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//! A pointer type for heap allocation. //! //! [`Box<T, A>`], casually referred to as a 'box', provides the simplest form of allocation in //! Rust. Boxes provide ownership for this allocation, and drop their contents when they go out of //! scope. //! //! # Examples //! //! Move a value from the stack to the heap by creating a [`Box`]: //! //! ``` //! use alloc_wg::boxed::Box; //! //! let val: u8 = 5; //! # #[allow(unused_variables)] //! let boxed: Box<u8> = Box::new(val); //! ``` //! //! Move a value from a [`Box`] back to the stack by [dereferencing]: //! //! ``` //! use alloc_wg::boxed::Box; //! //! let boxed: Box<u8> = Box::new(5); //! # #[allow(unused_variables)] //! let val: u8 = *boxed; //! ``` //! //! Creating a recursive data structure: //! //! ``` //! use alloc_wg::boxed::Box; //! //! #[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, //! D>`], 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 if no //! allocator was specified. It is valid to convert both ways between a [`Box`] and a raw pointer //! allocated with the same allocator, given that the [`NonZeroLayout`] 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)`]. For other allocators, [`Box::<T>::from_raw_in(value, alloc)`] may //! be used. Conversely, the memory backing a `value: *mut T` obtained from [`Box::<T>::into_raw`] //! may be deallocated using the specific allocator with [`NonZeroLayout::for_value(&*value)`]. //! //! //! [dereferencing]: core::ops::Deref //! [`Box`]: crate::boxed::Box //! [`Box<T, A>`]: crate::boxed::Box //! [`Box::<T>::from_raw(value)`]: crate::boxed::Box::from_raw //! [`Box::<T>::from_raw(value, alloc)`]: crate::boxed::Box::from_raw_in //! [`Box::<T>::into_raw`]: crate::boxed::Box::into_raw //! [`Global`]: crate::alloc::Global //! [`NonZeroLayout`]: crate::alloc::NonZeroLayout //! [`NonZeroLayout::for_value(&*value)`]: crate::alloc::NonZeroLayout::for_value use crate::{ alloc::{handle_alloc_error, AllocErr, AllocRef, Global, Layout}, clone::CloneIn, collections::TryReserveError::{self, AllocError}, handle_reserve_error, ptr::Unique, raw_vec::RawVec, }; use core::{ any::Any, borrow, cmp::Ordering, fmt, future::Future, hash::{Hash, Hasher}, iter::FusedIterator, mem, mem::MaybeUninit, ops::{Deref, DerefMut}, pin::Pin, ptr::{self, NonNull}, task::{Context, Poll}, }; /// A pointer type for heap allocation. /// /// See the [module-level documentation](index.html) for more. pub struct Box<T: ?Sized, A: AllocRef = Global> { ptr: Unique<T>, alloc: A, } #[allow(clippy::use_self)] 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. /// /// # Example /// /// ``` /// use alloc_wg::boxed::Box; /// /// # #[allow(unused_variables)] /// let five = Box::new(5); /// ``` #[allow(clippy::inline_always)] #[inline(always)] #[must_use] pub fn new(x: T) -> Self { Self::new_in(x, Global) } /// Constructs a new box with uninitialized contents. /// /// # Example /// /// ``` /// use alloc_wg::boxed::Box; /// /// 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) /// ``` #[allow(clippy::inline_always)] #[inline(always)] #[must_use] pub fn new_uninit() -> Box<MaybeUninit<T>> { Self::new_uninit_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. #[allow(clippy::inline_always)] #[inline(always)] pub fn pin(x: T) -> Pin<Self> { Self::pin_in(x, Global) } } #[allow(clippy::use_self)] impl<T, A: AllocRef> Box<T, A> { /// Allocates memory with the given allocator and then places `x` into it. /// /// This doesn't actually allocate if `T` is zero-sized. /// /// # Example /// /// ``` /// #![feature(allocator_api)] /// use