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//! The `Box<T>` type for heap allocation.↩
//!↩
//! [`Box<T>`], casually referred to as a 'box', provides the simplest form of↩
//! heap allocation in Rust. Boxes provide ownership for this allocation, and↩
//! drop their contents when they go out of scope. Boxes also ensure that they↩
//! never allocate more than `isize::MAX` bytes.↩
//!↩
//! # Examples↩
//!↩
//! Move a value from the stack to the heap by creating a [`Box`]:↩
//!↩
//! ```↩
//! let val: u8 = 5;↩
//! let boxed: Box<u8> = Box::new(val);↩
//! ```↩
//!↩
//! Move a value from a [`Box`] back to the stack by [dereferencing]:↩
//!↩
//! ```↩
//! let boxed: Box<u8> = Box::new(5);↩
//! let val: u8 = *boxed;↩
//! ```↩
//!↩
//! Creating a recursive data structure:↩
//!↩
//! ```↩
//! #[derive(Debug)]↩
//! enum List<T> {↩
//! Cons(T, Box<List<T>>),↩
//! Nil,↩
//! }↩
//!↩
//! let list: List<i32> = List::Cons(1, Box::new(List::Cons(2, Box::new(List::Nil))));↩
//! println!("{list:?}");↩
//! ```↩
//!↩
//! This will print `Cons(1, Cons(2, Nil))`.↩
//!↩
//! Recursive structures must be boxed, because if the definition of `Cons`↩
//! looked like this:↩
//!↩
//! ```compile_fail,E0072↩
//! # enum List<T> {↩
//! Cons(T, List<T>),↩
//! # }↩
//! ```↩
//!↩
//! It wouldn't work. This is because the size of a `List` depends on how many↩
//! elements are in the list, and so we don't know how much memory to allocate↩
//! for a `Cons`. By introducing a [`Box<T>`], which has a defined size, we know how↩
//! big `Cons` needs to be.↩
//!↩
//! # Memory layout↩
//!↩
//! For non-zero-sized values, a [`Box`] will use the [`Global`] allocator for↩
//! its allocation. It is valid to convert both ways between a [`Box`] and a↩
//! raw pointer allocated with the [`Global`] allocator, given that the↩
//! [`Layout`] used with the allocator is correct for the type. More precisely,↩
//! a `value: *mut T` that has been allocated with the [`Global`] allocator↩
//! with `Layout::for_value(&*value)` may be converted into a box using↩
//! [`Box::<T>::from_raw(value)`]. Conversely, the memory backing a `value: *mut↩
//! T` obtained from [`Box::<T>::into_raw`] may be deallocated using the↩
//! [`Global`] allocator with [`Layout::for_value(&*value)`].↩
//!↩
//! For zero-sized values, the `Box` pointer still has to be [valid] for reads↩
//! and writes and sufficiently aligned. In particular, casting any aligned↩
//! non-zero integer literal to a raw pointer produces a valid pointer, but a↩
//! pointer pointing into previously allocated memory that since got freed is↩
//! not valid. The recommended way to build a Box to a ZST if `Box::new` cannot↩
//! be used is to use [`ptr::NonNull::dangling`].↩
//!↩
//! So long as `T: Sized`, a `Box<T>` is guaranteed to be represented↩
//! as a single pointer and is also ABI-compatible with C pointers↩
//! (i.e. the C type `T*`). This means that if you have extern "C"↩
//! Rust functions that will be called from C, you can define those↩
//! Rust functions using `Box<T>` types, and use `T*` as corresponding↩
//! type on the C side. As an example, consider this C header which↩
//! declares functions that create and destroy some kind of `Foo`↩
//! value:↩
//!↩
//! ```c↩
//! /* C header */↩
//!↩
//! /* Returns ownership to the caller */↩
//! struct Foo* foo_new(void);↩
//!↩
//! /* Takes ownership from the caller; no-op when invoked with null */↩
//! void foo_delete(struct Foo*);↩
//! ```↩
//!↩
//! These two functions might be implemented in Rust as follows. Here, the↩
//! `struct Foo*` type from C is translated to `Box<Foo>`, which captures↩
//! the ownership constraints. Note also that the nullable argument to↩
//! `foo_delete` is represented in Rust as `Option<Box<Foo>>`, since `Box<Foo>`↩
//! cannot be null.↩
//!↩
//! ```↩
//! #[repr(C)]↩
//! pub struct Foo;↩
//!↩
//! #[no_mangle]↩
//! pub extern "C" fn foo_new() -> Box<Foo> {↩
//! Box::new(Foo)↩
//! }↩
//!↩
//! #[no_mangle]↩
//! pub extern "C" fn foo_delete(_: Option<Box<Foo>>) {}↩
//! ```↩
//!↩
//! Even though `Box<T>` has the same representation and C ABI as a C pointer,↩
//! this does not mean that you can convert an arbitrary `T*` into a `Box<T>`↩
//! and expect things to work. `Box<T>` values will always be fully aligned,↩
//! non-null pointers. Moreover, the destructor for `Box<T>` will attempt to↩
//! free the value with the global allocator. In general, the best practice↩
//! is to only use `Box<T>` for pointers that originated from the global↩
//! allocator.↩
//!↩
//! **Important.** At least at present, you should avoid using↩
//! `Box<T>` types for functions that are defined in C but invoked↩
//! from Rust. In those cases, you should directly mirror the C types↩
//! as closely as possible. Using types like `Box<T>` where the C↩
//! definition is just using `T*` can lead to undefined behavior, as↩
//! described in [rust-lang/unsafe-code-guidelines#198][ucg#198].↩
//!↩
//! # Considerations for unsafe code↩
//!↩
//! **Warning: This section is not normative and is subject to change, possibly↩
//! being relaxed in the future! It is a simplified summary of the rules↩
//! currently implemented in the compiler.**↩
//!↩
//! The aliasing rules for `Box<T>` are the same as for `&mut T`. `Box<T>`↩
//! asserts uniqueness over its content. Using raw pointers derived from a box↩
//! after that box has been mutated through, moved or borrowed as `&mut T`↩
//! is not allowed. For more guidance on working with box from unsafe code, see↩
//! [rust-lang/unsafe-code-guidelines#326][ucg#326].↩
//!↩
//!↩
//! [dereferencing]: core::ops::Deref↩
//! [`Box::<T>::from_raw(value)`]: Box::from_raw↩
//! [`Global`]: crate::alloc::Global↩
//! [`Layout`]: crate::alloc::Layout↩
//! [`Layout::for_value(&*value)`]: crate::alloc::Layout::for_value↩
//! [valid]: ptr#safety↩
↩
use core::any::Any;↩
use core::borrow;↩
use core::cmp::Ordering;↩
use core::convert::{From, TryFrom};↩
↩
// use core::error::Error;↩
use core::fmt;↩
use core::future::Future;↩
use core::hash::{Hash, Hasher};↩
#[cfg(not(no_global_oom_handling))]↩
use core::iter::FromIterator;↩
use core::iter::{FusedIterator, Iterator};↩
use core::marker::Unpin;↩
use core::mem;↩
use core::ops::{Deref, DerefMut};↩
use core::pin::Pin;↩
use core::ptr::{self, NonNull};↩
use core::task::{Context, Poll};↩
↩
use super::alloc::{AllocError, Allocator, Global, Layout};↩
use super::raw_vec::RawVec;↩
#[cfg(not(no_global_oom_handling))]↩
use super::vec::Vec;↩
#[cfg(not(no_global_oom_handling))]↩
use alloc_crate::alloc::handle_alloc_error;↩
↩
/// A pointer type for heap allocation.↩
///↩
/// See the [module-level documentation](../../std/boxed/index.html) for more.↩
pub struct Box<T: ?Sized, A: Allocator = Global>(NonNull<T>, A);↩
↩
// Safety: Box owns both T and A, so sending is safe if↩
// sending is safe for T and A.↩
unsafe impl<T: ?Sized, A: Allocator> Send for Box<T, A>↩
