Struct wplot::LinkedList
1.0.0 · source · [−]pub struct LinkedList<T> { /* private fields */ }Expand description
A doubly-linked list with owned nodes.
The LinkedList allows pushing and popping elements at either end
in constant time.
A LinkedList with a known list of items can be initialized from an array:
use std::collections::LinkedList;
let list = LinkedList::from([1, 2, 3]);NOTE: It is almost always better to use Vec or VecDeque because
array-based containers are generally faster,
more memory efficient, and make better use of CPU cache.
Implementations
sourceimpl<T> LinkedList<T>
impl<T> LinkedList<T>
const: 1.39.0 · sourcepub const fn new() -> LinkedList<T>
pub const fn new() -> LinkedList<T>
Creates an empty LinkedList.
Examples
use std::collections::LinkedList;
let list: LinkedList<u32> = LinkedList::new();sourcepub fn append(&mut self, other: &mut LinkedList<T>)
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());sourcepub fn iter(&self) -> Iter<'_, 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);sourcepub fn iter_mut(&mut self) -> IterMut<'_, 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);sourcepub fn cursor_front(&self) -> Cursor<'_, T>
🔬 This is a nightly-only experimental API. (linked_list_cursors)
pub fn cursor_front(&self) -> Cursor<'_, T>
linked_list_cursors)Provides a cursor at the front element.
The cursor is pointing to the “ghost” non-element if the list is empty.
sourcepub fn cursor_front_mut(&mut self) -> CursorMut<'_, T>
🔬 This is a nightly-only experimental API. (linked_list_cursors)
pub fn cursor_front_mut(&mut self) -> CursorMut<'_, T>
linked_list_cursors)Provides a cursor with editing operations at the front element.
The cursor is pointing to the “ghost” non-element if the list is empty.
sourcepub fn cursor_back(&self) -> Cursor<'_, T>
🔬 This is a nightly-only experimental API. (linked_list_cursors)
pub fn cursor_back(&self) -> Cursor<'_, T>
linked_list_cursors)Provides a cursor at the back element.
The cursor is pointing to the “ghost” non-element if the list is empty.
sourcepub fn cursor_back_mut(&mut self) -> CursorMut<'_, T>
🔬 This is a nightly-only experimental API. (linked_list_cursors)
pub fn cursor_back_mut(&mut self) -> CursorMut<'_, T>
linked_list_cursors)Provides a cursor with editing operations at the back element.
The cursor is pointing to the “ghost” non-element if the list is empty.
sourcepub fn is_empty(&self) -> bool
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());sourcepub fn len(&self) -> usize
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);sourcepub fn clear(&mut self)
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);1.12.0 · sourcepub fn contains(&self, x: &T) -> bool where
T: PartialEq<T>,
pub fn contains(&self, x: &T) -> bool where
T: PartialEq<T>,
Returns true if the LinkedList contains an element equal to the
given value.
This operation should compute linearly in O(n) time.
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);sourcepub fn front(&self) -> Option<&T>
pub fn front(&self) -> Option<&T>
Provides a reference to the front element, or None if the list is
empty.
This operation should compute in O(1) time.
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));sourcepub fn front_mut(&mut self) -> Option<&mut T>
pub fn front_mut(&mut self) -> Option<&mut T>
Provides a mutable reference to the front element, or None if the list
is empty.
This operation should compute in O(1) time.
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));sourcepub fn back(&self) -> Option<&T>
pub fn back(&self) -> Option<&T>
Provides a reference to the back element, or None if the list is
empty.
This operation should compute in O(1) time.
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));sourcepub fn back_mut(&mut self) -> Option<&mut T>
pub fn back_mut(&mut self) -> Option<&mut T>
Provides a mutable reference to the back element, or None if the list
is empty.
This operation should compute in O(1) time.
