std::boxed::Box - Rust
Description: API documentation for the Rust `Box` struct in crate `std`.
Keywords: rust, rustlang, rust-lang, Box

# 1.0.0[−][src]Struct std::boxed::Box

    #[lang = "owned_box"]pub struct Box<T>(_)
     where
        T: ?Sized;

A pointer type for heap allocation.

See the module-level documentation for more.

## Implementations

### `impl<T> Box<T>`[src]

#### `pub fn new(x: T) -> Box<T>`[src]

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

#### `pub fn new_uninit() -> Box<MaybeUninit<T>>`[src]

🔬 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

#### `pub fn new_zeroed() -> Box<MaybeUninit<T>>`[src]

🔬 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

#### `pub fn pin(x: T) -> Pin<Box<T>>`1.33.0[src]

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

#### `pub fn into_boxed_slice(boxed: Box<T>) -> Box<[T]>`[src]

🔬 This is a nightly-only experimental API. (`box_into_boxed_slice` #71582)

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

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

### `impl<T> Box<[T]>`[src]

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

🔬 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

### `impl<T> Box<MaybeUninit<T>>`[src]

#### `pub unsafe fn assume_init(self) -> Box<T>`[src]

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

Converts to `Box<T>`.

# 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

    #![feature(new_uninit)]

    let mut five = Box::<u32>::new_uninit();

    let five: Box<u32> = unsafe {
        // Deferred initialization:
        five.as_mut_ptr().write(5);

        five.assume_init()
    };

    assert_eq!(*five, 5)

Run

### `impl<T> Box<[MaybeUninit<T>]>`[src]

#### `pub unsafe fn assume_init(self) -> Box<[T]>`[src]

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

Converts to `Box<[T]>`.

# 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

    #![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

### `impl<T> Box<T> where
T: ?Sized,` [src]

#### `pub unsafe fn from_raw(raw: *mut T) -> Box<T>`1.4.0[src]

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.

# 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;
        *ptr = 5;
        let x = Box::from_raw(ptr);
    }

Run

#### `pub fn into_raw(b: Box<T>) -> *mut T`1.4.0[src]

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) };

Run

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

Run

#### `pub fn into_raw_non_null(b: Box<T>) -> NonNull<T>`[src]

👎 Deprecated since 1.44.0:

use `Box::leak(b).into()` or `NonNull::from(Box::leak(b))` instead

🔬 This is a nightly-only experimental API. (`box_into_raw_non_null` #47336)

Consumes the `Box`, returning the wrapped pointer as `NonNull<T>`.

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. The easiest way to do so is to convert the `NonNull<T>` pointer into a raw pointer and back into a `Box` with the `Box::from_raw` function.

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

# Examples

    #![feature(box_into_raw_non_null)]
    #![allow(deprecated)]

    let x = Box::new(5);
    let ptr = Box::into_raw_non_null(x);

    // Clean up the memory by converting the NonNull pointer back
    // into a Box and letting the Box be dropped.
    let x = unsafe { Box::from_raw(ptr.as_ptr()) };

Run

#### `pub fn leak<'a>(b: Box<T>) -> &'a mut T where
T: 'a,` 1.26.0[src]

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);

Run

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]);

Run

#### `pub fn into_pin(boxed: Box<T>) -> Pin<Box<T>>`[src]

🔬 This is a nightly-only experimental API. (`box_into_pin` #62370)

Converts a `Box<T>` into a `Pin<Box<T>>`

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

This is also available via `From`.

### `impl Box<dyn Any + 'static>`[src]

#### `pub fn downcast<T>(self) -> Result<Box<T>, Box<dyn Any + 'static>> where
T: Any,` [src]

Attempt 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));

Run

### `impl Box<dyn Any + 'static + Send>`[src]

#### `pub fn downcast<T>(self) -> Result<Box<T>, Box<dyn Any + 'static + Send>> where
T: Any,` [src]

Attempt 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));

Run

## Trait Implementations

### `impl<T> AsMut<T> for Box<T> where
T: ?Sized,` 1.5.0[src]

#### `fn as_mut(&mut self) -> &mut T`[src]

Performs the conversion.

### `impl<T> AsRef<T> for Box<T> where
T: ?Sized,` 1.5.0[src]

#### `fn as_ref(&self) -> &T`[src]

Performs the conversion.

### `impl<T> Borrow<T> for Box<T> where
T: ?Sized,` 1.1.0[src]

#### `fn borrow(&self) -> &T`[src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for Box<T> where
T: ?Sized,` 1.1.0[src]

#### `fn borrow_mut(&mut self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

### `impl<B: BufRead + ?Sized> BufRead for Box<B>`[src]

#### `fn fill_buf(&mut self) -> Result<&[u8]>`[src]

Returns the contents of the internal buffer, filling it with more data from the inner reader if it is empty. Read more

#### `fn consume(&mut self, amt: usize)`[src]

Tells this buffer that `amt` bytes have been consumed from the buffer, so they should no longer be returned in calls to `read`. Read more

#### `fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize>`[src]

Read all bytes into `buf` until the delimiter `byte` or EOF is reached. Read more

#### `fn read_line(&mut self, buf: &mut String) -> Result<usize>`[src]

Read all bytes until a newline (the 0xA byte) is reached, and append them to the provided buffer. Read more

#### `fn split(self, byte: u8) -> Split<Self> where
Self: Sized,` [src]

Returns an iterator over the contents of this reader split on the byte `byte`. Read more

#### `fn lines(self) -> Lines<Self> where
Self: Sized,` [src]

Returns an iterator over the lines of this reader. Read more

### `impl<T> Clone for Box<[T]> where
T: Clone,` 1.3.0[src]

#### `fn clone(&self) -> Box<[T]>`[src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, other: &Box<[T]>)`[src]

Performs copy-assignment from `source`. Read more

### `impl Clone for Box<str>`1.3.0[src]

#### `fn clone(&self) -> Box<str>`[src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`[src]

Performs copy-assignment from `source`. Read more

### `impl<T> Clone for Box<T> where
T: Clone,` [src]

#### `fn clone(&self) -> Box<T>`[src]

Returns a new box with a `clone()` of this box's contents.