where↩
T: Send,↩
A: Send,↩
{↩
}↩
↩
// Safety: Box owns both T and A, so sharing is safe if↩
// sharing is safe for T and A.↩
unsafe impl<T: ?Sized, A: Allocator> Sync for Box<T, A>↩
where↩
T: Sync,↩
A: Sync,↩
{↩
}↩
↩
impl<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);↩
/// ```↩
#[cfg(all(not(no_global_oom_handling)))]↩
#[inline(always)]↩
#[must_use]↩
pub fn new(x: T) -> Self {↩
Self::new_in(x, Global)↩
}↩
↩
/// 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)↩
/// ```↩
#[cfg(not(no_global_oom_handling))]↩
#[must_use]↩
#[inline(always)]↩
pub fn new_uninit() -> Box<mem::MaybeUninit<T>> {↩
Self::new_uninit_in(Global)↩
}↩
↩
/// Constructs a new `Box` with uninitialized contents, with the memory↩
/// being filled with `0` bytes.↩
///↩
/// See [`MaybeUninit::zeroed`][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)↩
/// ```↩
///↩
/// [zeroed]: mem::MaybeUninit::zeroed↩
#[cfg(not(no_global_oom_handling))]↩
#[must_use]↩
#[inline(always)]↩
pub fn new_zeroed() -> Box<mem::MaybeUninit<T>> {↩
Self::new_zeroed_in(Global)↩
}↩
↩
/// Constructs a new `Pin<Box<T>>`. If `T` does not implement [`Unpin`], then↩
/// `x` will be pinned in memory and unable to be moved.↩
///↩
/// Constructing and pinning of the `Box` can also be done in two steps: `Box::pin(x)`↩
/// does the same as <code>[Box::into_pin]\([Box::new]\(x))</code>. Consider using↩
/// [`into_pin`](Box::into_pin) if you already have a `Box<T>`, or if you want to↩
/// construct a (pinned) `Box` in a different way than with [`Box::new`].↩
#[cfg(not(no_global_oom_handling))]↩
#[must_use]↩
#[inline(always)]↩
pub fn pin(x: T) -> Pin<Box<T>> {↩
Box::new(x).into()↩
}↩
↩
/// Allocates memory on the heap then places `x` into it,↩
/// returning an error if the allocation fails↩
///↩
/// This doesn't actually allocate if `T` is zero-sized.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api)]↩
///↩
/// let five = Box::try_new(5)?;↩
/// # Ok::<(), std::alloc::AllocError>(())↩
/// ```↩
#[inline(always)]↩
pub fn try_new(x: T) -> Result<Self, AllocError> {↩
Self::try_new_in(x, Global)↩
}↩
↩
/// Constructs a new box with uninitialized contents on the heap,↩
/// returning an error if the allocation fails↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api, new_uninit)]↩
///↩
/// let mut five = Box::<u32>::try_new_uninit()?;↩
///↩
/// let five = unsafe {↩
/// // Deferred initialization:↩
/// five.as_mut_ptr().write(5);↩
///↩
/// five.assume_init()↩
/// };↩
///↩
/// assert_eq!(*five, 5);↩
/// # Ok::<(), std::alloc::AllocError>(())↩
/// ```↩
#[inline(always)]↩
pub fn try_new_uninit() -> Result<Box<mem::MaybeUninit<T>>, AllocError> {↩
Box::try_new_uninit_in(Global)↩
}↩
↩
/// Constructs a new `Box` with uninitialized contents, with the memory↩
/// being filled with `0` bytes on the heap↩
///↩
/// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage↩
/// of this method.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api, new_uninit)]↩
///↩
/// let zero = Box::<u32>::try_new_zeroed()?;↩
/// let zero = unsafe { zero.assume_init() };↩
///↩
/// assert_eq!(*zero, 0);↩
/// # Ok::<(), std::alloc::AllocError>(())↩
/// ```↩
///↩
/// [zeroed]: mem::MaybeUninit::zeroed↩
#[inline(always)]↩
pub fn try_new_zeroed() -> Result<Box<mem::MaybeUninit<T>>, AllocError> {↩
Box::try_new_zeroed_in(Global)↩
}↩
}↩
↩
impl<T, A: Allocator> Box<T, A> {↩
/// Allocates memory in the given allocator then places `x` into it.↩
///↩
/// This doesn't actually allocate if `T` is zero-sized.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api)]↩
///↩
/// use std::alloc::System;↩
///↩
/// let five = Box::new_in(5, System);↩
/// ```↩
#[cfg(not(no_global_oom_handling))]↩
#[must_use]↩
#[inline(always)]↩
pub fn new_in(x: T, alloc: A) -> Self↩
where↩
A: Allocator,↩
{↩
let mut boxed = Self::new_uninit_in(alloc);↩
unsafe {↩
boxed.as_mut_ptr().write(x);↩
boxed.assume_init()↩
}↩
}↩
↩
/// Allocates memory in the given allocator then places `x` into it,↩
/// returning an error if the allocation fails↩
///↩
/// This doesn't actually allocate if `T` is zero-sized.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api)]↩
///↩
/// use std::alloc::System;↩
///↩
/// let five = Box::try_new_in(5, System)?;↩
/// # Ok::<(), std::alloc::AllocError>(())↩
/// ```↩
#[inline(always)]↩
pub fn try_new_in(x: T, alloc: A) -> Result<Self, AllocError>↩
where↩
A: Allocator,↩
{↩
let mut boxed = Self::try_new_uninit_in(alloc)?;↩
unsafe {↩
boxed.as_mut_ptr().write(x);↩
Ok(boxed.assume_init())↩
}↩
}↩
↩
/// Constructs a new box with uninitialized contents in the provided allocator.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api, new_uninit)]↩
///↩
/// use std::alloc::System;↩
///↩
/// let mut five = Box::<u32, _>::new_uninit_in(System);↩
///↩
/// let five = unsafe {↩
/// // Deferred initialization:↩
/// five.as_mut_ptr().write(5);↩
///↩
/// five.assume_init()↩
/// };↩
///↩
/// assert_eq!(*five, 5)↩
/// ```↩
#[cfg(not(no_global_oom_handling))]↩
#[must_use]↩
// #[unstable(feature = "new_uninit", issue = "63291")]↩
#[inline(always)]↩
pub fn new_uninit_in(alloc: A) -> Box<mem::MaybeUninit<T>, A>↩
where↩
A: Allocator,↩
{↩
let layout = Layout::new::<mem::MaybeUninit<T>>();↩
// NOTE: Prefer match over unwrap_or_else since closure sometimes not inlineable.↩
// That would make code size bigger.↩
match Box::try_new_uninit_in(alloc) {↩
Ok(m) => m,↩
Err(_) => handle_alloc_error(layout),↩
}↩
}↩
↩
/// Constructs a new box with uninitialized contents in the provided allocator,↩
/// returning an error if the allocation fails↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api, new_uninit)]↩
///↩
/// use std::alloc::System;↩
///↩
/// let mut five = Box::<u32, _>::try_new_uninit_in(System)?;↩
///↩
/// let five = unsafe {↩
/// // Deferred initialization:↩
/// five.as_mut_ptr().write(5);↩
///↩
/// five.assume_init()↩
/// };↩
///↩
/// assert_eq!(*five, 5);↩
/// # Ok::<(), std::alloc::AllocError>(())↩
/// ```↩
#[inline(always)]↩
pub fn try_new_uninit_in(alloc: A) -> Result<Box<mem::MaybeUninit<T>, A>, AllocError>↩
where↩
A: Allocator,↩
{↩
let layout = Layout::new::<mem::MaybeUninit<T>>();↩
let ptr = alloc.allocate(layout)?.cast();↩
unsafe { Ok(Box::from_raw_in(ptr.as_ptr(), alloc)) }↩
}↩
↩
/// Constructs a new `Box` with uninitialized contents, with the memory↩
/// being filled with `0` bytes in the provided allocator.↩
///↩
/// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage↩
/// of this method.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api, new_uninit)]↩
///↩
/// use std::alloc::System;↩
///↩
/// let zero = Box::<u32, _>::new_zeroed_in(System);↩
/// let zero = unsafe { zero.assume_init() };↩
///↩
/// assert_eq!(*zero, 0)↩
/// ```↩
///↩
/// [zeroed]: mem::MaybeUninit::zeroed↩
#[cfg(not(no_global_oom_handling))]↩
// #[unstable(feature = "new_uninit", issue = "63291")]↩
#[must_use]↩
#[inline(always)]↩
