diff options
Diffstat (limited to 'rust/alloc')
| -rw-r--r-- | rust/alloc/README.md | 36 | ||||
| -rw-r--r-- | rust/alloc/alloc.rs | 452 | ||||
| -rw-r--r-- | rust/alloc/boxed.rs | 2463 | ||||
| -rw-r--r-- | rust/alloc/collections/mod.rs | 160 | ||||
| -rw-r--r-- | rust/alloc/lib.rs | 288 | ||||
| -rw-r--r-- | rust/alloc/raw_vec.rs | 611 | ||||
| -rw-r--r-- | rust/alloc/slice.rs | 890 | ||||
| -rw-r--r-- | rust/alloc/vec/drain.rs | 255 | ||||
| -rw-r--r-- | rust/alloc/vec/extract_if.rs | 115 | ||||
| -rw-r--r-- | rust/alloc/vec/into_iter.rs | 454 | ||||
| -rw-r--r-- | rust/alloc/vec/is_zero.rs | 204 | ||||
| -rw-r--r-- | rust/alloc/vec/mod.rs | 3683 | ||||
| -rw-r--r-- | rust/alloc/vec/partial_eq.rs | 49 | ||||
| -rw-r--r-- | rust/alloc/vec/set_len_on_drop.rs | 35 | ||||
| -rw-r--r-- | rust/alloc/vec/spec_extend.rs | 119 |
15 files changed, 0 insertions, 9814 deletions
diff --git a/rust/alloc/README.md b/rust/alloc/README.md deleted file mode 100644 index eb6f22e94e..0000000000 --- a/rust/alloc/README.md +++ /dev/null @@ -1,36 +0,0 @@ -# `alloc` - -These source files come from the Rust standard library, hosted in -the <https://github.com/rust-lang/rust> repository, licensed under -"Apache-2.0 OR MIT" and adapted for kernel use. For copyright details, -see <https://github.com/rust-lang/rust/blob/master/COPYRIGHT>. - -Please note that these files should be kept as close as possible to -upstream. In general, only additions should be performed (e.g. new -methods). Eventually, changes should make it into upstream so that, -at some point, this fork can be dropped from the kernel tree. - -The Rust upstream version on top of which these files are based matches -the output of `scripts/min-tool-version.sh rustc`. - - -## Rationale - -On one hand, kernel folks wanted to keep `alloc` in-tree to have more -freedom in both workflow and actual features if actually needed -(e.g. receiver types if we ended up using them), which is reasonable. - -On the other hand, Rust folks wanted to keep `alloc` as close as -upstream as possible and avoid as much divergence as possible, which -is also reasonable. - -We agreed on a middle-ground: we would keep a subset of `alloc` -in-tree that would be as small and as close as possible to upstream. -Then, upstream can start adding the functions that we add to `alloc` -etc., until we reach a point where the kernel already knows exactly -what it needs in `alloc` and all the new methods are merged into -upstream, so that we can drop `alloc` from the kernel tree and go back -to using the upstream one. - -By doing this, the kernel can go a bit faster now, and Rust can -slowly incorporate and discuss the changes as needed. diff --git a/rust/alloc/alloc.rs b/rust/alloc/alloc.rs deleted file mode 100644 index abb791cc23..0000000000 --- a/rust/alloc/alloc.rs +++ /dev/null @@ -1,452 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -//! Memory allocation APIs - -#![stable(feature = "alloc_module", since = "1.28.0")] - -#[cfg(not(test))] -use core::intrinsics; - -#[cfg(not(test))] -use core::ptr::{self, NonNull}; - -#[stable(feature = "alloc_module", since = "1.28.0")] -#[doc(inline)] -pub use core::alloc::*; - -#[cfg(test)] -mod tests; - -extern "Rust" { - // These are the magic symbols to call the global allocator. rustc generates - // them to call `__rg_alloc` etc. if there is a `#[global_allocator]` attribute - // (the code expanding that attribute macro generates those functions), or to call - // the default implementations in std (`__rdl_alloc` etc. in `library/std/src/alloc.rs`) - // otherwise. - // The rustc fork of LLVM 14 and earlier also special-cases these function names to be able to optimize them - // like `malloc`, `realloc`, and `free`, respectively. - #[rustc_allocator] - #[rustc_nounwind] - fn __rust_alloc(size: usize, align: usize) -> *mut u8; - #[rustc_deallocator] - #[rustc_nounwind] - fn __rust_dealloc(ptr: *mut u8, size: usize, align: usize); - #[rustc_reallocator] - #[rustc_nounwind] - fn __rust_realloc(ptr: *mut u8, old_size: usize, align: usize, new_size: usize) -> *mut u8; - #[rustc_allocator_zeroed] - #[rustc_nounwind] - fn __rust_alloc_zeroed(size: usize, align: usize) -> *mut u8; - - static __rust_no_alloc_shim_is_unstable: u8; -} - -/// The global memory allocator. -/// -/// This type implements the [`Allocator`] trait by forwarding calls -/// to the allocator registered with the `#[global_allocator]` attribute -/// if there is one, or the `std` crate’s default. -/// -/// Note: while this type is unstable, the functionality it provides can be -/// accessed through the [free functions in `alloc`](self#functions). -#[unstable(feature = "allocator_api", issue = "32838")] -#[derive(Copy, Clone, Default, Debug)] -#[cfg(not(test))] -pub struct Global; - -#[cfg(test)] -pub use std::alloc::Global; - -/// Allocate memory with the global allocator. -/// -/// This function forwards calls to the [`GlobalAlloc::alloc`] method -/// of the allocator registered with the `#[global_allocator]` attribute -/// if there is one, or the `std` crate’s default. -/// -/// This function is expected to be deprecated in favor of the `alloc` method -/// of the [`Global`] type when it and the [`Allocator`] trait become stable. -/// -/// # Safety -/// -/// See [`GlobalAlloc::alloc`]. -/// -/// # Examples -/// -/// ``` -/// use std::alloc::{alloc, dealloc, handle_alloc_error, Layout}; -/// -/// unsafe { -/// let layout = Layout::new::<u16>(); -/// let ptr = alloc(layout); -/// if ptr.is_null() { -/// handle_alloc_error(layout); -/// } -/// -/// *(ptr as *mut u16) = 42; -/// assert_eq!(*(ptr as *mut u16), 42); -/// -/// dealloc(ptr, layout); -/// } -/// ``` -#[stable(feature = "global_alloc", since = "1.28.0")] -#[must_use = "losing the pointer will leak memory"] -#[inline] -pub unsafe fn alloc(layout: Layout) -> *mut u8 { - unsafe { - // Make sure we don't accidentally allow omitting the allocator shim in - // stable code until it is actually stabilized. - core::ptr::read_volatile(&__rust_no_alloc_shim_is_unstable); - - __rust_alloc(layout.size(), layout.align()) - } -} - -/// Deallocate memory with the global allocator. -/// -/// This function forwards calls to the [`GlobalAlloc::dealloc`] method -/// of the allocator registered with the `#[global_allocator]` attribute -/// if there is one, or the `std` crate’s default. -/// -/// This function is expected to be deprecated in favor of the `dealloc` method -/// of the [`Global`] type when it and the [`Allocator`] trait become stable. -/// -/// # Safety -/// -/// See [`GlobalAlloc::dealloc`]. -#[stable(feature = "global_alloc", since = "1.28.0")] -#[inline] -pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) { - unsafe { __rust_dealloc(ptr, layout.size(), layout.align()) } -} - -/// Reallocate memory with the global allocator. -/// -/// This function forwards calls to the [`GlobalAlloc::realloc`] method -/// of the allocator registered with the `#[global_allocator]` attribute -/// if there is one, or the `std` crate’s default. -/// -/// This function is expected to be deprecated in favor of the `realloc` method -/// of the [`Global`] type when it and the [`Allocator`] trait become stable. -/// -/// # Safety -/// -/// See [`GlobalAlloc::realloc`]. -#[stable(feature = "global_alloc", since = "1.28.0")] -#[must_use = "losing the pointer will leak memory"] -#[inline] -pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { - unsafe { __rust_realloc(ptr, layout.size(), layout.align(), new_size) } -} - -/// Allocate zero-initialized memory with the global allocator. -/// -/// This function forwards calls to the [`GlobalAlloc::alloc_zeroed`] method -/// of the allocator registered with the `#[global_allocator]` attribute -/// if there is one, or the `std` crate’s default. -/// -/// This function is expected to be deprecated in favor of the `alloc_zeroed` method -/// of the [`Global`] type when it and the [`Allocator`] trait become stable. -/// -/// # Safety -/// -/// See [`GlobalAlloc::alloc_zeroed`]. -/// -/// # Examples -/// -/// ``` -/// use std::alloc::{alloc_zeroed, dealloc, Layout}; -/// -/// unsafe { -/// let layout = Layout::new::<u16>(); -/// let ptr = alloc_zeroed(layout); -/// -/// assert_eq!(*(ptr as *mut u16), 0); -/// -/// dealloc(ptr, layout); -/// } -/// ``` -#[stable(feature = "global_alloc", since = "1.28.0")] -#[must_use = "losing the pointer will leak memory"] -#[inline] -pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 { - unsafe { __rust_alloc_zeroed(layout.size(), layout.align()) } -} - -#[cfg(not(test))] -impl Global { - #[inline] - fn alloc_impl(&self, layout: Layout, zeroed: bool) -> Result<NonNull<[u8]>, AllocError> { - match layout.size() { - 0 => Ok(NonNull::slice_from_raw_parts(layout.dangling(), 0)), - // SAFETY: `layout` is non-zero in size, - size => unsafe { - let raw_ptr = if zeroed { alloc_zeroed(layout) } else { alloc(layout) }; - let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?; - Ok(NonNull::slice_from_raw_parts(ptr, size)) - }, - } - } - - // SAFETY: Same as `Allocator::grow` - #[inline] - unsafe fn grow_impl( - &self, - ptr: NonNull<u8>, - old_layout: Layout, - new_layout: Layout, - zeroed: bool, - ) -> Result<NonNull<[u8]>, AllocError> { - debug_assert!( - new_layout.size() >= old_layout.size(), - "`new_layout.size()` must be greater than or equal to `old_layout.size()`" - ); - - match old_layout.size() { - 0 => self.alloc_impl(new_layout, zeroed), - - // SAFETY: `new_size` is non-zero as `old_size` is greater than or equal to `new_size` - // as required by safety conditions. Other conditions must be upheld by the caller - old_size if old_layout.align() == new_layout.align() => unsafe { - let new_size = new_layout.size(); - - // `realloc` probably checks for `new_size >= old_layout.size()` or something similar. - intrinsics::assume(new_size >= old_layout.size()); - - let raw_ptr = realloc(ptr.as_ptr(), old_layout, new_size); - let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?; - if zeroed { - raw_ptr.add(old_size).write_bytes(0, new_size - old_size); - } - Ok(NonNull::slice_from_raw_parts(ptr, new_size)) - }, - - // SAFETY: because `new_layout.size()` must be greater than or equal to `old_size`, - // both the old and new memory allocation are valid for reads and writes for `old_size` - // bytes. Also, because the old allocation wasn't yet deallocated, it cannot overlap - // `new_ptr`. Thus, the call to `copy_nonoverlapping` is safe. The safety contract - // for `dealloc` must be upheld by the caller. - old_size => unsafe { - let new_ptr = self.alloc_impl(new_layout, zeroed)?; - ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_mut_ptr(), old_size); - self.deallocate(ptr, old_layout); - Ok(new_ptr) - }, - } - } -} - -#[unstable(feature = "allocator_api", issue = "32838")] -#[cfg(not(test))] -unsafe impl Allocator for Global { - #[inline] - fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> { - self.alloc_impl(layout, false) - } - - #[inline] - fn allocate_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> { - self.alloc_impl(layout, true) - } - - #[inline] - unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) { - if layout.size() != 0 { - // SAFETY: `layout` is non-zero in size, - // other conditions must be upheld by the caller - unsafe { dealloc(ptr.as_ptr(), layout) } - } - } - - #[inline] - unsafe fn grow( - &self, - ptr: NonNull<u8>, - old_layout: Layout, - new_layout: Layout, - ) -> Result<NonNull<[u8]>, AllocError> { - // SAFETY: all conditions must be upheld by the caller - unsafe { self.grow_impl(ptr, old_layout, new_layout, false) } - } - - #[inline] - unsafe fn grow_zeroed( - &self, - ptr: NonNull<u8>, - old_layout: Layout, - new_layout: Layout, - ) -> Result<NonNull<[u8]>, AllocError> { - // SAFETY: all conditions must be upheld by the caller - unsafe { self.grow_impl(ptr, old_layout, new_layout, true) } - } - - #[inline] - unsafe fn shrink( - &self, - ptr: NonNull<u8>, - old_layout: Layout, - new_layout: Layout, - ) -> Result<NonNull<[u8]>, AllocError> { - debug_assert!