alloc_wg::{alloc::Global, boxed::Box}; /// /// # #[allow(unused_variables)] /// let five = Box::new_in(5, Global); /// ``` #[allow(clippy::inline_always)] #[inline(always)] pub fn new_in(x: T, a: A) -> Self { match Self::try_new_in(x, a) { Err(_) => handle_alloc_error(Layout::new::<T>()), Ok(b) => b, } } /// Tries to allocate memory with the given allocator and then places `x` into it. /// /// This doesn't actually allocate if `T` is zero-sized. /// /// # Example /// /// ``` /// #![feature(allocator_api)] /// use alloc_wg::{alloc::Global, boxed::Box}; /// /// # #[allow(unused_variables)] /// let five = Box::try_new_in(5, Global)?; /// # Ok::<_, alloc_wg::alloc::AllocErr>(()) /// ``` pub fn try_new_in(x: T, alloc: A) -> Result<Self, AllocErr> { let mut boxed = Self::try_new_uninit_in(alloc)?; unsafe { boxed.ptr.as_mut().write(x); Ok(boxed.assume_init()) } } /// Constructs a new box with uninitialized contents in a specified allocator. /// /// # Example /// /// ``` /// #![feature(allocator_api)] /// use alloc_wg::{alloc::Global, boxed::Box}; /// /// let mut five = Box::<u32, _>::new_uninit_in(Global); /// /// let five = unsafe { /// // Deferred initialization: /// five.as_mut_ptr().write(5); /// /// five.assume_init() /// }; /// /// assert_eq!(*five, 5) /// ``` #[allow(clippy::inline_always)] #[inline(always)] pub fn new_uninit_in(a: A) -> Box<MaybeUninit<T>, A> { match Self::try_new_uninit_in(a) { Ok(b) => b, Err(_) => handle_alloc_error(Layout::new::<T>()), } } /// Tries to construct a new box with uninitialized contents in a specified allocator. /// /// # Example /// /// ``` /// #![feature(allocator_api)] /// use alloc_wg::{alloc::Global, boxed::Box}; /// /// let mut five = Box::<u32, Global>::try_new_uninit_in(Global)?; /// /// let five = unsafe { /// // Deferred initialization: /// five.as_mut_ptr().write(5); /// /// five.assume_init() /// }; /// /// assert_eq!(*five, 5); /// # Ok::<_, alloc_wg::alloc::AllocErr>(()) /// ``` pub fn try_new_uninit_in(mut alloc: A) -> Result<Box<MaybeUninit<T>, A>, AllocErr> { let memory = alloc.alloc(Layout::new::<MaybeUninit<T>>())?; let ptr = memory.as_mut_ptr(); unsafe { Ok(Box::from_raw_in(ptr.cast(), alloc)) } } /// Constructs a new `Pin<Box<T, A>>` with the specified allocator. If `T` does not implement /// `Unpin`, then `x` will be pinned in memory and unable to be moved. #[allow(clippy::inline_always)] #[inline(always)] pub fn pin_in(x: T, a: A) -> Pin<Self> { Pin::from(Self::new_in(x, a)) } /// Constructs a new `Pin<Box<T, A>>` with the specified allocator. If `T` does not implement /// `Unpin`, then `x` will be pinned in memory and unable to be moved. #[inline] pub fn try_pin_in(x: T, a: A) -> Result<Pin<Self>, AllocErr> { Self::try_new_in(x, a).map(Pin::from) } } #[allow(clippy::use_self)] impl<T> Box<[T]> { /// Construct a new boxed slice with uninitialized contents. /// /// # Example /// /// ``` /// use alloc_wg::boxed::Box; /// /// 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]); /// ``` #[allow(clippy::inline_always)] #[inline(always)] #[must_use] pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>]> { Self::new_uninit_slice_in(len, Global) } } #[allow(clippy::use_self)] impl<T, A: AllocRef> Box<[T], A> { /// Construct a new boxed slice with uninitialized contents with the spoecified allocator. /// /// # Example /// /// ``` /// #![feature(allocator_api)] /// use alloc_wg::{alloc::Global, boxed::Box}; /// /// let mut values = Box::<[u32], _>::new_uninit_slice_in(3, Global); /// /// 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]); /// ``` #[allow(clippy::inline_always)] #[inline(always)] pub fn new_uninit_slice_in(len: usize, a: A) -> Box<[MaybeUninit<T>], A> { handle_reserve_error(Self::try_new_uninit_slice_in(len, a)) } /// Tries to construct a new boxed slice with uninitialized contents with the spoecified /// allocator. /// /// # Example /// /// ``` /// #![feature(allocator_api)] /// use alloc_wg::{alloc::Global, boxed::Box}; /// /// let mut values = Box::<[u32], Global>::try_new_uninit_slice_in(3, Global)?; /// /// 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::<_, alloc_wg::collections::TryReserveError>(()) /// ``` pub fn try_new_uninit_slice_in( len: usize, a: A, ) -> Result<Box<[MaybeUninit<T>], A>, TryReserveError> { unsafe { Ok(RawVec::try_with_capacity_in(len, a)?.into_box(len)) } } } #[allow(clippy::use_self)] impl<T, A: AllocRef> Box<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`]: core::mem::MaybeUninit::assume_init /// /// # Example /// /// ``` /// use alloc_wg::boxed::Box; /// /// 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) /// ``` #[inline] pub unsafe fn assume_init(self) -> Box<T, A> { let (ptr, alloc) = Self::into_raw_alloc(self); Box::from_raw_in((*ptr).as_mut_ptr(), alloc) } } #[allow(clippy::use_self)] impl<T, A: AllocRef> Box<[MaybeUninit<T>], A> { /// Converts to `Box<[T], B>`. /// /// # 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`]: core::mem::MaybeUninit::assume_init /// /// # Example /// /// ``` /// use alloc_wg::boxed::Box; /// /// 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] pub unsafe fn assume_init(self) -> Box<[T], A> { let (ptr, b) = Self::into_raw_alloc(self); Box::from_raw_in(ptr as *mut [T], b) } } 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`.2 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`][]: /// ``` /// use alloc_wg::boxed::Box; /// /// let x = Box::new(5); /// let ptr = Box::into_raw(x); /// # #[allow(unused_variables)] /// let x = unsafe { Box::from_raw(ptr) }; /// ``` /// Manually create a `Box` from scratch by using the global allocator: /// ``` /// use alloc_wg::{alloc::alloc, boxed::Box}; /// use core::alloc::Layout; /// /// unsafe { /// let ptr = alloc(Layout::new::<i32>()) as *mut i32; /// *ptr = 5; /// # #[allow(unused_variables)] /// let x = Box::from_raw(ptr); /// } /// ``` /// /// [memory layout]: index.html#memory-layout #[allow(clippy::inline_always)] #[inline(always)] pub unsafe fn from_raw(raw: *mut T) -> Self { Self::from_raw_in(raw, Global) } } impl<T: ?Sized, A: AllocRef> Box<T, A> { /// 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. /// /// # Example /// /// Manually create a `Box` from scratch by using the global allocator: /// ``` /// #![feature(allocator_api)] /// use alloc_wg::{ /// alloc::{alloc, Global}, /// boxed::Box, /// }; /// use core::alloc::Layout; /// /// unsafe { /// let ptr = alloc(Layout::new::<i32>()) as *mut i32; /// *ptr = 5; /// # #[allow(unused_variables)] /// let x: Box<_, Global> = Box::from_raw_in(ptr, Global); /// } /// ``` #[inline] pub unsafe fn from_raw_in(raw: *mut T, alloc: A) -> Self { Self { ptr: Unique::new_unchecked(raw), alloc, } } /// Returns a shared reference to the associated `BuildAlloc` pub fn build_alloc(&self) -> &A { &self.alloc } /// Returns a mutable reference to the associated `BuildAlloc` pub fn build_alloc_mut(&mut self) -> &mut A { &mut self.alloc } /// Returns a shared reference to the allocator. pub fn alloc_ref(&self) -> &A { &self.alloc } /// Returns a mutable reference to the allocator. pub fn alloc_ref_mut(&mut self) -> &mut A { &mut self.