Struct std::alloc::Global

source ·

pub struct Global;

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Expand description

The global memory allocator.

This type implements the Allocator trait by forwarding calls to the allocator registered with the #[global_allocator] attribute if there is one, or the std crate’s default.

Note: while this type is unstable, the functionality it provides can be accessed through the free functions in alloc.

Implementations

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impl<T> Box<T, Global>

1.0.0 · source

pub fn new(x: T) -> Box<T, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Allocates memory on the heap and then places x into it.

This doesn’t actually allocate if T is zero-sized.

Examples

let five = Box::new(5);

Run

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pub fn new_uninit() -> Box<MaybeUninit<T>, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

🔬 This is a nightly-only experimental API. (new_uninit #63291)

Constructs a new box with uninitialized contents.

Examples

#![feature(new_uninit)]
let mut five = Box::<u32>::new_uninit();
let five = unsafe {
 // Deferred initialization:
 five.as_mut_ptr().write(5);
 five.assume_init()
};
assert_eq!(*five, 5)

Run

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pub fn new_zeroed() -> Box<MaybeUninit<T>, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

🔬 This is a nightly-only experimental API. (new_uninit #63291)

Constructs a new Box with uninitialized contents, with the memory being filled with 0 bytes.

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples

#![feature(new_uninit)]
let zero = Box::<u32>::new_zeroed();
let zero = unsafe { zero.assume_init() };
assert_eq!(*zero, 0)

Run

1.33.0 · source

pub fn pin(x: T) -> Pin<Box<T, Global>>iNotable traits for Pin<P>impl<P> Future for Pin<P> where
P: DerefMut,
<P as Deref>::Target: Future, type Output = <<P as Deref>::Target as Future>::Output;

Constructs a new Pin<Box<T>>. If T does not implement Unpin, then x will be pinned in memory and unable to be moved.

Constructing and pinning of the Box can also be done in two steps: Box::pin(x) does the same as Box::into_pin(Box::new(x)). Consider using into_pin if you already have a Box<T>, or if you want to construct a (pinned) Box in a different way than with Box::new.

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pub fn try_new(x: T) -> Result<Box<T, Global>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Allocates memory on the heap then places x into it, returning an error if the allocation fails

This doesn’t actually allocate if T is zero-sized.

Examples

#![feature(allocator_api)]
let five = Box::try_new(5)?;

Run

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pub fn try_new_uninit() -> Result<Box<MaybeUninit<T>, Global>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new box with uninitialized contents on the heap, returning an error if the allocation fails

Examples

#![feature(allocator_api, new_uninit)]
let mut five = Box::<u32>::try_new_uninit()?;
let five = unsafe {
 // Deferred initialization:
 five.as_mut_ptr().write(5);
 five.assume_init()
};
assert_eq!(*five, 5);

Run

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pub fn try_new_zeroed() -> Result<Box<MaybeUninit<T>, Global>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new Box with uninitialized contents, with the memory being filled with 0 bytes on the heap

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples

#![feature(allocator_api, new_uninit)]
let zero = Box::<u32>::try_new_zeroed()?;
let zero = unsafe { zero.assume_init() };
assert_eq!(*zero, 0);

Run

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impl<T> Box<[T], Global>

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pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>], Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

🔬 This is a nightly-only experimental API. (new_uninit #63291)

Constructs a new boxed slice with uninitialized contents.

Examples

#![feature(new_uninit)]
let mut values = Box::<[u32]>::new_uninit_slice(3);
let values = unsafe {
 // Deferred initialization:
 values[0].as_mut_ptr().write(1);
 values[1].as_mut_ptr().write(2);
 values[2].as_mut_ptr().write(3);
 values.assume_init()
};
assert_eq!(*values, [1, 2, 3])

Run

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pub fn new_zeroed_slice(len: usize) -> Box<[MaybeUninit<T>], Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

🔬 This is a nightly-only experimental API. (new_uninit #63291)

Constructs a new boxed slice with uninitialized contents, with the memory being filled with 0 bytes.

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples

#![feature(new_uninit)]
let values = Box::<[u32]>::new_zeroed_slice(3);
let values = unsafe { values.assume_init() };
assert_eq!(*values, [0, 0, 0])

Run

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pub fn try_new_uninit_slice(
len: usize
) -> Result<Box<[MaybeUninit<T>], Global>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new boxed slice with uninitialized contents. Returns an error if the allocation fails

Examples

#![feature(allocator_api, new_uninit)]
let mut values = Box::<[u32]>::try_new_uninit_slice(3)?;
let values = unsafe {
 // Deferred initialization:
 values[0].as_mut_ptr().write(1);
 values[1].as_mut_ptr().write(2);
 values[2].as_mut_ptr().write(3);
 values.assume_init()
};
assert_eq!(*values, [1, 2, 3]);

Run

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pub fn try_new_zeroed_slice(
len: usize
) -> Result<Box<[MaybeUninit<T>], Global>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new boxed slice with uninitialized contents, with the memory being filled with 0 bytes. Returns an error if the allocation fails

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples

#![feature(allocator_api, new_uninit)]
let values = Box::<[u32]>::try_new_zeroed_slice(3)?;
let values = unsafe { values.assume_init() };
assert_eq!(*values, [0, 0, 0]);

Run

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impl<T> Box<T, Global> where
T: ?Sized,

1.4.0 · source

pub unsafe fn from_raw(raw: *mut T) -> Box<T, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Constructs a box from a raw pointer.

