Struct collections::vec::Vec
[−]
[src]
pub struct Vec<T> {
// some fields omitted
}A growable list type, written Vec<T> but pronounced 'vector.'
Examples
#![feature(collections)] extern crate collections; fn main() { let mut vec = Vec::new(); vec.push(1); vec.push(2); assert_eq!(vec.len(), 2); assert_eq!(vec[0], 1); assert_eq!(vec.pop(), Some(2)); assert_eq!(vec.len(), 1); vec[0] = 7; assert_eq!(vec[0], 7); vec.push_all(&[1, 2, 3]); for x in vec.iter() { println!("{}", x); } assert_eq!(vec, [7, 1, 2, 3]); }let mut vec = Vec::new(); vec.push(1); vec.push(2); assert_eq!(vec.len(), 2); assert_eq!(vec[0], 1); assert_eq!(vec.pop(), Some(2)); assert_eq!(vec.len(), 1); vec[0] = 7; assert_eq!(vec[0], 7); vec.push_all(&[1, 2, 3]); for x in vec.iter() { println!("{}", x); } assert_eq!(vec, [7, 1, 2, 3]);
The vec! macro is provided to make initialization more convenient:
let mut vec = vec![1, 2, 3]; vec.push(4); assert_eq!(vec, [1, 2, 3, 4]);
Use a Vec<T> as an efficient stack:
let mut stack = Vec::new(); stack.push(1); stack.push(2); stack.push(3); while let Some(top) = stack.pop() { // Prints 3, 2, 1 println!("{}", top); }
Capacity and reallocation
The capacity of a vector is the amount of space allocated for any future elements that will be added onto the vector. This is not to be confused with the length of a vector, which specifies the number of actual elements within the vector. If a vector's length exceeds its capacity, its capacity will automatically be increased, but its elements will have to be reallocated.
For example, a vector with capacity 10 and length 0 would be an empty vector
with space for 10 more elements. Pushing 10 or fewer elements onto the
vector will not change its capacity or cause reallocation to occur. However,
if the vector's length is increased to 11, it will have to reallocate, which
can be slow. For this reason, it is recommended to use Vec::with_capacity
whenever possible to specify how big the vector is expected to get.
Methods
impl<T> Vec<T>
fn new() -> Vec<T>
Constructs a new, empty Vec<T>.
The vector will not allocate until elements are pushed onto it.
Examples
fn main() { let mut vec: Vec<i32> = Vec::new(); }let mut vec: Vec<i32> = Vec::new();
fn with_capacity(capacity: usize) -> Vec<T>
Constructs a new, empty Vec<T> with the specified capacity.
The vector will be able to hold exactly capacity elements without reallocating. If
capacity is 0, the vector will not allocate.
It is important to note that this function does not specify the length of the returned
vector, but only the capacity. (For an explanation of the difference between length and
capacity, see the main Vec<T> docs above, 'Capacity and reallocation'.)
Examples
fn main() { let mut vec = Vec::with_capacity(10); // The vector contains no items, even though it has capacity for more assert_eq!(vec.len(), 0); // These are all done without reallocating... for i in 0..10 { vec.push(i); } // ...but this may make the vector reallocate vec.push(11); }let mut vec = Vec::with_capacity(10); // The vector contains no items, even though it has capacity for more assert_eq!(vec.len(), 0); // These are all done without reallocating... for i in 0..10 { vec.push(i); } // ...but this may make the vector reallocate vec.push(11);
unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Vec<T>
Creates a Vec<T> directly from the raw components of another vector.
This is highly unsafe, due to the number of invariants that aren't checked.
Examples
use std::ptr; use std::mem; fn main() { let mut v = vec![1, 2, 3]; // Pull out the various important pieces of information about `v` let p = v.as_mut_ptr(); let len = v.len(); let cap = v.capacity(); unsafe { // Cast `v` into the void: no destructor run, so we are in // complete control of the allocation to which `p` points. mem::forget(v); // Overwrite memory with 4, 5, 6 for i in 0..len as isize { ptr::write(p.offset(i), 4 + i); } // Put everything back together into a Vec let rebuilt = Vec::from_raw_parts(p, len, cap); assert_eq!(rebuilt, [4, 5, 6]); } }use std::ptr; use std::mem; fn main() { let mut v = vec![1, 2, 3]; // Pull out the various important pieces of information about `v` let p = v.as_mut_ptr(); let len = v.len(); let cap = v.capacity(); unsafe { // Cast `v` into the void: no destructor run, so we are in // complete control of the allocation to which `p` points. mem::forget(v); // Overwrite memory with 4, 5, 6 for i in 0..len as isize { ptr::write(p.offset(i), 4 + i); } // Put everything back together into a Vec let rebuilt = Vec::from_raw_parts(p, len, cap); assert_eq!(rebuilt, [4, 5, 6]); } }
unsafe fn from_raw_buf(ptr: *const T, elts: usize) -> Vec<T>
: may be better expressed via composition
Creates a vector by copying the elements from a raw pointer.