# 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);

Run

#### `fn clone_from(&mut self, source: &Box<T>)`[src]

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);

Run

### `impl Clone for Box<CStr>`1.29.0[src]

#### `fn clone(&self) -> Self`[src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`[src]

Performs copy-assignment from `source`. Read more

### `impl Clone for Box<OsStr>`1.29.0[src]

#### `fn clone(&self) -> Self`[src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`[src]

Performs copy-assignment from `source`. Read more

### `impl Clone for Box<Path>`1.29.0[src]

#### `fn clone(&self) -> Self`[src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`[src]

Performs copy-assignment from `source`. Read more

### `impl<T, U> CoerceUnsized<Box<U>> for Box<T> where
T: Unsize<U> + ?Sized,
U: ?Sized,` [src]

### `impl<T> Debug for Box<T> where
T: Debug + ?Sized,` [src]

#### `fn fmt(&self, f: &mut Formatter) -> Result<(), Error>`[src]

Formats the value using the given formatter. Read more

### `impl<T> Default for Box<[T]>`[src]

#### `fn default() -> Box<[T]>`[src]

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

### `impl<T> Default for Box<T> where
T: Default,` [src]

#### `fn default() -> Box<T>`[src]

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

### `impl Default for Box<str>`1.17.0[src]

#### `fn default() -> Box<str>`[src]

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

### `impl Default for Box<CStr>`1.17.0[src]

#### `fn default() -> Box<CStr>`[src]

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

### `impl Default for Box<OsStr>`1.17.0[src]

#### `fn default() -> Box<OsStr>`[src]

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

### `impl<T> Deref for Box<T> where
T: ?Sized,` [src]

#### `type Target = T`

The resulting type after dereferencing.

#### `fn deref(&self) -> &T`[src]

Dereferences the value.

### `impl<T> DerefMut for Box<T> where
T: ?Sized,` [src]

#### `fn deref_mut(&mut self) -> &mut T`[src]

Mutably dereferences the value.

### `impl<T, U> DispatchFromDyn<Box<U>> for Box<T> where
T: Unsize<U> + ?Sized,
U: ?Sized,` [src]

### `impl<T> Display for Box<T> where
T: Display + ?Sized,` [src]

#### `fn fmt(&self, f: &mut Formatter) -> Result<(), Error>`[src]

Formats the value using the given formatter. Read more

### `impl<I> DoubleEndedIterator for Box<I> where
I: DoubleEndedIterator + ?Sized,` [src]

#### `fn next_back(&mut self) -> Option<<I as Iterator>::Item>`[src]

Removes and returns an element from the end of the iterator. Read more

#### `fn nth_back(&mut self, n: usize) -> Option<<I as Iterator>::Item>`[src]

Returns the `n`th element from the end of the iterator. Read more

#### `fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> R where
F: FnMut(B, Self::Item) -> R,
R: Try<Ok = B>,` 1.27.0[src]

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

#### `fn rfold<B, F>(self, init: B, f: F) -> B where
F: FnMut(B, Self::Item) -> B,` 1.27.0[src]

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

#### `fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item> where
P: FnMut(&Self::Item) -> bool,` 1.27.0[src]

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

### `impl<T> Drop for Box<T> where
T: ?Sized,` [src]

#### `fn drop(&mut self)`[src]

Executes the destructor for this type. Read more

### `impl<T> Eq for Box<T> where
T: Eq + ?Sized,` [src]

### `impl<T: Error> Error for Box<T>`1.8.0[src]

#### `fn description(&self) -> &str`[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

`if let Err(e) = "xc".parse::<u32>() { // Print` e`itself, no need for description(). eprintln!("Error: {}", e); }` Read more

#### `fn cause(&self) -> Option<&dyn Error>`[src]

👎 Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

#### `fn source(&self) -> Option<&(dyn Error + 'static)>`[src]

The lower-level source of this error, if any. Read more

#### `fn backtrace(&self) -> Option<&Backtrace>`[src]

🔬 This is a nightly-only experimental API. (`backtrace` #53487)

Returns a stack backtrace, if available, of where this error occurred. Read more

### `impl<I> ExactSizeIterator for Box<I> where
I: ExactSizeIterator + ?Sized,` [src]

#### `fn len(&self) -> usize`[src]

Returns the exact length of the iterator. Read more

#### `fn is_empty(&self) -> bool`[src]

🔬 This is a nightly-only experimental API. (`exact_size_is_empty` #35428)

Returns `true` if the iterator is empty. Read more

### `impl<A, F> Fn<A> for Box<F> where
F: Fn<A> + ?Sized,` 1.35.0[src]

#### `extern "rust-call" fn call(&self, args: A) -> <Box<F> as FnOnce<A>>::Output`[src]

🔬 This is a nightly-only experimental API. (`fn_traits` #29625)

Performs the call operation.