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: /// ``` /// use alloc_wg::boxed::Box; /// /// let x = Box::new(String::from("Hello")); /// let ptr = Box::into_raw(x); /// # #[allow(unused_variables)] /// let x = unsafe { Box::from_raw(ptr) }; /// ``` /// Manual cleanup by explicitly running the destructor and deallocating /// the memory: /// ``` /// use alloc_wg::{alloc::dealloc, boxed::Box}; /// use core::{alloc::Layout, 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]: index.html#memory-layout #[inline] pub fn into_raw(b: Self) -> *mut T { Self::into_raw_alloc(b).0 } #[inline] pub fn into_raw_alloc(b: Self) -> (*mut T, A) { let (p, b) = Self::into_raw_non_null_alloc(b); (p.as_ptr(), b) } /// Consumes the `Box`, returning the wrapped pointer as `NonNull<T>`. /// /// After calling this function, the caller is responsible for the memory previously managed by /// the `Box`. In particular, the caller should properly destroy `T` and release the memory. /// The easiest way to do so is to convert the `NonNull<T>` pointer /// into a raw pointer and back into a `Box` with the [`Box::from_raw`][] /// function. /// /// Note: this is an associated function, which means that you have to call it as /// `Box::into_raw_non_null(b)` instead of `b.into_raw_non_null()`. This is so that there is no /// conflict with a method on the inner type. /// /// # Examples /// /// ``` /// use alloc_wg::boxed::Box; /// /// let x = Box::new(5); /// let ptr = Box::into_raw_non_null(x); /// /// // Clean up the memory by converting the NonNull pointer back /// // into a Box and letting the Box be dropped. /// # #[allow(unused_variables)] /// let x = unsafe { Box::from_raw(ptr.as_ptr()) }; /// ``` #[inline] pub fn into_raw_non_null(b: Self) -> NonNull<T> { Self::into_raw_non_null_alloc(b).0 } #[inline] pub fn into_raw_non_null_alloc(b: Self) -> (NonNull<T>, A) { let (unique, alloc) = Self::into_unique_alloc(b); (unique.into(), alloc) } #[inline] #[doc(hidden)] pub fn into_unique(b: Self) -> Unique<T> { Self::into_unique_alloc(b).0 } #[inline] #[doc(hidden)] pub fn into_unique_alloc(mut b: Self) -> (Unique<T>, A) { let ptr = b.ptr; let alloc = unsafe { ptr::read(b.alloc_ref_mut()) }; mem::forget(b); // Box is kind-of a library type, but recognized as a "unique pointer" by // Stacked Borrows. This function here corresponds to "reborrowing to // a raw pointer", but there is no actual reborrow here -- so // without some care, the pointer we are returning here still carries // the tag of `b`, with `Unique` permission. // We round-trip through a mutable reference to avoid that. (ptr, alloc) } /// 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: /// /// ``` /// use alloc_wg::boxed::Box; /// /// let x = Box::new(41); /// let static_ref: &'static mut usize = Box::leak(x); /// *static_ref += 1; /// assert_eq!(*static_ref, 42); /// ``` // TODO: Example for unsized data #[inline] pub fn leak<'a>(b: Self) -> &'a mut T where T: 'a, // Technically not needed, but kept to be explicit. { unsafe { &mut *Self::into_raw(b) } } /// Converts a `Box<T, A>` into a `Pin<Box<T, A>>` /// /// This conversion does not allocate and happens in place. /// /// This is also available via [`From`][]. pub fn into_pin(boxed: Self) -> Pin<Self> { // 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) } } } fn drop_box<T: ?Sized, A: AllocRef>(boxed: &mut Box<T, A>) { unsafe { let layout = Layout::for_value(boxed.as_ref()); let ptr = boxed.ptr; ptr::drop_in_place(ptr.as_ptr()); boxed.alloc.dealloc(ptr.cast().into(), layout); } } unsafe impl<#[may_dangle] T: ?Sized, A: AllocRef> Drop for Box<T, A> { fn drop(&mut self) { drop_box(self); } } impl<T, A> Default for Box<T, A> where T: Default, A: Default + AllocRef, { #[must_use] fn default() -> Self { Self::new_in(T::default(), A::default()) } } #[allow(clippy::use_self)] impl<T, A: AllocRef> Default for Box<[T], A> where A: Default, { #[must_use] fn default() -> Self { Box::<[T; 0], A>::new_in([], A::default()) } } #[inline] unsafe fn from_boxed_utf8_unchecked<A: AllocRef>(v: Box<[u8], A>) -> Box<str, A> { let (ptr, b) = Box::into_raw_alloc(v); Box::from_raw_in(ptr as *mut str, b) } #[allow(clippy::use_self)] impl<A> Default for Box<str, A> where A: Default + AllocRef, { #[must_use] fn default() -> Self { unsafe { from_boxed_utf8_unchecked(Box::default()) } } } impl<T: Clone, A: AllocRef + Clone> Clone for Box<T, A> { /// Returns a new box with a `clone()` of this box's contents. /// /// # Examples /// /// ``` /// # #![allow(trivial_casts)] /// use alloc_wg::boxed::Box; /// /// 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] fn clone(&self) -> Self { self.clone_in(self.alloc.clone()) } /// Copies `source`'s contents into `self` without creating a new allocation. /// /// # Examples /// /// ``` /// use alloc_wg::boxed::Box; /// /// 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] fn clone_from(&mut self, source: &Self) { (**self).clone_from(&(**source)); } } #[allow(clippy::use_self)] impl<T: Clone, A: AllocRef, B: AllocRef> CloneIn<B> for Box<T, A> { type Cloned = Box<T, B>; fn clone_in(&self, a: B) -> Self::Cloned { Box::new_in(self.as_ref().clone(), a) } fn try_clone_in(&self, a: B) -> Result<Self::Cloned, TryReserveError> { Box::try_new_in(self.as_ref().clone(), a).map_err(|_| AllocError { layout: Layout::new::<T>(), }) } } impl<T: ?Sized + PartialEq, A: AllocRef> PartialEq for Box<T, A> { #[inline] fn eq(&self, other: &Self) -> bool { PartialEq::eq(&**self, &**other) } #[allow(clippy::partialeq_ne_impl)] #[inline] fn ne(&self, other: &Self) -> bool { PartialEq::ne(&**self, &**other) } } impl<T: ?Sized + PartialOrd, A: AllocRef> PartialOrd for Box<T, A> { #[inline] fn partial_cmp(&self, other: &Self) -> Option<Ordering> { PartialOrd::partial_cmp(&**self, &**other) } #[inline] fn lt(&self, other: &Self) -> bool { PartialOrd::lt(&**self, &**other) } #[inline] fn le(&self, other: &Self) -> bool { PartialOrd::le(&**self, &**other) } #[inline] fn gt(&self, other: &Self) -> bool { PartialOrd::gt(&**self, &**other) } #[inline] fn ge(&self, other: &Self) -> bool { PartialOrd::ge(&**self, &**other) } } impl<T: ?Sized + Ord, A: AllocRef> Ord for Box<T, A> { #[inline] fn cmp(&self, other: &Self) -> Ordering { Ord::cmp(&**self, &**other) } } impl<T: ?Sized + Eq, A: AllocRef> Eq for Box<T, A> {} impl<T: ?Sized + Hash, A: AllocRef> Hash for Box<T, A> { fn hash<H: Hasher>(&self, state: &mut H) { (**self).hash(state); } } impl<T: ?Sized + Hasher, A: AllocRef> Hasher for Box<T, A> { fn finish(&self) -> u64 { (**self).finish() } fn write(&mut self, bytes: &[u8]) { (**self).write(bytes) } fn write_u8(&mut self, i: u8) { (**self).write_u8(i) } fn write_u16(&mut self, i: u16) { (**self).write_u16(i) } fn write_u32(&mut self, i: u32) { (**self).write_u32(i) } fn write_u64(&mut self, i: u64) { (**self).write_u64(i) } fn write_u128(&mut self, i: u128) { (**self).write_u128(i) } fn write_usize(&mut self, i: usize) { (**self).write_usize(i) } fn write_i8(&mut self, i: i8) { (**self).write_i8(i) } fn write_i16(&mut self, i: i16) { (**self).write_i16(i) } fn write_i32(&mut self, i: i32) { (**self).write_i32(i) } fn write_i64(&mut self, i: i64) { (**self).write_i64(i) } fn write_i128(&mut self, i: i128) { (**self).write_i128(i) } fn write_isize(&mut self, i: isize) { (**self).write_isize(i) } } impl<T, A> From<T> for Box<T, A> where A: Default + AllocRef, { /// Converts a generic type `T` into a `Box<T>` /// /// The conversion allocates on the heap and moves `t` /// from the stack into it. /// /// # Examples /// /// ```rust /// use alloc_wg::boxed::Box; /// /// let x = 5; /// let boxed = Box::new(5); /// /// assert_eq!