pub fn new_zeroed_in(alloc: A) -> Box<mem::MaybeUninit<T>, A>↩
where↩
A: Allocator,↩
{↩
let layout = Layout::new::<mem::MaybeUninit<T>>();↩
// NOTE: Prefer match over unwrap_or_else since closure sometimes not inlineable.↩
// That would make code size bigger.↩
match Box::try_new_zeroed_in(alloc) {↩
Ok(m) => m,↩
Err(_) => handle_alloc_error(layout),↩
}↩
}↩
↩
/// Constructs a new `Box` with uninitialized contents, with the memory↩
/// being filled with `0` bytes in the provided allocator,↩
/// returning an error if the allocation fails,↩
///↩
/// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage↩
/// of this method.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api, new_uninit)]↩
///↩
/// use std::alloc::System;↩
///↩
/// let zero = Box::<u32, _>::try_new_zeroed_in(System)?;↩
/// let zero = unsafe { zero.assume_init() };↩
///↩
/// assert_eq!(*zero, 0);↩
/// # Ok::<(), std::alloc::AllocError>(())↩
/// ```↩
///↩
/// [zeroed]: mem::MaybeUninit::zeroed↩
#[inline(always)]↩
pub fn try_new_zeroed_in(alloc: A) -> Result<Box<mem::MaybeUninit<T>, A>, AllocError>↩
where↩
A: Allocator,↩
{↩
let layout = Layout::new::<mem::MaybeUninit<T>>();↩
let ptr = alloc.allocate_zeroed(layout)?.cast();↩
unsafe { Ok(Box::from_raw_in(ptr.as_ptr(), alloc)) }↩
}↩
↩
/// Constructs a new `Pin<Box<T, A>>`. If `T` does not implement [`Unpin`], then↩
/// `x` will be pinned in memory and unable to be moved.↩
///↩
/// Constructing and pinning of the `Box` can also be done in two steps: `Box::pin_in(x, alloc)`↩
/// does the same as <code>[Box::into_pin]\([Box::new_in]\(x, alloc))</code>. Consider using↩
/// [`into_pin`](Box::into_pin) if you already have a `Box<T, A>`, or if you want to↩
/// construct a (pinned) `Box` in a different way than with [`Box::new_in`].↩
#[cfg(not(no_global_oom_handling))]↩
#[must_use]↩
#[inline(always)]↩
pub fn pin_in(x: T, alloc: A) -> Pin<Self>↩
where↩
A: 'static + Allocator,↩
{↩
Self::into_pin(Self::new_in(x, alloc))↩
}↩
↩
/// Converts a `Box<T>` into a `Box<[T]>`↩
///↩
/// This conversion does not allocate on the heap and happens in place.↩
#[inline(always)]↩
pub fn into_boxed_slice(boxed: Self) -> Box<[T], A> {↩
let (raw, alloc) = Box::into_raw_with_allocator(boxed);↩
unsafe { Box::from_raw_in(raw as *mut [T; 1], alloc) }↩
}↩
↩
/// Consumes the `Box`, returning the wrapped value.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(box_into_inner)]↩
///↩
/// let c = Box::new(5);↩
///↩
/// assert_eq!(Box::into_inner(c), 5);↩
/// ```↩
#[inline(always)]↩
pub fn into_inner(boxed: Self) -> T {↩
let ptr = boxed.0;↩
let unboxed = unsafe { ptr.as_ptr().read() };↩
unsafe { boxed.1.deallocate(ptr.cast(), Layout::new::<T>()) };↩
unboxed↩
}↩
}↩
↩
impl<T> Box<[T]> {↩
/// 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])↩
/// ```↩
#[cfg(not(no_global_oom_handling))]↩
#[must_use]↩
#[inline(always)]↩
pub fn new_uninit_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {↩
unsafe { RawVec::with_capacity(len).into_box(len) }↩
}↩
↩
/// Constructs a new boxed slice with uninitialized contents, with the memory↩
/// being filled with `0` bytes.↩
///↩
/// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage↩
/// of this method.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(new_uninit)]↩
///↩
/// let values = Box::<[u32]>::new_zeroed_slice(3);↩
/// let values = unsafe { values.assume_init() };↩
///↩
/// assert_eq!(*values, [0, 0, 0])↩
/// ```↩
///↩
/// [zeroed]: mem::MaybeUninit::zeroed↩
#[cfg(not(no_global_oom_handling))]↩
#[must_use]↩
#[inline(always)]↩
pub fn new_zeroed_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {↩
unsafe { RawVec::with_capacity_zeroed(len).into_box(len) }↩
}↩
↩
/// Constructs a new boxed slice with uninitialized contents. Returns an error if↩
/// the allocation fails↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api, new_uninit)]↩
///↩
/// let mut values = Box::<[u32]>::try_new_uninit_slice(3)?;↩
/// let values = unsafe {↩
/// // Deferred initialization:↩
/// values[0].as_mut_ptr().write(1);↩
/// values[1].as_mut_ptr().write(2);↩
/// values[2].as_mut_ptr().write(3);↩
/// values.assume_init()↩
/// };↩
///↩
/// assert_eq!(*values, [1, 2, 3]);↩
/// # Ok::<(), std::alloc::AllocError>(())↩
/// ```↩
#[inline(always)]↩
pub fn try_new_uninit_slice(len: usize) -> Result<Box<[mem::MaybeUninit<T>]>, AllocError> {↩
unsafe {↩
let layout = match Layout::array::<mem::MaybeUninit<T>>(len) {↩
Ok(l) => l,↩
Err(_) => return Err(AllocError),↩
};↩
let ptr = Global.allocate(layout)?;↩
Ok(RawVec::from_raw_parts_in(ptr.as_ptr() as *mut _, len, Global).into_box(len))↩
}↩
}↩
↩
/// Constructs a new boxed slice with uninitialized contents, with the memory↩
/// being filled with `0` bytes. Returns an error if the allocation fails↩
///↩
/// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage↩
/// of this method.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api, new_uninit)]↩
///↩
/// let values = Box::<[u32]>::try_new_zeroed_slice(3)?;↩
/// let values = unsafe { values.assume_init() };↩
///↩
/// assert_eq!(*values, [0, 0, 0]);↩
/// # Ok::<(), std::alloc::AllocError>(())↩
/// ```↩
///↩
/// [zeroed]: mem::MaybeUninit::zeroed↩
#[inline(always)]↩
pub fn try_new_zeroed_slice(len: usize) -> Result<Box<[mem::MaybeUninit<T>]>, AllocError> {↩
unsafe {↩
let layout = match Layout::array::<mem::MaybeUninit<T>>(len) {↩
Ok(l) => l,↩
Err(_) => return Err(AllocError),↩
};↩
let ptr = Global.allocate_zeroed(layout)?;↩
Ok(RawVec::from_raw_parts_in(ptr.as_ptr() as *mut _, len, Global).into_box(len))↩
}↩
}↩
}↩
↩
impl<T, A: Allocator> Box<[T], A> {↩
/// Constructs a new boxed slice with uninitialized contents in the provided allocator.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api, new_uninit)]↩
///↩
/// use std::alloc::System;↩
///↩
/// let mut values = Box::<[u32], _>::new_uninit_slice_in(3, System);↩
///↩
/// 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])↩
/// ```↩
#[cfg(not(no_global_oom_handling))]↩
#[must_use]↩
#[inline(always)]↩
pub fn new_uninit_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A> {↩
unsafe { RawVec::with_capacity_in(len, alloc).into_box(len) }↩
}↩
↩
/// Constructs a new boxed slice with uninitialized contents in the provided allocator,↩
/// with the memory being filled with `0` bytes.↩
///↩
/// See [`MaybeUninit::zeroed`][zeroed] for examples of correct and incorrect usage↩
/// of this method.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(allocator_api, new_uninit)]↩
///↩
/// use std::alloc::System;↩
///↩
/// let values = Box::<[u32], _>::new_zeroed_slice_in(3, System);↩
/// let values = unsafe { values.assume_init() };↩
///↩
/// assert_eq!(*values, [0, 0, 0])↩
/// ```↩
///↩
/// [zeroed]: mem::MaybeUninit::zeroed↩
#[cfg(not(no_global_oom_handling))]↩
#[must_use]↩
#[inline(always)]↩
pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A> {↩
unsafe { RawVec::with_capacity_zeroed_in(len, alloc).into_box(len) }↩
