# Struct tmp_vec::BorrowMut
[−]
[src]

pub struct BorrowMut<'a, T: 'a> { /* fields omitted */ }

## Methods from Deref<Target = Vec<T>>

`fn capacity(&self) -> usize`

1.0.0

Returns the number of elements the vector can hold without reallocating.

# Examples

let vec: Vec<i32> = Vec::with_capacity(10); assert_eq!(vec.capacity(), 10);

`fn reserve(&mut self, additional: usize)`

1.0.0

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. After calling `reserve`

, capacity will be
greater than or equal to `self.len() + additional`

. Does nothing if
capacity is already sufficient.

# Panics

Panics if the new capacity overflows `usize`

.

# Examples

let mut vec = vec![1]; vec.reserve(10); assert!(vec.capacity() >= 11);

`fn reserve_exact(&mut self, additional: usize)`

1.0.0

Reserves the minimum capacity for exactly `additional`

more elements to
be inserted in the given `Vec<T>`

. After calling `reserve_exact`

,
capacity will be greater than or equal to `self.len() + additional`

.
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

let mut vec = vec![1]; vec.reserve_exact(10); assert!(vec.capacity() >= 11);

`fn shrink_to_fit(&mut self)`

1.0.0

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

let mut vec = Vec::with_capacity(10); vec.extend([1, 2, 3].iter().cloned()); assert_eq!(vec.capacity(), 10); vec.shrink_to_fit(); assert!(vec.capacity() >= 3);

`fn into_boxed_slice(self) -> Box<[T]>`

1.0.0

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`

.

# Examples

let v = vec![1, 2, 3]; let slice = v.into_boxed_slice();

Any excess capacity is removed:

let mut vec = Vec::with_capacity(10); vec.extend([1, 2, 3].iter().cloned()); assert_eq!(vec.capacity(), 10); let slice = vec.into_boxed_slice(); assert_eq!(slice.into_vec().capacity(), 3);

`fn truncate(&mut self, len: usize)`

1.0.0

Shortens the vector, keeping the first `len`

elements and dropping
the rest.

If `len`

is greater than the vector's current length, this has no
effect.

The `drain`

method can emulate `truncate`

, but causes the excess
elements to be returned instead of dropped.

Note that this method has no effect on the allocated capacity of the vector.

# Examples

Truncating a five element vector to two elements:

let mut vec = vec![1, 2, 3, 4, 5]; vec.truncate(2); assert_eq!(vec, [1, 2]);

No truncation occurs when `len`

is greater than the vector's current
length:

let mut vec = vec![1, 2, 3]; vec.truncate(8); assert_eq!(vec, [1, 2, 3]);

Truncating when `len == 0`

is equivalent to calling the `clear`

method.

let mut vec = vec![1, 2, 3]; vec.truncate(0); assert_eq!(vec, []);

`fn as_slice(&self) -> &[T]`

1.7.0

Extracts a slice containing the entire vector.

Equivalent to `&s[..]`

.

# Examples

use std::io::{self, Write}; let buffer = vec![1, 2, 3, 5, 8]; io::sink().write(buffer.as_slice()).unwrap();

`fn as_mut_slice(&mut self) -> &mut [T]`

1.7.0

Extracts a mutable slice of the entire vector.

Equivalent to `&mut s[..]`

.

# Examples

use std::io::{self, Read}; let mut buffer = vec![0; 3]; io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap();

`unsafe fn set_len(&mut self, len: usize)`

1.0.0

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

use std::ptr; let mut vec = vec!['r', 'u', 's', 't']; unsafe { ptr::drop_in_place(&mut vec[3]); vec.set_len(3); } assert_eq!(vec, ['r', 'u', 's']);

In this example, there is a memory leak since the memory locations
owned by the inner vectors were not freed prior to the `set_len`

call:

let mut vec = vec![vec![1, 0, 0], vec![0, 1, 0], vec![0, 0, 1]]; unsafe { vec.set_len(0); }

In this example, the vector gets expanded from zero to four items without any memory allocations occurring, resulting in vector values of unallocated memory:

let mut vec: Vec<char> = Vec::new(); unsafe { vec.set_len(4); }

`fn swap_remove(&mut self, index: usize) -> T`

1.0.0

Removes an element from the vector and returns it.

