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

# 1.0.0[−][src]Struct alloc::boxed::Box

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

A pointer type for heap allocation.

See the module-level documentation for more.

## Methods

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

####
ⓘImportant traits for Box<I>

### Important traits for Box<I>

`impl<I: Iterator + ?Sized> Iterator for Box<I> type Item = I::Item;`
`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);

#### `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.

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

#### `pub unsafe fn from_raw(raw: *mut T) -> Self`
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. Since the way `Box` allocates and releases memory is unspecified, the only valid pointer to pass to this function is the one taken from another `Box` via the `Box::into_raw` function.

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

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

#### `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. The proper way to do so is to convert the raw pointer 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(b)` instead of `b.into_raw()`. This is so that there is no conflict with a method on the inner type.

# Examples

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

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

🔬 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 proper 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)]

    fn main() {
        let x = Box::new(5);
        let ptr = Box::into_raw_non_null(x);
    }

#### `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:

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

Unsized data:

    fn main() {
        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]);
    }

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

🔬 This is a nightly-only experimental API. (`box_into_pin` #0)

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>`[src]

#### `pub fn downcast<T: Any>(self) -> Result<Box<T>, Box<dyn 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);
        }
    }

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

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

#### `pub fn downcast<T: Any>(self) -> Result<Box<T>, Box<dyn Any + Send>>`[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);
        }
    }

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

## Trait Implementations

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

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

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

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

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

Compares and returns the maximum of two values. Read more

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

Compares and returns the minimum of two values. Read more

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

#### `type Target = T`

The resulting type after dereferencing.

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

Dereferences the value.

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

#### `fn from(t: T) -> Self`[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);

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

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

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

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

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

####
ⓘImportant traits for Box<I>

### Important traits for Box<I>

`impl<I: Iterator + ?Sized> Iterator for Box<I> type Item = I::Item;`
`fn from(slice: &'a [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);

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

####
ⓘImportant traits for Box<I>

### Important traits for Box<I>

`impl<I: Iterator + ?Sized> Iterator for Box<I> type Item = I::Item;`
`fn from(s: &'a 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);

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

#### `fn from(s: Box<str>) -> Self`[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);

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

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

Performs the conversion.

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

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

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

####
ⓘImportant traits for Box<I>

### Important traits for Box<I>

`impl<I: Iterator + ?Sized> Iterator for Box<I> type Item = I::Item;`
`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)

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

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

Performs the conversion.

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

####
ⓘImportant traits for Box<I>

### Important traits for Box<I>

`impl<I: Iterator + ?Sized> Iterator for Box<I> type Item = I::Item;`
`fn from(v: Vec<T>) -> Box<[T]>`[src]

Performs the conversion.

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

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

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

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

Formats the value using the given formatter. Read more

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

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

Formats the value using the given formatter. Read more

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

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

Mutably dereferences the value.

### `impl<T: ?Sized> Receiver for Box<T>`[src]

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

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

Executes the destructor for this type. Read more

### `impl<'a, A, R> FnOnce<A> for Box<dyn FnBox<A, Output = R> + 'a>`[src]

#### `type Output = R`

The returned type after the call operator is used.

#### `extern "rust-call" fn call_once(self, args: A) -> R`[src]

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

Performs the call operation.

### `impl<'a, A, R> FnOnce<A> for Box<dyn FnBox<A, Output = R> + Send + 'a>`[src]

#### `type Output = R`

The returned type after the call operator is used.

#### `extern "rust-call" fn call_once(self, args: A) -> R`[src]

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

Performs the call operation.