}↩
↩
pub fn into_vec(self) -> Vec<T, A>↩
where↩
A: Allocator,↩
{↩
unsafe {↩
let len = self.len();↩
let (b, alloc) = Box::into_raw_with_allocator(self);↩
Vec::from_raw_parts_in(b as *mut T, len, len, alloc)↩
}↩
}↩
}↩
↩
impl<T, A: Allocator> Box<mem::MaybeUninit<T>, A> {↩
/// Converts to `Box<T, A>`.↩
///↩
/// # Safety↩
///↩
/// As with [`MaybeUninit::assume_init`],↩
/// it is up to the caller to guarantee that the value↩
/// really is in an initialized state.↩
/// Calling this when the content is not yet fully initialized↩
/// causes immediate undefined behavior.↩
///↩
/// [`MaybeUninit::assume_init`]: mem::MaybeUninit::assume_init↩
///↩
/// # 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)↩
/// ```↩
#[inline(always)]↩
pub unsafe fn assume_init(self) -> Box<T, A> {↩
let (raw, alloc) = Box::into_raw_with_allocator(self);↩
unsafe { Box::from_raw_in(raw as *mut T, alloc) }↩
}↩
↩
/// Writes the value and converts to `Box<T, A>`.↩
///↩
/// This method converts the box similarly to [`Box::assume_init`] but↩
/// writes `value` into it before conversion thus guaranteeing safety.↩
/// In some scenarios use of this method may improve performance because↩
/// the compiler may be able to optimize copying from stack.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(new_uninit)]↩
///↩
/// let big_box = Box::<[usize; 1024]>::new_uninit();↩
///↩
/// let mut array = [0; 1024];↩
/// for (i, place) in array.iter_mut().enumerate() {↩
/// *place = i;↩
/// }↩
///↩
/// // The optimizer may be able to elide this copy, so previous code writes↩
/// // to heap directly.↩
/// let big_box = Box::write(big_box, array);↩
///↩
/// for (i, x) in big_box.iter().enumerate() {↩
/// assert_eq!(*x, i);↩
/// }↩
/// ```↩
#[inline(always)]↩
pub fn write(mut boxed: Self, value: T) -> Box<T, A> {↩
unsafe {↩
(*boxed).write(value);↩
boxed.assume_init()↩
}↩
}↩
}↩
↩
impl<T, A: Allocator> Box<[mem::MaybeUninit<T>], A> {↩
/// Converts to `Box<[T], A>`.↩
///↩
/// # Safety↩
///↩
/// As with [`MaybeUninit::assume_init`],↩
/// it is up to the caller to guarantee that the values↩
/// really are in an initialized state.↩
/// Calling this when the content is not yet fully initialized↩
/// causes immediate undefined behavior.↩
///↩
/// [`MaybeUninit::assume_init`]: mem::MaybeUninit::assume_init↩
///↩
/// # 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])↩
/// ```↩
#[inline(always)]↩
pub unsafe fn assume_init(self) -> Box<[T], A> {↩
let (raw, alloc) = Box::into_raw_with_allocator(self);↩
unsafe { Box::from_raw_in(raw as *mut [T], alloc) }↩
}↩
}↩
↩
impl<T: ?Sized> Box<T> {↩
/// Constructs a box from a raw pointer.↩
///↩
/// After calling this function, the raw pointer is owned by the↩
/// resulting `Box`. Specifically, the `Box` destructor will call↩
/// the destructor of `T` and free the allocated memory. For this↩
/// to be safe, the memory must have been allocated in accordance↩
/// with the [memory layout] used by `Box` .↩
///↩
/// # Safety↩
///↩
/// This function is unsafe because improper use may lead to↩
/// memory problems. For example, a double-free may occur if the↩
/// function is called twice on the same raw pointer.↩
///↩
/// The safety conditions are described in the [memory layout] section.↩
///↩
/// # Examples↩
///↩
/// Recreate a `Box` which was previously converted to a raw pointer↩
/// using [`Box::into_raw`]:↩
/// ```↩
/// let x = Box::new(5);↩
/// let ptr = Box::into_raw(x);↩
/// let x = unsafe { Box::from_raw(ptr) };↩
/// ```↩
/// Manually create a `Box` from scratch by using the global allocator:↩
/// ```↩
/// use std::alloc::{alloc, Layout};↩
///↩
/// unsafe {↩
/// let ptr = alloc(Layout::new::<i32>()) as *mut i32;↩
/// // In general .write is required to avoid attempting to destruct↩
/// // the (uninitialized) previous contents of `ptr`, though for this↩
/// // simple example `*ptr = 5` would have worked as well.↩
/// ptr.write(5);↩
/// let x = Box::from_raw(ptr);↩
/// }↩
/// ```↩
///↩
/// [memory layout]: self#memory-layout↩
/// [`Layout`]: crate::Layout↩
#[must_use = "call `drop(from_raw(ptr))` if you intend to drop the `Box`"]↩
#[inline(always)]↩
pub unsafe fn from_raw(raw: *mut T) -> Self {↩
unsafe { Self::from_raw_in(raw, Global) }↩
}↩
}↩
↩
impl<T: ?Sized, A: Allocator> Box<T, A> {↩
/// Constructs a box from a raw pointer in the given allocator.↩
///↩
/// After calling this function, the raw pointer is owned by the↩
/// resulting `Box`. Specifically, the `Box` destructor will call↩
/// the destructor of `T` and free the allocated memory. For this↩
/// to be safe, the memory must have been allocated in accordance↩
/// with the [memory layout] used by `Box` .↩
///↩
/// # Safety↩
///↩
/// This function is unsafe because improper use may lead to↩
/// memory problems. For example, a double-free may occur if the↩
/// function is called twice on the same raw pointer.↩
///↩
///↩
/// # Examples↩
///↩
/// Recreate a `Box` which was previously converted to a raw pointer↩
/// using [`Box::into_raw_with_allocator`]:↩
/// ```↩
/// use std::alloc::System;↩
/// # use allocator_api2::boxed::Box;↩
///↩
/// let x = Box::new_in(5, System);↩
/// let (ptr, alloc) = Box::into_raw_with_allocator(x);↩
/// let x = unsafe { Box::from_raw_in(ptr, alloc) };↩
/// ```↩
/// Manually create a `Box` from scratch by using the system allocator:↩
/// ```↩
/// use allocator_api2::alloc::{Allocator, Layout, System};↩
/// # use allocator_api2::boxed::Box;↩
///↩
/// unsafe {↩
/// let ptr = System.allocate(Layout::new::<i32>())?.as_ptr().cast::<i32>();↩
/// // In general .write is required to avoid attempting to destruct↩
/// // the (uninitialized) previous contents of `ptr`, though for this↩
/// // simple example `*ptr = 5` would have worked as well.↩
/// ptr.write(5);↩
/// let x = Box::from_raw_in(ptr, System);↩
/// }↩
/// # Ok::<(), allocator_api2::alloc::AllocError>(())↩
/// ```↩
///↩
/// [memory layout]: self#memory-layout↩
/// [`Layout`]: crate::Layout↩
#[inline(always)]↩
pub const unsafe fn from_raw_in(raw: *mut T, alloc: A) -> Self {↩
Box(unsafe { NonNull::new_unchecked(raw) }, alloc)↩
}↩
↩
/// Consumes the `Box`, returning a wrapped raw pointer.↩
///↩
/// The pointer will be properly aligned and non-null.↩
///↩
/// After calling this function, the caller is responsible for the↩
/// memory previously managed by the `Box`. In particular, the↩
/// caller should properly destroy `T` and release the memory, taking↩
/// into account the [memory layout] used by `Box`. The easiest way to↩
/// do this is to convert the raw pointer back into a `Box` with the↩
/// [`Box::from_raw`] function, allowing the `Box` destructor to perform↩
/// the cleanup.↩
///↩
/// Note: this is an associated function, which means that you have↩
/// to call it as `Box::into_raw(b)` instead of `b.into_raw()`. This↩
/// is so that there is no conflict with a method on the inner type.↩