This function will copy elts contiguous elements starting at ptr
into a new allocation owned by the returned Vec<T>. The elements of
the buffer are copied into the vector without cloning, as if
ptr::read() were called on them.
fn capacity(&self) -> usize
Returns the number of elements the vector can hold without reallocating.
Examples
fn main() { let vec: Vec<i32> = Vec::with_capacity(10); assert_eq!(vec.capacity(), 10); }let vec: Vec<i32> = Vec::with_capacity(10); assert_eq!(vec.capacity(), 10);
fn reserve(&mut self, additional: usize)
Reserves capacity for at least additional more elements to be inserted
in the given Vec<T>. The collection may reserve more space to avoid
frequent reallocations.
Panics
Panics if the new capacity overflows usize.
Examples
fn main() { let mut vec = vec![1]; vec.reserve(10); assert!(vec.capacity() >= 11); }let mut vec = vec![1]; vec.reserve(10); assert!(vec.capacity() >= 11);
fn reserve_exact(&mut self, additional: usize)
Reserves the minimum capacity for exactly additional more elements to
be inserted in the given Vec<T>. Does nothing if the capacity is already
sufficient.
Note that the allocator may give the collection more space than it
requests. Therefore capacity can not be relied upon to be precisely
minimal. Prefer reserve if future insertions are expected.
Panics
Panics if the new capacity overflows usize.
Examples
fn main() { let mut vec = vec![1]; vec.reserve_exact(10); assert!(vec.capacity() >= 11); }let mut vec = vec![1]; vec.reserve_exact(10); assert!(vec.capacity() >= 11);
fn shrink_to_fit(&mut self)
Shrinks the capacity of the vector as much as possible.
It will drop down as close as possible to the length but the allocator may still inform the vector that there is space for a few more elements.
Examples
#![feature(collections)] extern crate collections; fn main() { let mut vec = Vec::with_capacity(10); vec.push_all(&[1, 2, 3]); assert_eq!(vec.capacity(), 10); vec.shrink_to_fit(); assert!(vec.capacity() >= 3); }let mut vec = Vec::with_capacity(10); vec.push_all(&[1, 2, 3]); assert_eq!(vec.capacity(), 10); vec.shrink_to_fit(); assert!(vec.capacity() >= 3);
fn into_boxed_slice(self) -> Box<[T]>
Converts the vector into Box<[T]>.
Note that this will drop any excess capacity. Calling this and
converting back to a vector with into_vec() is equivalent to calling
shrink_to_fit().
fn truncate(&mut self, len: usize)
Shorten a vector, dropping excess elements.
If len is greater than the vector's current length, this has no
effect.
Examples
#![feature(collections)] extern crate collections; fn main() { let mut vec = vec![1, 2, 3, 4]; vec.truncate(2); assert_eq!(vec, [1, 2]); }let mut vec = vec![1, 2, 3, 4]; vec.truncate(2); assert_eq!(vec, [1, 2]);
fn as_slice(&self) -> &[T]
: waiting on RFC revision
Extracts a slice containing the entire vector.
fn as_mut_slice(&mut self) -> &mut [T]
: waiting on RFC revision
Deprecated: use &mut s[..] instead.
unsafe fn set_len(&mut self, len: usize)
Sets the length of a vector.
This will explicitly set the size of the vector, without actually modifying its buffers, so it is up to the caller to ensure that the vector is actually the specified size.
Examples
fn main() { let mut v = vec![1, 2, 3, 4]; unsafe { v.set_len(1); } }let mut v = vec![1, 2, 3, 4]; unsafe { v.set_len(1); }
fn swap_remove(&mut self, index: usize) -> T
Removes an element from anywhere in the vector and return it, replacing it with the last element.
This does not preserve ordering, but is O(1).
Panics
Panics if index is out of bounds.
Examples
fn main() { let mut v = vec!["foo", "bar", "baz", "qux"]; assert_eq!(v.swap_remove(1), "bar"); assert_eq!(v, ["foo", "qux", "baz"]); assert_eq!(v.swap_remove(0), "foo"); assert_eq!(v, ["baz", "qux"]); }let mut v = vec!["foo", "bar", "baz", "qux"]; assert_eq!(v.swap_remove(1), "bar"); assert_eq!(v, ["foo", "qux", "baz"]); assert_eq!(v.swap_remove(0), "foo"); assert_eq!(v, ["baz", "qux"]);
fn insert(&mut self, index: usize, element: T)
Inserts an element at position index within the vector, shifting all
elements after position i one position to the right.
