Struct std::collections::LinkedList

pub struct LinkedList<T> { /* fields omitted */ }

A doubly-linked list with owned nodes.

The LinkedList allows pushing and popping elements at either end in constant time.

Almost always it is better to use Vec or VecDeque instead of LinkedList. In general, array-based containers are faster, more memory efficient and make better use of CPU cache.

Methods

impl<T> LinkedList<T>

pub fn new() -> LinkedList<T>

Creates an empty LinkedList.

Examples

use std::collections::LinkedList;

let list: LinkedList<u32> = LinkedList::new();

pub fn append(&mut self, other: &mut LinkedList<T>)

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());

Important traits for Iter<'a, T>

impl<'a, T> Iterator for Iter<'a, T> type Item = &'a T;

pub fn iter(&self) -> Iter<T>

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);

Important traits for IterMut<'a, T>

impl<'a, T> Iterator for IterMut<'a, T> type Item = &'a mut T;

pub fn iter_mut(&mut self) -> IterMut<T>

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);

pub fn is_empty(&self) -> bool

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());

pub fn len(&self) -> usize

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);

pub fn clear(&mut self)

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);

pub fn contains(&self, x: &T) -> bool where
    T: PartialEq<T>, 

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);

pub fn front(&self) -> Option<&T>

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));

pub fn front_mut(&mut self) -> Option<&mut T>

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));

pub fn back(&self) -> Option<&T>

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));

pub fn back_mut(&mut self) -> Option<&mut T>

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));

pub fn push_front(&mut self, elt: T)

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);

pub fn pop_front(&mut self) -> Option<T>

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);

pub fn push_back(&mut self, elt: T)

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());

pub fn pop_back(&mut self) -> Option<T>

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));

pub fn split_off(&mut self, at: usize) -> LinkedList<T>

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);

Important traits for DrainFilter<'_, T, F>

impl<'_, T, F> Iterator for DrainFilter<'_, T, F> where
    F: FnMut(&mut T) -> bool,  type Item = T;

pub fn drain_filter<F>(&mut self, filter: F) -> DrainFilter<T, F> where
    F: FnMut(&mut T) -> bool, 

🔬 This is a nightly-only experimental API. (drain_filter #43244)

recently added

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]);

Trait Implementations

impl<T> Eq for LinkedList<T> where
    T: Eq, 

impl<T> FromIterator<T> for LinkedList<T>

fn from_iter<I>(iter: I) -> LinkedList<T> where
    I: IntoIterator<Item = T>, 

Creates a value from an iterator.

impl<T> PartialOrd<LinkedList<T>> for LinkedList<T> where
    T: PartialOrd<T>, 

fn partial_cmp(&self, other: &LinkedList<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T> Drop for LinkedList<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T> PartialEq<LinkedList<T>> for LinkedList<T> where
    T: PartialEq<T>, 

fn eq(&self, other: &LinkedList<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &LinkedList<T>) -> bool

This method tests for !=.

impl<T> Ord for LinkedList<T> where
    T: Ord, 

fn cmp(&self, other: &LinkedList<T>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

🔬 This is a nightly-only experimental API. (clamp #44095)

Restrict a value to a certain interval.

impl<T> Send for LinkedList<T> where
    T: Send, 

impl<T> Hash for LinkedList<T> where
    T: Hash, 

fn hash<H>(&self, state: &mut H) where
    H: Hasher, 

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].

impl<T> Default for LinkedList<T>

fn default() -> LinkedList<T>

Creates an empty LinkedList<T>.

impl<T> Sync for LinkedList<T> where
    T: Sync, 

impl<T> Debug for LinkedList<T> where
    T: Debug, 

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.

impl<T> Clone for LinkedList<T> where
    T: Clone, 

fn clone(&self) -> LinkedList<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a, T> IntoIterator for &'a LinkedList<T>

type Item = &'a T

The type of the elements being iterated over.

type IntoIter = Iter<'a, T>

Which kind of iterator are we turning this into?

Important traits for Iter<'a, T>

impl<'a, T> Iterator for Iter<'a, T> type Item = &'a T;

fn into_iter(self) -> Iter<'a, T>

Creates an iterator from a value.

impl<'a, T> IntoIterator for &'a mut LinkedList<T>

type Item = &'a mut T

The type of the elements being iterated over.

type IntoIter = IterMut<'a, T>

Which kind of iterator are we turning this into?

Important traits for IterMut<'a, T>

impl<'a, T> Iterator for IterMut<'a, T> type Item = &'a mut T;

fn into_iter(self) -> IterMut<'a, T>

Creates an iterator from a value.

impl<T> IntoIterator for LinkedList<T>

type Item = T

The type of the elements being iterated over.

type IntoIter = IntoIter<T>

Which kind of iterator are we turning this into?

Important traits for IntoIter<T>

impl<T> Iterator for IntoIter<T> type Item = T;

fn into_iter(self) -> IntoIter<T>

Consumes the list into an iterator yielding elements by value.

impl<'a, T> Extend<&'a T> for LinkedList<T> where
    T: 'a + Copy, 

fn extend<I>(&mut self, iter: I) where
    I: IntoIterator<Item = &'a T>, 

Extends a collection with the contents of an iterator.

impl<T> Extend<T> for LinkedList<T>

fn extend<I>(&mut self, iter: I) where
    I: IntoIterator<Item = T>, 

Extends a collection with the contents of an iterator.