///↩
/// # Examples↩
/// Converting the raw pointer back into a `Box` with [`Box::from_raw`]↩
/// for automatic cleanup:↩
/// ```↩
/// let x = Box::new(String::from("Hello"));↩
/// let ptr = Box::into_raw(x);↩
/// let x = unsafe { Box::from_raw(ptr) };↩
/// ```↩
/// Manual cleanup by explicitly running the destructor and deallocating↩
/// the memory:↩
/// ```↩
/// use std::alloc::{dealloc, Layout};↩
/// use std::ptr;↩
///↩
/// let x = Box::new(String::from("Hello"));↩
/// let p = Box::into_raw(x);↩
/// unsafe {↩
/// ptr::drop_in_place(p);↩
/// dealloc(p as *mut u8, Layout::new::<String>());↩
/// }↩
/// ```↩
///↩
/// [memory layout]: self#memory-layout↩
#[inline(always)]↩
pub fn into_raw(b: Self) -> *mut T {↩
Self::into_raw_with_allocator(b).0↩
}↩
↩
/// Consumes the `Box`, returning a wrapped raw pointer and the allocator.↩
///↩
/// The pointer will be properly aligned and non-null.↩
///↩
/// After calling this function, the caller is responsible for the↩
/// memory previously managed by the `Box`. In particular, the↩
/// caller should properly destroy `T` and release the memory, taking↩
/// into account the [memory layout] used by `Box`. The easiest way to↩
/// do this is to convert the raw pointer back into a `Box` with the↩
/// [`Box::from_raw_in`] function, allowing the `Box` destructor to perform↩
/// the cleanup.↩
///↩
/// Note: this is an associated function, which means that you have↩
/// to call it as `Box::into_raw_with_allocator(b)` instead of `b.into_raw_with_allocator()`. This↩
/// is so that there is no conflict with a method on the inner type.↩
///↩
/// # Examples↩
/// Converting the raw pointer back into a `Box` with [`Box::from_raw_in`]↩
/// for automatic cleanup:↩
/// ```↩
/// #![feature(allocator_api)]↩
///↩
/// use std::alloc::System;↩
///↩
/// let x = Box::new_in(String::from("Hello"), System);↩
/// let (ptr, alloc) = Box::into_raw_with_allocator(x);↩
/// let x = unsafe { Box::from_raw_in(ptr, alloc) };↩
/// ```↩
/// Manual cleanup by explicitly running the destructor and deallocating↩
/// the memory:↩
/// ```↩
/// #![feature(allocator_api)]↩
///↩
/// use std::alloc::{Allocator, Layout, System};↩
/// use std::ptr::{self, NonNull};↩
///↩
/// let x = Box::new_in(String::from("Hello"), System);↩
/// let (ptr, alloc) = Box::into_raw_with_allocator(x);↩
/// unsafe {↩
/// ptr::drop_in_place(ptr);↩
/// let non_null = NonNull::new_unchecked(ptr);↩
/// alloc.deallocate(non_null.cast(), Layout::new::<String>());↩
/// }↩
/// ```↩
///↩
/// [memory layout]: self#memory-layout↩
#[inline(always)]↩
pub fn into_raw_with_allocator(b: Self) -> (*mut T, A) {↩
let (leaked, alloc) = Box::into_non_null(b);↩
(leaked.as_ptr(), alloc)↩
}↩
↩
#[inline(always)]↩
pub fn into_non_null(b: Self) -> (NonNull<T>, A) {↩
// Box is recognized as a "unique pointer" by Stacked Borrows, but internally it is a↩
// raw pointer for the type system. Turning it directly into a raw pointer would not be↩
// recognized as "releasing" the unique pointer to permit aliased raw accesses,↩
// so all raw pointer methods have to go through `Box::leak`. Turning *that* to a raw pointer↩
// behaves correctly.↩
let alloc = unsafe { ptr::read(&b.1) };↩
(NonNull::from(Box::leak(b)), alloc)↩
}↩
↩
/// Returns a reference to the underlying allocator.↩
///↩
/// Note: this is an associated function, which means that you have↩
/// to call it as `Box::allocator(&b)` instead of `b.allocator()`. This↩
/// is so that there is no conflict with a method on the inner type.↩
#[inline(always)]↩
pub const fn allocator(b: &Self) -> &A {↩
&b.1↩
}↩
↩
/// Consumes and leaks the `Box`, returning a mutable reference,↩
/// `&'a mut T`. Note that the type `T` must outlive the chosen lifetime↩
/// `'a`. If the type has only static references, or none at all, then this↩
/// may be chosen to be `'static`.↩
///↩
/// This function is mainly useful for data that lives for the remainder of↩
/// the program's life. Dropping the returned reference will cause a memory↩
/// leak. If this is not acceptable, the reference should first be wrapped↩
/// with the [`Box::from_raw`] function producing a `Box`. This `Box` can↩
/// then be dropped which will properly destroy `T` and release the↩
/// allocated memory.↩
///↩
/// Note: this is an associated function, which means that you have↩
/// to call it as `Box::leak(b)` instead of `b.leak()`. This↩
/// is so that there is no conflict with a method on the inner type.↩
///↩
/// # Examples↩
///↩
/// Simple usage:↩
///↩
/// ```↩
/// let x = Box::new(41);↩
/// let static_ref: &'static mut usize = Box::leak(x);↩
/// *static_ref += 1;↩
/// assert_eq!(*static_ref, 42);↩
/// ```↩
///↩
/// Unsized data:↩
///↩
/// ```↩
/// let x = vec![1, 2, 3].into_boxed_slice();↩
/// let static_ref = Box::leak(x);↩
/// static_ref[0] = 4;↩
/// assert_eq!(*static_ref, [4, 2, 3]);↩
/// ```↩
#[inline(always)]↩
fn leak<'a>(b: Self) -> &'a mut T↩
where↩
A: 'a,↩
{↩
unsafe { &mut *mem::ManuallyDrop::new(b).0.as_ptr() }↩
}↩
↩
/// Converts a `Box<T>` into a `Pin<Box<T>>`. If `T` does not implement [`Unpin`], then↩
/// `*boxed` will be pinned in memory and unable to be moved.↩
///↩
/// This conversion does not allocate on the heap and happens in place.↩
///↩
/// This is also available via [`From`].↩
///↩
/// Constructing and pinning a `Box` with <code>Box::into_pin([Box::new]\(x))</code>↩
/// can also be written more concisely using <code>[Box::pin]\(x)</code>.↩
/// This `into_pin` method is useful if you already have a `Box<T>`, or you are↩
/// constructing a (pinned) `Box` in a different way than with [`Box::new`].↩
///↩
/// # Notes↩
///↩
/// It's not recommended that crates add an impl like `From<Box<T>> for Pin<T>`,↩
/// as it'll introduce an ambiguity when calling `Pin::from`.↩
/// A demonstration of such a poor impl is shown below.↩
///↩
/// ```compile_fail↩
/// # use std::pin::Pin;↩
/// struct Foo; // A type defined in this crate.↩
/// impl From<Box<()>> for Pin<Foo> {↩
/// fn from(_: Box<()>) -> Pin<Foo> {↩
/// Pin::new(Foo)↩
/// }↩
/// }↩
///↩
/// let foo = Box::new(());↩
/// let bar = Pin::from(foo);↩
/// ```↩
#[inline(always)]↩
pub fn into_pin(boxed: Self) -> Pin<Self>↩
where↩
A: 'static,↩
{↩
// It's not possible to move or replace the insides of a `Pin<Box<T>>`↩
// when `T: !Unpin`, so it's safe to pin it directly without any↩
// additional requirements.↩
unsafe { Pin::new_unchecked(boxed) }↩
}↩
}↩
↩
impl<T: ?Sized, A: Allocator> Drop for Box<T, A> {↩
#[inline(always)]↩
fn drop(&mut self) {↩
let layout = Layout::for_value::<T>(&**self);↩
unsafe {↩
ptr::drop_in_place(self.0.as_mut());↩
self.1.deallocate(self.0.cast(), layout);↩
}↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl<T: Default> Default for Box<T> {↩
/// Creates a `Box<T>`, with the `Default` value for T.↩
#[inline(always)]↩
fn default() -> Self {↩
Box::new(T::default())↩
}↩
}↩
↩