Panics
Panics if index is greater than the vector's length.
Examples
fn main() { let mut vec = vec![1, 2, 3]; vec.insert(1, 4); assert_eq!(vec, [1, 4, 2, 3]); vec.insert(4, 5); assert_eq!(vec, [1, 4, 2, 3, 5]); }let mut vec = vec![1, 2, 3]; vec.insert(1, 4); assert_eq!(vec, [1, 4, 2, 3]); vec.insert(4, 5); assert_eq!(vec, [1, 4, 2, 3, 5]);
fn remove(&mut self, index: usize) -> T
Removes and returns the element at position index within the vector,
shifting all elements after position index one position to the left.
Panics
Panics if index is out of bounds.
Examples
#![feature(collections)] extern crate collections; fn main() { let mut v = vec![1, 2, 3]; assert_eq!(v.remove(1), 2); assert_eq!(v, [1, 3]); }let mut v = vec![1, 2, 3]; assert_eq!(v.remove(1), 2); assert_eq!(v, [1, 3]);
fn retain<F>(&mut self, f: F) where F: FnMut(&T) -> bool
Retains only the elements specified by the predicate.
In other words, remove all elements e such that f(&e) returns false.
This method operates in place and preserves the order of the retained
elements.
Examples
fn main() { let mut vec = vec![1, 2, 3, 4]; vec.retain(|&x| x%2 == 0); assert_eq!(vec, [2, 4]); }let mut vec = vec![1, 2, 3, 4]; vec.retain(|&x| x%2 == 0); assert_eq!(vec, [2, 4]);
fn push(&mut self, value: T)
Appends an element to the back of a collection.
Panics
Panics if the number of elements in the vector overflows a usize.
Examples
fn main() { let mut vec = vec!(1, 2); vec.push(3); assert_eq!(vec, [1, 2, 3]); }let mut vec = vec!(1, 2); vec.push(3); assert_eq!(vec, [1, 2, 3]);
fn pop(&mut self) -> Option<T>
Removes the last element from a vector and returns it, or None if it is empty.
Examples
fn main() { let mut vec = vec![1, 2, 3]; assert_eq!(vec.pop(), Some(3)); assert_eq!(vec, [1, 2]); }let mut vec = vec![1, 2, 3]; assert_eq!(vec.pop(), Some(3)); assert_eq!(vec, [1, 2]);
fn append(&mut self, other: &mut Self)
: new API, waiting for dust to settle
Moves all the elements of other into Self, leaving other empty.
Panics
Panics if the number of elements in the vector overflows a usize.
Examples
#![feature(collections)] extern crate collections; fn main() { let mut vec = vec![1, 2, 3]; let mut vec2 = vec![4, 5, 6]; vec.append(&mut vec2); assert_eq!(vec, [1, 2, 3, 4, 5, 6]); assert_eq!(vec2, []); }let mut vec = vec![1, 2, 3]; let mut vec2 = vec![4, 5, 6]; vec.append(&mut vec2); assert_eq!(vec, [1, 2, 3, 4, 5, 6]); assert_eq!(vec2, []);
fn drain<R>(&mut self, range: R) -> Drain<T> where R: RangeArgument<usize>
: recently added, matches RFC
Create a draining iterator that removes the specified range in the vector and yields the removed items from start to end. The element range is removed even if the iterator is not consumed until the end.
Note: It is unspecified how many elements are removed from the vector,
if the Drain value is leaked.
Panics
Panics if the starting point is greater than the end point or if the end point is greater than the length of the vector.
Examples
#![feature(collections_drain, collections_range)] extern crate collections; fn main() { // Draining using `..` clears the whole vector. let mut v = vec![1, 2, 3]; let u: Vec<_> = v.drain(..).collect(); assert_eq!(v, &[]); assert_eq!(u, &[1, 2, 3]); }// Draining using `..` clears the whole vector. let mut v = vec![1, 2, 3]; let u: Vec<_> = v.drain(..).collect(); assert_eq!(v, &[]); assert_eq!(u, &[1, 2, 3]);
fn clear(&mut self)
Clears the vector, removing all values.
Examples
fn main() { let mut v = vec![1, 2, 3]; v.clear(); assert!(v.is_empty()); }let mut v = vec![1, 2, 3]; v.clear(); assert!(v.is_empty());
fn len(&self) -> usize
Returns the number of elements in the vector.