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));sourcepub fn push_front(&mut self, elt: T)
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);sourcepub fn pop_front(&mut self) -> Option<T>
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);sourcepub fn push_back(&mut self, elt: T)
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());sourcepub fn pop_back(&mut self) -> Option<T>
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));sourcepub fn split_off(&mut self, at: usize) -> LinkedList<T>
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 split = d.split_off(2);
assert_eq!(split.pop_front(), Some(1));
assert_eq!(split.pop_front(), None);sourcepub fn remove(&mut self, at: usize) -> T
🔬 This is a nightly-only experimental API. (linked_list_remove)
pub fn remove(&mut self, at: usize) -> T
linked_list_remove)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);sourcepub fn drain_filter<F>(&mut self, filter: F) -> DrainFilter<'_, T, F> where
F: for<'_> FnMut(&mut T) -> bool,
🔬 This is a nightly-only experimental API. (drain_filter)
pub fn drain_filter<F>(&mut self, filter: F) -> DrainFilter<'_, T, F> where
F: for<'_> FnMut(&mut T) -> bool,
drain_filter)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
sourceimpl<T> Clone for LinkedList<T> where
T: Clone,
impl<T> Clone for LinkedList<T> where
T: Clone,
sourcefn clone(&self) -> LinkedList<T>
fn clone(&self) -> LinkedList<T>
Returns a copy of the value. Read more
sourcefn clone_from(&mut self, other: &LinkedList<T>)
fn clone_from(&mut self, other: &LinkedList<T>)
Performs copy-assignment from source. Read more
sourceimpl<T> Debug for LinkedList<T> where
T: Debug,
impl<T> Debug for LinkedList<T> where
T: Debug,
sourceimpl<T> Default for LinkedList<T>
impl<T> Default for LinkedList<T>
sourcefn default() -> LinkedList<T>
fn default() -> LinkedList<T>
Creates an empty LinkedList<T>.
sourceimpl<T> Drop for LinkedList<T>
impl<T> Drop for LinkedList<T>
1.2.0 · sourceimpl<'a, T> Extend<&'a T> for LinkedList<T> where
T: 'a + Copy,
impl<'a, T> Extend<&'a T> for LinkedList<T> where
T: 'a + Copy,
sourcefn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = &'a T>,
fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = &'a T>,
Extends a collection with the contents of an iterator. Read more
sourcefn extend_one(&mut self, &'a T)
fn extend_one(&mut self, &'a T)
extend_one)Extends a collection with exactly one element.
sourcefn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one)Reserves capacity in a collection for the given number of additional elements. Read more
sourceimpl<T> Extend<T> for LinkedList<T>
impl<T> Extend<T> for LinkedList<T>
sourcefn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = T>,
fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = T>,
Extends a collection with the contents of an iterator. Read more
sourcefn extend_one(&mut self, elem: T)
fn extend_one(&mut self, elem: T)
extend_one)Extends a collection with exactly one element.
sourcefn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one)Reserves capacity in a collection for the given number of additional elements. Read more
1.56.0 · sourceimpl<T, const N: usize> From<[T; N]> for LinkedList<T>
impl<T, const N: usize> From<[T; N]> for LinkedList<T>
sourcefn from(arr: [T; N]) -> LinkedList<T>
fn from(arr: [T; N]) -> LinkedList<T>
Converts a [T; N] into a 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);sourceimpl<T> FromIterator<T> for LinkedList<T>
impl<T> FromIterator<T> for LinkedList<T>
sourcefn from_iter<I>(iter: I) -> LinkedList<T> where
I: IntoIterator<Item = T>,
fn from_iter<I>(iter: I) -> LinkedList<T> where
I: IntoIterator<Item = T>,
Creates a value from an iterator. Read more
sourceimpl<T> FromParallelIterator<T> for LinkedList<T> where
T: Send,
impl<T> FromParallelIterator<T> for LinkedList<T> where
T: Send,
Collects items from a parallel iterator into a freshly allocated linked list.
sourcefn from_par_iter<I>(par_iter: I) -> LinkedList<T> where
I: IntoParallelIterator<Item = T>,
fn from_par_iter<I>(par_iter: I) -> LinkedList<T> where
I: IntoParallelIterator<Item = T>,
Creates an instance of the collection from the parallel iterator par_iter. Read more
sourceimpl<T> Hash for LinkedList<T> where
T: Hash,
impl<T> Hash for LinkedList<T> where
T: Hash,
sourceimpl<T> IntoIterator for LinkedList<T>
impl<T> IntoIterator for LinkedList<T>
sourceimpl<'a, T> IntoIterator for &'a mut LinkedList<T>
impl<'a, T> IntoIterator for &'a mut LinkedList<T>
sourceimpl<'a, T> IntoIterator for &'a LinkedList<T>
impl<'a, T> IntoIterator for &'a LinkedList<T>
sourceimpl<'a, T> IntoParallelIterator for &'a LinkedList<T> where
T: Sync,
impl<'a, T> IntoParallelIterator for &'a LinkedList<T> where
T: Sync,
type Item = <&'a LinkedList<T> as IntoIterator>::Item
type Item = <&'a LinkedList<T> as IntoIterator>::Item
The type of item that the parallel iterator will produce.