### `impl<A, F> FnMut<A> for Box<F> where
F: FnMut<A> + ?Sized,` 1.35.0[src]

#### `extern "rust-call" fn call_mut(
&mut self,
args: A
) -> <Box<F> as FnOnce<A>>::Output`[src]

🔬 This is a nightly-only experimental API. (`fn_traits` #29625)

Performs the call operation.

### `impl<A, F> FnOnce<A> for Box<F> where
F: FnOnce<A> + ?Sized,` 1.35.0[src]

#### `type Output = <F as FnOnce<A>>::Output`

The returned type after the call operator is used.

#### `extern "rust-call" fn call_once(self, args: A) -> <Box<F> as FnOnce<A>>::Output`[src]

🔬 This is a nightly-only experimental API. (`fn_traits` #29625)

Performs the call operation.

### `impl<'_, T> From<&'_ [T]> for Box<[T]> where
T: Copy,` 1.17.0[src]

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

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

### `impl<'_> From<&'_ CStr> for Box<CStr>`1.17.0[src]

#### `fn from(s: &CStr) -> Box<CStr>`[src]

Performs the conversion.

### `impl<'_> From<&'_ OsStr> for Box<OsStr>`1.17.0[src]

#### `fn from(s: &OsStr) -> Box<OsStr>`[src]

Performs the conversion.

### `impl<'_> From<&'_ Path> for Box<Path>`1.17.0[src]

#### `fn from(path: &Path) -> Box<Path>`[src]

Performs the conversion.

### `impl<'_> From<&'_ str> for Box<str>`1.17.0[src]

#### `fn from(s: &str) -> Box<str>`[src]

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

### `impl<'a, '_> From<&'_ str> for Box<dyn Error + Send + Sync + 'a>`[src]

#### `fn from(err: &str) -> Box<dyn Error + Send + Sync + 'a>`[src]

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

# Examples

    use std::error::Error;
    use std::mem;

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

Run

### `impl<'_> From<&'_ str> for Box<dyn Error>`1.6.0[src]

#### `fn from(err: &str) -> Box<dyn Error>`[src]

Converts a `str` into a box of dyn `Error`.

# Examples

    use std::error::Error;
    use std::mem;

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

Run

### `impl<const N: usize, T> From<[T; N]> for Box<[T]> where
[T; N]: LengthAtMost32,` 1.45.0[src]

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

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

### `impl<T> From<Box<[T]>> for Vec<T>`1.18.0[src]

#### `fn from(s: Box<[T]>) -> Vec<T>`[src]

Performs the conversion.

### `impl From<Box<CStr>> for CString` 1.18.0[src]

#### `fn from(s: Box<CStr>) -> CString`[src]

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

### `impl From<Box<OsStr>> for OsString` 1.18.0[src]

#### `fn from(boxed: Box<OsStr>) -> OsString`[src]

Converts a `Box``<``OsStr``>` into a `OsString` without copying or allocating.

### `impl From<Box<Path>> for PathBuf` 1.18.0[src]

#### `fn from(boxed: Box<Path>) -> PathBuf`[src]

Converts a `Box<Path>` into a `PathBuf`

This conversion does not allocate or copy memory.

### `impl<T> From<Box<T>> for Pin<Box<T>> where
T: ?Sized,` 1.33.0[src]

#### `fn from(boxed: Box<T>) -> Pin<Box<T>>`[src]

Converts a `Box<T>` into a `Pin<Box<T>>`

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

### `impl<T> From<Box<T>> for Rc<T> where
T: ?Sized,` 1.21.0[src]

#### `fn from(v: Box<T>) -> Rc<T>`[src]

Performs the conversion.

### `impl<T> From<Box<T>> for Arc<T> where
T: ?Sized,` 1.21.0[src]

#### `fn from(v: Box<T>) -> Arc<T>`[src]

Performs the conversion.

### `impl From<Box<str>> for String` 1.18.0[src]

#### `fn from(s: Box<str>) -> String`[src]

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

# Examples

Basic usage:

    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)

Run

### `impl From<Box<str>> for Box<[u8]>`1.19.0[src]

#### `fn from(s: Box<str>) -> Box<[u8]>`[src]

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);

Run

### `impl From<CString> for Box<CStr>`1.20.0[src]

#### `fn from(s: CString) -> Box<CStr>`[src]

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

### `impl<'_, T> From<Cow<'_, [T]>> for Box<[T]> where
T: Copy,` 1.45.0[src]

#### `fn from(cow: Cow<[T]>) -> Box<[T]>`[src]

Performs the conversion.

### `impl<'_> From<Cow<'_, CStr>> for Box<CStr>`1.45.0[src]

#### `fn from(cow: Cow<CStr>) -> Box<CStr>`[src]

Performs the conversion.

### `impl<'_> From<Cow<'_, OsStr>> for Box<OsStr>`1.45.0[src]

#### `fn from(cow: Cow<OsStr>) -> Box<OsStr>`[src]

Performs the conversion.

### `impl<'_> From<Cow<'_, Path>> for Box<Path>`1.45.0[src]

#### `fn from(cow: Cow<Path>) -> Box<Path>`[src]

Performs the conversion.

