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>

Important traits for Box<I>

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

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);

impl<T: ?Sized> Box<T>

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

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

Consumes the Box, returning the wrapped raw pointer.

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>

🔬 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 into_unique(b: Box<T>) -> Unique<T>

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

use into_raw_non_null instead

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

🔬 This is a nightly-only experimental API. (box_leak #46179)

needs an FCP to stabilize

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

#![feature(box_leak)]

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:

#![feature(box_leak)]

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]);
}

impl Box<Any>

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

Attempt to downcast the box to a concrete type.

Examples

use std::any::Any;

fn print_if_string(value: Box<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<Any + Send>

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

Attempt to downcast the box to a concrete type.

Examples

use std::any::Any;

fn print_if_string(value: Box<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> Boxed for Box<T>

type Data = T

🔬 This is a nightly-only experimental API. (placement_new_protocol #27779)

The kind of data that is stored in this kind of box.

type Place = IntermediateBox<T>

🔬 This is a nightly-only experimental API. (placement_new_protocol #27779)

The place that will negotiate the storage of the data.

Important traits for Box<I>

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

unsafe fn finalize(b: IntermediateBox<T>) -> Box<T>

🔬 This is a nightly-only experimental API. (placement_new_protocol #27779)

Converts filled place into final owning value, shifting deallocation/cleanup responsibilities (if any remain), over to returned instance of Self and forgetting filled.

impl<T: ?Sized> Drop for Box<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T: Default> Default for Box<T>

Important traits for Box<I>

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

fn default() -> Box<T>

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

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

Important traits for Box<I>

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

fn default() -> Box<[T]>

Returns the "default value" for a type.

impl Default for Box<str>

Important traits for Box<I>

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

fn default() -> Box<str>

Returns the "default value" for a type.

impl<T: Clone> Clone for Box<T>

Important traits for Box<I>

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

fn clone(&self) -> Box<T>

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>)

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>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: ?Sized + PartialEq> PartialEq for Box<T>

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

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

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

This method tests for !=.

impl<T: ?Sized + PartialOrd> PartialOrd for Box<T>

fn partial_cmp(&self, other: &Box<T>) -> Option<Ordering>

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

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

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

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

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

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

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

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

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

impl<T: ?Sized + Ord> Ord for Box<T>

fn cmp(&self, other: &Box<T>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

impl<T: ?Sized + Eq> Eq for Box<T>

impl<T: ?Sized + Hash> Hash for Box<T>

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

Feeds this value into the given [Hasher].

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

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

impl<T: ?Sized + Hasher> Hasher for Box<T>

fn finish(&self) -> u64

Returns the hash value for the values written so far.

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

Writes some data into this Hasher.

fn write_u8(&mut self, i: u8)

Writes a single u8 into this hasher.

fn write_u16(&mut self, i: u16)

Writes a single u16 into this hasher.

fn write_u32(&mut self, i: u32)

Writes a single u32 into this hasher.

fn write_u64(&mut self, i: u64)

Writes a single u64 into this hasher.

fn write_u128(&mut self, i: u128)

🔬 This is a nightly-only experimental API. (i128 #35118)

Writes a single u128 into this hasher.

fn write_usize(&mut self, i: usize)

Writes a single usize into this hasher.

fn write_i8(&mut self, i: i8)

Writes a single i8 into this hasher.

fn write_i16(&mut self, i: i16)

Writes a single i16 into this hasher.

fn write_i32(&mut self, i: i32)

Writes a single i32 into this hasher.

fn write_i64(&mut self, i: i64)

Writes a single i64 into this hasher.

fn write_i128(&mut self, i: i128)

🔬 This is a nightly-only experimental API. (i128 #35118)

Writes a single i128 into this hasher.

fn write_isize(&mut self, i: isize)

Writes a single isize into this hasher.

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

fn from(t: T) -> Self

Performs the conversion.

impl<'a, T: Copy> From<&'a [T]> for Box<[T]>

Important traits for Box<I>

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

fn from(slice: &'a [T]) -> Box<[T]>

Performs the conversion.

impl<'a> From<&'a str> for Box<str>

Important traits for Box<I>

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

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

Performs the conversion.

impl From<Box<str>> for Box<[u8]>

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

Performs the conversion.

impl<T: Display + ?Sized> Display for Box<T>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<T: Debug + ?Sized> Debug for Box<T>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<T: ?Sized> Pointer for Box<T>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<T: ?Sized> Deref for Box<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T: ?Sized> DerefMut for Box<T>

fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<I: Iterator + ?Sized> Iterator for Box<I>

type Item = I::Item

The type of the elements being iterated over.

fn next(&mut self) -> Option<I::Item>

Advances the iterator and returns the next value.