( - new_layout.size() <= old_layout.size(), - "`new_layout.size()` must be smaller than or equal to `old_layout.size()`" - ); - - match new_layout.size() { - // SAFETY: conditions must be upheld by the caller - 0 => unsafe { - self.deallocate(ptr, old_layout); - Ok(NonNull::slice_from_raw_parts(new_layout.dangling(), 0)) - }, - - // SAFETY: `new_size` is non-zero. Other conditions must be upheld by the caller - new_size if old_layout.align() == new_layout.align() => unsafe { - // `realloc` probably checks for `new_size <= old_layout.size()` or something similar. - intrinsics::assume(new_size <= old_layout.size()); - - let raw_ptr = realloc(ptr.as_ptr(), old_layout, new_size); - let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?; - Ok(NonNull::slice_from_raw_parts(ptr, new_size)) - }, - - // SAFETY: because `new_size` must be smaller than or equal to `old_layout.size()`, - // both the old and new memory allocation are valid for reads and writes for `new_size` - // bytes. Also, because the old allocation wasn't yet deallocated, it cannot overlap - // `new_ptr`. Thus, the call to `copy_nonoverlapping` is safe. The safety contract - // for `dealloc` must be upheld by the caller. - new_size => unsafe { - let new_ptr = self.allocate(new_layout)?; - ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_mut_ptr(), new_size); - self.deallocate(ptr, old_layout); - Ok(new_ptr) - }, - } - } -} - -/// The allocator for unique pointers. -#[cfg(all(not(no_global_oom_handling), not(test)))] -#[lang = "exchange_malloc"] -#[inline] -unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 { - let layout = unsafe { Layout::from_size_align_unchecked(size, align) }; - match Global.allocate(layout) { - Ok(ptr) => ptr.as_mut_ptr(), - Err(_) => handle_alloc_error(layout), - } -} - -// # Allocation error handler - -#[cfg(not(no_global_oom_handling))] -extern "Rust" { - // This is the magic symbol to call the global alloc error handler. rustc generates - // it to call `__rg_oom` if there is a `#[alloc_error_handler]`, or to call the - // default implementations below (`__rdl_oom`) otherwise. - fn __rust_alloc_error_handler(size: usize, align: usize) -> !; -} - -/// Signal a memory allocation error. -/// -/// Callers of memory allocation APIs wishing to cease execution -/// in response to an allocation error are encouraged to call this function, -/// rather than directly invoking [`panic!`] or similar. -/// -/// This function is guaranteed to diverge (not return normally with a value), but depending on -/// global configuration, it may either panic (resulting in unwinding or aborting as per -/// configuration for all panics), or abort the process (with no unwinding). -/// -/// The default behavior is: -/// -/// * If the binary links against `std` (typically the case), then -/// print a message to standard error and abort the process. -/// This behavior can be replaced with [`set_alloc_error_hook`] and [`take_alloc_error_hook`]. -/// Future versions of Rust may panic by default instead. -/// -/// * If the binary does not link against `std` (all of its crates are marked -/// [`#![no_std]`][no_std]), then call [`panic!`] with a message. -/// [The panic handler] applies as to any panic. -/// -/// [`set_alloc_error_hook`]: ../../std/alloc/fn.set_alloc_error_hook.html -/// [`take_alloc_error_hook`]: ../../std/alloc/fn.take_alloc_error_hook.html -/// [The panic handler]: https://doc.rust-lang.org/reference/runtime.html#the-panic_handler-attribute -/// [no_std]: https://doc.rust-lang.org/reference/names/preludes.html#the-no_std-attribute -#[stable(feature = "global_alloc", since = "1.28.0")] -#[rustc_const_unstable(feature = "const_alloc_error", issue = "92523")] -#[cfg(all(not(no_global_oom_handling), not(test)))] -#[cold] -pub const fn handle_alloc_error(layout: Layout) -> ! { - const fn ct_error(_: Layout) -> ! { - panic!("allocation failed"); - } - - #[inline] - fn rt_error(layout: Layout) -> ! { - unsafe { - __rust_alloc_error_handler(layout.size(), layout.align()); - } - } - - #[cfg(not(feature = "panic_immediate_abort"))] - unsafe { - core::intrinsics::const_eval_select((layout,), ct_error, rt_error) - } - - #[cfg(feature = "panic_immediate_abort")] - ct_error(layout) -} - -// For alloc test `std::alloc::handle_alloc_error` can be used directly. -#[cfg(all(not(no_global_oom_handling), test))] -pub use std::alloc::handle_alloc_error; - -#[cfg(all(not(no_global_oom_handling), not(test)))] -#[doc(hidden)] -#[allow(unused_attributes)] -#[unstable(feature = "alloc_internals", issue = "none")] -pub mod __alloc_error_handler { - // called via generated `__rust_alloc_error_handler` if there is no - // `#[alloc_error_handler]`. - #[rustc_std_internal_symbol] - pub unsafe fn __rdl_oom(size: usize, _align: usize) -> ! { - extern "Rust" { - // This symbol is emitted by rustc next to __rust_alloc_error_handler. - // Its value depends on the -Zoom={panic,abort} compiler option. - static __rust_alloc_error_handler_should_panic: u8; - } - - if unsafe { __rust_alloc_error_handler_should_panic != 0 } { - panic!("memory allocation of {size} bytes failed") - } else { - core::panicking::panic_nounwind_fmt( - format_args!("memory allocation of {size} bytes failed"), - /* force_no_backtrace */ false, - ) - } - } -} - -#[cfg(not(no_global_oom_handling))] -/// Specialize clones into pre-allocated, uninitialized memory. -/// Used by `Box::clone` and `Rc`/`Arc::make_mut`. -pub(crate) trait WriteCloneIntoRaw: Sized { - unsafe fn write_clone_into_raw(&self, target: *mut Self); -} - -#[cfg(not(no_global_oom_handling))] -impl<T: Clone> WriteCloneIntoRaw for T { - #[inline] - default unsafe fn write_clone_into_raw(&self, target: *mut Self) { - // Having allocated *first* may allow the optimizer to create - // the cloned value in-place, skipping the local and move. - unsafe { target.write(self.clone()) }; - } -} - -#[cfg(not(no_global_oom_handling))] -impl<T: Copy> WriteCloneIntoRaw for T { - #[inline] - unsafe fn write_clone_into_raw(&self, target: *mut Self) { - // We can always copy in-place, without ever involving a local value. - unsafe { target.copy_from_nonoverlapping(self, 1) }; - } -} diff --git a/rust/alloc/boxed.rs b/rust/alloc/boxed.rs deleted file mode 100644 index c93a22a5c9..0000000000 --- a/rust/alloc/boxed.rs +++ /dev/null @@ -1,2463 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -//! 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]. -//! -//! -//! [ucg#198]: https://github.com/rust-lang/unsafe-code-guidelines/issues/198 -//! [ucg#326]: https://github.com/rust-lang/unsafe-code-guidelines/issues/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 - -#![stable(feature = "rust1", since = "1.0.0")] - -use core::any::Any; -use core::async_iter::AsyncIterator; -use core::borrow; -use core::cmp::Ordering; -use core::error::Error; -use core::fmt; -use core::future::Future; -use core::hash::{Hash, Hasher}; -use core::iter::FusedIterator; -use core::marker::Tuple; -use core::marker::Unsize; -use core::mem::{self, SizedTypeProperties}; -use core::ops::{ - CoerceUnsized, Coroutine, CoroutineState, Deref, DerefMut, DispatchFromDyn, Receiver, -}; -use core::pin::Pin; -use core::ptr::{self, NonNull, Unique}; -use core::task::{Context, Poll}; - -#[cfg(not(no_global_oom_handling))] -use crate::alloc::{handle_alloc_error, WriteCloneIntoRaw}; -use crate::alloc::{AllocError, Allocator, Global, Layout}; -#[cfg(not(no_global_oom_handling))] -use crate::borrow::Cow; -use crate::raw_vec::RawVec; -#[cfg(not(no_global_oom_handling))] -use crate::str::from_boxed_utf8_unchecked; -#[cfg(not(no_global_oom_handling))] -use crate::string::String; -#[cfg(not(no_global_oom_handling))] -use crate::vec::Vec; - -#[cfg(not(no_thin))] -#[unstable(feature = "thin_box", issue = "92791")] -pub use thin::ThinBox; - -#[cfg(not(no_thin))] -mod thin; - -/// A pointer type that uniquely owns a heap allocation of type `T`. -/// -/// See the [module-level documentation](../../std/boxed/index.html) for more. -#[lang = "owned_box"] -#[fundamental] -#[stable(feature = "rust1", since = "1.0.0")] -// The declaration of the `Box` struct must be kept in sync with the -// `alloc::alloc::box_free` function or ICEs will happen. See the comment -// on `box_free` for more details. -pub struct Box< - T: ?Sized, - #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global, ->(Unique<T>, A); - -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(not(no_global_oom_handling))] - #[inline(always)] - #[stable(feature = "rust1", since = "1.0.0")] - #[must_use] - #[rustc_diagnostic_item = "box_new"] - pub fn new(x: T) -> Self { - #[rustc_box] - Box::new(x) - } - - /// 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))] - #[unstable(feature = "new_uninit", issue = "63291")] - #[must_use] - #[inline] - 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))] - #[inline] - #[unstable(feature = "new_uninit", issue = "63291")] - #[must_use] - 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))] - #[stable(feature = "pin", since = "1.33.0")] - #[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>(()) - /// ``` - #[unstable(feature = "allocator_api", issue = "32838")] - #[inline] - 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>(()) - /// ``` - #[unstable(feature = "allocator_api", issue = "32838")] - // #[unstable(feature = "new_uninit", issue = "63291")] - #[inline] - 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 - #[unstable(feature = "allocator_api", issue = "32838")] - // #[unstable(feature = "new_uninit", issue = "63291")] - #[inline] - 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))] - #[unstable(feature = "allocator_api", issue = "32838")] - #[must_use] - #[inline] - 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>(()) - /// ``` - #[unstable(feature = "allocator_api", issue = "32838")] - #[inline] - 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) - /// ``` - #[unstable(feature = "allocator_api", issue = "32838")] - #[cfg(not(no_global_oom_handling))] - #[must_use] - // #[unstable(feature = "new_uninit", issue = "63291")] - 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>(()) - /// ``` - #[unstable(feature = "allocator_api", issue = "32838")] - // #[unstable(feature = "new_uninit", issue = "63291")] - pub fn try_new_uninit_in(alloc: A) -> Result<Box<mem::MaybeUninit<T>, A>, AllocError> - where - A: Allocator, - { - let ptr = if T::IS_ZST { - NonNull::dangling() - } else { - let layout = Layout::new::<mem::MaybeUninit<T>>(); - 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 - #[unstable(feature = "allocator_api", issue = "32838")] - #[cfg(not(no_global_oom_handling))] - // #[unstable(feature = "new_uninit", issue = "63291")] - #[must_use] - 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 - #[unstable(feature = "allocator_api", issue = "32838")] - // #[unstable(feature = "new_uninit", issue = "63291")] - pub fn try_new_zeroed_in(alloc: A) -> Result<Box<mem::MaybeUninit<T>, A>, AllocError> - where - A: Allocator, - { - let ptr = if T::IS_ZST { - NonNull::dangling() - } else { - let layout = Layout::new::<mem::MaybeUninit<T>>(); - 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))] - #[unstable(feature = "allocator_api", issue = "32838")] - #[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. - #[unstable(feature = "box_into_boxed_slice", issue = "71582")] - 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); - /// ``` - #[unstable(feature = "box_into_inner", issue = "80437")] - #[inline] - pub fn into_inner(boxed: Self) -> T { - *boxed - } -} - -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))] - #[unstable(feature = "new_uninit", issue = "63291")] - #[must_use] - 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))] - #[unstable(feature = "new_uninit", issue = "63291")] - #[must_use] - 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>(()) - /// ``` - #[unstable(feature = "allocator_api", issue = "32838")] - #[inline] - pub fn try_new_uninit_slice(len: usize) -> Result<Box<[mem::MaybeUninit<T>]>, AllocError> { - let ptr = if T::IS_ZST || len == 0 { - NonNull::dangling() - } else { - let layout = match Layout::array::<mem::MaybeUninit<T>>(len) { - Ok(l) => l, - Err(_) => return Err(AllocError), - }; - Global.allocate(layout)?.cast() - }; - unsafe { Ok(RawVec::from_raw_parts_in(ptr.as_ptr(), 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 - #[unstable(feature = "allocator_api", issue = "32838")] - #[inline] - pub fn try_new_zeroed_slice(len: usize) -> Result<Box<[mem::MaybeUninit<T>]>, AllocError> { - let ptr = if T::IS_ZST || len == 0 { - NonNull::dangling() - } else { - let layout = match Layout::array::<mem::MaybeUninit<T>>(len) { - Ok(l) => l, - Err(_) => return Err(AllocError), - }; - Global.allocate_zeroed(layout)?.cast() - }; - unsafe { Ok(RawVec::from_raw_parts_in(ptr.as_ptr(), 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))] - #[unstable(feature = "allocator_api", issue = "32838")] - // #[unstable(feature = "new_uninit", issue = "63291")] - #[must_use] - 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))] - #[unstable(feature = "allocator_api", issue = "32838")] - // #[unstable(feature = "new_uninit", issue = "63291")] - #[must_use] - 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) } - } -} - -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) - /// ``` - #[unstable(feature = "new_uninit", issue = "63291")] - #[inline] - 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); - /// } - /// ``` - #[unstable(feature = "new_uninit", issue = "63291")] - #[inline] - 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]) - /// ``` - #[unstable(feature = "new_uninit", issue = "63291")] - #[inline] - 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 - #[stable(feature = "box_raw", since = "1.4.0")] - #[inline] - #[must_use = "call `drop(Box::from_raw(ptr))` if you intend to drop the `Box`"] - 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`]: - /// ``` - /// #![feature(allocator_api)] - /// - /// use std::alloc::System; - /// - /// 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: - /// ``` - /// #![feature(allocator_api, slice_ptr_get)] - /// - /// use std::alloc::{Allocator, Layout, System}; - /// - /// unsafe { - /// let ptr = System.allocate(Layout::new::<i32>())?.as_mut_ptr() 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_in(ptr, System); - /// } - /// # Ok::<(), std::alloc::AllocError>(()) - /// ``` - /// - /// [memory layout]: self#memory-layout - /// [`Layout`]: crate::Layout - #[unstable(feature = "allocator_api", issue = "32838")] - #[rustc_const_unstable(feature = "const_box", issue = "92521")] - #[inline] - pub const unsafe fn from_raw_in(raw: *mut T, alloc: A) -> Self { - Box(unsafe { Unique::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 ptr = Box::into_raw(x); - /// unsafe { - /// ptr::drop_in_place(ptr); - /// dealloc(ptr as *mut u8, Layout::new::<String>()); - /// } - /// ``` - /// Note: This is equivalent to the following: - /// ``` - /// let x = Box::new(String::from("Hello")); - /// let ptr = Box::into_raw(x); - /// unsafe { - /// drop(Box::from_raw(ptr)); - /// } - /// ``` - /// - /// [memory layout]: self#memory-layout - #[stable(feature = "box_raw", since = "1.4.0")] - #[inline] - 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 - #[unstable(feature = "allocator_api", issue = "32838")] - #[inline] - pub fn into_raw_with_allocator(b: Self) -> (*mut T, A) { - let (leaked, alloc) = Box::into_unique(b); - (leaked.as_ptr(), alloc) - } - - #[unstable( - feature = "ptr_internals", - issue = "none", - reason = "use `Box::leak(b).into()` or `Unique::from(Box::leak(b))` instead" - )] - #[inline] - #[doc(hidden)] - pub fn into_unique(b: Self) -> (Unique<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) }; - (Unique::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. - #[unstable(feature = "allocator_api", issue = "32838")] - #[rustc_const_unstable(feature = "const_box", issue = "92521")] - #[inline] - 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]); - /// ``` - #[stable(feature = "box_leak", since = "1.26.0")] - #[inline] - pub 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); - /// ``` - #[stable(feature = "box_into_pin", since = "1.63.0")] - #[rustc_const_unstable(feature = "const_box", issue = "92521")] - pub const 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) } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -unsafe impl<#[may_dangle] T: ?Sized, A: Allocator> Drop for Box<T, A> { - #[inline] - fn drop(&mut self) { - // the T in the Box is dropped by the compiler before the destructor is run - - let ptr = self.0; - - unsafe { - let layout = Layout::for_value_raw(ptr.as_ptr()); - if layout.size() != 0 { - self.1.deallocate(From::from(ptr.cast()), layout); - } - } - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: Default> Default for Box<T> { - /// Creates a `Box<T>`, with the `Default` value for T. - #[inline] - fn default() -> Self { - Box::new(T::default()) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -impl<T> Default for Box<[T]> { - #[inline] - fn default() -> Self { - let ptr: Unique<[T]> = Unique::<[T; 0]>::dangling(); - Box(ptr, Global) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "default_box_extra", since = "1.17.0")] -impl Default for Box<str> { - #[inline] - fn default() -> Self { - // SAFETY: This is the same as `Unique::cast<U>` but with an unsized `U = str`. - let ptr: Unique<str> = unsafe { - let bytes: Unique<[u8]> = Unique::<[u8; 0]>::dangling(); - Unique::new_unchecked(bytes.as_ptr() as *mut str) - }; - Box(ptr, Global) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -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] - 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 { - (**self).write_clone_into_raw(boxed.as_mut_ptr()); - 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] - fn clone_from(&mut self, source: &Self) { - (**self).clone_from(&(**source)); - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "box_slice_clone", since = "1.3.0")] -impl Clone for Box<str> { - fn clone(&self) -> Self { - // this makes a copy of the data - let buf: Box<[u8]> = self.as_bytes().into(); - unsafe { from_boxed_utf8_unchecked(buf) } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: ?Sized + PartialEq, A: Allocator> PartialEq for Box<T, A> { - #[inline] - fn eq(&self, other: &Self) -> bool { - PartialEq::eq(&**self, &**other) - } - #[inline] - fn ne(&self, other: &Self) -> bool { - PartialEq::ne(&**self, &**other) - } -} -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: ?Sized + PartialOrd, A: Allocator> 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 ge(&self, other: &Self) -> bool { - PartialOrd::ge(&**self, &**other) - } - #[inline] - fn gt(&self, other: &Self) -> bool { - PartialOrd::gt(&**self, &**other) - } -} -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: ?Sized + Ord, A: Allocator> Ord for Box<T, A> { - #[inline] - fn cmp(&self, other: &Self) -> Ordering { - Ord::cmp(&**self, &**other) - } -} -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: ?Sized + Eq, A: Allocator> Eq for Box<T, A> {} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: ?Sized + Hash, A: Allocator> Hash for Box<T, A> { - fn hash<H: Hasher>(&self, state: &mut H) { - (**self).hash(state); - } -} - -#[stable(feature = "indirect_hasher_impl", since = "1.22.0")] -impl<T: ?Sized + Hasher, A: Allocator> 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) - } - fn write_length_prefix(&mut self, len: usize) { - (**self).write_length_prefix(len) - } - fn write_str(&mut self, s: &str) { - (**self).write_str(s) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "from_for_ptrs", since = "1.6.0")] -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); - /// ``` - fn from(t: T) -> Self { - Box::new(t) - } -} - -#[stable(feature = "pin", since = "1.33.0")] -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`]. - fn from(boxed: Box<T, A>) -> Self { - Box::into_pin(boxed) - } -} - -/// Specialization trait used for `From<&[T]>`. -#[cfg(not(no_global_oom_handling))] -trait BoxFromSlice<T> { - fn from_slice(slice: &[T]) -> Self; -} - -#[cfg(not(no_global_oom_handling))] -impl<T: Clone> BoxFromSlice<T> for Box<[T]> { - #[inline] - default fn from_slice(slice: &[T]) -> Self { - slice.to_vec().into_boxed_slice() - } -} - -#[cfg(not(no_global_oom_handling))] -impl<T: Copy> BoxFromSlice<T> for Box<[T]> { - #[inline] - fn from_slice(slice: &[T]) -> Self { - let len = slice.len(); - let buf = RawVec::with_capacity(len); - unsafe { - ptr::copy_nonoverlapping(slice.as_ptr(), buf.ptr(), len); - buf.into_box(slice.len()).assume_init() - } - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "box_from_slice", since = "1.17.0")] -impl<T: Clone> From<&[T]> for Box<[T]> { - /// 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] - fn from(slice: &[T]) -> Box<[T]> { - <Self as BoxFromSlice<T>>::from_slice(slice) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "box_from_cow", since = "1.45.0")] -impl<T: Clone> From<Cow<'_, [T]>> for Box<[T]> { - /// Converts a `Cow<'_, [T]>` into a `Box<[T]>` - /// - /// When `cow` is the `Cow::Borrowed` variant, this - /// conversion allocates on the heap and copies the - /// underlying slice. Otherwise, it will try to reuse the owned - /// `Vec`'s allocation. - #[inline] - fn from(cow: Cow<'_, [T]>) -> Box<[T]> { - match cow { - Cow::Borrowed(slice) => Box::from(slice), - Cow::Owned(slice) => Box::from(slice), - } - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "box_from_slice", since = "1.17.0")] -impl From<&str> for Box<str> { - /// 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] - fn from(s: &str) -> Box<str> { - unsafe { from_boxed_utf8_unchecked(Box::from(s.as_bytes())) } - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "box_from_cow", since = "1.45.0")] -impl From<Cow<'_, str>> for Box<str> { - /// Converts a `Cow<'_, str>` into a `Box<str>` - /// - /// When `cow` is the `Cow::Borrowed` variant, this - /// conversion allocates on the heap and copies the - /// underlying `str`. Otherwise, it will try to reuse the owned - /// `String`'s allocation. - /// - /// # Examples - /// - /// ```rust - /// use std::borrow::Cow; - /// - /// let unboxed = Cow::Borrowed("hello"); - /// let boxed: Box<str> = Box::from(unboxed); - /// println!