Examples
fn main() { let a = vec![1, 2, 3]; assert_eq!(a.len(), 3); }let a = vec![1, 2, 3]; assert_eq!(a.len(), 3);
fn is_empty(&self) -> bool
Returns true if the vector contains no elements.
Examples
fn main() { let mut v = Vec::new(); assert!(v.is_empty()); v.push(1); assert!(!v.is_empty()); }let mut v = Vec::new(); assert!(v.is_empty()); v.push(1); assert!(!v.is_empty());
fn map_in_place<U, F>(self, f: F) -> Vec<U> where F: FnMut(T) -> U
: API may change to provide stronger guarantees
Converts a Vec<T> to a Vec<U> where T and U have the same
size and in case they are not zero-sized the same minimal alignment.
Panics
Panics if T and U have differing sizes or are not zero-sized and
have differing minimal alignments.
Examples
#![feature(collections, core)] extern crate collections; fn main() { let v = vec![0, 1, 2]; let w = v.map_in_place(|i| i + 3); assert_eq!(&w[..], &[3, 4, 5]); #[derive(PartialEq, Debug)] struct Newtype(u8); let bytes = vec![0x11, 0x22]; let newtyped_bytes = bytes.map_in_place(|x| Newtype(x)); assert_eq!(&newtyped_bytes[..], &[Newtype(0x11), Newtype(0x22)]); }let v = vec![0, 1, 2]; let w = v.map_in_place(|i| i + 3); assert_eq!(&w[..], &[3, 4, 5]); #[derive(PartialEq, Debug)] struct Newtype(u8); let bytes = vec![0x11, 0x22]; let newtyped_bytes = bytes.map_in_place(|x| Newtype(x)); assert_eq!(&newtyped_bytes[..], &[Newtype(0x11), Newtype(0x22)]);
fn split_off(&mut self, at: usize) -> Self
: new API, waiting for dust to settle
Splits the collection into two at the given index.
Returns a newly allocated Self. self contains elements [0, at),
and the returned Self contains elements [at, len).
Note that the capacity of self does not change.
Panics
Panics if at > len.
Examples
#![feature(collections)] extern crate collections; fn main() { let mut vec = vec![1,2,3]; let vec2 = vec.split_off(1); assert_eq!(vec, [1]); assert_eq!(vec2, [2, 3]); }let mut vec = vec![1,2,3]; let vec2 = vec.split_off(1); assert_eq!(vec, [1]); assert_eq!(vec2, [2, 3]);
impl<T: Clone> Vec<T>
fn resize(&mut self, new_len: usize, value: T)
: matches collection reform specification; waiting for dust to settle
Resizes the Vec in-place so that len() is equal to new_len.
Calls either extend() or truncate() depending on whether new_len
is larger than the current value of len() or not.
Examples
#![feature(collections)] extern crate collections; fn main() { let mut vec = vec!["hello"]; vec.resize(3, "world"); assert_eq!(vec, ["hello", "world", "world"]); let mut vec = vec![1, 2, 3, 4]; vec.resize(2, 0); assert_eq!(vec, [1, 2]); }let mut vec = vec!["hello"]; vec.resize(3, "world"); assert_eq!(vec, ["hello", "world", "world"]); let mut vec = vec![1, 2, 3, 4]; vec.resize(2, 0); assert_eq!(vec, [1, 2]);
fn push_all(&mut self, other: &[T])
: likely to be replaced by a more optimized extend
Appends all elements in a slice to the Vec.
Iterates over the slice other, clones each element, and then appends
it to this Vec. The other vector is traversed in-order.
Examples
#![feature(collections)] extern crate collections; fn main() { let mut vec = vec![1]; vec.push_all(&[2, 3, 4]); assert_eq!(vec, [1, 2, 3, 4]); }let mut vec = vec![1]; vec.push_all(&[2, 3, 4]); assert_eq!(vec, [1, 2, 3, 4]);
impl<T: PartialEq> Vec<T>
fn dedup(&mut self)
Removes consecutive repeated elements in the vector.
If the vector is sorted, this removes all duplicates.
Examples
fn main() { let mut vec = vec![1, 2, 2, 3, 2]; vec.dedup(); assert_eq!(vec, [1, 2, 3, 2]); }let mut vec = vec![1, 2, 2, 3, 2]; vec.dedup(); assert_eq!(vec, [1, 2, 3, 2]);
Methods from Deref<Target=[T]>
fn sort_by<F>(&mut self, compare: F) where F: FnMut(&T, &T) -> Ordering
Sorts the slice, in place, using compare to compare
elements.