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

Returns the bounds on the remaining length of the iterator.

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

Returns the nth element of the iterator.

fn count(self) -> usize

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

fn last(self) -> Option<Self::Item>

Consumes the iterator, returning the last element.

Important traits for StepBy<I>

impl<I> Iterator for StepBy<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;

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

🔬 This is a nightly-only experimental API. (iterator_step_by #27741)

unstable replacement of Range::step_by

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

Important traits for Chain<A, B>

impl<A, B> Iterator for Chain<A, B> where
    A: Iterator,
    B: Iterator<Item = <A as Iterator>::Item>,  type Item = <A as Iterator>::Item;

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

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

Important traits for Zip<A, B>

impl<A, B> Iterator for Zip<A, B> where
    A: Iterator,
    B: Iterator,  type Item = (<A as Iterator>::Item, <B as Iterator>::Item);

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

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

Important traits for Map<I, F>

impl<B, I, F> Iterator for Map<I, F> where
    F: FnMut(<I as Iterator>::Item) -> B,
    I: Iterator,  type Item = B;

fn map<B, F>(self, f: F) -> Map<Self, F> where
    F: FnMut(Self::Item) -> B, 

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

fn for_each<F>(self, f: F) where
    F: FnMut(Self::Item), 

Calls a closure on each element of an iterator.

Important traits for Filter<I, P>

impl<I, P> Iterator for Filter<I, P> where
    I: Iterator,
    P: FnMut(&<I as Iterator>::Item) -> bool,  type Item = <I as Iterator>::Item;

fn filter<P>(self, predicate: P) -> Filter<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

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

Important traits for FilterMap<I, F>

impl<B, I, F> Iterator for FilterMap<I, F> where
    F: FnMut(<I as Iterator>::Item) -> Option<B>,
    I: Iterator,  type Item = B;

fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
    F: FnMut(Self::Item) -> Option<B>, 

Creates an iterator that both filters and maps.

Important traits for Enumerate<I>

impl<I> Iterator for Enumerate<I> where
    I: Iterator,  type Item = (usize, <I as Iterator>::Item);

fn enumerate(self) -> Enumerate<Self>

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

Important traits for Peekable<I>

impl<I> Iterator for Peekable<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;

fn peekable(self) -> Peekable<Self>

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

Important traits for SkipWhile<I, P>

impl<I, P> Iterator for SkipWhile<I, P> where
    I: Iterator,
    P: FnMut(&<I as Iterator>::Item) -> bool,  type Item = <I as Iterator>::Item;

fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

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

Important traits for TakeWhile<I, P>

impl<I, P> Iterator for TakeWhile<I, P> where
    I: Iterator,
    P: FnMut(&<I as Iterator>::Item) -> bool,  type Item = <I as Iterator>::Item;

fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator that yields elements based on a predicate.

Important traits for Skip<I>

impl<I> Iterator for Skip<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;

fn skip(self, n: usize) -> Skip<Self>

Creates an iterator that skips the first n elements.

Important traits for Take<I>

impl<I> Iterator for Take<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;

fn take(self, n: usize) -> Take<Self>

Creates an iterator that yields its first n elements.

Important traits for Scan<I, St, F>

impl<B, I, St, F> Iterator for Scan<I, St, F> where
    F: FnMut(&mut St, <I as Iterator>::Item) -> Option<B>,
    I: Iterator,  type Item = B;

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

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

Important traits for FlatMap<I, U, F>

impl<I, U, F> Iterator for FlatMap<I, U, F> where
    F: FnMut(<I as Iterator>::Item) -> U,
    I: Iterator,
    U: IntoIterator,  type Item = <U as IntoIterator>::Item;

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
    F: FnMut(Self::Item) -> U,
    U: IntoIterator, 

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

Important traits for Fuse<I>

impl<I> Iterator for Fuse<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;impl<I> Iterator for Fuse<I> where
    I: FusedIterator, 

fn fuse(self) -> Fuse<Self>

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

Important traits for Inspect<I, F>

impl<I, F> Iterator for Inspect<I, F> where
    F: FnMut(&<I as Iterator>::Item),
    I: Iterator,  type Item = <I as Iterator>::Item;

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

Do something with each element of an iterator, passing the value on.

fn by_ref(&mut self) -> &mut Self

Borrows an iterator, rather than consuming it.

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

Transforms an iterator into a collection.

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

Consumes an iterator, creating two collections from it.

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

🔬 This is a nightly-only experimental API. (iterator_try_fold #45594)

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

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

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

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

Tests if every element of the iterator matches a predicate.

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

Tests if any element of the iterator matches a predicate.

