Struct Box Copy item path

impl<A> Box<dyn Any, A>
where A: Allocator,

1.0.0 · Source

pub fn downcast<T>(self) -> Result<Box<T, A>, Box<dyn Any, A>>
where T: Any,

Attempts to downcast the box to a concrete type.

§Examples

use std::any::Any;

fn print_if_string(value: Box<dyn Any>) {
    if let Ok(string) = value.downcast::<String>() {
        println!("String ({}): {}", string.len(), string);
    }
}

let my_string = "Hello World".to_string();
print_if_string(Box::new(my_string));
print_if_string(Box::new(0i8));

pub unsafe fn downcast_unchecked<T>(self) -> Box<T, A>
where T: Any,

🔬This is a nightly-only experimental API. (downcast_unchecked)

Downcasts the box to a concrete type.

For a safe alternative see downcast.

§Examples

#![feature(downcast_unchecked)]

use std::any::Any;

let x: Box<dyn Any> = Box::new(1_usize);

unsafe {
    assert_eq!(*x.downcast_unchecked::<usize>(), 1);
}

§Safety

The contained value must be of type T. Calling this method with the incorrect type is undefined behavior.

impl<A> Box<dyn Any + Send, A>
where A: Allocator,

1.0.0 · Source

pub fn downcast<T>(self) -> Result<Box<T, A>, Box<dyn Any + Send, A>>
where T: Any,

Attempts to downcast the box to a concrete type.

§Examples

use std::any::Any;

fn print_if_string(value: Box<dyn Any + Send>) {
    if let Ok(string) = value.downcast::<String>() {
        println!("String ({}): {}", string.len(), string);
    }
}

let my_string = "Hello World".to_string();
print_if_string(Box::new(my_string));
print_if_string(Box::new(0i8));

pub unsafe fn downcast_unchecked<T>(self) -> Box<T, A>
where T: Any,

🔬This is a nightly-only experimental API. (downcast_unchecked)

Downcasts the box to a concrete type.

For a safe alternative see downcast.

§Examples

#![feature(downcast_unchecked)]

use std::any::Any;

let x: Box<dyn Any + Send> = Box::new(1_usize);

unsafe {
    assert_eq!(*x.downcast_unchecked::<usize>(), 1);
}

§Safety

The contained value must be of type T. Calling this method with the incorrect type is undefined behavior.

impl<A> Box<dyn Any + Sync + Send, A>
where A: Allocator,

1.51.0 · Source

pub fn downcast<T>(self) -> Result<Box<T, A>, Box<dyn Any + Sync + Send, A>>
where T: Any,

Attempts to downcast the box to a concrete type.

§Examples

use std::any::Any;

fn print_if_string(value: Box<dyn Any + Send + Sync>) {
    if let Ok(string) = value.downcast::<String>() {
        println!("String ({}): {}", string.len(), string);
    }
}

let my_string = "Hello World".to_string();
print_if_string(Box::new(my_string));
print_if_string(Box::new(0i8));

pub unsafe fn downcast_unchecked<T>(self) -> Box<T, A>
where T: Any,

🔬This is a nightly-only experimental API. (downcast_unchecked)

Downcasts the box to a concrete type.

For a safe alternative see downcast.

§Examples

#![feature(downcast_unchecked)]

use std::any::Any;

let x: Box<dyn Any + Send + Sync> = Box::new(1_usize);

unsafe {
    assert_eq!(*x.downcast_unchecked::<usize>(), 1);
}

§Safety

The contained value must be of type T. Calling this method with the incorrect type is undefined behavior.

impl<T> Box<T>

1.0.0 · Source

pub fn new(x: T) -> Box<T>

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);

1.82.0 · Source

pub fn new_uninit() -> Box<MaybeUninit<T>>

Constructs a new box with uninitialized contents.

§Examples

let mut five = Box::<u32>::new_uninit();
// Deferred initialization:
five.write(5);
let five = unsafe { five.assume_init() };

assert_eq!(*five, 5)

pub fn new_zeroed() -> Box<MaybeUninit<T>>

🔬This is a nightly-only experimental API. (new_zeroed_alloc)

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_zeroed_alloc)]

let zero = Box::<u32>::new_zeroed();
let zero = unsafe { zero.assume_init() };

assert_eq!(*zero, 0)

1.33.0 · Source

pub fn pin(x: T) -> Pin<Box<T>>

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.

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

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

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)?;

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

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

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

§Examples

#![feature(allocator_api)]

let mut five = Box::<u32>::try_new_uninit()?;
// Deferred initialization:
five.write(5);
let five = unsafe { five.assume_init() };

assert_eq!(*five, 5);

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

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

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)]

let zero = Box::<u32>::try_new_zeroed()?;
let zero = unsafe { zero.assume_init() };

assert_eq!(*zero, 0);

impl<T, A> Box<T, A>
where A: Allocator,

pub fn new_in(x: T, alloc: A) -> Box<T, A>
where A: Allocator,

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

Allocates memory in the given allocator then places x into it.

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

§Examples

#![feature(allocator_api)]

use std::alloc::System;

let five = Box::new_in(5, System);

pub fn try_new_in(x: T, alloc: A) -> Result<Box<T, A>, AllocError>
where A: Allocator,

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

Allocates memory in the given allocator 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)]

use std::alloc::System;

let five = Box::try_new_in(5, System)?;

pub fn new_uninit_in(alloc: A) -> Box<MaybeUninit<T>, A>
where A: Allocator,

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

Constructs a new box with uninitialized contents in the provided allocator.

§Examples

#![feature(allocator_api)]

use std::alloc::System;

let mut five = Box::<u32, _>::new_uninit_in(System);
// Deferred initialization:
five.write(5);
let five = unsafe { five.assume_init() };

assert_eq!(*five, 5)

pub fn try_new_uninit_in(alloc: A) -> Result<Box<MaybeUninit<T>, A>, AllocError>
where A: Allocator,

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

Constructs a new box with uninitialized contents in the provided allocator, returning an error if the allocation fails

§Examples

#![feature(allocator_api)]

use std::alloc::System;

let mut five = Box::<u32, _>::try_new_uninit_in(System)?;
// Deferred initialization:
five.write(5);
let five = unsafe { five.assume_init() };

assert_eq!(*five, 5);

pub fn new_zeroed_in(alloc: A) -> Box<MaybeUninit<T>, A>
where A: Allocator,

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

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

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

§Examples

#![feature(allocator_api)]

use std::alloc::System;

let zero = Box::<u32, _>::new_zeroed_in(System);
let zero = unsafe { zero.assume_init() };

assert_eq!(*zero, 0)

pub fn try_new_zeroed_in(alloc: A) -> Result<Box<MaybeUninit<T>, A>, AllocError>
where A: Allocator,

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

Constructs a new Box with uninitialized contents, with the memory being filled with 0 bytes in the provided allocator, returning an error if the allocation fails,

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

§Examples

#![feature(allocator_api)]

use std::alloc::System;

let zero = Box::<u32, _>::try_new_zeroed_in(System)?;
let zero = unsafe { zero.assume_init() };

assert_eq!(*zero, 0);

pub fn pin_in(x: T, alloc: A) -> Pin<Box<T, A>>
where A: 'static + Allocator,

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

Constructs a new Pin<Box<T, A>>. 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_in(x, alloc) does the same as Box::into_pin(Box::new_in(x, alloc)). Consider using into_pin if you already have a Box<T, A>, or if you want to construct a (pinned) Box in a different way than with Box::new_in.

pub fn into_boxed_slice(boxed: Box<T, A>) -> Box<[T], A>

🔬This is a nightly-only experimental API. (box_into_boxed_slice)

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

This conversion does not allocate on the heap and happens in place.

pub fn into_inner(boxed: Box<T, A>) -> T

🔬This is a nightly-only experimental API. (box_into_inner)

Consumes the Box, returning the wrapped value.

§Examples

#![feature(box_into_inner)]

let c = Box::new(5);

assert_eq!(Box::into_inner(c), 5);

impl<T> Box<[T]>

1.82.0 · Source

pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>]>

Constructs a new boxed slice with uninitialized contents.