("{boxed}"); - /// ``` - /// - /// ```rust - /// # use std::borrow::Cow; - /// let unboxed = Cow::Owned("hello".to_string()); - /// let boxed: Box<str> = Box::from(unboxed); - /// println!("{boxed}"); - /// ``` - #[inline] - fn from(cow: Cow<'_, str>) -> Box<str> { - match cow { - Cow::Borrowed(s) => Box::from(s), - Cow::Owned(s) => Box::from(s), - } - } -} - -#[stable(feature = "boxed_str_conv", since = "1.19.0")] -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] - 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) } - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "box_from_array", since = "1.45.0")] -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:?}"); - /// ``` - fn from(array: [T; N]) -> Box<[T]> { - Box::new(array) - } -} - -/// Casts a boxed slice to a boxed array. -/// -/// # Safety -/// -/// `boxed_slice.len()` must be exactly `N`. -unsafe fn boxed_slice_as_array_unchecked<T, A: Allocator, const N: usize>( - boxed_slice: Box<[T], A>, -) -> Box<[T; N], A> { - debug_assert_eq!(boxed_slice.len(), N); - - let (ptr, alloc) = Box::into_raw_with_allocator(boxed_slice); - // SAFETY: Pointer and allocator came from an existing box, - // and our safety condition requires that the length is exactly `N` - unsafe { Box::from_raw_in(ptr as *mut [T; N], alloc) } -} - -#[stable(feature = "boxed_slice_try_from", since = "1.43.0")] -impl<T, const N: usize> TryFrom<Box<[T]>> for Box<[T; N]> { - type Error = Box<[T]>; - - /// 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`. - fn try_from(boxed_slice: Box<[T]>) -> Result<Self, Self::Error> { - if boxed_slice.len() == N { - Ok(unsafe { boxed_slice_as_array_unchecked(boxed_slice) }) - } else { - Err(boxed_slice) - } - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "boxed_array_try_from_vec", since = "1.66.0")] -impl<T, const N: usize> TryFrom<Vec<T>> for Box<[T; N]> { - type Error = Vec<T>; - - /// Attempts to convert a `Vec<T>` into a `Box<[T; N]>`. - /// - /// Like [`Vec::into_boxed_slice`], this is in-place if `vec.capacity() == N`, - /// but will require a reallocation otherwise. - /// - /// # Errors - /// - /// Returns the original `Vec<T>` in the `Err` variant if - /// `boxed_slice.len()` does not equal `N`. - /// - /// # Examples - /// - /// This can be used with [`vec!`] to create an array on the heap: - /// - /// ``` - /// let state: Box<[f32; 100]> = vec![1.0; 100].try_into().unwrap(); - /// assert_eq!(state.len(), 100); - /// ``` - fn try_from(vec: Vec<T>) -> Result<Self, Self::Error> { - if vec.len() == N { - let boxed_slice = vec.into_boxed_slice(); - Ok(unsafe { boxed_slice_as_array_unchecked(boxed_slice) }) - } else { - Err(vec) - } - } -} - -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] - #[stable(feature = "rust1", since = "1.0.0")] - 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] - #[unstable(feature = "downcast_unchecked", issue = "90850")] - 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] - #[stable(feature = "rust1", since = "1.0.0")] - 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] - #[unstable(feature = "downcast_unchecked", issue = "90850")] - 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] - #[stable(feature = "box_send_sync_any_downcast", since = "1.51.0")] - 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] - #[unstable(feature = "downcast_unchecked", issue = "90850")] - 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) - } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: fmt::Display + ?Sized, A: Allocator> fmt::Display for Box<T, A> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Display::fmt(&**self, f) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: fmt::Debug + ?Sized, A: Allocator> fmt::Debug for Box<T, A> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: ?Sized, A: Allocator> 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) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: ?Sized, A: Allocator> Deref for Box<T, A> { - type Target = T; - - fn deref(&self) -> &T { - &**self - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: ?Sized, A: Allocator> DerefMut for Box<T, A> { - fn deref_mut(&mut self) -> &mut T { - &mut **self - } -} - -#[unstable(feature = "receiver_trait", issue = "none")] -impl<T: ?Sized, A: Allocator> Receiver for Box<T, A> {} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<I: Iterator + ?Sized, A: Allocator> 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 nth(&mut self, n: usize) -> Option<I::Item> { - (**self).nth(n) - } - 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; - default fn last(self) -> Option<I::Item> { - #[inline] - fn some<T>(_: Option<T>, x: T) -> Option<T> { - Some(x) - } - - self.fold(None, some) - } -} - -/// Specialization for sized `I`s that uses `I`s implementation of `last()` -/// instead of the default. -#[stable(feature = "rust1", since = "1.0.0")] -impl<I: Iterator, A: Allocator> BoxIter for Box<I, A> { - fn last(self) -> Option<I::Item> { - (*self).last() - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<I: DoubleEndedIterator + ?Sized, A: Allocator> 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) - } -} -#[stable(feature = "rust1", since = "1.0.0")] -impl<I: ExactSizeIterator + ?Sized, A: Allocator> ExactSizeIterator for Box<I, A> { - fn len(&self) -> usize { - (**self).len() - } - fn is_empty(&self) -> bool { - (**self).is_empty() - } -} - -#[stable(feature = "fused", since = "1.26.0")] -impl<I: FusedIterator + ?Sized, A: Allocator> FusedIterator for Box<I, A> {} - -#[stable(feature = "boxed_closure_impls", since = "1.35.0")] -impl<Args: Tuple, F: FnOnce<Args> + ?Sized, A: Allocator> 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) - } -} - -#[stable(feature = "boxed_closure_impls", since = "1.35.0")] -impl<Args: Tuple, F: FnMut<Args> + ?Sized, A: Allocator> 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) - } -} - -#[stable(feature = "boxed_closure_impls", since = "1.35.0")] -impl<Args: Tuple, F: Fn<Args> + ?Sized, A: Allocator> Fn<Args> for Box<F, A> { - extern "rust-call" fn call(&self, args: Args) -> Self::Output { - <F as Fn<Args>>::call(self, args) - } -} - -#[unstable(feature = "coerce_unsized", issue = "18598")] -impl<T: ?Sized + Unsize<U>, U: ?Sized, A: Allocator> CoerceUnsized<Box<U, A>> for Box<T, A> {} - -#[unstable(feature = "dispatch_from_dyn", issue = "none")] -impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Box<U>> for Box<T, Global> {} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "boxed_slice_from_iter", since = "1.32.0")] -impl<I> FromIterator<I> for Box<[I]> { - fn from_iter<T: IntoIterator<Item = I>>(iter: T) -> Self { - iter.into_iter().collect::<Vec<_>>().into_boxed_slice() - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "box_slice_clone", since = "1.3.0")] -impl<T: Clone, A: Allocator + Clone> Clone for Box<[T], A> { - fn clone(&self) -> Self { - let alloc = Box::allocator(self).clone(); - self.to_vec_in(alloc).into_boxed_slice() - } - - fn clone_from(&mut self, other: &Self) { - if self.len() == other.len() { - self.clone_from_slice(&other); - } else { - *self = other.clone(); - } - } -} - -#[stable(feature = "box_borrow", since = "1.1.0")] -impl<T: ?Sized, A: Allocator> borrow::Borrow<T> for Box<T, A> { - fn borrow(&self) -> &T { - &**self - } -} - -#[stable(feature = "box_borrow", since = "1.1.0")] -impl<T: ?Sized, A: Allocator> borrow::BorrowMut<T> for Box<T, A> { - fn borrow_mut(&mut self) -> &mut T { - &mut **self - } -} - -#[stable(since = "1.5.0", feature = "smart_ptr_as_ref")] -impl<T: ?Sized, A: Allocator> AsRef<T> for Box<T, A> { - fn as_ref(&self) -> &T { - &**self - } -} - -#[stable(since = "1.5.0", feature = "smart_ptr_as_ref")] -impl<T: ?Sized, A: Allocator> 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. - */ -#[stable(feature = "pin", since = "1.33.0")] -impl<T: ?Sized, A: Allocator> Unpin for Box<T, A> where A: 'static {} - -#[unstable(feature = "coroutine_trait", issue = "43122")] -impl<G: ?Sized + Coroutine<R> + Unpin, R, A: Allocator> Coroutine<R> for Box<G, A> -where - A: 'static, -{ - type Yield = G::Yield; - type Return = G::Return; - - fn resume(mut self: Pin<&mut Self>, arg: R) -> CoroutineState<Self::Yield, Self::Return> { - G::resume(Pin::new(&mut *self), arg) - } -} - -#[unstable(feature = "coroutine_trait", issue = "43122")] -impl<G: ?Sized + Coroutine<R>, R, A: Allocator> Coroutine<R> for Pin<Box<G, A>> -where - A: 'static, -{ - type Yield = G::Yield; - type Return = G::Return; - - fn resume(mut self: Pin<&mut Self>, arg: R) -> CoroutineState<Self::Yield, Self::Return> { - G::resume((*self).as_mut(), arg) - } -} - -#[stable(feature = "futures_api", since = "1.36.0")] -impl<F: ?Sized + Future + Unpin, A: Allocator> Future for Box<F, A> -where - A: 'static, -{ - type Output = F::Output; - - fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { - F::poll(Pin::new(&mut *self), cx) - } -} - -#[unstable(feature = "async_iterator", issue = "79024")] -impl<S: ?Sized + AsyncIterator + Unpin> AsyncIterator for Box<S> { - type Item = S::Item; - - fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { - Pin::new(&mut **self).poll_next(cx) - } - - fn size_hint(&self) -> (usize, Option<usize>) { - (**self).size_hint() - } -} - -impl dyn Error { - #[inline] - #[stable(feature = "error_downcast", since = "1.3.0")] - #[rustc_allow_incoherent_impl] - /// Attempts to downcast the box to a concrete type. - pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<dyn Error>> { - if self.is::<T>() { - unsafe { - let raw: *mut dyn Error = Box::into_raw(self); - Ok(Box::from_raw(raw as *mut T)) - } - } else { - Err(self) - } - } -} - -impl dyn Error + Send { - #[inline] - #[stable(feature = "error_downcast", since = "1.3.0")] - #[rustc_allow_incoherent_impl] - /// Attempts to downcast the box to a concrete type. - pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<dyn Error + Send>> { - let err: Box<dyn Error> = self; - <dyn Error>::downcast(err).map_err(|s| unsafe { - // Reapply the `Send` marker. - Box::from_raw(Box::into_raw(s) as *mut (dyn Error + Send)) - }) - } -} - -impl dyn Error + Send + Sync { - #[inline] - #[stable(feature = "error_downcast", since = "1.3.0")] - #[rustc_allow_incoherent_impl] - /// Attempts to downcast the box to a concrete type. - pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<Self>> { - let err: Box<dyn Error> = self; - <dyn Error>::downcast(err).map_err(|s| unsafe { - // Reapply the `Send + Sync` marker. - Box::from_raw(Box::into_raw(s) as *mut (dyn Error + Send + Sync)) - }) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -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)) - /// ``` - fn from(err: E) -> Box<dyn Error + 'a> { - Box::new(err) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -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)) - /// ``` - fn from(err: E) -> Box<dyn Error + Send + Sync + 'a> { - Box::new(err) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -impl From<String> for Box<dyn Error + Send + Sync> { - /// Converts a [`String`] into a box of dyn [`Error`] + [`Send`] + [`Sync`]. - /// - /// # Examples - /// - /// ``` - /// use std::error::Error; - /// use std::mem; - /// - /// let a_string_error = "a string error".to_string(); - /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_string_error); - /// assert!