impl<T, A: Allocator + Default> Default for Box<[T], A> {↩
#[inline(always)]↩
fn default() -> Self {↩
let ptr: NonNull<[T]> = NonNull::<[T; 0]>::dangling();↩
Box(ptr, A::default())↩
}↩
}↩
↩
impl<A: Allocator + Default> Default for Box<str, A> {↩
#[inline(always)]↩
fn default() -> Self {↩
// SAFETY: This is the same as `Unique::cast<U>` but with an unsized `U = str`.↩
let ptr: NonNull<str> = unsafe {↩
let bytes: NonNull<[u8]> = NonNull::<[u8; 0]>::dangling();↩
NonNull::new_unchecked(bytes.as_ptr() as *mut str)↩
};↩
Box(ptr, A::default())↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl<T: Clone, A: Allocator + Clone> Clone for Box<T, A> {↩
/// 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);↩
/// ```↩
#[inline(always)]↩
fn clone(&self) -> Self {↩
// Pre-allocate memory to allow writing the cloned value directly.↩
let mut boxed = Self::new_uninit_in(self.1.clone());↩
unsafe {↩
boxed.write((**self).clone());↩
boxed.assume_init()↩
}↩
}↩
↩
/// 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);↩
/// ```↩
#[inline(always)]↩
fn clone_from(&mut self, source: &Self) {↩
(**self).clone_from(&(**source));↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl Clone for Box<str> {↩
#[inline(always)]↩
fn clone(&self) -> Self {↩
// this makes a copy of the data↩
let buf: Box<[u8]> = self.as_bytes().into();↩
unsafe { Box::from_raw(Box::into_raw(buf) as *mut str) }↩
}↩
}↩
↩
impl<T: ?Sized + PartialEq, A: Allocator> PartialEq for Box<T, A> {↩
#[inline(always)]↩
fn eq(&self, other: &Self) -> bool {↩
PartialEq::eq(&**self, &**other)↩
}↩
#[inline(always)]↩
fn ne(&self, other: &Self) -> bool {↩
PartialEq::ne(&**self, &**other)↩
}↩
}↩
↩
impl<T: ?Sized + PartialOrd, A: Allocator> PartialOrd for Box<T, A> {↩
#[inline(always)]↩
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {↩
PartialOrd::partial_cmp(&**self, &**other)↩
}↩
#[inline(always)]↩
fn lt(&self, other: &Self) -> bool {↩
PartialOrd::lt(&**self, &**other)↩
}↩
#[inline(always)]↩
fn le(&self, other: &Self) -> bool {↩
PartialOrd::le(&**self, &**other)↩
}↩
#[inline(always)]↩
fn ge(&self, other: &Self) -> bool {↩
PartialOrd::ge(&**self, &**other)↩
}↩
#[inline(always)]↩
fn gt(&self, other: &Self) -> bool {↩
PartialOrd::gt(&**self, &**other)↩
}↩
}↩
↩
impl<T: ?Sized + Ord, A: Allocator> Ord for Box<T, A> {↩
#[inline(always)]↩
fn cmp(&self, other: &Self) -> Ordering {↩
Ord::cmp(&**self, &**other)↩
}↩
}↩
↩
impl<T: ?Sized + Eq, A: Allocator> Eq for Box<T, A> {}↩
↩
impl<T: ?Sized + Hash, A: Allocator> Hash for Box<T, A> {↩
#[inline(always)]↩
fn hash<H: Hasher>(&self, state: &mut H) {↩
(**self).hash(state);↩
}↩
}↩
↩
impl<T: ?Sized + Hasher, A: Allocator> Hasher for Box<T, A> {↩
#[inline(always)]↩
fn finish(&self) -> u64 {↩
(**self).finish()↩
}↩
#[inline(always)]↩
fn write(&mut self, bytes: &[u8]) {↩
(**self).write(bytes)↩
}↩
#[inline(always)]↩
fn write_u8(&mut self, i: u8) {↩
(**self).write_u8(i)↩
}↩
#[inline(always)]↩
fn write_u16(&mut self, i: u16) {↩
(**self).write_u16(i)↩
}↩
#[inline(always)]↩
fn write_u32(&mut self, i: u32) {↩
(**self).write_u32(i)↩
}↩
#[inline(always)]↩
fn write_u64(&mut self, i: u64) {↩
(**self).write_u64(i)↩
}↩
#[inline(always)]↩
fn write_u128(&mut self, i: u128) {↩
(**self).write_u128(i)↩
}↩
#[inline(always)]↩
fn write_usize(&mut self, i: usize) {↩
(**self).write_usize(i)↩
}↩
#[inline(always)]↩
fn write_i8(&mut self, i: i8) {↩
(**self).write_i8(i)↩
}↩
#[inline(always)]↩
fn write_i16(&mut self, i: i16) {↩
(**self).write_i16(i)↩
}↩
#[inline(always)]↩
fn write_i32(&mut self, i: i32) {↩
(**self).write_i32(i)↩
}↩
#[inline(always)]↩
fn write_i64(&mut self, i: i64) {↩
(**self).write_i64(i)↩
}↩
#[inline(always)]↩
fn write_i128(&mut self, i: i128) {↩
(**self).write_i128(i)↩
}↩
#[inline(always)]↩
fn write_isize(&mut self, i: isize) {↩
(**self).write_isize(i)↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl<T> From<T> for Box<T> {↩
/// Converts a `T` into a `Box<T>`↩
///↩
/// The conversion allocates on the heap and moves `t`↩
/// from the stack into it.↩
///↩
/// # Examples↩
///↩
/// ```rust↩
/// let x = 5;↩
/// let boxed = Box::new(5);↩
///↩
/// assert_eq!(Box::from(x), boxed);↩
/// ```↩
#[inline(always)]↩
fn from(t: T) -> Self {↩
Box::new(t)↩
}↩
}↩
↩
impl<T: ?Sized, A: Allocator> From<Box<T, A>> for Pin<Box<T, A>>↩
where↩
A: 'static,↩
{↩
/// Converts a `Box<T>` into a `Pin<Box<T>>`. If `T` does not implement [`Unpin`], then↩
/// `*boxed` will be pinned in memory and unable to be moved.↩
///↩
/// This conversion does not allocate on the heap and happens in place.↩
///↩
/// This is also available via [`Box::into_pin`].↩
///↩
/// Constructing and pinning a `Box` with <code><Pin<Box\<T>>>::from([Box::new]\(x))</code>↩
/// can also be written more concisely using <code>[Box::pin]\(x)</code>.↩
/// This `From` implementation is useful if you already have a `Box<T>`, or you are↩
/// constructing a (pinned) `Box` in a different way than with [`Box::new`].↩
#[inline(always)]↩
fn from(boxed: Box<T, A>) -> Self {↩
Box::into_pin(boxed)↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl<T: Copy, A: Allocator + Default> From<&[T]> for Box<[T], A> {↩
/// Converts a `&[T]` into a `Box<[T]>`↩
///↩
/// This conversion allocates on the heap↩
/// and performs a copy of `slice` and its contents.↩
///↩
/// # Examples↩
/// ```rust↩
/// // 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:?}");↩
/// ```↩
#[inline(always)]↩
fn from(slice: &[T]) -> Box<[T], A> {↩
let len = slice.len();↩
let buf = RawVec::with_capacity_in(len, A::default());↩
unsafe {↩
ptr::copy_nonoverlapping(slice.as_ptr(), buf.ptr(), len);↩
buf.into_box(slice.len()).assume_init()↩
}↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl<A: Allocator + Default> From<&str> for Box<str, A> {↩
/// Converts a `&str` into a `Box<str>`↩
///↩
/// This conversion allocates on the heap↩
/// and performs a copy of `s`.↩
///↩
/// # Examples↩
///↩
/// ```rust↩
/// let boxed: Box<str> = Box::from("hello");↩
/// println!("{boxed}");↩
/// ```↩
#[inline(always)]↩
fn from(s: &str) -> Box<str, A> {↩
let (raw, alloc) = Box::into_raw_with_allocator(Box::<[u8], A>::from(s.as_bytes()));↩
unsafe { Box::from_raw_in(raw as *mut str, alloc) }↩
}↩
}↩
↩
impl<A: Allocator> From<Box<str, A>> for Box<[u8], A> {↩
/// Converts a `Box<str>` into a `Box<[u8]>`↩
///↩
/// This conversion does not allocate on the heap and happens in place.↩
///↩
/// # Examples↩
/// ```rust↩
/// // 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);↩
/// ```↩
#[inline(always)]↩
fn from(s: Box<str, A>) -> Self {↩
let (raw, alloc) = Box::into_raw_with_allocator(s);↩
unsafe { Box::from_raw_in(raw as *mut [u8], alloc) }↩
}↩
}↩
↩
impl<T, A: Allocator, const N: usize> Box<[T; N], A> {↩
#[inline(always)]↩
pub fn slice(b: Self) -> Box<[T], A> {↩
let (ptr, alloc) = Box::into_raw_with_allocator(b);↩
unsafe { Box::from_raw_in(ptr, alloc) }↩
}↩
↩
pub fn into_vec(self) -> Vec<T, A>↩
where↩
A: Allocator,↩