§Examples

let mut values = Box::<[u32]>::new_uninit_slice(3);
// Deferred initialization:
values[0].write(1);
values[1].write(2);
values[2].write(3);
let values = unsafe {values.assume_init() };

assert_eq!(*values, [1, 2, 3])

pub fn new_zeroed_slice(len: usize) -> Box<[MaybeUninit<T>]>

🔬This is a nightly-only experimental API. (new_zeroed_alloc)

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_zeroed_alloc)]

let values = Box::<[u32]>::new_zeroed_slice(3);
let values = unsafe { values.assume_init() };

assert_eq!(*values, [0, 0, 0])

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

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

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

§Examples

#![feature(allocator_api)]

let mut values = Box::<[u32]>::try_new_uninit_slice(3)?;
// Deferred initialization:
values[0].write(1);
values[1].write(2);
values[2].write(3);
let values = unsafe { values.assume_init() };

assert_eq!(*values, [1, 2, 3]);

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

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

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)]

let values = Box::<[u32]>::try_new_zeroed_slice(3)?;
let values = unsafe { values.assume_init() };

assert_eq!(*values, [0, 0, 0]);

pub fn into_array<const N: usize>(self) -> Option<Box<[T; N]>>

🔬This is a nightly-only experimental API. (slice_as_array)

Converts the boxed slice into a boxed array.

This operation does not reallocate; the underlying array of the slice is simply reinterpreted as an array type.

If N is not exactly equal to the length of self, then this method returns None.

impl<T, A> Box<[T], A>
where A: Allocator,

pub fn new_uninit_slice_in(len: usize, alloc: A) -> Box<[MaybeUninit<T>], A>

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

Constructs a new boxed slice with uninitialized contents in the provided allocator.

§Examples

#![feature(allocator_api)]

use std::alloc::System;

let mut values = Box::<[u32], _>::new_uninit_slice_in(3, System);
// Deferred initialization:
values[0].write(1);
values[1].write(2);
values[2].write(3);
let values = unsafe { values.assume_init() };

assert_eq!(*values, [1, 2, 3])

pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Box<[MaybeUninit<T>], A>

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

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

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

§Examples

#![feature(allocator_api)]

use std::alloc::System;

let values = Box::<[u32], _>::new_zeroed_slice_in(3, System);
let values = unsafe { values.assume_init() };

assert_eq!(*values, [0, 0, 0])

pub fn try_new_uninit_slice_in( len: usize, alloc: A, ) -> Result<Box<[MaybeUninit<T>], A>, AllocError>

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

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

§Examples

#![feature(allocator_api)]

use std::alloc::System;

let mut values = Box::<[u32], _>::try_new_uninit_slice_in(3, System)?;
// Deferred initialization:
values[0].write(1);
values[1].write(2);
values[2].write(3);
let values = unsafe { values.assume_init() };

assert_eq!(*values, [1, 2, 3]);

pub fn try_new_zeroed_slice_in( len: usize, alloc: A, ) -> Result<Box<[MaybeUninit<T>], A>, AllocError>

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

Constructs a new boxed slice with uninitialized contents in the provided allocator, 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)]

use std::alloc::System;

let values = Box::<[u32], _>::try_new_zeroed_slice_in(3, System)?;
let values = unsafe { values.assume_init() };

assert_eq!(*values, [0, 0, 0]);

impl<T, A> Box<MaybeUninit<T>, A>
where A: Allocator,

1.82.0 · Source

pub unsafe fn assume_init(self) -> Box<T, A>

Converts to Box<T, A>.

§Safety

As with MaybeUninit::assume_init, it is up to the caller to guarantee that the value really is in an initialized state. Calling this when the content is not yet fully initialized causes immediate undefined behavior.

§Examples

let mut five = Box::<u32>::new_uninit();
// Deferred initialization:
five.write(5);
let five: Box<u32> = unsafe { five.assume_init() };

assert_eq!(*five, 5)

1.87.0 · Source

pub fn write(boxed: Box<MaybeUninit<T>, A>, value: T) -> Box<T, A>

Writes the value and converts to Box<T, A>.

This method converts the box similarly to Box::assume_init but writes value into it before conversion thus guaranteeing safety. In some scenarios use of this method may improve performance because the compiler may be able to optimize copying from stack.

§Examples

let big_box = Box::<[usize; 1024]>::new_uninit();

let mut array = [0; 1024];
for (i, place) in array.iter_mut().enumerate() {
    *place = i;
}

// The optimizer may be able to elide this copy, so previous code writes
// to heap directly.
let big_box = Box::write(big_box, array);

for (i, x) in big_box.iter().enumerate() {
    assert_eq!(*x, i);
}

impl<T, A> Box<[MaybeUninit<T>], A>
where A: Allocator,

1.82.0 · Source

pub unsafe fn assume_init(self) -> Box<[T], A>

Converts to Box<[T], A>.

§Safety

As with MaybeUninit::assume_init, it is up to the caller to guarantee that the values really are in an initialized state. Calling this when the content is not yet fully initialized causes immediate undefined behavior.

§Examples

let mut values = Box::<[u32]>::new_uninit_slice(3);
// Deferred initialization:
values[0].write(1);
values[1].write(2);
values[2].write(3);
let values = unsafe { values.assume_init() };

assert_eq!(*values, [1, 2, 3])

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

1.4.0 · Source

pub unsafe fn from_raw(raw: *mut T) -> Box<T>

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 raw pointer must point to a block of memory allocated by the global allocator.

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) };

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);
}

pub unsafe fn from_non_null(ptr: NonNull<T>) -> Box<T>

🔬This is a nightly-only experimental API. (box_vec_non_null)

Constructs a box from a NonNull pointer.

After calling this function, the NonNull 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 NonNull pointer.

The non-null pointer must point to a block of memory allocated by the global allocator.

The safety conditions are described in the memory layout section.

§Examples

Recreate a Box which was previously converted to a NonNull pointer using Box::into_non_null:

#![feature(box_vec_non_null)]

let x = Box::new(5);
let non_null = Box::into_non_null(x);
let x = unsafe { Box::from_non_null(non_null) };

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

#![feature(box_vec_non_null)]

use std::alloc::{alloc, Layout};
use std::ptr::NonNull;

unsafe {
    let non_null = NonNull::new(alloc(Layout::new::<i32>()).cast::<i32>())
        .expect("allocation failed");
    // In general .write is required to avoid attempting to destruct
    // the (uninitialized) previous contents of `non_null`.
    non_null.write(5);
    let x = Box::from_non_null(non_null);
}

impl<T, A> Box<T, A>
where A: Allocator, T: ?Sized,

pub unsafe fn from_raw_in(raw: *mut T, alloc: A) -> Box<T, A>

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

Constructs a box from a raw pointer in the given allocator.

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 raw pointer must point to a block of memory allocated by alloc.

§Examples

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

#![feature(allocator_api)]

use std::alloc::System;

let x = Box::new_in(5, System);
let (ptr, alloc) = Box::into_raw_with_allocator(x);
let x = unsafe { Box::from_raw_in(ptr, alloc) };

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

#![feature(allocator_api, slice_ptr_get)]

use std::alloc::{Allocator, Layout, System};

unsafe {
    let ptr = System.allocate(Layout::new::<i32>())?.as_mut_ptr() 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_in(ptr, System);
}

pub unsafe fn from_non_null_in(raw: NonNull<T>, alloc: A) -> Box<T, A>

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

Constructs a box from a NonNull pointer in the given allocator.

After calling this function, the NonNull 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 non-null pointer must point to a block of memory allocated by alloc.

§Examples

Recreate a Box which was previously converted to a NonNull pointer using Box::into_non_null_with_allocator:

#![feature(allocator_api, box_vec_non_null)]

use std::alloc::System;

let x = Box::new_in(5, System);
let (non_null, alloc) = Box::into_non_null_with_allocator(x);
let x = unsafe { Box::from_non_null_in(non_null, alloc) };

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

#![feature(allocator_api, box_vec_non_null, slice_ptr_get)]

use std::alloc::{Allocator, Layout, System};

unsafe {
    let non_null = System.allocate(Layout::new::<i32>())?.cast::<i32>();
    // In general .write is required to avoid attempting to destruct
    // the (uninitialized) previous contents of `non_null`.
    non_null.write(5);
    let x = Box::from_non_null_in(non_null, System);
}

1.4.0 · Source

pub fn into_raw(b: Box<T, A>) -> *mut T

Consumes the Box, returning a wrapped raw pointer.

The pointer will be properly aligned and non-null.

After calling this function, the caller is responsible for the memory previously managed by the Box. In particular, the caller should properly destroy T and release the memory, taking into account the memory layout used by Box. The easiest way to do this is to convert the raw pointer back into a Box with the Box::from_raw function, allowing the Box destructor to perform the cleanup.