This sort is O(n log n) worst-case and stable, but allocates
approximately 2 * n, where n is the length of self.
Examples
fn main() { let mut v = [5, 4, 1, 3, 2]; v.sort_by(|a, b| a.cmp(b)); assert!(v == [1, 2, 3, 4, 5]); // reverse sorting v.sort_by(|a, b| b.cmp(a)); assert!(v == [5, 4, 3, 2, 1]); }let mut v = [5, 4, 1, 3, 2]; v.sort_by(|a, b| a.cmp(b)); assert!(v == [1, 2, 3, 4, 5]); // reverse sorting v.sort_by(|a, b| b.cmp(a)); assert!(v == [5, 4, 3, 2, 1]);
fn move_from(&mut self, src: Vec<T>, start: usize, end: usize) -> usize
: uncertain about this API approach
Consumes src and moves as many elements as it can into self
from the range [start,end).
Returns the number of elements copied (the shorter of self.len()
and end - start).
Arguments
- src - A mutable vector of
T - start - The index into
srcto start copying from - end - The index into
srcto stop copying from
Examples
#![feature(collections)] extern crate collections; fn main() { let mut a = [1, 2, 3, 4, 5]; let b = vec![6, 7, 8]; let num_moved = a.move_from(b, 0, 3); assert_eq!(num_moved, 3); assert!(a == [6, 7, 8, 4, 5]); }let mut a = [1, 2, 3, 4, 5]; let b = vec![6, 7, 8]; let num_moved = a.move_from(b, 0, 3); assert_eq!(num_moved, 3); assert!(a == [6, 7, 8, 4, 5]);
fn split_at(&self, mid: usize) -> (&[T], &[T])
Divides one slice into two at an index.
The first will contain all indices from [0, mid) (excluding
the index mid itself) and the second will contain all
indices from [mid, len) (excluding the index len itself).
Panics if mid > len.
Examples
fn main() { let v = [10, 40, 30, 20, 50]; let (v1, v2) = v.split_at(2); assert_eq!([10, 40], v1); assert_eq!([30, 20, 50], v2); }let v = [10, 40, 30, 20, 50]; let (v1, v2) = v.split_at(2); assert_eq!([10, 40], v1); assert_eq!([30, 20, 50], v2);
fn iter(&self) -> Iter<T>
Returns an iterator over the slice.
fn split<F>(&self, pred: F) -> Split<T, F> where F: FnMut(&T) -> bool
Returns an iterator over subslices separated by elements that match
pred. The matched element is not contained in the subslices.
Examples
Print the slice split by numbers divisible by 3 (i.e. [10, 40],
[20], [50]):
let v = [10, 40, 30, 20, 60, 50]; for group in v.split(|num| *num % 3 == 0) { println!("{:?}", group); }
fn splitn<F>(&self, n: usize, pred: F) -> SplitN<T, F> where F: FnMut(&T) -> bool
Returns an iterator over subslices separated by elements that match
pred, limited to returning at most n items. The matched element is
not contained in the subslices.
The last element returned, if any, will contain the remainder of the slice.
Examples
Print the slice split once by numbers divisible by 3 (i.e. [10, 40],
[20, 60, 50]):
let v = [10, 40, 30, 20, 60, 50]; for group in v.splitn(2, |num| *num % 3 == 0) { println!("{:?}", group); }
fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<T, F> where F: FnMut(&T) -> bool
Returns an iterator over subslices separated by elements that match
pred limited to returning at most n items. This starts at the end of
the slice and works backwards. The matched element is not contained in
the subslices.
The last element returned, if any, will contain the remainder of the slice.
Examples
Print the slice split once, starting from the end, by numbers divisible
by 3 (i.e. [50], [10, 40, 30, 20]):
let v = [10, 40, 30, 20, 60, 50]; for group in v.rsplitn(2, |num| *num % 3 == 0) { println!("{:?}", group); }
fn windows(&self, size: usize) -> Windows<T>
Returns an iterator over all contiguous windows of length
size. The windows overlap. If the slice is shorter than
size, the iterator returns no values.
Panics
Panics if size is 0.
Example
Print the adjacent pairs of a slice (i.e. [1,2], [2,3],
[3,4]):
let v = &[1, 2, 3, 4]; for win in v.windows(2) { println!("{:?}", win); }
fn chunks(&self, size: usize) -> Chunks<T>
Returns an iterator over size elements of the slice at a
time. The chunks do not overlap. If size does not divide the
length of the slice, then the last chunk will not have length
size.
Panics
Panics if size is 0.