The removed element is replaced by the last element of the vector.

This does not preserve ordering, but is O(1).

# Panics

Panics if `index`

is out of bounds.

# Examples

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)`

1.0.0

Inserts an element at position `index`

within the vector, shifting all
elements after it to the right.

# Panics

Panics if `index`

is out of bounds.

# Examples

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`

1.0.0

Removes and returns the element at position `index`

within the vector,
shifting all elements after it to the left.

# Panics

Panics if `index`

is out of bounds.

# Examples

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,

1.0.0

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

let mut vec = vec![1, 2, 3, 4]; vec.retain(|&x| x%2 == 0); assert_eq!(vec, [2, 4]);

`fn dedup_by_key<F, K>(&mut self, key: F) where`

F: FnMut(&mut T) -> K,

K: PartialEq<K>,

1.16.0

F: FnMut(&mut T) -> K,

K: PartialEq<K>,

Removes consecutive elements in the vector that resolve to the same key.

If the vector is sorted, this removes all duplicates.

# Examples

let mut vec = vec![10, 20, 21, 30, 20]; vec.dedup_by_key(|i| *i / 10); assert_eq!(vec, [10, 20, 30, 20]);

`fn dedup_by<F>(&mut self, same_bucket: F) where`

F: FnMut(&mut T, &mut T) -> bool,

1.16.0

F: FnMut(&mut T, &mut T) -> bool,

Removes consecutive elements in the vector according to a predicate.

The `same_bucket`

function is passed references to two elements from the vector, and
returns `true`

if the elements compare equal, or `false`

if they do not. Only the first
of adjacent equal items is kept.

If the vector is sorted, this removes all duplicates.

# Examples

use std::ascii::AsciiExt; let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"]; vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b)); assert_eq!(vec, ["foo", "bar", "baz", "bar"]);

`fn push(&mut self, value: T)`

1.0.0

Appends an element to the back of a collection.

# Panics

Panics if the number of elements in the vector overflows a `usize`

.

# Examples

let mut vec = vec![1, 2]; vec.push(3); assert_eq!(vec, [1, 2, 3]);

`fn place_back(&mut self) -> PlaceBack<T>`

## 🔬 This is a nightly-only experimental API. (`collection_placement`

)

placement protocol is subject to change

Returns a place for insertion at the back of the `Vec`

.

Using this method with placement syntax is equivalent to `push`

,
but may be more efficient.

# Examples

#![feature(collection_placement)] #![feature(placement_in_syntax)] let mut vec = vec![1, 2]; vec.place_back() <- 3; vec.place_back() <- 4; assert_eq!(&vec, &[1, 2, 3, 4]);

`fn pop(&mut self) -> Option<T>`

1.0.0

Removes the last element from a vector and returns it, or `None`

if it
is empty.

# Examples

let mut vec = vec![1, 2, 3]; assert_eq!(vec.pop(), Some(3)); assert_eq!(vec, [1, 2]);

`fn append(&mut self, other: &mut Vec<T>)`

1.4.0

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

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>,

1.6.0

R: RangeArgument<usize>,

Creates a draining iterator that removes the specified range in the vector and yields the removed items.

Note 1: The element range is removed even if the iterator is only partially consumed or not consumed at all.

Note 2: 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

let mut v = vec![1, 2, 3]; let u: Vec<_> = v.drain(1..).collect(); assert_eq!(v, &[1]); assert_eq!(u, &[2, 3]); // A full range clears the vector v.drain(..); assert_eq!(v, &[]);

`fn clear(&mut self)`

1.0.0

Clears the vector, removing all values.

Note that this method has no effect on the allocated capacity of the vector.

# Examples

let mut v = vec![1, 2, 3]; v.clear(); assert!(v.is_empty());

`fn len(&self) -> usize`

1.0.0

Returns the number of elements in the vector, also referred to as its 'length'.

# Examples

let a = vec![1, 2, 3]; assert_eq!(a.len(), 3);

`fn is_empty(&self) -> bool`

1.0.0

Returns `true`

if the vector contains no elements.