Note: this is an associated function, which means that you have to call it as Box::into_raw(b) instead of b.into_raw(). This is so that there is no conflict with a method on the inner type.

§Examples

Converting the raw pointer back into a Box with Box::from_raw for automatic cleanup:

let x = Box::new(String::from("Hello"));
let ptr = Box::into_raw(x);
let x = unsafe { Box::from_raw(ptr) };

Manual cleanup by explicitly running the destructor and deallocating the memory:

use std::alloc::{dealloc, Layout};
use std::ptr;

let x = Box::new(String::from("Hello"));
let ptr = Box::into_raw(x);
unsafe {
    ptr::drop_in_place(ptr);
    dealloc(ptr as *mut u8, Layout::new::<String>());
}

Note: This is equivalent to the following:

let x = Box::new(String::from("Hello"));
let ptr = Box::into_raw(x);
unsafe {
    drop(Box::from_raw(ptr));
}

pub fn into_non_null(b: Box<T, A>) -> NonNull<T>

🔬This is a nightly-only experimental API. (box_vec_non_null)

Consumes the Box, returning a wrapped NonNull pointer.

The pointer will be properly aligned.

After calling this function, the caller is responsible for the memory previously managed by the Box. In particular, the caller should properly destroy T and release the memory, taking into account the memory layout used by Box. The easiest way to do this is to convert the NonNull pointer back into a Box with the Box::from_non_null function, allowing the Box destructor to perform the cleanup.

Note: this is an associated function, which means that you have to call it as Box::into_non_null(b) instead of b.into_non_null(). This is so that there is no conflict with a method on the inner type.

§Examples

Converting the NonNull pointer back into a Box with Box::from_non_null for automatic cleanup:

#![feature(box_vec_non_null)]

let x = Box::new(String::from("Hello"));
let non_null = Box::into_non_null(x);
let x = unsafe { Box::from_non_null(non_null) };

Manual cleanup by explicitly running the destructor and deallocating the memory:

#![feature(box_vec_non_null)]

use std::alloc::{dealloc, Layout};

let x = Box::new(String::from("Hello"));
let non_null = Box::into_non_null(x);
unsafe {
    non_null.drop_in_place();
    dealloc(non_null.as_ptr().cast::<u8>(), Layout::new::<String>());
}

Note: This is equivalent to the following:

#![feature(box_vec_non_null)]

let x = Box::new(String::from("Hello"));
let non_null = Box::into_non_null(x);
unsafe {
    drop(Box::from_non_null(non_null));
}

pub fn into_raw_with_allocator(b: Box<T, A>) -> (*mut T, A)

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

Consumes the Box, returning a wrapped raw pointer and the allocator.

The pointer will be properly aligned and non-null.

After calling this function, the caller is responsible for the memory previously managed by the Box. In particular, the caller should properly destroy T and release the memory, taking into account the memory layout used by Box. The easiest way to do this is to convert the raw pointer back into a Box with the Box::from_raw_in function, allowing the Box destructor to perform the cleanup.

Note: this is an associated function, which means that you have to call it as Box::into_raw_with_allocator(b) instead of b.into_raw_with_allocator(). This is so that there is no conflict with a method on the inner type.

§Examples

Converting the raw pointer back into a Box with Box::from_raw_in for automatic cleanup:

#![feature(allocator_api)]

use std::alloc::System;

let x = Box::new_in(String::from("Hello"), System);
let (ptr, alloc) = Box::into_raw_with_allocator(x);
let x = unsafe { Box::from_raw_in(ptr, alloc) };

Manual cleanup by explicitly running the destructor and deallocating the memory:

#![feature(allocator_api)]

use std::alloc::{Allocator, Layout, System};
use std::ptr::{self, NonNull};

let x = Box::new_in(String::from("Hello"), System);
let (ptr, alloc) = Box::into_raw_with_allocator(x);
unsafe {
    ptr::drop_in_place(ptr);
    let non_null = NonNull::new_unchecked(ptr);
    alloc.deallocate(non_null.cast(), Layout::new::<String>());
}

pub fn into_non_null_with_allocator(b: Box<T, A>) -> (NonNull<T>, A)

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

Consumes the Box, returning a wrapped NonNull pointer and the allocator.

The pointer will be properly aligned.

After calling this function, the caller is responsible for the memory previously managed by the Box. In particular, the caller should properly destroy T and release the memory, taking into account the memory layout used by Box. The easiest way to do this is to convert the NonNull pointer back into a Box with the Box::from_non_null_in function, allowing the Box destructor to perform the cleanup.

Note: this is an associated function, which means that you have to call it as Box::into_non_null_with_allocator(b) instead of b.into_non_null_with_allocator(). This is so that there is no conflict with a method on the inner type.

§Examples

Converting the NonNull pointer back into a Box with Box::from_non_null_in for automatic cleanup:

#![feature(allocator_api, box_vec_non_null)]

use std::alloc::System;

let x = Box::new_in(String::from("Hello"), System);
let (non_null, alloc) = Box::into_non_null_with_allocator(x);
let x = unsafe { Box::from_non_null_in(non_null, alloc) };

Manual cleanup by explicitly running the destructor and deallocating the memory:

#![feature(allocator_api, box_vec_non_null)]

use std::alloc::{Allocator, Layout, System};

let x = Box::new_in(String::from("Hello"), System);
let (non_null, alloc) = Box::into_non_null_with_allocator(x);
unsafe {
    non_null.drop_in_place();
    alloc.deallocate(non_null.cast::<u8>(), Layout::new::<String>());
}

pub fn as_mut_ptr(b: &mut Box<T, A>) -> *mut T

🔬This is a nightly-only experimental API. (box_as_ptr)

Returns a raw mutable pointer to the Box’s contents.

The caller must ensure that the Box outlives the pointer this function returns, or else it will end up dangling.

This method guarantees that for the purpose of the aliasing model, this method does not materialize a reference to the underlying memory, and thus the returned pointer will remain valid when mixed with other calls to as_ptr and as_mut_ptr. Note that calling other methods that materialize references to the memory may still invalidate this pointer. See the example below for how this guarantee can be used.

§Examples

Due to the aliasing guarantee, the following code is legal:

#![feature(box_as_ptr)]

unsafe {
    let mut b = Box::new(0);
    let ptr1 = Box::as_mut_ptr(&mut b);
    ptr1.write(1);
    let ptr2 = Box::as_mut_ptr(&mut b);
    ptr2.write(2);
    // Notably, the write to `ptr2` did *not* invalidate `ptr1`:
    ptr1.write(3);
}

pub fn as_ptr(b: &Box<T, A>) -> *const T

🔬This is a nightly-only experimental API. (box_as_ptr)

Returns a raw pointer to the Box’s contents.

The caller must ensure that the Box outlives the pointer this function returns, or else it will end up dangling.

The caller must also ensure that the memory the pointer (non-transitively) points to is never written to (except inside an UnsafeCell) using this pointer or any pointer derived from it. If you need to mutate the contents of the Box, use as_mut_ptr.

This method guarantees that for the purpose of the aliasing model, this method does not materialize a reference to the underlying memory, and thus the returned pointer will remain valid when mixed with other calls to as_ptr and as_mut_ptr. Note that calling other methods that materialize mutable references to the memory, as well as writing to this memory, may still invalidate this pointer. See the example below for how this guarantee can be used.

§Examples

Due to the aliasing guarantee, the following code is legal:

#![feature(box_as_ptr)]

unsafe {
    let mut v = Box::new(0);
    let ptr1 = Box::as_ptr(&v);
    let ptr2 = Box::as_mut_ptr(&mut v);
    let _val = ptr2.read();
    // No write to this memory has happened yet, so `ptr1` is still valid.
    let _val = ptr1.read();
    // However, once we do a write...
    ptr2.write(1);
    // ... `ptr1` is no longer valid.
    // This would be UB: let _val = ptr1.read();
}

pub fn allocator(b: &Box<T, A>) -> &A

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

Returns a reference to the underlying allocator.

Note: this is an associated function, which means that you have to call it as Box::allocator(&b) instead of b.allocator(). This is so that there is no conflict with a method on the inner type.

1.26.0 · Source

pub fn leak<'a>(b: Box<T, A>) -> &'a mut T
where A: 'a,

Consumes and leaks the Box, returning a mutable reference, &'a mut T.

Note that the type T must outlive the chosen lifetime 'a. If the type has only static references, or none at all, then this may be chosen to be 'static.