After calling this function, the raw pointer is owned by the resulting Box. Specifically, the Box destructor will call the destructor of T and free the allocated memory. For this to be safe, the memory must have been allocated in accordance with the memory layout used by Box .

Safety

This function is unsafe because improper use may lead to memory problems. For example, a double-free may occur if the function is called twice on the same raw pointer.

The safety conditions are described in the memory layout section.

Examples

Recreate a Box which was previously converted to a raw pointer using Box::into_raw:

let x = Box::new(5);
let ptr = Box::into_raw(x);
let x = unsafe { Box::from_raw(ptr) };

Run

Manually create a Box from scratch by using the global allocator:

use std::alloc::{alloc, Layout};
unsafe {
 let ptr = alloc(Layout::new::<i32>()) as *mut i32;
 // In general .write is required to avoid attempting to destruct
 // the (uninitialized) previous contents of `ptr`, though for this
 // simple example `*ptr = 5` would have worked as well.
 ptr.write(5);
 let x = Box::from_raw(ptr);
}

Run

Trait Implementations

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impl Allocator for Global

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fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Attempts to allocate a block of memory. Read more

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fn allocate_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Behaves like allocate, but also ensures that the returned memory is zero-initialized. Read more

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unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout)

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Deallocates the memory referenced by ptr. Read more

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unsafe fn grow(
&self,
ptr: NonNull<u8>,
old_layout: Layout,
new_layout: Layout
) -> Result<NonNull<[u8]>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Attempts to extend the memory block. Read more

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unsafe fn grow_zeroed(
&self,
ptr: NonNull<u8>,
old_layout: Layout,
new_layout: Layout
) -> Result<NonNull<[u8]>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Behaves like grow, but also ensures that the new contents are set to zero before being returned. Read more

source

unsafe fn shrink(
&self,
ptr: NonNull<u8>,
old_layout: Layout,
new_layout: Layout
) -> Result<NonNull<[u8]>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Attempts to shrink the memory block. Read more

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fn by_ref(&self) -> &Self

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Creates a "by reference" adapter for this instance of Allocator. Read more

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impl<S> AsyncIterator for Box<S, Global> where
S: AsyncIterator + Unpin + ?Sized,

type Item = <S as AsyncIterator>::Item

🔬 This is a nightly-only experimental API. (async_iterator #79024)

The type of items yielded by the async iterator.

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fn poll_next(
self: Pin<&mut Box<S, Global>>,
cx: &mut Context<'_>
) -> Poll<Option<<Box<S, Global> as AsyncIterator>::Item>>

🔬 This is a nightly-only experimental API. (async_iterator #79024)

Attempt to pull out the next value of this async iterator, registering the current task for wakeup if the value is not yet available, and returning None if the async iterator is exhausted. Read more

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fn size_hint(&self) -> (usize, Option<usize>)

🔬 This is a nightly-only experimental API. (async_iterator #79024)

Returns the bounds on the remaining length of the async iterator. Read more

1.29.0 · source

impl Clone for Box<CStr, Global>

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fn clone(&self) -> Box<CStr, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Returns a copy of the value. Read more

1.0.0 · source

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

Performs copy-assignment from source. Read more

1.3.0 · source

impl Clone for Box<str, Global>

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fn clone(&self) -> Box<str, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Returns a copy of the value. Read more

1.0.0 · source

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

Performs copy-assignment from source. Read more

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impl Clone for Global

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fn clone(&self) -> Global

Returns a copy of the value. Read more

1.0.0 · source

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

Performs copy-assignment from source. Read more

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impl Debug for Global

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

Formats the value using the given formatter. Read more

1.0.0 (const: unstable) · source

impl<T> Default for Box<[T], Global>

const: unstable · source

fn default() -> Box<[T], Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Returns the "default value" for a type. Read more

1.17.0 · source

impl Default for Box<CStr, Global>

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fn default() -> Box<CStr, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Returns the "default value" for a type. Read more

1.0.0 · source

impl<T> Default for Box<T, Global> where
T: Default,

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fn default() -> Box<T, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Creates a Box<T>, with the Default value for T.