{↩
unsafe {↩
let (b, alloc) = Box::into_raw_with_allocator(self);↩
Vec::from_raw_parts_in(b as *mut T, N, N, alloc)↩
}↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl<T, const N: usize> From<[T; N]> for Box<[T]> {↩
/// Converts a `[T; N]` into a `Box<[T]>`↩
///↩
/// This conversion moves the array to newly heap-allocated memory.↩
///↩
/// # Examples↩
///↩
/// ```rust↩
/// let boxed: Box<[u8]> = Box::from([4, 2]);↩
/// println!("{boxed:?}");↩
/// ```↩
#[inline(always)]↩
fn from(array: [T; N]) -> Box<[T]> {↩
Box::slice(Box::new(array))↩
}↩
}↩
↩
impl<T, A: Allocator, const N: usize> TryFrom<Box<[T], A>> for Box<[T; N], A> {↩
type Error = Box<[T], A>;↩
↩
/// Attempts to convert a `Box<[T]>` into a `Box<[T; N]>`.↩
///↩
/// The conversion occurs in-place and does not require a↩
/// new memory allocation.↩
///↩
/// # Errors↩
///↩
/// Returns the old `Box<[T]>` in the `Err` variant if↩
/// `boxed_slice.len()` does not equal `N`.↩
#[inline(always)]↩
fn try_from(boxed_slice: Box<[T], A>) -> Result<Self, Self::Error> {↩
if boxed_slice.len() == N {↩
let (ptr, alloc) = Box::into_raw_with_allocator(boxed_slice);↩
Ok(unsafe { Box::from_raw_in(ptr as *mut [T; N], alloc) })↩
} else {↩
Err(boxed_slice)↩
}↩
}↩
}↩
↩
impl<A: Allocator> Box<dyn Any, A> {↩
/// 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));↩
/// ```↩
#[inline(always)]↩
pub fn downcast<T: Any>(self) -> Result<Box<T, A>, Self> {↩
if self.is::<T>() {↩
unsafe { Ok(self.downcast_unchecked::<T>()) }↩
} else {↩
Err(self)↩
}↩
}↩
↩
/// Downcasts the box to a concrete type.↩
///↩
/// For a safe alternative see [`downcast`].↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(downcast_unchecked)]↩
///↩
/// use std::any::Any;↩
///↩
/// let x: Box<dyn Any> = Box::new(1_usize);↩
///↩
/// unsafe {↩
/// assert_eq!(*x.downcast_unchecked::<usize>(), 1);↩
/// }↩
/// ```↩
///↩
/// # Safety↩
///↩
/// The contained value must be of type `T`. Calling this method↩
/// with the incorrect type is *undefined behavior*.↩
///↩
/// [`downcast`]: Self::downcast↩
#[inline(always)]↩
pub unsafe fn downcast_unchecked<T: Any>(self) -> Box<T, A> {↩
debug_assert!(self.is::<T>());↩
unsafe {↩
let (raw, alloc): (*mut dyn Any, _) = Box::into_raw_with_allocator(self);↩
Box::from_raw_in(raw as *mut T, alloc)↩
}↩
}↩
}↩
↩
impl<A: Allocator> Box<dyn Any + Send, A> {↩
/// 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));↩
/// ```↩
#[inline(always)]↩
pub fn downcast<T: Any>(self) -> Result<Box<T, A>, Self> {↩
if self.is::<T>() {↩
unsafe { Ok(self.downcast_unchecked::<T>()) }↩
} else {↩
Err(self)↩
}↩
}↩
↩
/// Downcasts the box to a concrete type.↩
///↩
/// For a safe alternative see [`downcast`].↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(downcast_unchecked)]↩
///↩
/// use std::any::Any;↩
///↩
/// let x: Box<dyn Any + Send> = Box::new(1_usize);↩
///↩
/// unsafe {↩
/// assert_eq!(*x.downcast_unchecked::<usize>(), 1);↩
/// }↩
/// ```↩
///↩
/// # Safety↩
///↩
/// The contained value must be of type `T`. Calling this method↩
/// with the incorrect type is *undefined behavior*.↩
///↩
/// [`downcast`]: Self::downcast↩
#[inline(always)]↩
pub unsafe fn downcast_unchecked<T: Any>(self) -> Box<T, A> {↩
debug_assert!(self.is::<T>());↩
unsafe {↩
let (raw, alloc): (*mut (dyn Any + Send), _) = Box::into_raw_with_allocator(self);↩
Box::from_raw_in(raw as *mut T, alloc)↩
}↩
}↩
}↩
↩
impl<A: Allocator> Box<dyn Any + Send + Sync, A> {↩
/// Attempt to downcast the box to a concrete type.↩
///↩
/// # Examples↩
///↩
/// ```↩
/// use std::any::Any;↩
///↩
/// fn print_if_string(value: Box<dyn Any + Send + Sync>) {↩
/// if let Ok(string) = value.downcast::<String>() {↩
/// println!("String ({}): {}", string.len(), string);↩
/// }↩
/// }↩
///↩
/// let my_string = "Hello World".to_string();↩
/// print_if_string(Box::new(my_string));↩
/// print_if_string(Box::new(0i8));↩
/// ```↩
#[inline(always)]↩
pub fn downcast<T: Any>(self) -> Result<Box<T, A>, Self> {↩
if self.is::<T>() {↩
unsafe { Ok(self.downcast_unchecked::<T>()) }↩
} else {↩
Err(self)↩
}↩
}↩
↩
/// Downcasts the box to a concrete type.↩
///↩
/// For a safe alternative see [`downcast`].↩
///↩
/// # Examples↩
///↩
/// ```↩
/// #![feature(downcast_unchecked)]↩
///↩
/// use std::any::Any;↩
///↩
/// let x: Box<dyn Any + Send + Sync> = Box::new(1_usize);↩
///↩
/// unsafe {↩
/// assert_eq!(*x.downcast_unchecked::<usize>(), 1);↩
/// }↩
/// ```↩
///↩
/// # Safety↩
///↩
/// The contained value must be of type `T`. Calling this method↩
/// with the incorrect type is *undefined behavior*.↩
///↩
/// [`downcast`]: Self::downcast↩
#[inline(always)]↩
pub unsafe fn downcast_unchecked<T: Any>(self) -> Box<T, A> {↩
debug_assert!(self.is::<T>());↩
unsafe {↩
let (raw, alloc): (*mut (dyn Any + Send + Sync), _) =↩
Box::into_raw_with_allocator(self);↩
Box::from_raw_in(raw as *mut T, alloc)↩
}↩
}↩
}↩
↩
impl<T: fmt::Display + ?Sized, A: Allocator> fmt::Display for Box<T, A> {↩
#[inline(always)]↩
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {↩
fmt::Display::fmt(&**self, f)↩
}↩
}↩
↩
impl<T: fmt::Debug + ?Sized, A: Allocator> fmt::Debug for Box<T, A> {↩
#[inline(always)]↩
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {↩
fmt::Debug::fmt(&**self, f)↩
}↩
}↩
↩
impl<T: ?Sized, A: Allocator> fmt::Pointer for Box<T, A> {↩
#[inline(always)]↩
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {↩
// It's not possible to extract the inner Uniq directly from the Box,↩
// instead we cast it to a *const which aliases the Unique↩
let ptr: *const T = &**self;↩
fmt::Pointer::fmt(&ptr, f)↩
}↩
}↩
↩
impl<T: ?Sized, A: Allocator> Deref for Box<T, A> {↩
type Target = T;↩
↩
#[inline(always)]↩
fn deref(&self) -> &T {↩
unsafe { self.0.as_ref() }↩
}↩
}↩
↩
impl<T: ?Sized, A: Allocator> DerefMut for Box<T, A> {↩
#[inline(always)]↩
fn deref_mut(&mut self) -> &mut T {↩
unsafe { self.0.as_mut() }↩
}↩
}↩
↩
impl<I: Iterator + ?Sized, A: Allocator> Iterator for Box<I, A> {↩
type Item = I::Item;↩
↩
#[inline(always)]↩
fn next(&mut self) -> Option<I::Item> {↩
(**self).next()↩
}↩
↩
#[inline(always)]↩
fn size_hint(&self) -> (usize, Option<usize>) {↩
(**self).size_hint()↩
}↩
↩
#[inline(always)]↩
fn nth(&mut self, n: usize) -> Option<I::Item> {↩
(**self).nth(n)↩
}↩
↩
#[inline(always)]↩
fn last(self) -> Option<I::Item> {↩
BoxIter::last(self)↩
}↩
}↩
↩
trait BoxIter {↩
type Item;↩
fn last(self) -> Option<Self::Item>;↩
}↩
↩
impl<I: Iterator + ?Sized, A: Allocator> BoxIter for Box<I, A> {↩
type Item = I::Item;↩
↩
#[inline(always)]↩
fn last(self) -> Option<I::Item> {↩
#[inline(always)]↩
fn some<T>(_: Option<T>, x: T) -> Option<T> {↩
Some(x)↩
}↩
↩
self.fold(None, some)↩
}↩
}↩
↩
impl<I: DoubleEndedIterator + ?Sized, A: Allocator> DoubleEndedIterator for Box<I, A> {↩
#[inline(always)]↩
fn next_back(&mut self) -> Option<I::Item> {↩
(**self).next_back()↩
}↩
#[inline(always)]↩
fn nth_back(&mut self, n: usize) -> Option<I::Item> {↩