### `impl<'_> From<Cow<'_, str>> for Box<str>`1.45.0[src]

#### `fn from(cow: Cow<str>) -> Box<str>`[src]

Performs the conversion.

### `impl<'a> From<Cow<'a, str>> for Box<dyn Error>`1.22.0[src]

#### `fn from(err: Cow<'a, str>) -> Box<dyn Error>`[src]

Converts a `Cow` into a box of dyn `Error`.

# Examples

    use std::error::Error;
    use std::mem;
    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!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))

Run

### `impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + Send + Sync + 'a>`1.22.0[src]

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

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

# Examples

    use std::error::Error;
    use std::mem;
    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!(
        mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))

Run

### `impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a>`[src]

#### `fn from(err: E) -> Box<dyn Error + 'a>`[src]

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

# Examples

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

    #[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 == mem::size_of_val(&an_error));
    let a_boxed_error = Box::<dyn Error>::from(an_error);
    assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))

Run

### `impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<dyn Error + Send + Sync + 'a>`[src]

#### `fn from(err: E) -> Box<dyn Error + Send + Sync + 'a>`[src]

Converts a type of `Error` + `Send` + `Sync` into a box of dyn `Error` + `Send` + `Sync`.

# Examples

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

    #[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 {}

    unsafe impl Send for AnError {}

    unsafe impl Sync for AnError {}

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

Run

### `impl From<OsString> for Box<OsStr>`1.20.0[src]

#### `fn from(s: OsString) -> Box<OsStr>`[src]

Converts a `OsString` into a `Box``<OsStr>` without copying or allocating.

### `impl From<PathBuf> for Box<Path>`1.20.0[src]

#### `fn from(p: PathBuf) -> Box<Path>`[src]

Converts a `PathBuf` into a `Box<Path>`

This conversion currently should not allocate memory, but this behavior is not guaranteed on all platforms or in all future versions.

### `impl From<String> for Box<str>`1.20.0[src]

#### `fn from(s: String) -> Box<str>`[src]

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

### `impl From<String> for Box<dyn Error + Send + Sync>`[src]

#### `fn from(err: String) -> Box<dyn Error + Send + Sync>`[src]

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

# Examples

    use std::error::Error;
    use std::mem;

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

Run

### `impl From<String> for Box<dyn Error>`1.6.0[src]

#### `fn from(str_err: String) -> Box<dyn Error>`[src]

Converts a `String` into a box of dyn `Error`.

# Examples

    use std::error::Error;
    use std::mem;

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

Run

### `impl<T> From<T> for Box<T>`1.6.0[src]

#### `fn from(t: T) -> Box<T>`[src]

Converts a generic type `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

### `impl<T> From<Vec<T>> for Box<[T]>`1.20.0[src]

#### `fn from(v: Vec<T>) -> Box<[T]>`[src]

Performs the conversion.

### `impl<A> FromIterator<A> for Box<[A]>`1.32.0[src]

#### `fn from_iter<T>(iter: T) -> Box<[A]> where
T: IntoIterator<Item = A>,` [src]

Creates a value from an iterator. Read more

### `impl<I> FusedIterator for Box<I> where
I: FusedIterator + ?Sized,` 1.26.0[src]

### `impl<F> Future for Box<F> where
F: Unpin + Future + ?Sized,` 1.36.0[src]

#### `type Output = <F as Future>::Output`

The type of value produced on completion.

#### `fn poll(
self: Pin<&mut Box<F>>,
cx: &mut Context
) -> Poll<<Box<F> as Future>::Output>`[src]

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

### `impl<G, R> Generator<R> for Box<G> where
G: Unpin + Generator<R> + ?Sized,` [src]

#### `type Yield = <G as Generator<R>>::Yield`

🔬 This is a nightly-only experimental API. (`generator_trait` #43122)

The type of value this generator yields. Read more

#### `type Return = <G as Generator<R>>::Return`

🔬 This is a nightly-only experimental API. (`generator_trait` #43122)

The type of value this generator returns. Read more

#### `fn resume(
self: Pin<&mut Box<G>>,
arg: R
) -> GeneratorState<<Box<G> as Generator<R>>::Yield, <Box<G> as Generator<R>>::Return>`[src]

🔬 This is a nightly-only experimental API. (`generator_trait` #43122)

Resumes the execution of this generator. Read more

### `impl<T> Hash for Box<T> where
T: Hash + ?Sized,` [src]

#### `fn hash<H>(&self, state: &mut H) where
H: Hasher,` [src]

Feeds this value into the given [`Hasher`]. Read more

#### `fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,` 1.3.0[src]

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

### `impl<T> Hasher for Box<T> where
T: Hasher + ?Sized,` 1.22.0[src]

#### `fn finish(&self) -> u64`[src]

Returns the hash value for the values written so far. Read more

#### `fn write(&mut self, bytes: &[u8])`[src]

Writes some data into this `Hasher`. Read more

#### `fn write_u8(&mut self, i: u8)`[src]

Writes a single `u8` into this hasher.

#### `fn write_u16(&mut self, i: u16)`[src]

Writes a single `u16` into this hasher.

#### `fn write_u32(&mut self, i: u32)`[src]

Writes a single `u32` into this hasher.

#### `fn write_u64(&mut self, i: u64)`[src]

Writes a single `u64` into this hasher.

#### `fn write_u128(&mut self, i: u128)`[src]

Writes a single `u128` into this hasher.