1.17.0 (const: unstable) · source

impl Default for Box<str, Global>

const: unstable · source

fn default() -> Box<str, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Returns the "default value" for a type. Read more

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impl Default for Global

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fn default() -> Global

Returns the "default value" for a type. Read more

1.17.0 · source

impl<T> From<&[T]> for Box<[T], Global> where
T: Copy,

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fn from(slice: &[T]) -> Box<[T], Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Converts a &[T] into a Box<[T]>

This conversion allocates on the heap and performs a copy of slice.

Examples

// create a &[u8] which will be used to create a Box<[u8]>
let slice: &[u8] = &[104, 101, 108, 108, 111];
let boxed_slice: Box<[u8]> = Box::from(slice);
println!("{boxed_slice:?}");

Run

1.17.0 · source

impl From<&CStr> for Box<CStr, Global>

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fn from(s: &CStr) -> Box<CStr, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Converts a &CStr into a Box<CStr>, by copying the contents into a newly allocated Box.

1.17.0 · source

impl From<&str> for Box<str, Global>

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fn from(s: &str) -> Box<str, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Converts a &str into a Box<str>

This conversion allocates on the heap and performs a copy of s.

Examples

let boxed: Box<str> = Box::from("hello");
println!("{boxed}");

Run

1.45.0 · source

impl<T, const N: usize> From<[T; N]> for Box<[T], Global>

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fn from(array: [T; N]) -> Box<[T], Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Converts a [T; N] into a Box<[T]>

This conversion moves the array to newly heap-allocated memory.

Examples

let boxed: Box<[u8]> = Box::from([4, 2]);
println!("{boxed:?}");

Run

1.20.0 · source

impl From<CString> for Box<CStr, Global>

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fn from(s: CString) -> Box<CStr, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Converts a CString into a Box<CStr> without copying or allocating.

1.45.0 · source

impl<T> From<Cow<'_, [T]>> for Box<[T], Global> where
T: Copy,

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fn from(cow: Cow<'_, [T]>) -> Box<[T], Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Converts a Cow<'_, [T]> into a Box<[T]>

When cow is the Cow::Borrowed variant, this conversion allocates on the heap and copies the underlying slice. Otherwise, it will try to reuse the owned Vec’s allocation.

1.45.0 · source

impl From<Cow<'_, CStr>> for Box<CStr, Global>

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fn from(cow: Cow<'_, CStr>) -> Box<CStr, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Converts a Cow<'a, CStr> into a Box<CStr>, by copying the contents if they are borrowed.

1.45.0 · source

impl From<Cow<'_, str>> for Box<str, Global>

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fn from(cow: Cow<'_, str>) -> Box<str, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Converts a Cow<'_, str> into a Box<str>

When cow is the Cow::Borrowed variant, this conversion allocates on the heap and copies the underlying str. Otherwise, it will try to reuse the owned String’s allocation.

Examples

use std::borrow::Cow;
let unboxed = Cow::Borrowed("hello");
let boxed: Box<str> = Box::from(unboxed);
println!("{boxed}");

Run

let unboxed = Cow::Owned("hello".to_string());
let boxed: Box<str> = Box::from(unboxed);
println!("{boxed}");

Run

1.20.0 · source

impl From<String> for Box<str, Global>

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fn from(s: String) -> Box<str, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Converts the given String to a boxed str slice that is owned.

Examples

Basic usage:

let s1: String = String::from("hello world");
let s2: Box<str> = Box::from(s1);
let s3: String = String::from(s2);
assert_eq!("hello world", s3)

Run

1.6.0 · source

impl<T> From<T> for Box<T, Global>

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fn from(t: T) -> Box<T, Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W>

Converts a T into a Box<T>

The conversion allocates on the heap and moves t from the stack into it.

Examples

let x = 5;
let boxed = Box::new(5);
assert_eq!(Box::from(x), boxed);

Run

1.32.0 · source

impl<I> FromIterator<I> for Box<[I], Global>

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fn from_iter<T>(iter: T) -> Box<[I], Global>iNotable traits for Box<I, A>impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<R: Read + ?Sized> Read for Box<R>impl<W: Write + ?Sized> Write for Box<W> where
T: IntoIterator<Item = I>,

Creates a value from an iterator. Read more

1.43.0 · source

impl<T, const N: usize> TryFrom<Box<[T], Global>> for Box<[T; N], Global>

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fn try_from(
boxed_slice: Box<[T], Global>
) -> Result<Box<[T; N], Global>, <Box<[T; N], Global> as TryFrom<Box<[T], Global>>>::Error>

Attempts to convert a Box<[T]> into a Box<[T; N]>.

The conversion occurs in-place and does not require a new memory allocation.

Errors

Returns the old Box<[T]> in the Err variant if boxed_slice.len() does not equal N.

type Error = Box<[T], Global>

The type returned in the event of a conversion error.

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impl Copy for Global

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impl<T, U> DispatchFromDyn<Box<U, Global>> for Box<T, Global> where
T: Unsize<U> + ?Sized,
U: ?Sized,