointing to the back element. In that case, it
|
|
/// points to the "ghost" element.
|
|
///
|
|
/// This operation should compute in O(1) time.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn pop_back(&mut self) -> Option<T> {
|
|
if self.list.is_empty() {
|
|
None
|
|
} else {
|
|
if self.list.tail == self.current {
|
|
// The index now reflects the length of the list. It was the
|
|
// length of the list minus 1, but now the list is 1 smaller. No
|
|
// change is needed for `index`.
|
|
self.current = None;
|
|
} else if self.current.is_none() {
|
|
self.index = self.list.len - 1;
|
|
}
|
|
self.list.pop_back()
|
|
}
|
|
}
|
|
|
|
/// Provides a reference to the front element of the cursor's parent list,
|
|
/// or None if the list is empty.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn front(&self) -> Option<&T> {
|
|
self.list.front()
|
|
}
|
|
|
|
/// Provides a mutable reference to the front element of the cursor's
|
|
/// parent list, or None if the list is empty.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn front_mut(&mut self) -> Option<&mut T> {
|
|
self.list.front_mut()
|
|
}
|
|
|
|
/// Provides a reference to the back element of the cursor's parent list,
|
|
/// or None if the list is empty.
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn back(&self) -> Option<&T> {
|
|
self.list.back()
|
|
}
|
|
|
|
/// Provides a mutable reference to back element of the cursor's parent
|
|
/// list, or `None` if the list is empty.
|
|
///
|
|
/// # Examples
|
|
/// Building and mutating a list with a cursor, then getting the back element:
|
|
/// ```
|
|
/// #![feature(linked_list_cursors)]
|
|
/// use std::collections::LinkedList;
|
|
/// let mut dl = LinkedList::new();
|
|
/// dl.push_front(3);
|
|
/// dl.push_front(2);
|
|
/// dl.push_front(1);
|
|
/// let mut cursor = dl.cursor_front_mut();
|
|
/// *cursor.current().unwrap() = 99;
|
|
/// *cursor.back_mut().unwrap() = 0;
|
|
/// let mut contents = dl.into_iter();
|
|
/// assert_eq!(contents.next(), Some(99));
|
|
/// assert_eq!(contents.next(), Some(2));
|
|
/// assert_eq!(contents.next(), Some(0));
|
|
/// assert_eq!(contents.next(), None);
|
|
/// ```
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
pub fn back_mut(&mut self) -> Option<&mut T> {
|
|
self.list.back_mut()
|
|
}
|
|
}
|
|
|
|
/// 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) {
|
|
struct DropGuard<'r, 'a, T, F>(&'r mut DrainFilter<'a, T, F>)
|
|
where
|
|
F: FnMut(&mut T) -> bool;
|
|
|
|
impl<'r, 'a, T, F> Drop for DropGuard<'r, 'a, T, F>
|
|
where
|
|
F: FnMut(&mut T) -> bool,
|
|
{
|
|
fn drop(&mut self) {
|
|
self.0.for_each(drop);
|
|
}
|
|
}
|
|
|
|
while let Some(item) = self.next() {
|
|
let guard = DropGuard(self);
|
|
drop(item);
|
|
mem::forget(guard);
|
|
}
|
|
}
|
|
}
|
|
|
|
#[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);
|
|
}
|
|
|
|
#[inline]
|
|
fn extend_one(&mut self, elem: T) {
|
|
self.push_back(elem);
|
|
}
|
|
}
|
|
|
|
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());
|
|
}
|
|
|
|
#[inline]
|
|
fn extend_one(&mut self, &elem: &'a T) {
|
|
self.push_back(elem);
|
|
}
|
|
}
|
|
|
|
#[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);
|
|
}
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "std_collections_from_array", since = "1.56.0")]
|
|
impl<T, const N: usize> From<[T; N]> for LinkedList<T> {
|
|
/// ```
|
|
/// use std::collections::LinkedList;
|
|
///
|
|
/// let list1 = LinkedList::from([1, 2, 3, 4]);
|
|
/// let list2: LinkedList<_> = [1, 2, 3, 4].into();
|
|
/// assert_eq!(list1, list2);
|
|
/// ```
|
|
fn from(arr: [T; N]) -> Self {
|
|
core::array::IntoIter::new(arr).collect()
|
|
}
|
|
}
|
|
|
|
// 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> {}
|
|
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
unsafe impl<T: Sync> Send for Cursor<'_, T> {}
|
|
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
unsafe impl<T: Sync> Sync for Cursor<'_, T> {}
|
|
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
unsafe impl<T: Send> Send for CursorMut<'_, T> {}
|
|
|
|
#[unstable(feature = "linked_list_cursors", issue = "58533")]
|
|
unsafe impl<T: Sync> Sync for CursorMut<'_, T> {}
|