#### `fn write_usize(&mut self, i: usize)`[src]

Writes a single `usize` into this hasher.

#### `fn write_i8(&mut self, i: i8)`[src]

Writes a single `i8` into this hasher.

#### `fn write_i16(&mut self, i: i16)`[src]

Writes a single `i16` into this hasher.

#### `fn write_i32(&mut self, i: i32)`[src]

Writes a single `i32` into this hasher.

#### `fn write_i64(&mut self, i: i64)`[src]

Writes a single `i64` into this hasher.

#### `fn write_i128(&mut self, i: i128)`[src]

Writes a single `i128` into this hasher.

#### `fn write_isize(&mut self, i: isize)`[src]

Writes a single `isize` into this hasher.

### `impl<I> Iterator for Box<I> where
I: Iterator + ?Sized,` [src]

#### `type Item = <I as Iterator>::Item`

The type of the elements being iterated over.

#### `fn next(&mut self) -> Option<<I as Iterator>::Item>`[src]

Advances the iterator and returns the next value. Read more

#### `fn size_hint(&self) -> (usize, Option<usize>)`[src]

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

#### `fn nth(&mut self, n: usize) -> Option<<I as Iterator>::Item>`[src]

Returns the `n`th element of the iterator. Read more

#### `fn last(self) -> Option<<I as Iterator>::Item>`[src]

Consumes the iterator, returning the last element. Read more

#### `fn count(self) -> usize`[src]

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

#### `fn step_by(self, step: usize) -> StepBy<Self>`1.28.0[src]

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

#### `fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator<Item = Self::Item>,` [src]

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

#### `fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator,` [src]

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

#### `fn map<B, F>(self, f: F) -> Map<Self, F> where
F: FnMut(Self::Item) -> B,` [src]

Takes a closure and creates an iterator which calls that closure on each element. Read more

#### `fn for_each<F>(self, f: F) where
F: FnMut(Self::Item),` 1.21.0[src]

Calls a closure on each element of an iterator. Read more

#### `fn filter<P>(self, predicate: P) -> Filter<Self, P> where
P: FnMut(&Self::Item) -> bool,` [src]

Creates an iterator which uses a closure to determine if an element should be yielded. Read more

#### `fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
F: FnMut(Self::Item) -> Option<B>,` [src]

Creates an iterator that both filters and maps. Read more

#### `fn enumerate(self) -> Enumerate<Self>`[src]

Creates an iterator which gives the current iteration count as well as the next value. Read more

#### `fn peekable(self) -> Peekable<Self>`[src]

Creates an iterator which can use `peek` to look at the next element of the iterator without consuming it. Read more

#### `fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
P: FnMut(&Self::Item) -> bool,` [src]

Creates an iterator that [`skip`]s elements based on a predicate. Read more

#### `fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
P: FnMut(&Self::Item) -> bool,` [src]

Creates an iterator that yields elements based on a predicate. Read more

#### `fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P> where
P: FnMut(Self::Item) -> Option<B>,` [src]

🔬 This is a nightly-only experimental API. (`iter_map_while` #68537)

recently added

Creates an iterator that both yields elements based on a predicate and maps. Read more

#### `fn skip(self, n: usize) -> Skip<Self>`[src]

Creates an iterator that skips the first `n` elements. Read more

#### `fn take(self, n: usize) -> Take<Self>`[src]

Creates an iterator that yields its first `n` elements. Read more

#### `fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where
F: FnMut(&mut St, Self::Item) -> Option<B>,` [src]

An iterator adaptor similar to [`fold`] that holds internal state and produces a new iterator. Read more

#### `fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
F: FnMut(Self::Item) -> U,
U: IntoIterator,` [src]

Creates an iterator that works like map, but flattens nested structure. Read more

#### `fn flatten(self) -> Flatten<Self> where
Self::Item: IntoIterator,` 1.29.0[src]

Creates an iterator that flattens nested structure. Read more

#### `fn fuse(self) -> Fuse<Self>`[src]

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

#### `fn inspect<F>(self, f: F) -> Inspect<Self, F> where
F: FnMut(&Self::Item),` [src]

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

#### `fn by_ref(&mut self) -> &mut Self`[src]

Borrows an iterator, rather than consuming it. Read more

#### `#[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"]fn collect<B>(self) -> B where
B: FromIterator<Self::Item>,` [src]

Transforms an iterator into a collection. Read more

#### `fn partition<B, F>(self, f: F) -> (B, B) where
B: Default + Extend<Self::Item>,
F: FnMut(&Self::Item) -> bool,` [src]

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

#### `fn partition_in_place<'a, T, P>(self, predicate: P) -> usize where
P: FnMut(&T) -> bool,
Self: DoubleEndedIterator<Item = &'a mut T>,
T: 'a,` [src]

🔬 This is a nightly-only experimental API. (`iter_partition_in_place` #62543)

new API

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<P>(self, predicate: P) -> bool where
P: FnMut(Self::Item) -> bool,` [src]

🔬 This is a nightly-only experimental API. (`iter_is_partitioned` #62544)

new API

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

#### `fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
F: FnMut(B, Self::Item) -> R,
R: Try<Ok = B>,` 1.27.0[src]

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

#### `fn try_for_each<F, R>(&mut self, f: F) -> R where
F: FnMut(Self::Item) -> R,
R: Try<Ok = ()>,` 1.27.0[src]

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

#### `fn fold<B, F>(self, init: B, f: F) -> B where
F: FnMut(B, Self::Item) -> B,` [src]

An iterator method that applies a function, producing a single, final value. Read more