( - /// mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error)) - /// ``` - #[inline] - fn from(err: String) -> Box<dyn Error + Send + Sync> { - struct StringError(String); - - impl Error for StringError { - #[allow(deprecated)] - fn description(&self) -> &str { - &self.0 - } - } - - impl fmt::Display for StringError { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Display::fmt(&self.0, f) - } - } - - // Purposefully skip printing "StringError(..)" - impl fmt::Debug for StringError { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&self.0, f) - } - } - - Box::new(StringError(err)) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "string_box_error", since = "1.6.0")] -impl From<String> for Box<dyn Error> { - /// Converts a [`String`] into a box of dyn [`Error`]. - /// - /// # Examples - /// - /// ``` - /// use std::error::Error; - /// use std::mem; - /// - /// let a_string_error = "a string error".to_string(); - /// let a_boxed_error = Box::<dyn Error>::from(a_string_error); - /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error)) - /// ``` - fn from(str_err: String) -> Box<dyn Error> { - let err1: Box<dyn Error + Send + Sync> = From::from(str_err); - let err2: Box<dyn Error> = err1; - err2 - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -impl<'a> From<&str> for Box<dyn Error + Send + Sync + 'a> { - /// Converts a [`str`] into a box of dyn [`Error`] + [`Send`] + [`Sync`]. - /// - /// [`str`]: prim@str - /// - /// # Examples - /// - /// ``` - /// use std::error::Error; - /// use std::mem; - /// - /// let a_str_error = "a str error"; - /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_str_error); - /// assert!( - /// mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error)) - /// ``` - #[inline] - fn from(err: &str) -> Box<dyn Error + Send + Sync + 'a> { - From::from(String::from(err)) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "string_box_error", since = "1.6.0")] -impl From<&str> for Box<dyn Error> { - /// Converts a [`str`] into a box of dyn [`Error`]. - /// - /// [`str`]: prim@str - /// - /// # Examples - /// - /// ``` - /// use std::error::Error; - /// use std::mem; - /// - /// let a_str_error = "a str error"; - /// let a_boxed_error = Box::<dyn Error>::from(a_str_error); - /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error)) - /// ``` - fn from(err: &str) -> Box<dyn Error> { - From::from(String::from(err)) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "cow_box_error", since = "1.22.0")] -impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + Send + Sync + 'a> { - /// Converts a [`Cow`] into a box of dyn [`Error`] + [`Send`] + [`Sync`]. - /// - /// # Examples - /// - /// ``` - /// use std::error::Error; - /// use std::mem; - /// use std::borrow::Cow; - /// - /// let a_cow_str_error = Cow::from("a str error"); - /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_cow_str_error); - /// assert!( - /// mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error)) - /// ``` - fn from(err: Cow<'b, str>) -> Box<dyn Error + Send + Sync + 'a> { - From::from(String::from(err)) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "cow_box_error", since = "1.22.0")] -impl<'a> From<Cow<'a, str>> for Box<dyn Error> { - /// Converts a [`Cow`] into a box of dyn [`Error`]. - /// - /// # Examples - /// - /// ``` - /// use std::error::Error; - /// use std::mem; - /// use std::borrow::Cow; - /// - /// let a_cow_str_error = Cow::from("a str error"); - /// let a_boxed_error = Box::<dyn Error>::from(a_cow_str_error); - /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error)) - /// ``` - fn from(err: Cow<'a, str>) -> Box<dyn Error> { - From::from(String::from(err)) - } -} - -#[stable(feature = "box_error", since = "1.8.0")] -impl<T: core::error::Error> core::error::Error for Box<T> { - #[allow(deprecated, deprecated_in_future)] - fn description(&self) -> &str { - core::error::Error::description(&**self) - } - - #[allow(deprecated)] - fn cause(&self) -> Option<&dyn core::error::Error> { - core::error::Error::cause(&**self) - } - - fn source(&self) -> Option<&(dyn core::error::Error + 'static)> { - core::error::Error::source(&**self) - } - - fn provide<'b>(&'b self, request: &mut core::error::Request<'b>) { - core::error::Error::provide(&**self, request); - } -} diff --git a/rust/alloc/collections/mod.rs b/rust/alloc/collections/mod.rs deleted file mode 100644 index 00ffb3b973..0000000000 --- a/rust/alloc/collections/mod.rs +++ /dev/null @@ -1,160 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -//! Collection types. - -#![stable(feature = "rust1", since = "1.0.0")] - -#[cfg(not(no_global_oom_handling))] -pub mod binary_heap; -#[cfg(not(no_global_oom_handling))] -mod btree; -#[cfg(not(no_global_oom_handling))] -pub mod linked_list; -#[cfg(not(no_global_oom_handling))] -pub mod vec_deque; - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -pub mod btree_map { - //! An ordered map based on a B-Tree. - #[stable(feature = "rust1", since = "1.0.0")] - pub use super::btree::map::*; -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -pub mod btree_set { - //! An ordered set based on a B-Tree. - #[stable(feature = "rust1", since = "1.0.0")] - pub use super::btree::set::*; -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -#[doc(no_inline)] -pub use binary_heap::BinaryHeap; - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -#[doc(no_inline)] -pub use btree_map::BTreeMap; - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -#[doc(no_inline)] -pub use btree_set::BTreeSet; - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -#[doc(no_inline)] -pub use linked_list::LinkedList; - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -#[doc(no_inline)] -pub use vec_deque::VecDeque; - -use crate::alloc::{Layout, LayoutError}; -use core::fmt::Display; - -/// The error type for `try_reserve` methods. -#[derive(Clone, PartialEq, Eq, Debug)] -#[stable(feature = "try_reserve", since = "1.57.0")] -pub struct TryReserveError { - kind: TryReserveErrorKind, -} - -impl TryReserveError { - /// Details about the allocation that caused the error - #[inline] - #[must_use] - #[unstable( - feature = "try_reserve_kind", - reason = "Uncertain how much info should be exposed", - issue = "48043" - )] - pub fn kind(&self) -> TryReserveErrorKind { - self.kind.clone() - } -} - -/// Details of the allocation that caused a `TryReserveError` -#[derive(Clone, PartialEq, Eq, Debug)] -#[unstable( - feature = "try_reserve_kind", - reason = "Uncertain how much info should be exposed", - issue = "48043" -)] -pub enum TryReserveErrorKind { - /// Error due to the computed capacity exceeding the collection's maximum - /// (usually `isize::MAX` bytes). - CapacityOverflow, - - /// The memory allocator returned an error - AllocError { - /// The layout of allocation request that failed - layout: Layout, - - #[doc(hidden)] - #[unstable( - feature = "container_error_extra", - issue = "none", - reason = "\ - Enable exposing the allocator’s custom error value \ - if an associated type is added in the future: \ - https://github.com/rust-lang/wg-allocators/issues/23" - )] - non_exhaustive: (), - }, -} - -#[unstable( - feature = "try_reserve_kind", - reason = "Uncertain how much info should be exposed", - issue = "48043" -)] -impl From<TryReserveErrorKind> for TryReserveError { - #[inline] - fn from(kind: TryReserveErrorKind) -> Self { - Self { kind } - } -} - -#[unstable(feature = "try_reserve_kind", reason = "new API", issue = "48043")] -impl From<LayoutError> for TryReserveErrorKind { - /// Always evaluates to [`TryReserveErrorKind::CapacityOverflow`]. - #[inline] - fn from(_: LayoutError) -> Self { - TryReserveErrorKind::CapacityOverflow - } -} - -#[stable(feature = "try_reserve", since = "1.57.0")] -impl Display for TryReserveError { - fn fmt( - &self, - fmt: &mut core::fmt::Formatter<'_>, - ) -> core::result::Result<(), core::fmt::Error> { - fmt.write_str("memory allocation failed")?; - let reason = match self.kind { - TryReserveErrorKind::CapacityOverflow => { - " because the computed capacity exceeded the collection's maximum" - } - TryReserveErrorKind::AllocError { .. } => { - " because the memory allocator returned an error" - } - }; - fmt.write_str(reason) - } -} - -/// An intermediate trait for specialization of `Extend`. -#[doc(hidden)] -#[cfg(not(no_global_oom_handling))] -trait SpecExtend<I: IntoIterator> { - /// Extends `self` with the contents of the given iterator. - fn spec_extend(&mut self, iter: I); -} - -#[stable(feature = "try_reserve", since = "1.57.0")] -impl core::error::Error for TryReserveError {} diff --git a/rust/alloc/lib.rs b/rust/alloc/lib.rs deleted file mode 100644 index 36f79c0755..0000000000 --- a/rust/alloc/lib.rs +++ /dev/null @@ -1,288 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -//! # The Rust core allocation and collections library -//! -//! This library provides smart pointers and collections for managing -//! heap-allocated values. -//! -//! This library, like core, normally doesn’t need to be used directly -//! since its contents are re-exported in the [`std` crate](../std/index.html). -//! Crates that use the `#![no_std]` attribute however will typically -//! not depend on `std`, so they’d use this crate instead. -//! -//! ## Boxed values -//! -//! The [`Box`] type is a smart pointer type. There can only be one owner of a -//! [`Box`], and the owner can decide to mutate the contents, which live on the -//! heap. -//! -//! This type can be sent among threads efficiently as the size of a `Box` value -//! is the same as that of a pointer. Tree-like data structures are often built -//! with boxes because each node often has only one owner, the parent. -//! -//! ## Reference counted pointers -//! -//! The [`Rc`] type is a non-threadsafe reference-counted pointer type intended -//! for sharing memory within a thread. An [`Rc`] pointer wraps a type, `T`, and -//! only allows access to `&T`, a shared reference. -//! -//! This type is useful when inherited mutability (such as using [`Box`]) is too -//! constraining for an application, and is often paired with the [`Cell`] or -//! [`RefCell`] types in order to allow mutation. -//! -//! ## Atomically reference counted pointers -//! -//! The [`Arc`] type is the threadsafe equivalent of the [`Rc`] type. It -//! provides all the same functionality of [`Rc`], except it requires that the -//! contained type `T` is shareable. Additionally, [`Arc<T>`][`Arc`] is itself -//! sendable while [`Rc<T>`][`Rc`] is not. -//! -//! This type allows for shared access to the contained data, and is often -//! paired with synchronization primitives such as mutexes to allow mutation of -//! shared resources. -//! -//! ## Collections -//! -//! Implementations of the most common general purpose data structures are -//! defined in this library. They are re-exported through the -//! [standard