This function is mainly useful for data that lives for the remainder of the program’s life. Dropping the returned reference will cause a memory leak. If this is not acceptable, the reference should first be wrapped with the Box::from_raw function producing a Box. This Box can then be dropped which will properly destroy T and release the allocated memory.

Note: this is an associated function, which means that you have to call it as Box::leak(b) instead of b.leak(). This is so that there is no conflict with a method on the inner type.

§Examples

Simple usage:

let x = Box::new(41);
let static_ref: &'static mut usize = Box::leak(x);
*static_ref += 1;
assert_eq!(*static_ref, 42);

Unsized data:

let x = vec![1, 2, 3].into_boxed_slice();
let static_ref = Box::leak(x);
static_ref[0] = 4;
assert_eq!(*static_ref, [4, 2, 3]);

1.63.0 · Source

pub fn into_pin(boxed: Box<T, A>) -> Pin<Box<T, A>>
where A: 'static,

Converts a Box<T> into a Pin<Box<T>>. If T does not implement Unpin, then *boxed will be pinned in memory and unable to be moved.

This conversion does not allocate on the heap and happens in place.

This is also available via From.

Constructing and pinning a Box with Box::into_pin(Box::new(x)) can also be written more concisely using Box::pin(x). This into_pin method is useful if you already have a Box<T>, or you are constructing a (pinned) Box in a different way than with Box::new.

§Notes

It’s not recommended that crates add an impl like From<Box<T>> for Pin<T>, as it’ll introduce an ambiguity when calling Pin::from. A demonstration of such a poor impl is shown below.

struct Foo; // A type defined in this crate.
impl From<Box<()>> for Pin<Foo> {
    fn from(_: Box<()>) -> Pin<Foo> {
        Pin::new(Foo)
    }
}

let foo = Box::new(());
let bar = Pin::from(foo);

impl<Args, F, A> AsyncFnOnce<Args> for Box<F, A>
where Args: Tuple, F: AsyncFnOnce<Args> + ?Sized, A: Allocator,

type Output = <F as AsyncFnOnce<Args>>::Output

🔬This is a nightly-only experimental API. (async_fn_traits)

Output type of the called closure’s future.

type CallOnceFuture = <F as AsyncFnOnce<Args>>::CallOnceFuture

🔬This is a nightly-only experimental API. (async_fn_traits)

Future returned by AsyncFnOnce::async_call_once.

extern "rust-call" fn async_call_once( self, args: Args, ) -> <Box<F, A> as AsyncFnOnce<Args>>::CallOnceFuture

🔬This is a nightly-only experimental API. (async_fn_traits)

Call the AsyncFnOnce, returning a future which may move out of the called closure.

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

type Item = <S as AsyncIterator>::Item

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

The type of items yielded by the async iterator.

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

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

Attempts 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

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

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

impl<T> AsyncSeek for Box<T>
where T: AsyncSeek + Unpin + ?Sized,

fn start_seek(self: Pin<&mut Box<T>>, pos: SeekFrom) -> Result<(), Error>

Attempts to seek to an offset, in bytes, in a stream. Read more

Like poll_write, except that it writes from a slice of buffers. Read more

fn is_write_vectored(&self) -> bool

Determines if this writer has an efficient poll_write_vectored implementation. Read more

fn poll_flush( self: Pin<&mut Box<T>>, cx: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Attempts to flush the object, ensuring that any buffered data reach their destination. Read more

fn poll_shutdown( self: Pin<&mut Box<T>>, cx: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down. Read more

impl<T> AsyncWrite for Box<T>
where T: AsyncWrite + Unpin + ?Sized,

fn poll_write( self: Pin<&mut Box<T>>, cx: &mut Context<'_>, buf: &[u8], ) -> Poll<Result<usize, Error>>

Attempt to write bytes from buf into the object. Read more

fn poll_write_vectored( self: Pin<&mut Box<T>>, cx: &mut Context<'_>, bufs: &[IoSlice<'_>], ) -> Poll<Result<usize, Error>>

Attempt to write bytes from bufs into the object using vectored IO operations. Read more

fn poll_flush( self: Pin<&mut Box<T>>, cx: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Attempt to flush the object, ensuring that any buffered data reach their destination. Read more

fn poll_close( self: Pin<&mut Box<T>>, cx: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Attempt to close the object. Read more

1.0.0 · Source§

impl BufRead for Box
where B: BufRead + ?Sized,

fn fill_buf(&mut self) -> Result<&[u8], Error>

Returns the contents of the internal buffer, filling it with more data, via Read methods, if empty. Read more

fn consume(&mut self, amt: usize)

Marks the given amount of additional bytes from the internal buffer as having been read. Subsequent calls to read only return bytes that have not been marked as read. Read more

fn has_data_left(&mut self) -> Result<bool, Error>

🔬This is a nightly-only experimental API. (buf_read_has_data_left)

§Examples

let x = Box::new(5);
let y = x.clone();

// The value is the same
assert_eq!(x, y);

// But they are unique objects
assert_ne!(&*x as *const i32, &*y as *const i32);

fn clone_from(&mut self, source: &Box<T, A>)

Copies source’s contents into self without creating a new allocation.

§Examples

let x = Box::new(5);
let mut y = Box::new(10);
let yp: *const i32 = &*y;

y.clone_from(&x);

// The value is the same
assert_eq!(x, y);

// And no allocation occurred
assert_eq!(yp, &*y);

fn nth_back(&mut self, n: usize) -> Option<::Item>

Returns the nth element from the end of the iterator. Read more

fn advance_back_by(&mut self, n: usize) -> Result<(), NonZero<usize>>

🔬This is a nightly-only experimental API. (iter_advance_by)

Advances the iterator from the back by n elements. Read more

1.27.0 · Source§

fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> R
where Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Output = B>,

This is the reverse version of Iterator::try_fold(): it takes elements starting from the back of the iterator. Read more

1.27.0 · Source§

fn rfold<B, F>(self, init: B, f: F) -> B
where Self: Sized, F: FnMut(B, Self::Item) -> B,

An iterator method that reduces the iterator’s elements to a single, final value, starting from the back. Read more

Return the length, in bytes, of the corresponding [VarULE] type

fn encode_var_ule_write(&self, dst: &mut [u8])

Write the corresponding [VarULE] type to the dst buffer. dst should be the size of [Self::encode_var_ule_len()]

impl<T> EncodeAsVarULE<T> for Box<T>
where T: VarULE + ?Sized,

fn encode_var_ule_as_slices<R>(&self, cb: impl FnOnce(&[&[u8]]) -> R) -> R

Calls cb with a piecewise list of byte slices that when concatenated produce the memory pattern of the corresponding instance of T. Read more

fn encode_var_ule_len(&self) -> usize

Return the length, in bytes, of the corresponding [VarULE] type

fn encode_var_ule_write(&self, dst: &mut [u8])

Write the corresponding [VarULE] type to the dst buffer. dst should be the size of [Self::encode_var_ule_len()]

1.8.0 · Source§

impl<E> Error for Box<E>
where E: Error,

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements. Read more

extern "rust-call" fn call( &self, args: Args, ) -> <Box<F, A> as FnOnce<Args>>::Output

🔬This is a nightly-only experimental API. (fn_traits)

Performs the call operation.

1.35.0 · Source§

impl<Args, F, A> FnMut<Args> for Box<F, A>
where Args: Tuple, F: FnMut<Args> + ?Sized, A: Allocator,

extern "rust-call" fn call_mut( &mut self, args: Args, ) -> <Box<F, A> as FnOnce<Args>>::Output

🔬This is a nightly-only experimental API. (fn_traits)

Performs the call operation.

1.35.0 · Source§

impl<Args, F, A> FnOnce<Args> for Box<F, A>
where Args: Tuple, F: FnOnce<Args> + ?Sized, A: Allocator,

type Output = <F as FnOnce<Args>>::Output

The returned type after the call operator is used.

extern "rust-call" fn call_once( self, args: Args, ) -> <Box<F, A> as FnOnce<Args>>::Output

🔬This is a nightly-only experimental API. (fn_traits)

Performs the call operation.

1.17.0 · Source§

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

fn from(slice: &[T]) -> Box<[T]>

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

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

§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:?}");

impl From<&Box<dyn Error + Sync + Send>> for ReplyKind

fn from(err: &Box<dyn Error + Sync + Send>) -> ReplyKind

Converts to this type from the input type.

1.17.0 · Source§

impl From<&CStr> for Box<CStr>

fn from(s: &CStr) -> Box<CStr>

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

1.17.0 · Source§

impl From<&OsStr> for Box<OsStr>

fn from(s: &OsStr) -> Box<OsStr>

Copies the string into a newly allocated Box<OsStr>.