#### `fn fold_first<F>(self, f: F) -> Option<Self::Item> where
F: FnMut(Self::Item, Self::Item) -> Self::Item,` [src]

🔬 This is a nightly-only experimental API. (`iterator_fold_self` #68125)

The same as `fold()`, but uses the first element in the iterator as the initial value, folding every subsequent element into it. If the iterator is empty, return `None`; otherwise, return the result of the fold. Read more

#### `fn all<F>(&mut self, f: F) -> bool where
F: FnMut(Self::Item) -> bool,` [src]

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

#### `fn any<F>(&mut self, f: F) -> bool where
F: FnMut(Self::Item) -> bool,` [src]

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

#### `fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where
P: FnMut(&Self::Item) -> bool,` [src]

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

#### `fn find_map<B, F>(&mut self, f: F) -> Option<B> where
F: FnMut(Self::Item) -> Option<B>,` 1.30.0[src]

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

#### `fn try_find<F, E, R>(&mut self, f: F) -> Result<Option<Self::Item>, E> where
F: FnMut(&Self::Item) -> R,
R: Try<Ok = bool, Error = E>,` [src]

🔬 This is a nightly-only experimental API. (`try_find` #63178)

new API

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

#### `fn position<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,` [src]

Searches for an element in an iterator, returning its index. Read more

#### `fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,
Self: ExactSizeIterator + DoubleEndedIterator,` [src]

Searches for an element in an iterator from the right, returning its index. Read more

#### `fn max(self) -> Option<Self::Item> where
Self::Item: Ord,` [src]

Returns the maximum element of an iterator. Read more

#### `fn min(self) -> Option<Self::Item> where
Self::Item: Ord,` [src]

Returns the minimum element of an iterator. Read more

#### `fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where
B: Ord,
F: FnMut(&Self::Item) -> B,` 1.6.0[src]

Returns the element that gives the maximum value from the specified function. Read more

#### `fn max_by<F>(self, compare: F) -> Option<Self::Item> where
F: FnMut(&Self::Item, &Self::Item) -> Ordering,` 1.15.0[src]

Returns the element that gives the maximum value with respect to the specified comparison function. Read more

#### `fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where
B: Ord,
F: FnMut(&Self::Item) -> B,` 1.6.0[src]

Returns the element that gives the minimum value from the specified function. Read more

#### `fn min_by<F>(self, compare: F) -> Option<Self::Item> where
F: FnMut(&Self::Item, &Self::Item) -> Ordering,` 1.15.0[src]

Returns the element that gives the minimum value with respect to the specified comparison function. Read more

#### `fn rev(self) -> Rev<Self> where
Self: DoubleEndedIterator,` [src]

Reverses an iterator's direction. Read more

#### `fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where
FromA: Default + Extend<A>,
FromB: Default + Extend<B>,
Self: Iterator<Item = (A, B)>,` [src]

Converts an iterator of pairs into a pair of containers. Read more

#### `fn copied<'a, T>(self) -> Copied<Self> where
Self: Iterator<Item = &'a T>,
T: 'a + Copy,` 1.36.0[src]

Creates an iterator which copies all of its elements. Read more

#### `fn cloned<'a, T>(self) -> Cloned<Self> where
Self: Iterator<Item = &'a T>,
T: 'a + Clone,` [src]

Creates an iterator which [`clone`]s all of its elements. Read more

#### `fn cycle(self) -> Cycle<Self> where
Self: Clone,` [src]

Repeats an iterator endlessly. Read more

#### `fn sum<S>(self) -> S where
S: Sum<Self::Item>,` 1.11.0[src]

Sums the elements of an iterator. Read more

#### `fn product<P>(self) -> P where
P: Product<Self::Item>,` 1.11.0[src]

Iterates over the entire iterator, multiplying all the elements Read more

#### `fn cmp<I>(self, other: I) -> Ordering where
I: IntoIterator<Item = Self::Item>,
Self::Item: Ord,` 1.5.0[src]

Lexicographically compares the elements of this `Iterator` with those of another. Read more

#### `fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
I: IntoIterator,` [src]

🔬 This is a nightly-only experimental API. (`iter_order_by` #64295)

Lexicographically compares the elements of this `Iterator` with those of another with respect to the specified comparison function. Read more

#### `fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,` 1.5.0[src]

Lexicographically compares the elements of this `Iterator` with those of another. Read more

#### `fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering> where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
I: IntoIterator,` [src]

🔬 This is a nightly-only experimental API. (`iter_order_by` #64295)

Lexicographically compares the elements of this `Iterator` with those of another with respect to the specified comparison function. Read more

#### `fn eq<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,` 1.5.0[src]

Determines if the elements of this `Iterator` are equal to those of another. Read more

#### `fn eq_by<I, F>(self, other: I, eq: F) -> bool where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
I: IntoIterator,` [src]

🔬 This is a nightly-only experimental API. (`iter_order_by` #64295)

Determines if the elements of this `Iterator` are equal to those of another with respect to the specified equality function. Read more

#### `fn ne<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,` 1.5.0[src]

Determines if the elements of this `Iterator` are unequal to those of another. Read more

#### `fn lt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,` 1.5.0[src]

Determines if the elements of this `Iterator` are lexicographically less than those of another. Read more