sourcefn into_par_iter(self) -> <&'a LinkedList<T> as IntoParallelIterator>::Iter
fn into_par_iter(self) -> <&'a LinkedList<T> as IntoParallelIterator>::Iter
Converts self into a parallel iterator. Read more
sourceimpl<'a, T> IntoParallelIterator for &'a mut LinkedList<T> where
T: Send,
impl<'a, T> IntoParallelIterator for &'a mut LinkedList<T> where
T: Send,
type Item = <&'a mut LinkedList<T> as IntoIterator>::Item
type Item = <&'a mut LinkedList<T> as IntoIterator>::Item
The type of item that the parallel iterator will produce.
sourcefn into_par_iter(self) -> <&'a mut LinkedList<T> as IntoParallelIterator>::Iter
fn into_par_iter(self) -> <&'a mut LinkedList<T> as IntoParallelIterator>::Iter
Converts self into a parallel iterator. Read more
sourceimpl<T> IntoParallelIterator for LinkedList<T> where
T: Send,
impl<T> IntoParallelIterator for LinkedList<T> where
T: Send,
type Item = <LinkedList<T> as IntoIterator>::Item
type Item = <LinkedList<T> as IntoIterator>::Item
The type of item that the parallel iterator will produce.
sourcefn into_par_iter(self) -> <LinkedList<T> as IntoParallelIterator>::Iter
fn into_par_iter(self) -> <LinkedList<T> as IntoParallelIterator>::Iter
Converts self into a parallel iterator. Read more
sourceimpl<T> Ord for LinkedList<T> where
T: Ord,
impl<T> Ord for LinkedList<T> where
T: Ord,
sourceimpl<'a, T> ParallelExtend<&'a T> for LinkedList<T> where
T: 'a + Copy + Send + Sync,
impl<'a, T> ParallelExtend<&'a T> for LinkedList<T> where
T: 'a + Copy + Send + Sync,
Extends a linked list with copied items from a parallel iterator.
sourcefn par_extend<I>(&mut self, par_iter: I) where
I: IntoParallelIterator<Item = &'a T>,
fn par_extend<I>(&mut self, par_iter: I) where
I: IntoParallelIterator<Item = &'a T>,
Extends an instance of the collection with the elements drawn
from the parallel iterator par_iter. Read more
sourceimpl<T> ParallelExtend<T> for LinkedList<T> where
T: Send,
impl<T> ParallelExtend<T> for LinkedList<T> where
T: Send,
Extends a linked list with items from a parallel iterator.
sourcefn par_extend<I>(&mut self, par_iter: I) where
I: IntoParallelIterator<Item = T>,
fn par_extend<I>(&mut self, par_iter: I) where
I: IntoParallelIterator<Item = T>,
Extends an instance of the collection with the elements drawn
from the parallel iterator par_iter. Read more
sourceimpl<T> PartialEq<LinkedList<T>> for LinkedList<T> where
T: PartialEq<T>,
impl<T> PartialEq<LinkedList<T>> for LinkedList<T> where
T: PartialEq<T>,
sourcefn eq(&self, other: &LinkedList<T>) -> bool
fn eq(&self, other: &LinkedList<T>) -> bool
This method tests for self and other values to be equal, and is used
by ==. Read more
sourcefn ne(&self, other: &LinkedList<T>) -> bool
fn ne(&self, other: &LinkedList<T>) -> bool
This method tests for !=.