Example
Print the slice two elements at a time (i.e. [1,2],
[3,4], [5]):
let v = &[1, 2, 3, 4, 5]; for win in v.chunks(2) { println!("{:?}", win); }
fn get(&self, index: usize) -> Option<&T>
Returns the element of a slice at the given index, or None if the
index is out of bounds.
Examples
fn main() { let v = [10, 40, 30]; assert_eq!(Some(&40), v.get(1)); assert_eq!(None, v.get(3)); }let v = [10, 40, 30]; assert_eq!(Some(&40), v.get(1)); assert_eq!(None, v.get(3));
fn first(&self) -> Option<&T>
Returns the first element of a slice, or None if it is empty.
Examples
fn main() { let v = [10, 40, 30]; assert_eq!(Some(&10), v.first()); let w: &[i32] = &[]; assert_eq!(None, w.first()); }let v = [10, 40, 30]; assert_eq!(Some(&10), v.first()); let w: &[i32] = &[]; assert_eq!(None, w.first());
fn tail(&self) -> &[T]
: likely to be renamed
Returns all but the first element of a slice.
fn init(&self) -> &[T]
: likely to be renamed
Returns all but the last element of a slice.
fn last(&self) -> Option<&T>
Returns the last element of a slice, or None if it is empty.
Examples
fn main() { let v = [10, 40, 30]; assert_eq!(Some(&30), v.last()); let w: &[i32] = &[]; assert_eq!(None, w.last()); }let v = [10, 40, 30]; assert_eq!(Some(&30), v.last()); let w: &[i32] = &[]; assert_eq!(None, w.last());
unsafe fn get_unchecked(&self, index: usize) -> &T
Returns a pointer to the element at the given index, without doing bounds checking.
fn as_ptr(&self) -> *const T
Returns an unsafe pointer to the slice's buffer
The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.
Modifying the slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
fn binary_search_by<F>(&self, f: F) -> Result<usize, usize> where F: FnMut(&T) -> Ordering
Binary search a sorted slice with a comparator function.
The comparator function should implement an order consistent
with the sort order of the underlying slice, returning an
order code that indicates whether its argument is Less,
Equal or Greater the desired target.
If a matching value is found then returns Ok, containing
the index for the matched element; if no match is found then
Err is returned, containing the index where a matching
element could be inserted while maintaining sorted order.
Example
Looks up a series of four elements. The first is found, with a
uniquely determined position; the second and third are not
found; the fourth could match any position in [1,4].
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]; let seek = 13; assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9)); let seek = 4; assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7)); let seek = 100; assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13)); let seek = 1; let r = s.binary_search_by(|probe| probe.cmp(&seek)); assert!(match r { Ok(1...4) => true, _ => false, });
fn len(&self) -> usize
Returns the number of elements in the slice.
Example
fn main() { let a = [1, 2, 3]; assert_eq!(a.len(), 3); }let a = [1, 2, 3]; assert_eq!(a.len(), 3);
fn is_empty(&self) -> bool
Returns true if the slice has a length of 0
Example
fn main() { let a = [1, 2, 3]; assert!(!a.is_empty()); }let a = [1, 2, 3]; assert!(!a.is_empty());
fn get_mut(&mut self, index: usize) -> Option<&mut T>
Returns a mutable reference to the element at the given index,
or None if the index is out of bounds
fn iter_mut(&mut self) -> IterMut<T>
Returns an iterator that allows modifying each value
fn first_mut(&mut self) -> Option<&mut T>
Returns a mutable pointer to the first element of a slice, or None if it is empty
fn tail_mut(&mut self) -> &mut [T]
: likely to be renamed or removed
Returns all but the first element of a mutable slice
fn init_mut(&mut self) -> &mut [T]
: likely to be renamed or removed
Returns all but the last element of a mutable slice
fn last_mut(&mut self) -> Option<&mut T>
Returns a mutable pointer to the last item in the slice.
fn split_mut<F>(&mut self, pred: F) -> SplitMut<T, F> where F: FnMut(&T) -> bool
Returns an iterator over mutable subslices separated by elements that
match pred. The matched element is not contained in the subslices.
fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<T, F> where F: FnMut(&T) -> bool
Returns an iterator over subslices separated by elements that match
pred, limited to returning at most n items. The matched element is
not contained in the subslices.
The last element returned, if any, will contain the remainder of the slice.
fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<T, F> where F: FnMut(&T) -> bool
Returns an iterator over subslices separated by elements that match
pred limited to returning at most n items. This starts at the end of
the slice and works backwards. The matched element is not contained in
the subslices.