#### `fn le<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,` 1.5.0[src]

Determines if the elements of this `Iterator` are lexicographically less or equal to those of another. Read more

#### `fn gt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,` 1.5.0[src]

Determines if the elements of this `Iterator` are lexicographically greater than those of another. Read more

#### `fn ge<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,` 1.5.0[src]

Determines if the elements of this `Iterator` are lexicographically greater than or equal to those of another. Read more

#### `fn is_sorted(self) -> bool where
Self::Item: PartialOrd<Self::Item>,` [src]

🔬 This is a nightly-only experimental API. (`is_sorted` #53485)

new API

Checks if the elements of this iterator are sorted. Read more

#### `fn is_sorted_by<F>(self, compare: F) -> bool where
F: FnMut(&Self::Item, &Self::Item) -> Option<Ordering>,` [src]

🔬 This is a nightly-only experimental API. (`is_sorted` #53485)

new API

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

#### `fn is_sorted_by_key<F, K>(self, f: F) -> bool where
F: FnMut(Self::Item) -> K,
K: PartialOrd<K>,` [src]

🔬 This is a nightly-only experimental API. (`is_sorted` #53485)

new API

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

### `impl<T> Ord for Box<T> where
T: Ord + ?Sized,` [src]

#### `fn cmp(&self, other: &Box<T>) -> Ordering`[src]

This method returns an [`Ordering`] between `self` and `other`. Read more

#### `#[must_use]fn max(self, other: Self) -> Self`1.21.0[src]

Compares and returns the maximum of two values. Read more

#### `#[must_use]fn min(self, other: Self) -> Self`1.21.0[src]

Compares and returns the minimum of two values. Read more

#### `#[must_use]fn clamp(self, min: Self, max: Self) -> Self`[src]

🔬 This is a nightly-only experimental API. (`clamp` #44095)

Restrict a value to a certain interval. Read more

### `impl<T> PartialEq<Box<T>> for Box<T> where
T: PartialEq<T> + ?Sized,` [src]

#### `fn eq(&self, other: &Box<T>) -> bool`[src]

This method tests for `self` and `other` values to be equal, and is used by `==`. Read more

#### `fn ne(&self, other: &Box<T>) -> bool`[src]

This method tests for `!=`.

### `impl<T> PartialOrd<Box<T>> for Box<T> where
T: PartialOrd<T> + ?Sized,` [src]

#### `fn partial_cmp(&self, other: &Box<T>) -> Option<Ordering>`[src]

This method returns an ordering between `self` and `other` values if one exists. Read more

#### `fn lt(&self, other: &Box<T>) -> bool`[src]

This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more

#### `fn le(&self, other: &Box<T>) -> bool`[src]

This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more

#### `fn ge(&self, other: &Box<T>) -> bool`[src]

This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more

#### `fn gt(&self, other: &Box<T>) -> bool`[src]

This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more

### `impl<T> Pointer for Box<T> where
T: ?Sized,` [src]

#### `fn fmt(&self, f: &mut Formatter) -> Result<(), Error>`[src]

Formats the value using the given formatter.

### `impl<R: Read + ?Sized> Read for Box<R>`[src]

#### `fn read(&mut self, buf: &mut [u8]) -> Result<usize>`[src]

Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more

#### `fn read_vectored(&mut self, bufs: &mut [IoSliceMut]) -> Result<usize>`[src]

Like `read`, except that it reads into a slice of buffers. Read more

#### `fn is_read_vectored(&self) -> bool`[src]

🔬 This is a nightly-only experimental API. (`can_vector` #69941)

Determines if this `Read`er has an efficient `read_vectored` implementation. Read more

#### `unsafe fn initializer(&self) -> Initializer`[src]

🔬 This is a nightly-only experimental API. (`read_initializer` #42788)

Determines if this `Read`er can work with buffers of uninitialized memory. Read more

#### `fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>`[src]

Read all bytes until EOF in this source, placing them into `buf`. Read more

#### `fn read_to_string(&mut self, buf: &mut String) -> Result<usize>`[src]

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

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

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

#### `fn by_ref(&mut self) -> &mut Self where
Self: Sized,` [src]

Creates a "by reference" adaptor for this instance of `Read`. Read more

#### `fn bytes(self) -> Bytes<Self> where
Self: Sized,` [src]

Transforms this `Read` instance to an [`Iterator`] over its bytes. Read more

#### `fn chain<R: Read>(self, next: R) -> Chain<Self, R> where
Self: Sized,` [src]

Creates an adaptor which will chain this stream with another. Read more

#### `fn take(self, limit: u64) -> Take<Self> where
Self: Sized,` [src]

Creates an adaptor which will read at most `limit` bytes from it. Read more

### `impl<S: Seek + ?Sized> Seek for Box<S>`[src]

#### `fn seek(&mut self, pos: SeekFrom) -> Result<u64>`[src]

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

#### `fn stream_len(&mut self) -> Result<u64>`[src]

🔬 This is a nightly-only experimental API. (`seek_convenience` #59359)

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

#### `fn stream_position(&mut self) -> Result<u64>`[src]

🔬 This is a nightly-only experimental API. (`seek_convenience` #59359)

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

### `impl<const N: usize, T> TryFrom<Box<[T]>> for Box<[T; N]> where
[T; N]: LengthAtMost32,` 1.43.0[src]

#### `type Error = Box<[T]>`

The type returned in the event of a conversion error.