§Examples

// create a &mut [u8] which will be used to create a Box<[u8]>
let mut array = [104, 101, 108, 108, 111];
let slice: &mut [u8] = &mut array;
let boxed_slice: Box<[u8]> = Box::from(slice);

println!("{boxed_slice:?}");

This will allocate and clone path to it.

1.84.0 · Source§

impl From<&mut str> for Box<str>

fn from(s: &mut str) -> Box<str>

Converts a &mut str into a Box<str>

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

§Examples

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

1.6.0 · Source§

impl<'a> From<&str> for Box<dyn Error + 'a>

fn from(err: &str) -> Box<dyn Error + 'a>

Converts a str into a box of dyn Error.

§Examples

use std::error::Error;

let a_str_error = "a str error";
let a_boxed_error = Box::<dyn Error>::from(a_str_error);
assert!(size_of::<Box<dyn Error>>() == size_of_val(&a_boxed_error))

1.0.0 · Source§

impl<'a> From<&str> for Box<dyn Error + Sync + Send + 'a>

fn from(err: &str) -> Box<dyn Error + Sync + Send + 'a>

Converts a str into a box of dyn Error + Send + Sync.

§Examples

use std::error::Error;

let a_str_error = "a str error";
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_str_error);
assert!(
    size_of::<Box<dyn Error + Send + Sync>>() == size_of_val(&a_boxed_error))

1.17.0 · Source§

impl From<&str> for Box<str>

fn from(s: &str) -> Box<str>

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}");

1.45.0 · Source§

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

fn from(array: [T; N]) -> Box<[T]>

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:?}");

impl<'a> From<Box<[Item<'a>]>> for OwnedFormatItem

fn from(items: Box<[Item<'a>]>) -> OwnedFormatItem

Converts to this type from the input type.

1.18.0 · Source§

impl<T, A> From<Box<[T], A>> for Vec<T, A>
where A: Allocator,

fn from(s: Box<[T], A>) -> Vec<T, A>

Converts a boxed slice into a vector by transferring ownership of the existing heap allocation.

§Examples

let b: Box<[i32]> = vec![1, 2, 3].into_boxed_slice();
assert_eq!(Vec::from(b), vec![1, 2, 3]);

impl<T> From<Box<T>> for Owned<T>

fn from(b: Box<T>) -> Owned<T>

Returns a new owned pointer pointing to b.

§Panics

Panics if the pointer (the Box) is not properly aligned.

§Examples

use crossbeam_epoch::Owned;

let o = unsafe { Owned::from_raw(Box::into_raw(Box::new(1234))) };

1.21.0 · Source§

impl<T, A> From<Box<T, A>> for Arc<T, A>
where A: Allocator, T: ?Sized,

fn from(v: Box<T, A>) -> Arc<T, A>

Move a boxed object to a new, reference-counted allocation.

§Example

let unique: Box<str> = Box::from("eggplant");
let shared: Arc<str> = Arc::from(unique);
assert_eq!("eggplant", &shared[..]);

1.33.0 · Source§

impl<T, A> From<Box<T, A>> for Pin<Box<T, A>>
where A: Allocator + 'static, T: ?Sized,

fn from(boxed: Box<T, A>) -> Pin<Box<T, A>>

Converts a Box<T> into a Pin<Box<T>>. If T does not implement Unpin, then *boxed will be pinned in memory and unable to be moved.

This conversion does not allocate on the heap and happens in place.

This is also available via Box::into_pin.

Constructing and pinning a Box with <Pin<Box<T>>>::from(Box::new(x)) can also be written more concisely using Box::pin(x). This From implementation is useful if you already have a Box<T>, or you are constructing a (pinned) Box in a different way than with Box::new.

1.21.0 · Source§

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

§Examples

let s1: String = String::from("hello world");
let s2: Box<str> = s1.into_boxed_str();
let s3: String = String::from(s2);

assert_eq!("hello world", s3)

1.19.0 · Source§

impl<A> From<Box<str, A>> for Box<[u8], A>
where A: Allocator,

fn from(s: Box<str, A>) -> Box<[u8], A>

Converts a Box<str> into a Box<[u8]>

This conversion does not allocate on the heap and happens in place.

§Examples

// create a Box<str> which will be used to create a Box<[u8]>
let boxed: Box<str> = Box::from("hello");
let boxed_str: Box<[u8]> = Box::from(boxed);

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

assert_eq!(boxed_slice, boxed_str);

1.20.0 · Source§

impl From<CString> for Box<CStr>

fn from(s: CString) -> Box<CStr>

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

impl From<Cow<'_, OsStr>> for Box<OsStr>

fn from(cow: Cow<'_, OsStr>) -> Box<OsStr>

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

1.45.0 · Source§

impl From<Cow<'_, Path>> for Box<Path>

fn from(cow: Cow<'_, Path>) -> Box<Path>

Creates a boxed Path from a clone-on-write pointer.

Converting from a Cow::Owned does not clone or allocate.

1.45.0 · Source§

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

fn from(cow: Cow<'_, str>) -> Box<str>

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}");

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

1.22.0 · Source§

impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + 'a>

fn from(err: Cow<'b, str>) -> Box<dyn Error + 'a>

Converts a Cow into a box of dyn Error.

§Examples

use std::error::Error;
use std::borrow::Cow;

let a_cow_str_error = Cow::from("a str error");
let a_boxed_error = Box::<dyn Error>::from(a_cow_str_error);
assert!(size_of::<Box<dyn Error>>() == size_of_val(&a_boxed_error))

1.22.0 · Source§

impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + Sync + Send + 'a>

fn from(err: Cow<'b, str>) -> Box<dyn Error + Sync + Send + 'a>

Converts a Cow into a box of dyn Error + Send + Sync.

§Examples

use std::error::Error;
use std::borrow::Cow;

let a_cow_str_error = Cow::from("a str error");
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_cow_str_error);
assert!(
    size_of::<Box<dyn Error + Send + Sync>>() == size_of_val(&a_boxed_error))

1.0.0 · Source§

impl<'a, E> From<E> for Box<dyn Error + 'a>
where E: Error + 'a,

fn from(err: E) -> Box<dyn Error + 'a>

Converts a type of Error into a box of dyn Error.

§Examples

use std::error::Error;
use std::fmt;

#[derive(Debug)]
struct AnError;

impl fmt::Display for AnError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "An error")
    }
}

impl Error for AnError {}

let an_error = AnError;
assert!(0 == size_of_val(&an_error));
let a_boxed_error = Box::<dyn Error>::from(an_error);
assert!(size_of::<Box<dyn Error>>() == size_of_val(&a_boxed_error))

1.0.0 · Source§

use std::error::Error;

let a_string_error = "a string error".to_string();
let a_boxed_error = Box::<dyn Error>::from(a_string_error);
assert!(size_of::<Box<dyn Error>>() == size_of_val(&a_boxed_error))

1.0.0 · Source§

impl<'a> From<String> for Box<dyn Error + Sync + Send + 'a>

fn from(err: String) -> Box<dyn Error + Sync + Send + 'a>

Converts a String into a box of dyn Error + Send + Sync.

§Examples

use std::error::Error;

let a_string_error = "a string error".to_string();
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_string_error);
assert!(
    size_of::<Box<dyn Error + Send + Sync>>() == size_of_val(&a_boxed_error))

1.20.0 · Source§

impl From<String> for Box<str>

fn from(s: String) -> Box<str>

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

§Examples

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)

1.6.0 · Source§

impl<T> From<T> for Box<T>

fn from(t: T) -> Box<T>

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);

impl From<UriTemplateString> for Box<UriTemplateStr>

fn from(s: UriTemplateString) -> Box<UriTemplateStr>

Converts to this type from the input type.

1.20.0 · Source§

impl<T, A> From<Vec<T, A>> for Box<[T], A>
where A: Allocator,

fn from(v: Vec<T, A>) -> Box<[T], A>

Converts a vector into a boxed slice.

Before doing the conversion, this method discards excess capacity like Vec::shrink_to_fit.