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

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

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

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

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

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

fn max(self) -> Option<Self::Item> where
    Self::Item: Ord, 

Returns the maximum element of an iterator.

fn min(self) -> Option<Self::Item> where
    Self::Item: Ord, 

Returns the minimum element of an iterator.

fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where
    B: Ord,
    F: FnMut(&Self::Item) -> B, 

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

fn max_by<F>(self, compare: F) -> Option<Self::Item> where
    F: FnMut(&Self::Item, &Self::Item) -> Ordering, 

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

fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where
    B: Ord,
    F: FnMut(&Self::Item) -> B, 

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

fn min_by<F>(self, compare: F) -> Option<Self::Item> where
    F: FnMut(&Self::Item, &Self::Item) -> Ordering, 

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

Important traits for Rev<I>

impl<I> Iterator for Rev<I> where
    I: DoubleEndedIterator,  type Item = <I as Iterator>::Item;

fn rev(self) -> Rev<Self> where
    Self: DoubleEndedIterator, 

Reverses an iterator's direction.

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

Converts an iterator of pairs into a pair of containers.

Important traits for Cloned<I>

impl<'a, I, T> Iterator for Cloned<I> where
    I: Iterator<Item = &'a T>,
    T: 'a + Clone,  type Item = T;

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

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

Important traits for Cycle<I>

impl<I> Iterator for Cycle<I> where
    I: Clone + Iterator,  type Item = <I as Iterator>::Item;

fn cycle(self) -> Cycle<Self> where
    Self: Clone, 

Repeats an iterator endlessly.

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

Sums the elements of an iterator.

fn product<P>(self) -> P where
    P: Product<Self::Item>, 

Iterates over the entire iterator, multiplying all the elements

fn cmp<I>(self, other: I) -> Ordering where
    I: IntoIterator<Item = Self::Item>,
    Self::Item: Ord, 

Lexicographically compares the elements of this Iterator with those of another.

fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Lexicographically compares the elements of this Iterator with those of another.

fn eq<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>, 

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

fn ne<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>, 

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

fn lt<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

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

fn le<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

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

fn gt<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

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

fn ge<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

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

impl<I: DoubleEndedIterator + ?Sized> DoubleEndedIterator for Box<I>

fn next_back(&mut self) -> Option<I::Item>

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

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

🔬 This is a nightly-only experimental API. (iterator_try_fold #45594)

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

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

🔬 This is a nightly-only experimental API. (iter_rfold #44705)

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

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

🔬 This is a nightly-only experimental API. (iter_rfind #39480)

Searches for an element of an iterator from the right that satisfies a predicate.

impl<I: ExactSizeIterator + ?Sized> ExactSizeIterator for Box<I>

fn len(&self) -> usize

Returns the exact number of times the iterator will iterate.

fn is_empty(&self) -> bool

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

Returns whether the iterator is empty.

impl<I: FusedIterator + ?Sized> FusedIterator for Box<I>

impl<'a, A, R> FnOnce<A> for Box<FnBox<A, Output = R> + 'a>

type Output = R

The returned type after the call operator is used.

extern "rust-call" fn call_once(self, args: A) -> R

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

Performs the call operation.

impl<'a, A, R> FnOnce<A> for Box<FnBox<A, Output = R> + Send + 'a>

type Output = R

The returned type after the call operator is used.

extern "rust-call" fn call_once(self, args: A) -> R

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

Performs the call operation.

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

impl<T: Clone> Clone for Box<[T]>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: ?Sized> Borrow<T> for Box<T>

fn borrow(&self) -> &T

Immutably borrows from an owned value.

impl<T: ?Sized> BorrowMut<T> for Box<T>

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value.

impl<T: ?Sized> AsRef<T> for Box<T>

fn as_ref(&self) -> &T

Performs the conversion.

impl<T: ?Sized> AsMut<T> for Box<T>

fn as_mut(&mut self) -> &mut T

Performs the conversion.

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

type Yield = T::Yield

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

The type of value this generator yields.

type Return = T::Return

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

The type of value this generator returns.

fn resume(&mut self) -> GeneratorState<Self::Yield, Self::Return>

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

Resumes the execution of this generator.

impl<T: ?Sized> From<Box<T>> for Arc<T>

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

Performs the conversion.

impl<T: ?Sized> From<Box<T>> for Rc<T>

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

Performs the conversion.

impl From<Box<str>> for String

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

Performs the conversion.

impl From<String> for Box<str>

Important traits for Box<I>

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

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

Performs the conversion.

impl<T> From<Box<[T]>> for Vec<T>

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

Performs the conversion.

impl<T> From<Vec<T>> for Box<[T]>

Important traits for Box<I>

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

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

Performs the conversion.