The last element returned, if any, will contain the remainder of the slice.
fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T>
Returns an iterator over chunk_size elements of the slice at a time.
The chunks are mutable and do not overlap. If chunk_size does
not divide the length of the slice, then the last chunk will not
have length chunk_size.
Panics
Panics if chunk_size is 0.
fn swap(&mut self, a: usize, b: usize)
Swaps two elements in a slice.
Arguments
- a - The index of the first element
- b - The index of the second element
Panics
Panics if a or b are out of bounds.
Example
fn main() { let mut v = ["a", "b", "c", "d"]; v.swap(1, 3); assert!(v == ["a", "d", "c", "b"]); }let mut v = ["a", "b", "c", "d"]; v.swap(1, 3); assert!(v == ["a", "d", "c", "b"]);
fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])
Divides one &mut into two at an index.
The first will contain all indices from [0, mid) (excluding
the index mid itself) and the second will contain all
indices from [mid, len) (excluding the index len itself).
Panics
Panics if mid > len.
Example
fn main() { let mut v = [1, 2, 3, 4, 5, 6]; // scoped to restrict the lifetime of the borrows { let (left, right) = v.split_at_mut(0); assert!(left == []); assert!(right == [1, 2, 3, 4, 5, 6]); } { let (left, right) = v.split_at_mut(2); assert!(left == [1, 2]); assert!(right == [3, 4, 5, 6]); } { let (left, right) = v.split_at_mut(6); assert!(left == [1, 2, 3, 4, 5, 6]); assert!(right == []); } }let mut v = [1, 2, 3, 4, 5, 6]; // scoped to restrict the lifetime of the borrows { let (left, right) = v.split_at_mut(0); assert!(left == []); assert!(right == [1, 2, 3, 4, 5, 6]); } { let (left, right) = v.split_at_mut(2); assert!(left == [1, 2]); assert!(right == [3, 4, 5, 6]); } { let (left, right) = v.split_at_mut(6); assert!(left == [1, 2, 3, 4, 5, 6]); assert!(right == []); }
fn reverse(&mut self)
Reverse the order of elements in a slice, in place.
Example
fn main() { let mut v = [1, 2, 3]; v.reverse(); assert!(v == [3, 2, 1]); }let mut v = [1, 2, 3]; v.reverse(); assert!(v == [3, 2, 1]);
unsafe fn get_unchecked_mut(&mut self, index: usize) -> &mut T
Returns an unsafe mutable pointer to the element in index
fn as_mut_ptr(&mut self) -> *mut T
Returns an unsafe mutable pointer to the slice's buffer.
The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.
Modifying the slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
fn to_vec(&self) -> Vec<T> where T: Clone
Copies self into a new Vec.
fn permutations(&self) -> Permutations<T> where T: Clone
Creates an iterator that yields every possible permutation of the vector in succession.
Examples
#![feature(collections)] extern crate collections; fn main() { let v = [1, 2, 3]; let mut perms = v.permutations(); for p in perms { println!("{:?}", p); } }let v = [1, 2, 3]; let mut perms = v.permutations(); for p in perms { println!("{:?}", p); }
Iterating through permutations one by one.
#![feature(collections)] extern crate collections; fn main() { let v = [1, 2, 3]; let mut perms = v.permutations(); assert_eq!(Some(vec![1, 2, 3]), perms.next()); assert_eq!(Some(vec![1, 3, 2]), perms.next()); assert_eq!(Some(vec![3, 1, 2]), perms.next()); }let v = [1, 2, 3]; let mut perms = v.permutations(); assert_eq!(Some(vec![1, 2, 3]), perms.next()); assert_eq!(Some(vec![1, 3, 2]), perms.next()); assert_eq!(Some(vec![3, 1, 2]), perms.next());
fn clone_from_slice(&mut self, src: &[T]) -> usize where T: Clone
Copies as many elements from src as it can into self (the
shorter of self.len() and src.len()). Returns the number
of elements copied.
Example
#![feature(collections)] extern crate collections; fn main() { let mut dst = [0, 0, 0]; let src = [1, 2]; assert!(dst.clone_from_slice(&src) == 2); assert!(dst == [1, 2, 0]); let src2 = [3, 4, 5, 6]; assert!(dst.clone_from_slice(&src2) == 3); assert!(dst == [3, 4, 5]); }let mut dst = [0, 0, 0]; let src = [1, 2]; assert!(dst.clone_from_slice(&src) == 2); assert!(dst == [1, 2, 0]); let src2 = [3, 4, 5, 6]; assert!(dst.clone_from_slice(&src2) == 3); assert!(dst == [3, 4, 5]);
fn sort(&mut self) where T: Ord
Sorts the slice, in place.