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

Performs the conversion.

### `impl<T> Unpin for Box<T> where
T: ?Sized,` 1.33.0[src]

### `impl<W: Write + ?Sized> Write for Box<W>`[src]

#### `fn write(&mut self, buf: &[u8]) -> Result<usize>`[src]

Write a buffer into this writer, returning how many bytes were written. Read more

#### `fn write_vectored(&mut self, bufs: &[IoSlice]) -> Result<usize>`[src]

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

#### `fn is_write_vectored(&self) -> bool`[src]

🔬 This is a nightly-only experimental API. (`can_vector` #69941)

Determines if this `Write`er has an efficient `write_vectored` implementation. Read more

#### `fn flush(&mut self) -> Result<()>`[src]

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

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

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

#### `fn write_fmt(&mut self, fmt: Arguments) -> Result<()>`[src]

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

#### `fn write_all_vectored(&mut self, bufs: &mut [IoSlice]) -> Result<()>`[src]

🔬 This is a nightly-only experimental API. (`write_all_vectored` #70436)

Attempts to write multiple buffers into this writer. Read more

#### `fn by_ref(&mut self) -> &mut Self where
Self: Sized,` [src]

Creates a "by reference" adaptor for this instance of `Write`. Read more

## Auto Trait Implementations

### `impl<T: ?Sized> RefUnwindSafe for Box<T> where
T: RefUnwindSafe,`

### `impl<T: ?Sized> Send for Box<T> where
T: Send,`

### `impl<T: ?Sized> Sync for Box<T> where
T: Sync,`

### `impl<T: ?Sized> UnwindSafe for Box<T> where
T: UnwindSafe,`

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `fn type_id(&self) -> TypeId`[src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `fn borrow(&self) -> &T`[src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `fn borrow_mut(&mut self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

### `impl<T> From<!> for T`[src]

#### `fn from(t: !) -> T`[src]

Performs the conversion.

### `impl<T> From<T> for T`[src]

#### `fn from(t: T) -> T`[src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `fn into(self) -> U`[src]

Performs the conversion.

### `impl<F> IntoFuture for F where
F: Future,` [src]

#### `type Output = <F as Future>::Output`

🔬 This is a nightly-only experimental API. (`into_future` #67644)

The output that the future will produce on completion.

#### `type Future = F`

🔬 This is a nightly-only experimental API. (`into_future` #67644)

Which kind of future are we turning this into?

#### `fn into_future(self) -> <F as IntoFuture>::Future`[src]

🔬 This is a nightly-only experimental API. (`into_future` #67644)

Creates a future from a value.

### `impl<I> IntoIterator for I where
I: Iterator,` [src]

#### `type Item = <I as Iterator>::Item`

The type of the elements being iterated over.

#### `type IntoIter = I`

Which kind of iterator are we turning this into?

#### `fn into_iter(self) -> I`[src]

Creates an iterator from a value. Read more

### `impl<'a, F> Pattern<'a> for F where
F: FnMut(char) -> bool,` [src]

#### `type Searcher = CharPredicateSearcher<'a, F>`

🔬 This is a nightly-only experimental API. (`pattern` #27721)

API not fully fleshed out and ready to be stabilized

Associated searcher for this pattern

#### `fn into_searcher(self, haystack: &'a str) -> CharPredicateSearcher<'a, F>`[src]

🔬 This is a nightly-only experimental API. (`pattern` #27721)

API not fully fleshed out and ready to be stabilized

Constructs the associated searcher from `self` and the `haystack` to search in. Read more

#### `fn is_contained_in(self, haystack: &'a str) -> bool`[src]

🔬 This is a nightly-only experimental API. (`pattern` #27721)

API not fully fleshed out and ready to be stabilized

Checks whether the pattern matches anywhere in the haystack

#### `fn is_prefix_of(self, haystack: &'a str) -> bool`[src]

🔬 This is a nightly-only experimental API. (`pattern` #27721)

API not fully fleshed out and ready to be stabilized

Checks whether the pattern matches at the front of the haystack

#### `fn strip_prefix_of(self, haystack: &'a str) -> Option<&'a str>`[src]

🔬 This is a nightly-only experimental API. (`pattern` #27721)

API not fully fleshed out and ready to be stabilized

Removes the pattern from the front of haystack, if it matches.

#### `fn is_suffix_of(self, haystack: &'a str) -> bool where
CharPredicateSearcher<'a, F>: ReverseSearcher<'a>,` [src]

🔬 This is a nightly-only experimental API. (`pattern` #27721)

API not fully fleshed out and ready to be stabilized

Checks whether the pattern matches at the back of the haystack

#### `fn strip_suffix_of(self, haystack: &'a str) -> Option<&'a str> where
CharPredicateSearcher<'a, F>: ReverseSearcher<'a>,` [src]

🔬 This is a nightly-only experimental API. (`pattern` #27721)

API not fully fleshed out and ready to be stabilized

Removes the pattern from the back of haystack, if it matches.

### `impl<T> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `fn to_owned(&self) -> T`[src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `fn clone_into(&self, target: &mut T)`[src]

🔬 This is a nightly-only experimental API. (`toowned_clone_into` #41263)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

### `impl<T> ToString for T where
T: Display + ?Sized,` [src]

#### `default fn to_string(&self) -> String`[src]

Converts the given value to a `String`. Read more

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>`[src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>`[src]

Performs the conversion.