§Examples

assert_eq!(Box::from(vec![1, 2, 3]), vec![1, 2, 3].into_boxed_slice());

Any excess capacity is removed:

let mut vec = Vec::with_capacity(10);
vec.extend([1, 2, 3]);

assert_eq!(Box::from(vec), vec![1, 2, 3].into_boxed_slice());

fn poll( self: Pin<&mut Box<F, A>>, cx: &mut Context<'_>, ) -> Poll<<Box<F, A> as Future>::Output>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available. Read more

1.0.0 · Source§

impl<T, A> Hash for Box<T, A>
where T: Hash + ?Sized, A: Allocator,

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

Feeds this value into the given Hasher. Read more

1.3.0 · Source§

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

Feeds a slice of this type into the given Hasher. Read more

1.22.0 · Source§

Writes a single isize into this hasher.

fn write_length_prefix(&mut self, len: usize)

🔬This is a nightly-only experimental API. (hasher_prefixfree_extras)

Writes a length prefix into this hasher, as part of being prefix-free. Read more

fn write_str(&mut self, s: &str)

🔬This is a nightly-only experimental API. (hasher_prefixfree_extras)

Writes a single str into this hasher. Read more

fn into_response(self) -> Response<Body>

Create a response.

1.0.0 · Source§

🔬This is a nightly-only experimental API. (iter_next_chunk)

Advances the iterator and returns an array containing the next N values. Read more

1.0.0 · Source§

fn count(self) -> usize
where Self: Sized,

Consumes the iterator, counting the number of iterations and returning it. Read more

fn advance_by(&mut self, n: usize) -> Result<(), NonZero<usize>>

🔬This is a nightly-only experimental API. (iter_advance_by)

Advances the iterator by n elements. Read more

1.28.0 · Source§

fn step_by(self, step: usize) -> StepBy<Self> ⓘ
where Self: Sized,

Creates an iterator starting at the same point, but stepping by the given amount at each iteration. Read more

1.0.0 · Source§

fn chain(self, other: U) -> Chain<Self, ::IntoIter> ⓘ
where Self: Sized, U: IntoIterator<Item = Self::Item>,

Takes two iterators and creates a new iterator over both in sequence. Read more

1.0.0 · Source§

fn zip(self, other: U) -> Zip<Self, ::IntoIter> ⓘ
where Self: Sized, U: IntoIterator,

‘Zips up’ two iterators into a single iterator of pairs. Read more

fn intersperse(self, separator: Self::Item) -> Intersperse<Self> ⓘ
where Self: Sized, Self::Item: Clone,

🔬This is a nightly-only experimental API. (iter_intersperse)

Creates a new iterator which places a copy of separator between adjacent items of the original iterator. Read more

fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G> ⓘ
where Self: Sized, G: FnMut() -> Self::Item,

🔬This is a nightly-only experimental API. (iter_intersperse)

fn fuse(self) -> Fuse<Self> ⓘ
where Self: Sized,

Creates an iterator which ends after the first None. Read more

1.0.0 · Source§

fn inspect<F>(self, f: F) -> Inspect<Self, F> ⓘ
where Self: Sized, F: FnMut(&Self::Item),

Does something with each element of an iterator, passing the value on. Read more

1.0.0 · Source§

fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Creates a “by reference” adapter for this instance of Iterator. Read more

1.0.0 · Source§

fn collect(self) -> B
where B: FromIterator<Self::Item>, Self: Sized,

Transforms an iterator into a collection. Read more

fn try_collect( &mut self, ) -> <<Self::Item as Try>::Residual as Residual>::TryType
where Self: Sized, Self::Item: Try, <Self::Item as Try>::Residual: Residual, B: FromIterator<<Self::Item as Try>::Output>,

🔬This is a nightly-only experimental API. (iterator_try_collect)

Fallibly transforms an iterator into a collection, short circuiting if a failure is encountered. Read more

fn collect_into<E>(self, collection: &mut E) -> &mut E
where E: Extend<Self::Item>, Self: Sized,

🔬This is a nightly-only experimental API. (iter_collect_into)

Collects all the items from an iterator into a collection. Read more

1.0.0 · Source§

fn partition<B, F>(self, f: F) -> (B, B)
where Self: Sized, B: Default + Extend<Self::Item>, F: FnMut(&Self::Item) -> bool,

Consumes an iterator, creating two collections from it. Read more

fn partition_in_place<'a, T, P>(self, predicate: P) -> usize
where T: 'a, Self: Sized + DoubleEndedIterator<Item = &'a mut T>, P: FnMut(&T) -> bool,

🔬This is a nightly-only experimental API. (iter_partition_in_place)

Reorders the elements of this iterator in-place according to the given predicate, such that all those that return true precede all those that return false. Returns the number of true elements found. Read more

fn is_partitioned(self, predicate: P) -> bool
where Self: Sized, P: FnMut(Self::Item) -> bool,

🔬This is a nightly-only experimental API. (iter_is_partitioned)

Checks if the elements of this iterator are partitioned according to the given predicate, such that all those that return true precede all those that return false. Read more

1.27.0 · Source§

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R
where Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Output = B>,

An iterator method that applies a function as long as it returns successfully, producing a single, final value. Read more

1.27.0 · Source§

fn try_for_each<F, R>(&mut self, f: F) -> R
where Self: Sized, F: FnMut(Self::Item) -> R, R: Try<Output = ()>,

An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error. Read more

1.0.0 · Source§

fn fold<B, F>(self, init: B, f: F) -> B
where Self: Sized, F: FnMut(B, Self::Item) -> B,

Folds every element into an accumulator by applying an operation, returning the final result. Read more

1.51.0 · Source§

fn reduce<F>(self, f: F) -> Option<Self::Item>
where Self: Sized, F: FnMut(Self::Item, Self::Item) -> Self::Item,

Reduces the elements to a single one, by repeatedly applying a reducing operation. Read more

fn try_reduce<R>( &mut self, f: impl FnMut(Self::Item, Self::Item) -> R, ) -> <<R as Try>::Residual as Residual<Option<<R as Try>::Output>>>::TryType
where Self: Sized, R: Try<Output = Self::Item>, <R as Try>::Residual: Residual<Option<Self::Item>>,

🔬This is a nightly-only experimental API. (iterator_try_reduce)

Reduces the elements to a single one by repeatedly applying a reducing operation. If the closure returns a failure, the failure is propagated back to the caller immediately. Read more

1.0.0 · Source§

fn all<F>(&mut self, f: F) -> bool
where Self: Sized, F: FnMut(Self::Item) -> bool,

Tests if every element of the iterator matches a predicate. Read more

1.0.0 · Source§

fn any<F>(&mut self, f: F) -> bool
where Self: Sized, F: FnMut(Self::Item) -> bool,

Tests if any element of the iterator matches a predicate. Read more

1.0.0 · Source§

fn find(&mut self, predicate: P) -> Option<Self::Item>
where Self: Sized, P: FnMut(&Self::Item) -> bool,

Searches for an element of an iterator that satisfies a predicate. Read more

1.30.0 · Source§

fn find_map<B, F>(&mut self, f: F) -> Option
where Self: Sized, F: FnMut(Self::Item) -> Option,

Applies function to the elements of iterator and returns the first non-none result. Read more

fn try_find<R>( &mut self, f: impl FnMut(&Self::Item) -> R, ) -> <<R as Try>::Residual as Residual<Option<Self::Item>>>::TryType
where Self: Sized, R: Try<Output = bool>, <R as Try>::Residual: Residual<Option<Self::Item>>,

🔬This is a nightly-only experimental API. (try_find)

🔬This is a nightly-only experimental API. (iter_array_chunks)

Returns an iterator over N elements of the iterator at a time. Read more

1.11.0 · Source§

fn sum<S>(self) -> S
where Self: Sized, S: Sum<Self::Item>,

Sums the elements of an iterator. Read more

1.11.0 · Source§

Checks if the elements of this iterator are sorted using the given key extraction function. Read more

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

1.0.0 · Source§

Invoked right before the service makes a request, regardless of whether it is redirected or not. Read more

fn clone_body(&mut self, ctx: &Context, body: &B) -> Option

Try to clone a request body before the service makes a redirected request. Read more

impl<Request, P> Policy<Request> for Box
where P: Policy<Request>, Request: Send + 'static,

type Guard = >::Guard

The guard type that is returned when the request is allowed to proceed. Read more

type Error = >::Error

The error type that is returned when the request is not allowed to proceed, and should be aborted. Read more

async fn check( &self, ctx: Context, request: Request, ) -> PolicyResult<Request, <Box as Policy<Request>>::Guard, <Box as Policy<Request>>::Error>

Check whether the request is allowed to proceed. Read more

Reads all bytes until EOF in this source, appending them to buf. Read more

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Reads the exact number of bytes required to fill buf. Read more

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Reads the exact number of bytes required to fill cursor. Read more