collections library](../std/collections/index.html). -//! -//! ## Heap interfaces -//! -//! The [`alloc`](alloc/index.html) module defines the low-level interface to the -//! default global allocator. It is not compatible with the libc allocator API. -//! -//! [`Arc`]: sync -//! [`Box`]: boxed -//! [`Cell`]: core::cell -//! [`Rc`]: rc -//! [`RefCell`]: core::cell - -// To run alloc tests without x.py without ending up with two copies of alloc, Miri needs to be -// able to "empty" this crate. See <https://github.com/rust-lang/miri-test-libstd/issues/4>. -// rustc itself never sets the feature, so this line has no effect there. -#![cfg(any(not(feature = "miri-test-libstd"), test, doctest))] -// -#![allow(unused_attributes)] -#![stable(feature = "alloc", since = "1.36.0")] -#![doc( - html_playground_url = "https://play.rust-lang.org/", - issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/", - test(no_crate_inject, attr(allow(unused_variables), deny(warnings))) -)] -#![doc(cfg_hide( - not(test), - not(any(test, bootstrap)), - any(not(feature = "miri-test-libstd"), test, doctest), - no_global_oom_handling, - not(no_global_oom_handling), - not(no_rc), - not(no_sync), - target_has_atomic = "ptr" -))] -#![doc(rust_logo)] -#![feature(rustdoc_internals)] -#![no_std] -#![needs_allocator] -// Lints: -#![deny(unsafe_op_in_unsafe_fn)] -#![deny(fuzzy_provenance_casts)] -#![warn(deprecated_in_future)] -#![warn(missing_debug_implementations)] -#![warn(missing_docs)] -#![allow(explicit_outlives_requirements)] -#![warn(multiple_supertrait_upcastable)] -#![allow(internal_features)] -#![allow(rustdoc::redundant_explicit_links)] -// -// Library features: -// tidy-alphabetical-start -#![cfg_attr(not(no_global_oom_handling), feature(const_alloc_error))] -#![cfg_attr(not(no_global_oom_handling), feature(const_btree_len))] -#![cfg_attr(test, feature(is_sorted))] -#![cfg_attr(test, feature(new_uninit))] -#![feature(alloc_layout_extra)] -#![feature(allocator_api)] -#![feature(array_chunks)] -#![feature(array_into_iter_constructors)] -#![feature(array_methods)] -#![feature(array_windows)] -#![feature(ascii_char)] -#![feature(assert_matches)] -#![feature(async_iterator)] -#![feature(coerce_unsized)] -#![feature(const_align_of_val)] -#![feature(const_box)] -#![cfg_attr(not(no_borrow), feature(const_cow_is_borrowed))] -#![feature(const_eval_select)] -#![feature(const_maybe_uninit_as_mut_ptr)] -#![feature(const_maybe_uninit_write)] -#![feature(const_pin)] -#![feature(const_refs_to_cell)] -#![feature(const_size_of_val)] -#![feature(const_waker)] -#![feature(core_intrinsics)] -#![feature(core_panic)] -#![feature(deprecated_suggestion)] -#![feature(dispatch_from_dyn)] -#![feature(error_generic_member_access)] -#![feature(error_in_core)] -#![feature(exact_size_is_empty)] -#![feature(extend_one)] -#![feature(fmt_internals)] -#![feature(fn_traits)] -#![feature(hasher_prefixfree_extras)] -#![feature(inline_const)] -#![feature(inplace_iteration)] -#![feature(iter_advance_by)] -#![feature(iter_next_chunk)] -#![feature(iter_repeat_n)] -#![feature(layout_for_ptr)] -#![feature(maybe_uninit_slice)] -#![feature(maybe_uninit_uninit_array)] -#![feature(maybe_uninit_uninit_array_transpose)] -#![feature(pattern)] -#![feature(ptr_internals)] -#![feature(ptr_metadata)] -#![feature(ptr_sub_ptr)] -#![feature(receiver_trait)] -#![feature(set_ptr_value)] -#![feature(sized_type_properties)] -#![feature(slice_from_ptr_range)] -#![feature(slice_group_by)] -#![feature(slice_ptr_get)] -#![feature(slice_ptr_len)] -#![feature(slice_range)] -#![feature(std_internals)] -#![feature(str_internals)] -#![feature(strict_provenance)] -#![feature(trusted_fused)] -#![feature(trusted_len)] -#![feature(trusted_random_access)] -#![feature(try_trait_v2)] -#![feature(tuple_trait)] -#![feature(unchecked_math)] -#![feature(unicode_internals)] -#![feature(unsize)] -#![feature(utf8_chunks)] -// tidy-alphabetical-end -// -// Language features: -// tidy-alphabetical-start -#![cfg_attr(not(test), feature(coroutine_trait))] -#![cfg_attr(test, feature(panic_update_hook))] -#![cfg_attr(test, feature(test))] -#![feature(allocator_internals)] -#![feature(allow_internal_unstable)] -#![feature(associated_type_bounds)] -#![feature(c_unwind)] -#![feature(cfg_sanitize)] -#![feature(const_mut_refs)] -#![feature(const_precise_live_drops)] -#![feature(const_ptr_write)] -#![feature(const_trait_impl)] -#![feature(const_try)] -#![feature(dropck_eyepatch)] -#![feature(exclusive_range_pattern)] -#![feature(fundamental)] -#![feature(hashmap_internals)] -#![feature(lang_items)] -#![feature(min_specialization)] -#![feature(multiple_supertrait_upcastable)] -#![feature(negative_impls)] -#![feature(never_type)] -#![feature(pointer_is_aligned)] -#![feature(rustc_allow_const_fn_unstable)] -#![feature(rustc_attrs)] -#![feature(slice_internals)] -#![feature(staged_api)] -#![feature(stmt_expr_attributes)] -#![feature(unboxed_closures)] -#![feature(unsized_fn_params)] -#![feature(with_negative_coherence)] -// tidy-alphabetical-end -// -// Rustdoc features: -#![feature(doc_cfg)] -#![feature(doc_cfg_hide)] -// Technically, this is a bug in rustdoc: rustdoc sees the documentation on `#[lang = slice_alloc]` -// blocks is for `&[T]`, which also has documentation using this feature in `core`, and gets mad -// that the feature-gate isn't enabled. Ideally, it wouldn't check for the feature gate for docs -// from other crates, but since this can only appear for lang items, it doesn't seem worth fixing. -#![feature(intra_doc_pointers)] - -// Allow testing this library -#[cfg(test)] -#[macro_use] -extern crate std; -#[cfg(test)] -extern crate test; -#[cfg(test)] -mod testing; - -// Module with internal macros used by other modules (needs to be included before other modules). -#[cfg(not(no_macros))] -#[macro_use] -mod macros; - -mod raw_vec; - -// Heaps provided for low-level allocation strategies - -pub mod alloc; - -// Primitive types using the heaps above - -// Need to conditionally define the mod from `boxed.rs` to avoid -// duplicating the lang-items when building in test cfg; but also need -// to allow code to have `use boxed::Box;` declarations. -#[cfg(not(test))] -pub mod boxed; -#[cfg(test)] -mod boxed { - pub use std::boxed::Box; -} -#[cfg(not(no_borrow))] -pub mod borrow; -pub mod collections; -#[cfg(all(not(no_rc), not(no_sync), not(no_global_oom_handling)))] -pub mod ffi; -#[cfg(not(no_fmt))] -pub mod fmt; -#[cfg(not(no_rc))] -pub mod rc; -pub mod slice; -#[cfg(not(no_str))] -pub mod str; -#[cfg(not(no_string))] -pub mod string; -#[cfg(all(not(no_rc), not(no_sync), target_has_atomic = "ptr"))] -pub mod sync; -#[cfg(all(not(no_global_oom_handling), not(no_rc), not(no_sync), target_has_atomic = "ptr"))] -pub mod task; -#[cfg(test)] -mod tests; -pub mod vec; - -#[doc(hidden)] -#[unstable(feature = "liballoc_internals", issue = "none", reason = "implementation detail")] -pub mod __export { - pub use core::format_args; -} - -#[cfg(test)] -#[allow(dead_code)] // Not used in all configurations -pub(crate) mod test_helpers { - /// Copied from `std::test_helpers::test_rng`, since these tests rely on the - /// seed not being the same for every RNG invocation too. - pub(crate) fn test_rng() -> rand_xorshift::XorShiftRng { - use std::hash::{BuildHasher, Hash, Hasher}; - let mut hasher = std::hash::RandomState::new().build_hasher(); - std::panic::Location::caller().hash(&mut hasher); - let hc64 = hasher.finish(); - let seed_vec = - hc64.to_le_bytes().into_iter().chain(0u8..8).collect::<crate::vec::Vec<u8>>(); - let seed: [u8; 16] = seed_vec.as_slice().try_into().unwrap(); - rand::SeedableRng::from_seed(seed) - } -} diff --git a/rust/alloc/raw_vec.rs b/rust/alloc/raw_vec.rs deleted file mode 100644 index 98b6abf30a..0000000000 --- a/rust/alloc/raw_vec.rs +++ /dev/null @@ -1,611 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -#![unstable(feature = "raw_vec_internals", reason = "unstable const warnings", issue = "none")] - -use core::alloc::LayoutError; -use core::cmp; -use core::intrinsics; -use core::mem::{self, ManuallyDrop, MaybeUninit, SizedTypeProperties}; -use core::ptr::{self, NonNull, Unique}; -use core::slice; - -#[cfg(not(no_global_oom_handling))] -use crate::alloc::handle_alloc_error; -use crate::alloc::{Allocator, Global, Layout}; -use crate::boxed::Box; -use crate::collections::TryReserveError; -use crate::collections::TryReserveErrorKind::*; - -#[cfg(test)] -mod tests; - -enum AllocInit { - /// The contents of the new memory are uninitialized. - Uninitialized, - /// The new memory is guaranteed to be zeroed. - #[allow(dead_code)] - Zeroed, -} - -#[repr(transparent)] -#[cfg_attr(target_pointer_width = "16", rustc_layout_scalar_valid_range_end(0x7fff))] -#[cfg_attr(target_pointer_width = "32", rustc_layout_scalar_valid_range_end(0x7fff_ffff))] -#[cfg_attr(target_pointer_width = "64", rustc_layout_scalar_valid_range_end(0x7fff_ffff_ffff_ffff))] -struct Cap(usize); - -impl Cap { - const ZERO: Cap = unsafe { Cap(0) }; -} - -/// A low-level utility for more ergonomically allocating, reallocating, and deallocating -/// a buffer of memory on the heap without having to worry about all the corner cases -/// involved. This type is excellent for building your own data structures like Vec and VecDeque. -/// In particular: -/// -/// * Produces `Unique::dangling()` on zero-sized types. -/// * Produces `Unique::dangling()` on zero-length allocations. -/// * Avoids freeing `Unique::dangling()`. -/// * Catches all overflows in capacity computations (promotes them to "capacity overflow" panics). -/// * Guards against 32-bit systems allocating more than isize::MAX bytes. -/// * Guards against overflowing your length. -/// * Calls `handle_alloc_error` for fallible allocations. -/// * Contains a `ptr::Unique` and thus endows the user with all related benefits. -/// * Uses the excess returned from the allocator to use the largest available capacity. -/// -/// This type does not in anyway inspect the memory that it manages. When dropped it *will* -/// free its memory, but it *won't* try to drop its contents. It is up to the user of `RawVec` -/// to handle the actual things *stored* inside of a `RawVec`. -/// -/// Note that the excess of a zero-sized types is always infinite, so `capacity()` always returns -/// `usize::MAX`. This means that you need to be careful when round-tripping this type with a -/// `Box<[T]>`, since `capacity()` won't yield the length. -#[allow(missing_debug_implementations)] -pub(crate) struct RawVec<T, A: Allocator = Global> { - ptr: Unique<T>, - /// Never used for ZSTs; it's `capacity()`'s responsibility to return usize::MAX in that case. - /// - /// # Safety - /// - /// `cap` must be in the `0..