(Box::from(x), boxed); /// ``` fn from(t: T) -> Self { Self::new_in(t, A::default()) } } impl<T: ?Sized, A: AllocRef> From<Box<T, A>> for Pin<Box<T, A>> { /// Converts a `Box<T, A>` into a `Pin<Box<T, A>>` /// /// This conversion does not allocate on the heap and happens in place. fn from(boxed: Box<T, A>) -> Self { Box::into_pin(boxed) } } #[allow(clippy::use_self)] impl<T: Copy, A: AllocRef> From<&[T]> for Box<[T], A> where A: Default, { /// Converts a `&[T]` into a `Box<[T], B>` /// /// This conversion allocates and performs a copy of `slice`. /// /// # Examples /// ```rust /// use alloc_wg::boxed::Box; /// /// // 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); /// ``` fn from(slice: &[T]) -> Self { 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() } } } #[allow(clippy::use_self)] impl<A: AllocRef> From<&str> for Box<str, A> where A: Default, { /// Converts a `&str` into a `Box<str>` /// /// This conversion allocates on the heap /// and performs a copy of `s`. /// /// # Examples /// ```rust /// use alloc_wg::boxed::Box; /// /// let boxed: Box<str> = Box::from("hello"); /// println!("{}", boxed); /// ``` #[inline] #[must_use] fn from(s: &str) -> Self { unsafe { from_boxed_utf8_unchecked(Box::from(s.as_bytes())) } } } #[allow(clippy::use_self)] impl<A: AllocRef> 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] fn from(s: Box<str, A>) -> Self { let (ptr, b) = Box::into_raw_alloc(s); unsafe { Self::from_raw_in(ptr as *mut [u8], b) } } } #[allow(clippy::use_self)] impl<T, const N: usize> core::convert::TryFrom<Box<[T]>> for Box<[T; N]> { type Error = Box<[T]>; fn try_from(boxed_slice: Box<[T]>) -> Result<Self, Self::Error> { if boxed_slice.len() == N { Ok(unsafe { Self::from_raw(Box::into_raw(boxed_slice) as *mut [T; N]) }) } else { Err(boxed_slice) } } } #[allow(clippy::use_self)] impl<A: AllocRef> Box<dyn Any, A> { #[inline] /// 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)); /// ``` pub fn downcast<T: Any>(self) -> Result<Box<T, A>, Box<dyn Any, A>> { if self.is::<T>() { unsafe { let (raw, b): (*mut dyn Any, _) = Self::into_raw_alloc(self); Ok(Box::from_raw_in(raw as *mut T, b)) } } else { Err(self) } } } #[allow(clippy::use_self)] impl<A: AllocRef> Box<dyn Any + Send, A> { #[inline] /// 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)); /// ``` pub fn downcast<T: Any>(self) -> Result<Box<T, A>, Box<dyn Any + Send, A>> { if self.is::<T>() { unsafe { let (raw, b): (*mut (dyn Any + Send), _) = Self::into_raw_alloc(self); Ok(Box::from_raw_in(raw as *mut T, b)) } } else { Err(self) } } } impl<T: fmt::Display + ?Sized, A: AllocRef> fmt::Display for Box<T, A> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Display::fmt(&**self, f) } } impl<T: fmt::Debug + ?Sized, A: AllocRef> fmt::Debug for Box<T, A> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Debug::fmt(&**self, f) } } impl<T: ?Sized, A: AllocRef> fmt::Pointer for Box<T, A> { 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: AllocRef> Deref for Box<T, A> { type Target = T; fn deref(&self) -> &T { unsafe { self.ptr.as_ref() } } } impl<T: ?Sized, A: AllocRef> DerefMut for Box<T, A> { fn deref_mut(&mut self) -> &mut T { unsafe { self.ptr.as_mut() } } } impl<T: ?Sized, A: AllocRef> core::ops::Receiver for Box<T, A> {} impl<I: Iterator + ?Sized, A: AllocRef> Iterator for Box<I, A> { type Item = I::Item; fn next(&mut self) -> Option<I::Item> { (**self).next() } fn size_hint(&self) -> (usize, Option<usize>) { (**self).size_hint() } fn last(self) -> Option<I::Item> { BoxIter::last(self) } fn nth(&mut self, n: usize) -> Option<I::Item> { (**self).nth(n) } } trait BoxIter { type Item; fn last(self) -> Option<Self::Item>; } impl<I: Iterator + ?Sized, A: AllocRef> BoxIter for Box<I, A> { type Item = I::Item; fn last(self) -> Option<I::Item> { #[inline] #[allow(clippy::missing_const_for_fn)] fn some<T>(_: Option<T>, x: T) -> Option<T> { Some(x) } self.fold(None, some) } } impl<I: DoubleEndedIterator + ?Sized, A: AllocRef> DoubleEndedIterator for Box<I, A> { fn next_back(&mut self) -> Option<I::Item> { (**self).next_back() } fn nth_back(&mut self, n: usize) -> Option<I::Item> { (**self).nth_back(n) } } impl<I: ExactSizeIterator + ?Sized, A: AllocRef> ExactSizeIterator for Box<I, A> { fn len(&self) -> usize { (**self).len() } fn is_empty(&self) -> bool { (**self).is_empty() } } impl<I: FusedIterator + ?Sized, A: AllocRef> FusedIterator for Box<I, A> {} impl<Args, F: FnOnce<Args> + Copy + ?Sized, A: AllocRef> FnOnce<Args> for Box<F, A> { type Output = <F as FnOnce<Args>>::Output; extern "rust-call" fn call_once(self, args: Args) -> Self::Output { <F as FnOnce<Args>>::call_once(*self, args) } } impl<Args, F: FnMut<Args> + Copy + ?Sized, A: AllocRef> FnMut<Args> for Box<F, A> { extern "rust-call" fn call_mut(&mut self, args: Args) -> Self::Output { <F as FnMut<Args>>::call_mut(self, args) } } impl<Args, F: Fn<Args> + Copy + ?Sized, A: AllocRef> Fn<Args> for Box<F, A> { extern "rust-call" fn call(&self, args: Args) -> Self::Output { <F as Fn<Args>>::call(self, args) } } impl<T: ?Sized + core::marker::Unsize<U>, U: ?Sized, A: AllocRef> core::ops::CoerceUnsized<Box<U, A>> for Box<T, A> { } // DispatchFromDyn may only be implemented for ZSTs for now. Until this limitation is lifted, // implement it only for Global, and System macro_rules! impl_dispatch_from_dyn { ($alloc:ty) => { impl<T: ?Sized + core::marker::Unsize<U>, U: ?Sized> core::ops::DispatchFromDyn<Box<U, $alloc>> for Box<T, $alloc> { } }; } impl_dispatch_from_dyn!(Global); #[cfg(feature = "std")] impl_dispatch_from_dyn!(std::alloc::System); #[allow(clippy::items_after_statements)] impl<T: Clone, A: Clone> Clone for Box<[T], A> where A: AllocRef, { fn clone(&self) -> Self { let mut new = BoxBuilder { data: RawVec::with_capacity_in(self.len(), self.alloc_ref().clone()), len: 0, }; let mut target = new.data.ptr(); for item in self.iter() { unsafe { ptr::write(target, item.clone()); target = target.offset(1); }; new.len += 1; } return unsafe { new.into_box() }; // Helper type for responding to panics correctly. struct BoxBuilder<T, A: AllocRef> { data: RawVec<T, A>, len: usize, } impl<T, A: AllocRef> BoxBuilder<T, A> { unsafe fn into_box(self) -> Box<[T], A> { let raw = ptr::read(&self.data); let len = self.len; mem::forget(self); raw.into_box(len).assume_init() } } impl<T, A: AllocRef> Drop for BoxBuilder<T, A> { fn drop(&mut self) { let mut data = self.data.ptr(); let max = unsafe { data.add(self.len) }; while data != max { unsafe { ptr::read(data); data = data.offset(1); } } } } } } impl<T: ?Sized, A: AllocRef> borrow::Borrow<T> for Box<T, A> { fn borrow(&self) -> &T { &**self } } impl<T: ?Sized, A: AllocRef> borrow::BorrowMut<T> for Box<T, A> { fn borrow_mut(&mut self) -> &mut T { &mut **self } } impl<T: ?Sized, A: AllocRef> AsRef<T> for Box<T, A> { fn as_ref(&self) -> &T { &**self } } impl<T: ?Sized, A: AllocRef> AsMut<T> for Box<T, A> { fn as_mut(&mut self) -> &mut T { &mut **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: AllocRef> Unpin for Box<T, A> {} impl<F: ?Sized + Future + Unpin, A: AllocRef> Future for Box<F, A> { type Output = F::Output; fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { F::poll(Pin::new(&mut *self), cx) } }