1.0.0 · Source§

fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Creates a “by reference” adaptor for this instance of Read. Read more

1.0.0 · Source§

fn bytes(self) -> Bytes<Self> ⓘ
where Self: Sized,

fn next_range(&mut self, range: Range<u64>) -> u64

Randomly pick a value within the range. Read more

1.0.0 · Source§

impl<S> Seek for Box<S>
where S: Seek + ?Sized,

fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error>

Seek to an offset, in bytes, in a stream. Read more

fn rewind(&mut self) -> Result<(), Error>

Rewind to the beginning of a stream. Read more

fn stream_len(&mut self) -> Result<u64, Error>

🔬This is a nightly-only experimental API. (seek_stream_len)

Returns the length of this stream (in bytes). Read more

fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream. Read more

The type of error returned by the service.

fn serve( &self, ctx: Context, req: Request, ) -> impl Future<Output = Result<<Box<S> as Service<Request>>::Response, <Box<S> as Service<Request>>::Error>> + Send

Serve a response or error for the given request, using the given context.

fn boxed(self) -> BoxService<Request, Self::Response, Self::Error>

Box this service to allow for dynamic dispatch.

fn register( &mut self, registry: &Registry, token: Token, interests: Interest, ) -> Result<(), Error>

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

Returns the bounds on the remaining length of the stream. Read more

Notifies the subscriber that a span ID has been dropped, and returns true if there are now 0 IDs that refer to that span. Read more

fn drop_span(&self, id: Id)

👎Deprecated since 0.1.2: use Subscriber::try_close instead

This method is deprecated. Read more

fn current_span(&self) -> Current

Returns a type representing this subscriber’s view of the current span. Read more

unsafe fn downcast_raw(&self, id: TypeId) -> Option<*const ()>

If self is the same type as the provided TypeId, returns an untyped *const pointer to that type. Otherwise, returns None. Read more

fn on_register_dispatch(&self, subscriber: &Dispatch)

Invoked when this subscriber becomes a Dispatch. Read more

§Errors

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

type Error = Box<[T]>

The type returned in the event of a conversion error.

1.66.0 · Source§

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

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

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

Like Vec::into_boxed_slice, this is in-place if vec.capacity() == N, but will require a reallocation otherwise.

§Errors

Returns the original Vec<T> in the Err variant if boxed_slice.len() does not equal N.

§Examples

This can be used with vec! to create an array on the heap:

let state: Box<[f32; 100]> = vec![1.0; 100].try_into().unwrap();
assert_eq!(state.len(), 100);

Like write, except that it writes from a slice of buffers. Read more

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation. Read more

fn flush(&mut self) -> Result<(), Error>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination. Read more

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer. Read more

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer. Read more

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

Writes a formatted string into this writer, returning any error encountered. Read more

1.0.0 · Source§

fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Creates a “by reference” adapter for this instance of Write. Read more

impl<'a, T> Writeable for Box<T>
where T: Writeable + ?Sized,

fn write_to<W>(&self, sink: &mut W) -> Result<(), Error>
where W: Write + ?Sized,

Writes a string to the given sink. Errors from the sink are bubbled up. The default implementation delegates to write_to_parts, and discards any Part annotations.

fn write_to_parts<W>(&self, sink: &mut W) -> Result<(), Error>
where W: PartsWrite + ?Sized,

Write bytes and Part annotations to the given sink. Errors from the sink are bubbled up. The default implementation delegates to write_to, and doesn’t produce any Part annotations.

fn writeable_length_hint(&self) -> LengthHint

Returns a hint for the number of UTF-8 bytes that will be written to the sink. Read more

impl<T, U, A> CoerceUnsized<Box<U, A>> for Box<T, A>
where T: Unsize + ?Sized, A: Allocator, U: ?Sized,

impl<T, A> DerefPure for Box<T, A>
where A: Allocator, T: ?Sized,

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

1.0.0 · Source§

impl<T, A> Eq for Box<T, A>
where T: Eq + ?Sized, A: Allocator,

impl<T> FromStream<T> for Box<[T]>

1.26.0 · Source§

impl<I, A> FusedIterator for Box<I, A>
where I: FusedIterator + ?Sized, A: Allocator,

1.80.0 · Source§

impl<'a, I, A> !Iterator for &'a Box<[I], A>
where A: Allocator,

This implementation is required to make sure that the &Box<[I]>: IntoIterator implementation doesn’t overlap with IntoIterator for T where T: Iterator blanket.

1.80.0 · Source§

impl<'a, I, A> !Iterator for &'a mut Box<[I], A>
where A: Allocator,

This implementation is required to make sure that the &mut Box<[I]>: IntoIterator implementation doesn’t overlap with IntoIterator for T where T: Iterator blanket.

1.80.0 · Source§

impl<I, A> !Iterator for Box<[I], A>
where A: Allocator,

This implementation is required to make sure that the Box<[I]>: IntoIterator implementation doesn’t overlap with IntoIterator for T where T: Iterator blanket.

impl<T, A> PinCoerceUnsized for Box<T, A>
where A: Allocator, T: ?Sized,

impl<T> PointerLike for Box<T>

impl<T> StableDeref for Box<T>
where T: ?Sized,

1.33.0 · Source§

impl<T, A> Unpin for Box<T, A>
where A: Allocator, T: ?Sized,

impl<Z> ZeroizeOnDrop for Box<[Z]>
where Z: ZeroizeOnDrop,

impl<T, A, P> Access<T> for P
where A: Access<T> + ?Sized, P: Deref<Target = A>,

type Guard = <A as Access<T>>::Guard

A guard object containing the value and keeping it alive. Read more

fn load(&self) -> >::Guard

The loading method. Read more

impl<T> Any for T
where T: 'static + ?Sized,

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

fn seek(&mut self, pos: SeekFrom) -> Seek<'_, Self>
where Self: Unpin,

Creates a future which will seek an IO object, and then yield the new position in the object and the object itself. Read more

fn rewind(&mut self) -> Seek<'_, Self>
where Self: Unpin,

Creates a future which will rewind to the beginning of the stream. Read more

fn stream_position(&mut self) -> Seek<'_, Self>
where Self: Unpin,

Creates a future which will return the current seek position from the start of the stream. Read more

impl<S> AsyncSeekExt for S
where S: AsyncSeek + ?Sized,

fn seek(&mut self, pos: SeekFrom) -> Seek<'_, Self> ⓘ
where Self: Unpin,

Creates a future which will seek an IO object, and then yield the new position in the object and the object itself. Read more

fn stream_position(&mut self) -> Seek<'_, Self> ⓘ
where Self: Unpin,

Creates a future which will return the current seek position from the start of the stream. Read more

Authorize the given credentials.

impl<Q, K> Comparable<K> for Q
where Q: Ord + ?Sized, K: Borrow<Q> + ?Sized,

fn compare(&self, key: &K) -> Ordering

Compare self to key and return their ordering.

impl<S, Request, Connection> ConnectorService<Request> for S
where S: Service<Request, Response = EstablishedClientConnection<Connection, Request>>, <S as Service<Request>>::Error: Into<Box<dyn Error + Sync + Send>>,

type Connection = Connection

Connection returned by the ConnectorService

type Error = <S as Service<Request>>::Error

Error returned in case of connection / setup failure

Lazily wrap the error with a context. Read more

fn backtrace(self) -> OpaqueError

Add a Backtrace to the error. Read more

Combines two Filters so that spans and events are enabled if either filter returns true. Read more

fn not(self) -> Not<Self, S>
where Self: Sized,

Inverts self, returning a filter that enables spans and events only if self would not enable them. Read more

Attaches the current Context to this type, returning a WithContext wrapper. Read more

fn with_cancellation_token( self, cancellation_token: &CancellationToken, ) -> WithCancellationTokenFuture<'_, Self>
where Self: Sized,

Similar to [CancellationToken::run_until_cancelled], but with the advantage that it is easier to write fluent call chains, and biased towards waiting for [CancellationToken] to complete. Read more

fn with_cancellation_token_owned( self, cancellation_token: CancellationToken, ) -> WithCancellationTokenFutureOwned<Self>
where Self: Sized,

Similar to [CancellationToken::run_until_cancelled_owned], but with the advantage that it is easier to write fluent call chains, and biased towards waiting for [CancellationToken] to complete. Read more