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

#### `type Yield = T::Yield`

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

The type of value this generator yields. Read more

#### `type Return = T::Return`

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

The type of value this generator returns. Read more

#### `unsafe fn resume(&mut self) -> GeneratorState<Self::Yield, Self::Return>`[src]

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

Resumes the execution of this generator. Read more

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

#### `fn hash<H: Hasher>(&self, state: &mut H)`[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: ?Sized + Hasher> Hasher for Box<T>`
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: DoubleEndedIterator + ?Sized> DoubleEndedIterator for Box<I>`[src]

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

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

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

🔬 This is a nightly-only experimental API. (`iter_nth_back` #56995)

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

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

#### `type Item = I::Item`

The type of the elements being iterated over.

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

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

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

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

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

Consumes the iterator, returning the last element. 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 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]

Do 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 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 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 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,` [src]

🔬 This is a nightly-only experimental API. (`iter_copied` #57127)

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 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 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 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

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

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

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

Creates a value from an iterator. Read more

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

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

Returns the exact number of times the iterator will iterate. Read more

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

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

Returns whether the iterator is empty. Read more

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

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

Formats the value using the given formatter.

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

####
ⓘImportant traits for Box<I>

### Important traits for Box<I>

`impl<I: Iterator + ?Sized> Iterator for Box<I> type Item = I::Item;`
`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();

#### `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);

    y.clone_from(&x);

    assert_eq!(*y, 5);

### `impl Clone for Box<str>`
1.3.0
[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: Clone> Clone for Box<[T]>`
1.3.0
[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: ?Sized> AsRef<T> for Box<T>`
1.5.0
[src]

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

Performs the conversion.

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

####
ⓘImportant traits for Box<I>

### Important traits for Box<I>

`impl<I: Iterator + ?Sized> Iterator for Box<I> type Item = I::Item;`
`fn default() -> Box<T>`[src]

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

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

####
ⓘImportant traits for Box<I>

### Important traits for Box<I>

`impl<I: Iterator + ?Sized> Iterator for Box<I> type Item = I::Item;`
`fn default() -> Box<[T]>`[src]

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

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

####
ⓘImportant traits for Box<I>

### Important traits for Box<I>

`impl<I: Iterator + ?Sized> Iterator for Box<I> type Item = I::Item;`
`fn default() -> Box<str>`[src]

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

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

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

Performs the conversion.

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

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

Immutably borrows from an owned value. Read more

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

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

Mutably borrows from an owned value. Read more

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

#### `type Output = F::Output`

🔬 This is a nightly-only experimental API. (`futures_api` #50547)

futures in libcore are unstable

The result of the `Future`.

#### `fn poll(self: Pin<&mut Self>, lw: &LocalWaker) -> Poll<Self::Output>`[src]

🔬 This is a nightly-only experimental API. (`futures_api` #50547)

futures in libcore are unstable

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

## Auto Trait Implementations

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

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

## Blanket Implementations

### `impl<A, F> FnBox for F where
F: FnOnce<A>,` [src]

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

🔬 This is a nightly-only experimental API. (`fnbox` #28796)

will be deprecated if and when `Box<FnOnce>` becomes usable

#### `fn call_box(Box<F>, A) -> <F as FnOnce<A>>::Output`[src]

🔬 This is a nightly-only experimental API. (`fnbox` #28796)

will be deprecated if and when `Box<FnOnce>` becomes usable

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

#### `type Owned = T`

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

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

#### `fn clone_into(&Self, &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]

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

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

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

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

Performs the conversion.

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

#### `type Error = !`

🔬 This is a nightly-only experimental API. (`try_from` #33417)

The type returned in the event of a conversion error.

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

🔬 This is a nightly-only experimental API. (`try_from` #33417)

Performs the conversion.

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

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

🔬 This is a nightly-only experimental API. (`try_from` #33417)

The type returned in the event of a conversion error.

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

🔬 This is a nightly-only experimental API. (`try_from` #33417)

Performs the conversion.

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

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

Performs the conversion.

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

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

Immutably borrows from an owned value. Read more

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

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

Mutably borrows from an owned value. Read more

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

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

🔬 This is a nightly-only experimental API. (`get_type_id` #27745)

this method will likely be replaced by an associated static

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

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)