(**self).nth_back(n)↩
}↩
}↩
↩
impl<I: ExactSizeIterator + ?Sized, A: Allocator> ExactSizeIterator for Box<I, A> {↩
#[inline(always)]↩
fn len(&self) -> usize {↩
(**self).len()↩
}↩
}↩
↩
impl<I: FusedIterator + ?Sized, A: Allocator> FusedIterator for Box<I, A> {}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl<I> FromIterator<I> for Box<[I]> {↩
#[inline(always)]↩
fn from_iter<T: IntoIterator<Item = I>>(iter: T) -> Self {↩
iter.into_iter().collect::<Vec<_>>().into_boxed_slice()↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl<T: Clone, A: Allocator + Clone> Clone for Box<[T], A> {↩
#[inline(always)]↩
fn clone(&self) -> Self {↩
let alloc = Box::allocator(self).clone();↩
let mut vec = Vec::with_capacity_in(self.len(), alloc);↩
vec.extend_from_slice(self);↩
vec.into_boxed_slice()↩
}↩
↩
#[inline(always)]↩
fn clone_from(&mut self, other: &Self) {↩
if self.len() == other.len() {↩
self.clone_from_slice(other);↩
} else {↩
*self = other.clone();↩
}↩
}↩
}↩
↩
impl<T: ?Sized, A: Allocator> borrow::Borrow<T> for Box<T, A> {↩
#[inline(always)]↩
fn borrow(&self) -> &T {↩
self↩
}↩
}↩
↩
impl<T: ?Sized, A: Allocator> borrow::BorrowMut<T> for Box<T, A> {↩
#[inline(always)]↩
fn borrow_mut(&mut self) -> &mut T {↩
self↩
}↩
}↩
↩
impl<T: ?Sized, A: Allocator> AsRef<T> for Box<T, A> {↩
#[inline(always)]↩
fn as_ref(&self) -> &T {↩
self↩
}↩
}↩
↩
impl<T: ?Sized, A: Allocator> AsMut<T> for Box<T, A> {↩
#[inline(always)]↩
fn as_mut(&mut self) -> &mut T {↩
self↩
}↩
}↩
↩
/* Nota bene↩
*↩
* We could have chosen not to add this impl, and instead have written a↩
* function of Pin<Box<T>> to Pin<T>. Such a function would not be sound,↩
* because Box<T> implements Unpin even when T does not, as a result of↩
* this impl.↩
*↩
* We chose this API instead of the alternative for a few reasons:↩
* - Logically, it is helpful to understand pinning in regard to the↩
* memory region being pointed to. For this reason none of the↩
* standard library pointer types support projecting through a pin↩
* (Box<T> is the only pointer type in std for which this would be↩
* safe.)↩
* - It is in practice very useful to have Box<T> be unconditionally↩
* Unpin because of trait objects, for which the structural auto↩
* trait functionality does not apply (e.g., Box<dyn Foo> would↩
* otherwise not be Unpin).↩
*↩
* Another type with the same semantics as Box but only a conditional↩
* implementation of `Unpin` (where `T: Unpin`) would be valid/safe, and↩
* could have a method to project a Pin<T> from it.↩
*/↩
impl<T: ?Sized, A: Allocator> Unpin for Box<T, A> where A: 'static {}↩
↩
impl<F: ?Sized + Future + Unpin, A: Allocator> Future for Box<F, A>↩
where↩
A: 'static,↩
{↩
type Output = F::Output;↩
↩
#[inline(always)]↩
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {↩
F::poll(Pin::new(&mut *self), cx)↩
}↩
}↩
↩
#[cfg(feature = "std")]↩
mod error {↩
use std::error::Error;↩
↩
use super::Box;↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a> {↩
/// 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))↩
/// ```↩
#[inline(always)]↩
fn from(err: E) -> Box<dyn Error + 'a> {↩
unsafe { Box::from_raw(Box::leak(Box::new(err))) }↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<dyn Error + Send + Sync + 'a> {↩
/// 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))↩
/// ```↩
#[inline(always)]↩
fn from(err: E) -> Box<dyn Error + Send + Sync + 'a> {↩
unsafe { Box::from_raw(Box::leak(Box::new(err))) }↩
}↩
}↩
↩
impl<T: Error> Error for Box<T> {↩
#[inline(always)]↩
fn source(&self) -> Option<&(dyn Error + 'static)> {↩
Error::source(&**self)↩
}↩
}↩
}↩
↩
#[cfg(feature = "std")]↩
impl<R: std::io::Read + ?Sized, A: Allocator> std::io::Read for Box<R, A> {↩
#[inline]↩
fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {↩
(**self).read(buf)↩
}↩
↩
#[inline]↩
fn read_to_end(&mut self, buf: &mut std::vec::Vec<u8>) -> std::io::Result<usize> {↩
(**self).read_to_end(buf)↩
}↩
↩
#[inline]↩
fn read_to_string(&mut self, buf: &mut String) -> std::io::Result<usize> {↩
(**self).read_to_string(buf)↩
}↩
↩
#[inline]↩
fn read_exact(&mut self, buf: &mut [u8]) -> std::io::Result<()> {↩
(**self).read_exact(buf)↩
}↩
}↩
↩
#[cfg(feature = "std")]↩
impl<W: std::io::Write + ?Sized, A: Allocator> std::io::Write for Box<W, A> {↩
#[inline]↩
fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {↩
(**self).write(buf)↩
}↩
↩
#[inline]↩
fn flush(&mut self) -> std::io::Result<()> {↩
(**self).flush()↩
}↩
↩
#[inline]↩
fn write_all(&mut self, buf: &[u8]) -> std::io::Result<()> {↩
(**self).write_all(buf)↩
}↩
↩
#[inline]↩
fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> std::io::Result<()> {↩
(**self).write_fmt(fmt)↩
}↩
}↩
↩
#[cfg(feature = "std")]↩
impl<S: std::io::Seek + ?Sized, A: Allocator> std::io::Seek for Box<S, A> {↩
#[inline]↩
fn seek(&mut self, pos: std::io::SeekFrom) -> std::io::Result<u64> {↩
(**self).seek(pos)↩
}↩
↩
#[inline]↩
fn stream_position(&mut self) -> std::io::Result<u64> {↩
(**self).stream_position()↩
}↩
}↩
↩
#[cfg(feature = "std")]↩
impl<B: std::io::BufRead + ?Sized, A: Allocator> std::io::BufRead for Box<B, A> {↩
#[inline]↩
fn fill_buf(&mut self) -> std::io::Result<&[u8]> {↩
(**self).fill_buf()↩
}↩
↩
#[inline]↩
fn consume(&mut self, amt: usize) {↩
(**self).consume(amt)↩
}↩
↩
#[inline]↩
fn read_until(&mut self, byte: u8, buf: &mut std::vec::Vec<u8>) -> std::io::Result<usize> {↩
(**self).read_until(byte, buf)↩
}↩
↩
#[inline]↩
fn read_line(&mut self, buf: &mut std::string::String) -> std::io::Result<usize> {↩
(**self).read_line(buf)↩
}↩
}↩
↩
#[cfg(feature = "alloc")]↩
impl<A: Allocator> Extend<Box<str, A>> for alloc_crate::string::String {↩
fn extend<I: IntoIterator<Item = Box<str, A>>>(&mut self, iter: I) {↩
iter.into_iter().for_each(move |s| self.push_str(&s));↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl Clone for Box<core::ffi::CStr> {↩
#[inline]↩
fn clone(&self) -> Self {↩
(**self).into()↩
}↩
}↩
↩
#[cfg(not(no_global_oom_handling))]↩
impl From<&core::ffi::CStr> for Box<core::ffi::CStr> {↩
/// Converts a `&CStr` into a `Box<CStr>`,↩
/// by copying the contents into a newly allocated [`Box`].↩
fn from(s: &core::ffi::CStr) -> Box<core::ffi::CStr> {↩
let boxed: Box<[u8]> = Box::from(s.to_bytes_with_nul());↩
unsafe { Box::from_raw(Box::into_raw(boxed) as *mut core::ffi::CStr) }↩
}↩
}↩
↩
#[cfg(feature = "serde")]↩
impl<T, A> serde::Serialize for Box<T, A>↩
where↩
T: serde::Serialize,↩
A: Allocator,↩
{↩
#[inline(always)]↩
fn serialize<S: serde::ser::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {↩
(**self).serialize(serializer)↩
}↩
}↩
↩
#[cfg(feature = "serde")]↩
impl<'de, T, A> serde::Deserialize<'de> for Box<T, A>↩
where↩
T: serde::Deserialize<'de>,↩
A: Allocator + Default,↩
{↩
#[inline(always)]↩
fn deserialize<D: serde::de::Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {↩
let value = T::deserialize(deserializer)?;↩
Ok(Box::new_in(value, A::default()))↩
}↩
}↩