Executes a Request. Read more

impl<S, Body> HttpClientWebSocketExt<Body> for S
where S: Service<Request<Body>, Response = Response<Body>>, <S as Service<Request<Body>>>::Error: Into<Box<dyn Error + Sync + Send>>,

fn websocket( &self, url: impl IntoUrl, ) -> WebSocketRequestBuilder<WithService<'_, S, Body>>

Create a new WebSocketRequestBuilder] to be used to establish a WebSocket connection over http/1.1.

fn websocket_h2( &self, url: impl IntoUrl, ) -> WebSocketRequestBuilder<WithService<'_, S, Body>>

Create a new WebSocketRequestBuilder to be used to establish a WebSocket connection over h2.

fn websocket_with_request<RequestBody>( &self, req: Request<RequestBody>, ) -> WebSocketRequestBuilder<WithService<'_, S, Body>>
where RequestBody: Into<Body>,

Create a new WebSocketRequestBuilder starting from the given request. Read more

impl<T> Instrument for T

fn instrument(self, span: Span) -> Instrumented<Self> ⓘ

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more

fn in_current_span(self) -> Instrumented<Self> ⓘ

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more

Which kind of future are we turning this into?

fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more

impl IntoIterator for I
where I: Iterator,

type Item = ::Item

fn choose_multiple_fill<R>(self, rng: &mut R, buf: &mut [Self::Item]) -> usize
where R: Rng + ?Sized,

Uniformly sample amount distinct elements into a buffer Read more

fn choose_multiple<R>(self, rng: &mut R, amount: usize) -> Vec<Self::Item>
where R: Rng + ?Sized,

Uniformly sample amount distinct elements into a Vec Read more

👎Deprecated since 0.13.0: Use .chunk_by() instead

👎Deprecated since 0.10.2: Use Iterator::reduce instead

Accumulator of the elements in the iterator. Read more

fn tree_reduce<F>(self, f: F) -> Option<Self::Item>
where F: FnMut(Self::Item, Self::Item) -> Self::Item, Self: Sized,

Accumulate the elements in the iterator in a tree-like manner. Read more

fn tree_fold1<F>(self, f: F) -> Option<Self::Item>
where F: FnMut(Self::Item, Self::Item) -> Self::Item, Self: Sized,

👎Deprecated since 0.13.0: Use .tree_reduce() instead

Returns the length of the iterator if one exists. Otherwise return self.size_hint(). Read more

impl<Sp> LocalSpawnExt for Sp
where Sp: LocalSpawn + ?Sized,

fn spawn_local<Fut>(&self, future: Fut) -> Result<(), SpawnError>
where Fut: Future<Output = ()> + 'static,

Spawns a task that polls the given future with output () to completion. Read more

fn spawn_local_with_handle<Fut>( &self, future: Fut, ) -> Result<RemoteHandle<<Fut as Future>::Output>, SpawnError>
where Fut: Future + 'static,

Spawns a task that polls the given future to completion and returns a future that resolves to the spawned future’s output. Read more

impl<T, M> MakeExt<T> for M
where M: MakeVisitor<T> + Sealed<MakeExtMarker<T>>,

fn debug_alt(self) -> Alt<Self>

Wraps self so that any fmt::Debug fields are recorded using the alternate formatter ({:#?}).

fn display_messages(self) -> Messages<Self>

Wraps self so that any string fields named “message” are recorded using fmt::Display.

automatically converts the parser’s output and error values to another type, as long as they implement the From trait

🔬This is a nightly-only experimental API. (pattern)

Returns the pattern as utf-8 bytes if possible.

👎Deprecated since 1.2.0: please use read_f32_into instead

DEPRECATED. Read more

fn read_f64_into<T>(&mut self, dst: &mut [f64]) -> Result<(), Error>
where T: ByteOrder,

Reads a sequence of IEEE754 double-precision (8 bytes) floating point numbers from the underlying reader. Read more

fn read_f64_into_unchecked<T>(&mut self, dst: &mut [f64]) -> Result<(), Error>
where T: ByteOrder,

👎Deprecated since 1.2.0: please use read_f64_into instead

DEPRECATED. Read more

fn no_expansion<'r>(&'r mut self) -> Option<Cow<'r, [u8]>>

Return a fixed unchanging replacement byte string. Read more

fn by_ref<'r>(&'r mut self) -> ReplacerRef<'r, Self>

Returns a type that implements Replacer, but that borrows and wraps this Replacer. Read more

impl<F, T> Replacer for F
where F: FnMut(&Captures<'_>) -> T, T: AsRef<str>,

fn replace_append(&mut self, caps: &Captures<'_>, dst: &mut String)

Appends possibly empty data to dst to replace the current match. Read more

fn no_expansion<'r>(&'r mut self) -> Option<Cow<'r, str>>

Return a fixed unchanging replacement string. Read more

fn by_ref<'r>(&'r mut self) -> ReplacerRef<'r, Self>

Returns a type that implements Replacer, but that borrows and wraps this Replacer. Read more

fn next_u32(&mut self) -> u32

Return the next random u32. Read more

fn next_u64(&mut self) -> u64

Return the next random u64. Read more

type Socket = Socket

Socket returned by the SocketService

type Error = <S as Service<Interface>>::Error

Error returned in case of connection / setup failure

fn bind( &self, ctx: Context, interface: impl Into<Interface>, ) -> impl Future<Output = Result<(<S as SocketService>::Socket, Context), <S as SocketService>::Error>> + Send

Create a binding to a Unix/Linux/Windows socket.

impl<Sp> SpawnExt for Sp
where Sp: Spawn + ?Sized,

fn spawn<Fut>(&self, future: Fut) -> Result<(), SpawnError>
where Fut: Future<Output = ()> + Send + 'static,

Spawns a task that polls the given future with output () to completion. Read more

fn spawn_with_handle<Fut>( &self, future: Fut, ) -> Result<RemoteHandle<<Fut as Future>::Output>, SpawnError>
where Fut: Future + Send + 'static, <Fut as Future>::Output: Send,

Spawns a task that polls the given future to completion and returns a future that resolves to the spawned future’s output. Read more

impl<T> ToSmolStr for T
where T: Display + ?Sized,

The type returned in the event of a conversion error.

fn try_from(value: U) -> Result<T, <T as TryFrom>::Error>

Performs the conversion.

impl<F, T, E> TryFuture for F
where F: Future<Output = Result<T, E>> + ?Sized,

type Ok = T

The type of successful values yielded by this future

type Error = E

The type of failures yielded by this future

fn try_poll( self: Pin<&mut F>, cx: &mut Context<'_>, ) -> Poll<<F as Future>::Output>

Poll this TryFuture as if it were a Future. Read more

type Error = >::Error

The type returned in the event of a conversion error.

fn try_into(self) -> Result<U, >::Error>

Performs the conversion.

type Ok = T

The type of successful values yielded by this future

type Error = E

The type of failures yielded by this future

fn try_poll_next( self: Pin<&mut S>, cx: &mut Context<'_>, ) -> Poll<Option<Result<<S as TryStream>::Ok, <S as TryStream>::Error>>>

Poll this TryStream as if it were a Stream. Read more

Attempt to execute a predicate over an asynchronous stream and evaluate if any items satisfy the predicate. Exits early if an Err is encountered or if an Ok item is found that satisfies the predicate. Read more

impl<F, E> UdpInspector for F
where F: Fn(&Context, RelayDirection, SocketAddress, &[u8]) -> Result<UdpInspectAction, E> + Send + Sync + 'static, E: Into<Box<dyn Error + Sync + Send>> + Send + 'static,

type Error = E

fn inspect_packet( &self, ctx: &Context, direction: RelayDirection, server_address: SocketAddress, payload: &[u8], ) -> Result<UdpInspectAction, <F as UdpInspector>::Error>

Inspect a relayed udp packet respond with a UdpInspectAction.

An Iterator over the string with Conjoining Grapheme Joiner characters inserted according to the Stream-Safe Text Process (UAX15-D4)

impl<F> UsernameFormatter for F
where F: Fn(&Context, &Proxy, &ProxyFilter, &str) -> Option<String> + Send + Sync + 'static,

fn fmt_username( &self, ctx: &Context, proxy: &Proxy, filter: &ProxyFilter, username: &str, ) -> Option<String>

format the username based on the root properties of the given proxy.

impl<V, T> VZip<V> for T
where V: MultiLane<T>,

Records a type implementing Error. Read more

impl<T> WithSubscriber for T

fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> ⓘ
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more

fn with_current_subscriber(self) -> WithDispatch<Self> ⓘ

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more

Writes a IEEE754 double-precision (8 bytes) floating point number to the underlying writer. Read more