sourceimpl<T> PartialOrd<LinkedList<T>> for LinkedList<T> where
T: PartialOrd<T>,
impl<T> PartialOrd<LinkedList<T>> for LinkedList<T> where
T: PartialOrd<T>,
sourcefn partial_cmp(&self, other: &LinkedList<T>) -> Option<Ordering>
fn partial_cmp(&self, other: &LinkedList<T>) -> Option<Ordering>
This method returns an ordering between self and other values if one exists. Read more
sourcefn lt(&self, other: &Rhs) -> bool
fn lt(&self, other: &Rhs) -> bool
This method tests less than (for self and other) and is used by the < operator. Read more
sourcefn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
This method tests less than or equal to (for self and other) and is used by the <=
operator. Read more
impl<T> Eq for LinkedList<T> where
T: Eq,
impl<T> Send for LinkedList<T> where
T: Send,
impl<T> Sync for LinkedList<T> where
T: Sync,
Auto Trait Implementations
impl<T> RefUnwindSafe for LinkedList<T> where
T: RefUnwindSafe,
impl<T> Unpin for LinkedList<T>
impl<T> UnwindSafe for LinkedList<T> where
T: UnwindSafe + RefUnwindSafe,
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
impl<Target, Original> Into2<Target> for Original where
Target: From2<Original>,
impl<Target, Original> Into2<Target> for Original where
Target: From2<Original>,
fn into2(self) -> Target
fn into2(self) -> Target
Performs the conversion.
sourceimpl<'data, I> IntoParallelRefIterator<'data> for I where
I: 'data + ?Sized,
&'data I: IntoParallelIterator,
impl<'data, I> IntoParallelRefIterator<'data> for I where
I: 'data + ?Sized,
&'data I: IntoParallelIterator,
type Iter = <&'data I as IntoParallelIterator>::Iter
type Iter = <&'data I as IntoParallelIterator>::Iter
The type of the parallel iterator that will be returned.
type Item = <&'data I as IntoParallelIterator>::Item
type Item = <&'data I as IntoParallelIterator>::Item
The type of item that the parallel iterator will produce.
This will typically be an &'data T reference type. Read more
sourcefn par_iter(&'data self) -> <I as IntoParallelRefIterator<'data>>::Iter
fn par_iter(&'data self) -> <I as IntoParallelRefIterator<'data>>::Iter
Converts self into a parallel iterator. Read more
sourceimpl<'data, I> IntoParallelRefMutIterator<'data> for I where
I: 'data + ?Sized,
&'data mut I: IntoParallelIterator,
impl<'data, I> IntoParallelRefMutIterator<'data> for I where
I: 'data + ?Sized,
&'data mut I: IntoParallelIterator,
type Iter = <&'data mut I as IntoParallelIterator>::Iter
type Iter = <&'data mut I as IntoParallelIterator>::Iter
The type of iterator that will be created.
type Item = <&'data mut I as IntoParallelIterator>::Item
type Item = <&'data mut I as IntoParallelIterator>::Item
The type of item that will be produced; this is typically an
&'data mut T reference. Read more
sourcefn par_iter_mut(
&'data mut self
) -> <I as IntoParallelRefMutIterator<'data>>::Iter
fn par_iter_mut(
&'data mut self
) -> <I as IntoParallelRefMutIterator<'data>>::Iter
Creates the parallel iterator from self. Read more
impl<T> IntoResult<T> for T
impl<T> IntoResult<T> for T
type Err = Infallible
fn into_result(self) -> Result<T, <T as IntoResult<T>>::Err>
impl<T> Pointable for T
impl<T> Pointable for T
sourceimpl<R, P> ReadPrimitive<R> for P where
R: Read + ReadEndian<P>,
P: Default,
impl<R, P> ReadPrimitive<R> for P where
R: Read + ReadEndian<P>,
P: Default,
sourcefn read_from_little_endian(read: &mut R) -> Result<Self, Error>
fn read_from_little_endian(read: &mut R) -> Result<Self, Error>
Read this value from the supplied reader. Same as ReadEndian::read_from_little_endian().
sourcefn read_from_big_endian(read: &mut R) -> Result<Self, Error>
fn read_from_big_endian(read: &mut R) -> Result<Self, Error>
Read this value from the supplied reader. Same as ReadEndian::read_from_big_endian().
sourcefn read_from_native_endian(read: &mut R) -> Result<Self, Error>
fn read_from_native_endian(read: &mut R) -> Result<Self, Error>
Read this value from the supplied reader. Same as ReadEndian::read_from_native_endian().
sourceimpl<Target, Original> VectorizedInto<Target> for Original where
Target: VectorizedFrom<Original>,
impl<Target, Original> VectorizedInto<Target> for Original where
Target: VectorizedFrom<Original>,
sourcefn vectorized_into(self) -> Target
fn vectorized_into(self) -> Target
Performs the conversion.