This is equivalent to self.sort_by(|a, b| a.cmp(b)).
Examples
fn main() { let mut v = [-5, 4, 1, -3, 2]; v.sort(); assert!(v == [-5, -3, 1, 2, 4]); }let mut v = [-5, 4, 1, -3, 2]; v.sort(); assert!(v == [-5, -3, 1, 2, 4]);
fn binary_search(&self, x: &T) -> Result<usize, usize> where T: Ord
Binary search a sorted slice for a given element.
If the value is found then Ok is returned, containing the
index of the matching element; if the value is not found then
Err is returned, containing the index where a matching
element could be inserted while maintaining sorted order.
Example
Looks up a series of four elements. The first is found, with a
uniquely determined position; the second and third are not
found; the fourth could match any position in [1,4].
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]; assert_eq!(s.binary_search(&13), Ok(9)); assert_eq!(s.binary_search(&4), Err(7)); assert_eq!(s.binary_search(&100), Err(13)); let r = s.binary_search(&1); assert!(match r { Ok(1...4) => true, _ => false, });
fn next_permutation(&mut self) -> bool where T: Ord
: uncertain if this merits inclusion in std
Mutates the slice to the next lexicographic permutation.
Returns true if successful and false if the slice is at the
last-ordered permutation.
Example
#![feature(collections)] extern crate collections; fn main() { let v: &mut [_] = &mut [0, 1, 2]; v.next_permutation(); let b: &mut [_] = &mut [0, 2, 1]; assert!(v == b); v.next_permutation(); let b: &mut [_] = &mut [1, 0, 2]; assert!(v == b); }let v: &mut [_] = &mut [0, 1, 2]; v.next_permutation(); let b: &mut [_] = &mut [0, 2, 1]; assert!(v == b); v.next_permutation(); let b: &mut [_] = &mut [1, 0, 2]; assert!(v == b);
fn prev_permutation(&mut self) -> bool where T: Ord
: uncertain if this merits inclusion in std
Mutates the slice to the previous lexicographic permutation.
Returns true if successful and false if the slice is at the
first-ordered permutation.
Example
#![feature(collections)] extern crate collections; fn main() { let v: &mut [_] = &mut [1, 0, 2]; v.prev_permutation(); let b: &mut [_] = &mut [0, 2, 1]; assert!(v == b); v.prev_permutation(); let b: &mut [_] = &mut [0, 1, 2]; assert!(v == b); }let v: &mut [_] = &mut [1, 0, 2]; v.prev_permutation(); let b: &mut [_] = &mut [0, 2, 1]; assert!(v == b); v.prev_permutation(); let b: &mut [_] = &mut [0, 1, 2]; assert!(v == b);
fn position_elem(&self, t: &T) -> Option<usize> where T: PartialEq
Find the first index containing a matching value.
fn rposition_elem(&self, t: &T) -> Option<usize> where T: PartialEq
Find the last index containing a matching value.
fn contains(&self, x: &T) -> bool where T: PartialEq
Returns true if the slice contains an element with the given value.
Examples
fn main() { let v = [10, 40, 30]; assert!(v.contains(&30)); assert!(!v.contains(&50)); }let v = [10, 40, 30]; assert!(v.contains(&30)); assert!(!v.contains(&50));
fn starts_with(&self, needle: &[T]) -> bool where T: PartialEq
Returns true if needle is a prefix of the slice.
Examples
fn main() { let v = [10, 40, 30]; assert!(v.starts_with(&[10])); assert!(v.starts_with(&[10, 40])); assert!(!v.starts_with(&[50])); assert!(!v.starts_with(&[10, 50])); }let v = [10, 40, 30]; assert!(v.starts_with(&[10])); assert!(v.starts_with(&[10, 40])); assert!(!v.starts_with(&[50])); assert!(!v.starts_with(&[10, 50]));
fn ends_with(&self, needle: &[T]) -> bool where T: PartialEq
Returns true if needle is a suffix of the slice.
Examples
fn main() { let v = [10, 40, 30]; assert!(v.ends_with(&[30])); assert!(v.ends_with(&[40, 30])); assert!(!v.ends_with(&[50])); assert!(!v.ends_with(&[50, 30])); }let v = [10, 40, 30]; assert!(v.ends_with(&[30])); assert!(v.ends_with(&[40, 30])); assert!(!v.ends_with(&[50])); assert!(!v.ends_with(&[50, 30]));
fn into_vec(self: Box<Self>) -> Vec<T>
Converts self into a vector without clones or allocation.