# Examples

let mut v = Vec::new(); assert!(v.is_empty()); v.push(1); assert!(!v.is_empty());

`fn split_off(&mut self, at: usize) -> Vec<T>`

1.4.0

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

let mut vec = vec![1,2,3]; let vec2 = vec.split_off(1); assert_eq!(vec, [1]); assert_eq!(vec2, [2, 3]);

`fn resize(&mut self, new_len: usize, value: T)`

1.5.0

Resizes the `Vec`

in-place so that `len`

is equal to `new_len`

.

If `new_len`

is greater than `len`

, the `Vec`

is extended by the
difference, with each additional slot filled with `value`

.
If `new_len`

is less than `len`

, the `Vec`

is simply truncated.

This method requires `Clone`

to clone the passed value. If you'd
rather create a value with `Default`

instead, see `resize_default`

.

# Examples

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 extend_from_slice(&mut self, other: &[T])`

1.6.0

Clones and 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.

Note that this function is same as `extend`

except that it is
specialized to work with slices instead. If and when Rust gets
specialization this function will likely be deprecated (but still
available).

# Examples

let mut vec = vec![1]; vec.extend_from_slice(&[2, 3, 4]); assert_eq!(vec, [1, 2, 3, 4]);

`fn resize_default(&mut self, new_len: usize)`

`vec_resize_default`

)Resizes the `Vec`

in-place so that `len`

is equal to `new_len`

.

If `new_len`

is greater than `len`

, the `Vec`

is extended by the
difference, with each additional slot filled with `Default::default()`

.
If `new_len`

is less than `len`

, the `Vec`

is simply truncated.

This method uses `Default`

to create new values on every push. If
you'd rather `Clone`

a given value, use `resize`

.

# Examples

#![feature(vec_resize_default)] let mut vec = vec![1, 2, 3]; vec.resize_default(5); assert_eq!(vec, [1, 2, 3, 0, 0]); let mut vec = vec![1, 2, 3, 4]; vec.resize_default(2); assert_eq!(vec, [1, 2]);

`fn dedup(&mut self)`

1.0.0

Removes consecutive repeated elements in the vector.

If the vector is sorted, this removes all duplicates.

# Examples

let mut vec = vec![1, 2, 2, 3, 2]; vec.dedup(); assert_eq!(vec, [1, 2, 3, 2]);

`fn remove_item(&mut self, item: &T) -> Option<T>`

## 🔬 This is a nightly-only experimental API. (`vec_remove_item`

)

recently added

Removes the first instance of `item`

from the vector if the item exists.

# Examples

let mut vec = vec![1, 2, 3, 1]; vec.remove_item(&1); assert_eq!(vec, vec![2, 3, 1]);

`fn splice<R, I>(`

&mut self,

range: R,

replace_with: I

) -> Splice<<I as IntoIterator>::IntoIter> where

I: IntoIterator<Item = T>,

R: RangeArgument<usize>,

&mut self,

range: R,

replace_with: I

) -> Splice<<I as IntoIterator>::IntoIter> where

I: IntoIterator<Item = T>,

R: RangeArgument<usize>,

## 🔬 This is a nightly-only experimental API. (`splice`

)

recently added

Creates a splicing iterator that replaces the specified range in the vector
with the given `replace_with`

iterator and yields the removed items.
`replace_with`

does not need to be the same length as `range`

.

Note 1: The element range is removed even if the iterator is not consumed until the end.

Note 2: It is unspecified how many elements are removed from the vector,
if the `Splice`

value is leaked.

Note 3: The input iterator `replace_with`

is only consumed
when the `Splice`

value is dropped.

Note 4: This is optimal if:

- The tail (elements in the vector after
`range`

) is empty, - or
`replace_with`

yields fewer elements than`range`

’s length - or the lower bound of its
`size_hint()`

is exact.

Otherwise, a temporary vector is allocated and the tail is moved twice.

# 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(splice)] let mut v = vec![1, 2, 3]; let new = [7, 8]; let u: Vec<_> = v.splice(..2, new.iter().cloned()).collect(); assert_eq!(v, &[7, 8, 3]); assert_eq!(u, &[1, 2]);

## Trait Implementations

`impl<'a, T> Deref for BorrowMut<'a, T>`

[src]

`type Target = Vec<T>`

The resulting type after dereferencing

`fn deref(&self) -> &Self::Target`

The method called to dereference a value