=isize::MAX` range. - cap: Cap, - alloc: A, -} - -impl<T> RawVec<T, Global> { - /// HACK(Centril): This exists because stable `const fn` can only call stable `const fn`, so - /// they cannot call `Self::new()`. - /// - /// If you change `RawVec<T>::new` or dependencies, please take care to not introduce anything - /// that would truly const-call something unstable. - pub const NEW: Self = Self::new(); - - /// Creates the biggest possible `RawVec` (on the system heap) - /// without allocating. If `T` has positive size, then this makes a - /// `RawVec` with capacity `0`. If `T` is zero-sized, then it makes a - /// `RawVec` with capacity `usize::MAX`. Useful for implementing - /// delayed allocation. - #[must_use] - pub const fn new() -> Self { - Self::new_in(Global) - } - - /// Creates a `RawVec` (on the system heap) with exactly the - /// capacity and alignment requirements for a `[T; capacity]`. This is - /// equivalent to calling `RawVec::new` when `capacity` is `0` or `T` is - /// zero-sized. Note that if `T` is zero-sized this means you will - /// *not* get a `RawVec` with the requested capacity. - /// - /// # Panics - /// - /// Panics if the requested capacity exceeds `isize::MAX` bytes. - /// - /// # Aborts - /// - /// Aborts on OOM. - #[cfg(not(any(no_global_oom_handling, test)))] - #[must_use] - #[inline] - pub fn with_capacity(capacity: usize) -> Self { - Self::with_capacity_in(capacity, Global) - } - - /// Like `with_capacity`, but guarantees the buffer is zeroed. - #[cfg(not(any(no_global_oom_handling, test)))] - #[must_use] - #[inline] - pub fn with_capacity_zeroed(capacity: usize) -> Self { - Self::with_capacity_zeroed_in(capacity, Global) - } -} - -impl<T, A: Allocator> RawVec<T, A> { - // Tiny Vecs are dumb. Skip to: - // - 8 if the element size is 1, because any heap allocators is likely - // to round up a request of less than 8 bytes to at least 8 bytes. - // - 4 if elements are moderate-sized (<= 1 KiB). - // - 1 otherwise, to avoid wasting too much space for very short Vecs. - pub(crate) const MIN_NON_ZERO_CAP: usize = if mem::size_of::<T>() == 1 { - 8 - } else if mem::size_of::<T>() <= 1024 { - 4 - } else { - 1 - }; - - /// Like `new`, but parameterized over the choice of allocator for - /// the returned `RawVec`. - pub const fn new_in(alloc: A) -> Self { - // `cap: 0` means "unallocated". zero-sized types are ignored. - Self { ptr: Unique::dangling(), cap: Cap::ZERO, alloc } - } - - /// Like `with_capacity`, but parameterized over the choice of - /// allocator for the returned `RawVec`. - #[cfg(not(no_global_oom_handling))] - #[inline] - pub fn with_capacity_in(capacity: usize, alloc: A) -> Self { - Self::allocate_in(capacity, AllocInit::Uninitialized, alloc) - } - - /// Like `try_with_capacity`, but parameterized over the choice of - /// allocator for the returned `RawVec`. - #[inline] - pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> { - Self::try_allocate_in(capacity, AllocInit::Uninitialized, alloc) - } - - /// Like `with_capacity_zeroed`, but parameterized over the choice - /// of allocator for the returned `RawVec`. - #[cfg(not(no_global_oom_handling))] - #[inline] - pub fn with_capacity_zeroed_in(capacity: usize, alloc: A) -> Self { - Self::allocate_in(capacity, AllocInit::Zeroed, alloc) - } - - /// Converts the entire buffer into `Box<[MaybeUninit<T>]>` with the specified `len`. - /// - /// Note that this will correctly reconstitute any `cap` changes - /// that may have been performed. (See description of type for details.) - /// - /// # Safety - /// - /// * `len` must be greater than or equal to the most recently requested capacity, and - /// * `len` must be less than or equal to `self.capacity()`. - /// - /// Note, that the requested capacity and `self.capacity()` could differ, as - /// an allocator could overallocate and return a greater memory block than requested. - pub unsafe fn into_box(self, len: usize) -> Box<[MaybeUninit<T>], A> { - // Sanity-check one half of the safety requirement (we cannot check the other half). - debug_assert!( - len <= self.capacity(), - "`len` must be smaller than or equal to `self.capacity()`" - ); - - let me = ManuallyDrop::new(self); - unsafe { - let slice = slice::from_raw_parts_mut(me.ptr() as *mut MaybeUninit<T>, len); - Box::from_raw_in(slice, ptr::read(&me.alloc)) - } - } - - #[cfg(not(no_global_oom_handling))] - fn allocate_in(capacity: usize, init: AllocInit, alloc: A) -> Self { - // Don't allocate here because `Drop` will not deallocate when `capacity` is 0. - if T::IS_ZST || capacity == 0 { - Self::new_in(alloc) - } else { - // We avoid `unwrap_or_else` here because it bloats the amount of - // LLVM IR generated. - let layout = match Layout::array::<T>(capacity) { - Ok(layout) => layout, - Err(_) => capacity_overflow(), - }; - match alloc_guard(layout.size()) { - Ok(_) => {} - Err(_) => capacity_overflow(), - } - let result = match init { - AllocInit::Uninitialized => alloc.allocate(layout), - AllocInit::Zeroed => alloc.allocate_zeroed(layout), - }; - let ptr = match result { - Ok(ptr) => ptr, - Err(_) => handle_alloc_error(layout), - }; - - // Allocators currently return a `NonNull<[u8]>` whose length - // matches the size requested. If that ever changes, the capacity - // here should change to `ptr.len() / mem::size_of::<T>()`. - Self { - ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) }, - cap: unsafe { Cap(capacity) }, - alloc, - } - } - } - - fn try_allocate_in(capacity: usize, init: AllocInit, alloc: A) -> Result<Self, TryReserveError> { - // Don't allocate here because `Drop` will not deallocate when `capacity` is 0. - if T::IS_ZST || capacity == 0 { - return Ok(Self::new_in(alloc)); - } - - let layout = Layout::array::<T>(capacity).map_err(|_| CapacityOverflow)?; - alloc_guard(layout.size())?; - let result = match init { - AllocInit::Uninitialized => alloc.allocate(layout), - AllocInit::Zeroed => alloc.allocate_zeroed(layout), - }; - let ptr = result.map_err(|_| AllocError { layout, non_exhaustive: () })?; - - // Allocators currently return a `NonNull<[u8]>` whose length - // matches the size requested. If that ever changes, the capacity - // here should change to `ptr.len() / mem::size_of::<T>()`. - Ok(Self { - ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) }, - cap: unsafe { Cap(capacity) }, - alloc, - }) - } - - /// Reconstitutes a `RawVec` from a pointer, capacity, and allocator. - /// - /// # Safety - /// - /// The `ptr` must be allocated (via the given allocator `alloc`), and with the given - /// `capacity`. - /// The `capacity` cannot exceed `isize::MAX` for sized types. (only a concern on 32-bit - /// systems). For ZSTs capacity is ignored. - /// If the `ptr` and `capacity` come from a `RawVec` created via `alloc`, then this is - /// guaranteed. - #[inline] - pub unsafe fn from_raw_parts_in(ptr: *mut T, capacity: usize, alloc: A) -> Self { - let cap = if T::IS_ZST { Cap::ZERO } else { unsafe { Cap(capacity) } }; - Self { ptr: unsafe { Unique::new_unchecked(ptr) }, cap, alloc } - } - - /// Gets a raw pointer to the start of the allocation. Note that this is - /// `Unique::dangling()` if `capacity == 0` or `T` is zero-sized. In the former case, you must - /// be careful. - #[inline] - pub fn ptr(&self) -> *mut T { - self.ptr.as_ptr() - } - - /// Gets the capacity of the allocation. - /// - /// This will always be `usize::MAX` if `T` is zero-sized. - #[inline(always)] - pub fn capacity(&self) -> usize { - if T::IS_ZST { usize::MAX } else { self.cap.0 } - } - - /// Returns a shared reference to the allocator backing this `RawVec`. - pub fn allocator(&self) -> &A { - &self.alloc - } - - fn current_memory(&self) -> Option<(NonNull<u8>, Layout)> { - if T::IS_ZST || self.cap.0 == 0 { - None - } else { - // We could use Layout::array here which ensures the absence of isize and usize overflows - // and could hypothetically handle differences between stride and size, but this memory - // has already been allocated so we know it can't overflow and currently rust does not - // support such types. So we can do better by skipping some checks and avoid an unwrap. - let _: () = const { assert!(mem::size_of::<T>() % mem::align_of::<T>() == 0) }; - unsafe { - let align = mem::align_of::<T>(); - let size = mem::size_of::<T>().unchecked_mul(self.cap.0); - let layout = Layout::from_size_align_unchecked(size, align); - Some((self.ptr.cast().into(), layout)) - } - } - } - - /// Ensures that the buffer contains at least enough space to hold `len + - /// additional` elements. If it doesn't already have enough capacity, will - /// reallocate enough space plus comfortable slack space to get amortized - /// *O*(1) behavior. Will limit this behavior if it would needlessly cause - /// itself to panic. - /// - /// If `len` exceeds `self.capacity()`, this may fail to actually allocate - /// the requested space. This is not really unsafe, but the unsafe - /// code *you* write that relies on the behavior of this function may break. - /// - /// This is ideal for implementing a bulk-push operation like `extend`. - /// - /// # Panics - /// - /// Panics if the new capacity exceeds `isize::MAX` bytes. - /// - /// # Aborts - /// - /// Aborts on OOM. - #[cfg(not(no_global_oom_handling))] - #[inline] - pub fn reserve(&mut self, len: usize, additional: usize) { - // Callers expect this function to be very cheap when there is already sufficient capacity. - // Therefore, we move all the resizing and error-handling logic from grow_amortized and - // handle_reserve behind a call, while making sure that this function is likely to be - // inlined as just a comparison and a call if the comparison fails. - #[cold] - fn do_reserve_and_handle<T, A: Allocator>( - slf: &mut RawVec<T, A>, - len: usize, - additional: usize, - ) { - handle_reserve(slf.grow_amortized(len, additional)); - } - - if self.needs_to_grow(len, additional) { - do_reserve_and_handle(self, len, additional); - } - } - - /// A specialized version of `reserve()` used only by the hot and - /// oft-instantiated `Vec::push()`, which does its own capacity check. - #[cfg(not(no_global_oom_handling))] - #[inline(never)] - pub fn reserve_for_push(&mut self, len: usize) { - handle_reserve(self.grow_amortized(len, 1)); - } - - /// The same as `reserve`, but returns on errors instead of panicking or aborting. - pub fn try_reserve(&mut self, len: usize, additional: usize) -> Result<(), TryReserveError> { - if self.needs_to_grow(len, additional) { - self.grow_amortized(len, additional)?; - } - unsafe { - // Inform the optimizer that the reservation has succeeded or wasn't needed - core::intrinsics::assume(!self.needs_to_grow(len, additional)); - } - Ok(()) - } - - /// The same as `reserve_for_push`, but returns on errors instead of panicking or aborting. - #[inline(never)] - pub fn try_reserve_for_push(&mut self, len: usize) -> Result<(), TryReserveError> { - self.grow_amortized(len, 1) - } - - /// Ensures that the buffer contains at least enough space to hold `len + - /// additional` elements. If it doesn't already, will reallocate the - /// minimum possible amount of memory necessary. Generally this will be - /// exactly the amount of memory necessary, but in principle the allocator - /// is free to give back more than we asked for. - /// - /// If `len` exceeds `self.capacity()`, this may fail to actually allocate - /// the requested space. This is not really unsafe, but the unsafe code - /// *you* write that relies on the behavior of this function may break. - /// - /// # Panics - /// - /// Panics if the new capacity exceeds `isize::MAX` bytes. - /// - /// # Aborts - /// - /// Aborts on OOM. - #[cfg(not(no_global_oom_handling))] - pub fn reserve_exact(&mut self, len: usize, additional: usize) { - handle_reserve(self.try_reserve_exact(len, additional)); - } - - /// The same as `reserve_exact`, but returns on errors instead of panicking or aborting. - pub fn try_reserve_exact( - &mut self, - len: usize, - additional: usize, - ) -> Result<(), TryReserveError> { - if self.needs_to_grow(len, additional) { - self.grow_exact(len, additional)?; - } - unsafe { - // Inform the optimizer that the reservation has succeeded or wasn't needed - core::intrinsics::assume(!self.needs_to_grow(len, additional)); - } - Ok(()) - } - - /// Shrinks the buffer down to the specified capacity. If the given amount - /// is 0, actually completely deallocates. - /// - /// # Panics - /// - /// Panics if the given amount is *larger* than the current capacity. - /// - /// # Aborts - /// - /// Aborts on OOM. - #[cfg(not(no_global_oom_handling))] - pub fn shrink_to_fit(&mut self, cap: usize) { - handle_reserve(self.shrink(cap)); - } -} - -impl<T, A: Allocator> RawVec<T, A> { - /// Returns if the buffer needs to grow to fulfill the needed extra capacity. - /// Mainly used to make inlining reserve-calls possible without inlining `grow`. - fn needs_to_grow(&self, len: usize, additional: usize) -> bool { - additional > self.capacity().wrapping_sub(len) - } - - /// # Safety: - /// - /// `cap` must not exceed `isize::MAX`. - unsafe fn set_ptr_and_cap(&mut self, ptr: NonNull<[u8]>, cap: usize) { - // Allocators currently return a `NonNull<[u8]>` whose length matches - // the size requested. If that ever changes, the capacity here should - // change to `ptr.len() / mem::size_of::<T>()`. - self.ptr = unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) }; - self.cap = unsafe { Cap(cap) }; - } - - // This method is usually instantiated many times. So we want it to be as - // small as possible, to improve compile times. But we also want as much of - // its contents to be statically computable as possible, to make the - // generated code run faster. Therefore, this method is carefully written - // so that all of the code that depends on `T` is within it, while as much - // of the code that doesn't depend on `T` as possible is in functions that - // are non-generic over `T`. - fn grow_amortized(&mut self, len: usize, additional: usize) -> Result<(), TryReserveError> { - // This is ensured by the calling contexts. - debug_assert!(additional > 0); - - if T::IS_ZST { - // Since we return a capacity of `usize::MAX` when `elem_size` is - // 0, getting to here necessarily means the `RawVec` is overfull. - return Err(CapacityOverflow.into()); - } - - // Nothing we can really do about these checks, sadly. - let required_cap = len.checked_add(additional).ok_or(CapacityOverflow)?; - - // This guarantees exponential growth. The doubling cannot overflow - // because `cap <= isize::MAX` and the type of `cap` is `usize`. - let cap = cmp::max(self.cap.0 * 2, required_cap); - let cap = cmp::max(Self::MIN_NON_ZERO_CAP, cap); - - let new_layout = Layout::array::<T>(cap); - - // `finish_grow` is non-generic over `T`. - let ptr = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?; - // SAFETY: finish_grow would have resulted in a capacity overflow if we tried to allocate more than isize::MAX items - unsafe { self.set_ptr_and_cap(ptr, cap) }; - Ok(()) - } - - // The constraints on this method are much the same as those on - // `grow_amortized`, but this method is usually instantiated less often so - // it's less critical. - fn grow_exact(&mut self, len: usize, additional: usize) -> Result<(), TryReserveError> { - if T::IS_ZST { - // Since we return a capacity of `usize::MAX` when the type size is - // 0, getting to here necessarily means the `RawVec` is overfull. - return Err(CapacityOverflow.into()); - } - - let cap = len.checked_add(additional).ok_or(CapacityOverflow)?; - let new_layout = Layout::array::<T>(cap); - - // `finish_grow` is non-generic over `T`. - let ptr = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?; - // SAFETY: finish_grow would have resulted in a capacity overflow if we tried to allocate more than isize::MAX items - unsafe { - self.set_ptr_and_cap(ptr, cap); - } - Ok(()) - } - - #[cfg(not(no_global_oom_handling))] - fn shrink(&mut self, cap: usize) -> Result<(), TryReserveError> { - assert!(cap <= self.capacity(), "Tried to shrink to a larger capacity"); - - let (ptr, layout) = if let Some(mem) = self.current_memory() { mem } else { return Ok(()) }; - // See current_memory() why this assert is here - let _: () = const { assert!(mem::size_of::<T>() % mem::align_of::<T>() == 0) }; - - // If shrinking to 0, deallocate the buffer. We don't reach this point - // for the T::IS_ZST case since current_memory() will have returned - // None. - if cap == 0 { - unsafe { self.alloc.deallocate(ptr, layout) }; - self.ptr = Unique::dangling(); - self.cap = Cap::ZERO; - } else { - let ptr = unsafe { - // `Layout::array` cannot overflow here because it would have - // overflowed earlier when capacity was larger. - let new_size = mem::size_of::<T>().unchecked_mul(cap); - let new_layout = Layout::from_size_align_unchecked(new_size, layout.align()); - self.alloc - .shrink(ptr, layout, new_layout) - .map_err(|_| AllocError { layout: new_layout, non_exhaustive: () })? - }; - // SAFETY: if the allocation is valid, then the capacity is too - unsafe { - self.set_ptr_and_cap(ptr, cap); - } - } - Ok(()) - } -} - -// This function is outside `RawVec` to minimize compile times. See the comment -// above `RawVec::grow_amortized` for details. (The `A` parameter isn't -// significant, because the number of different `A` types seen in practice is -// much smaller than the number of `T` types.) -#[inline(never)] -fn finish_grow<A>( - new_layout: Result<Layout, LayoutError>, - current_memory: Option<(NonNull<u8>, Layout)>, - alloc: &mut A, -) -> Result<NonNull<[u8]>, TryReserveError> -where - A: Allocator, -{ - // Check for the error here to minimize the size of `RawVec::grow_*`. - let new_layout = new_layout.map_err(|_| CapacityOverflow)?; - - alloc_guard(new_layout.size())?; - - let memory = if let Some((ptr, old_layout)) = current_memory { - debug_assert_eq!(old_layout.align(), new_layout.align()); - unsafe { - // The allocator checks for alignment equality - intrinsics::assume(old_layout.align() == new_layout.align()); - alloc.grow(ptr, old_layout, new_layout) - } - } else { - alloc.allocate(new_layout) - }; - - memory.map_err(|_| AllocError { layout: new_layout, non_exhaustive: () }.into()) -} - -unsafe impl<#[may_dangle] T, A: Allocator> Drop for RawVec<T, A> { - /// Frees the memory owned by the `RawVec` *without* trying to drop its contents. - fn drop(&mut self) { - if let Some((ptr, layout)) = self.current_memory() { - unsafe { self.alloc.deallocate(ptr, layout) } - } - } -} - -// Central function for reserve error handling. -#[cfg(not(no_global_oom_handling))] -#[inline] -fn handle_reserve(result: Result<(), TryReserveError>) { - match result.map_err(|e| e.kind()) { - Err(CapacityOverflow) => capacity_overflow(), - Err(AllocError { layout, .. }) => handle_alloc_error(layout), - Ok(()) => { /* yay */ } - } -} - -// We need to guarantee the following: -// * We don't ever allocate `> isize::MAX` byte-size objects. -// * We don't overflow `usize::MAX` and actually allocate too little. -// -// On 64-bit we just need to check for overflow since trying to allocate -// `> isize::MAX` bytes will surely fail. On 32-bit and 16-bit we need to add -// an extra guard for this in case we're running on a platform which can use -// all 4GB in user-space, e.g., PAE or x32. - -#[inline] -fn alloc_guard(alloc_size: usize) -> Result<(), TryReserveError> { - if usize::BITS < 64 && alloc_size > isize::MAX as usize { - Err(CapacityOverflow.into()) - } else { - Ok(()) - } -} - -// One central function responsible for reporting capacity overflows. This'll -// ensure that the code generation related to these panics is minimal as there's -// only one location which panics rather than a bunch throughout the module. -#[cfg(not(no_global_oom_handling))] -#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] -fn capacity_overflow() -> ! { - panic!("capacity overflow"); -} diff --git a/rust/alloc/slice.rs b/rust/alloc/slice.rs deleted file mode 100644 index 1181836da5..0000000000 --- a/rust/alloc/slice.rs +++ /dev/null @@ -1,890 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -//! Utilities for the slice primitive type. -//! -//! *[See also the slice primitive type](slice).* -//! -//! Most of the structs in this module are iterator types which can only be created -//! using a certain function. For example, `slice.iter()` yields an [`Iter`]. -//! -//! A few functions are provided to create a slice from a value reference -//! or from a raw pointer. -#![stable(feature = "rust1", since = "1.0.0")] -// Many of the usings in this module are only used in the test configuration. -// It's cleaner to just turn off the unused_imports warning than to fix them. -#![cfg_attr(test, allow(unused_imports, dead_code))] - -use core::borrow::{Borrow, BorrowMut}; -#[cfg(not(no_global_oom_handling))] -use core::cmp::Ordering::{self, Less}; -#[cfg(not(no_global_oom_handling))] -use core::mem::{self, SizedTypeProperties}; -#[cfg(not(no_global_oom_handling))] -use core::ptr; -#[cfg(not(no_global_oom_handling))] -use core::slice::sort; - -use crate::alloc::Allocator; -#[cfg(not(no_global_oom_handling))] -use crate::alloc::{self, Global}; -#[cfg(not(no_global_oom_handling))] -use crate::borrow::ToOwned; -use crate::boxed::Box; -use crate::vec::Vec; - -#[cfg(test)] -mod tests; - -#[unstable(feature = "slice_range", issue = "76393")] -pub use core::slice::range; -#[unstable(feature = "array_chunks", issue = "74985")] -pub use core::slice::ArrayChunks; -#[unstable(feature = "array_chunks", issue = "74985")] -pub use core::slice::ArrayChunksMut; -#[unstable(feature = "array_windows", issue = "75027")] -pub use core::slice::ArrayWindows; -#[stable(feature = "inherent_ascii_escape", since = "1.60.0")] -pub use core::slice::EscapeAscii; -#[stable(feature = "slice_get_slice", since = "1.28.0")] -pub use core::slice::SliceIndex; -#[stable(feature = "from_ref", since = "1.28.0")] -pub use core::slice::{from_mut, from_ref}; -#[unstable(feature = "slice_from_ptr_range", issue = "89792")] -pub use core::slice::{from_mut_ptr_range, from_ptr_range}; -#[stable(feature = "rust1", since = "1.0.0")] -pub use core::slice::{from_raw_parts, from_raw_parts_mut}; -#[stable(feature = "rust1", since = "1.0.0")] -pub use core::slice::{Chunks, Windows}; -#[stable(feature = "chunks_exact", since = "1.31.0")] -pub use core::slice::{ChunksExact, ChunksExactMut}; -#[stable(feature = "rust1", since = "1.0.0")] -pub use core::slice::{ChunksMut, Split, SplitMut}; -#[unstable(feature = "slice_group_by", issue = "80552")] -pub use core::slice::{GroupBy, GroupByMut}; -#[stable(feature = "rust1", since = "1.0.0")] -pub use core::slice::{Iter, IterMut}; -#[stable(feature = "rchunks", since = "1.31.0")] -pub use core::slice::{RChunks, RChunksExact, RChunksExactMut, RChunksMut}; -#[stable(feature = "slice_rsplit", since = "1.27.0")] -pub use core::slice::{RSplit, RSplitMut}; -#[stable(feature = "rust1", since = "1.0.0")] -pub use core::slice::{RSplitN, RSplitNMut, SplitN, SplitNMut}; -#[stable(feature = "split_inclusive", since = "1.51.0")] -pub use core::slice::{SplitInclusive, SplitInclusiveMut}; - -//////////////////////////////////////////////////////////////////////////////// -// Basic slice extension methods -//////////////////////////////////////////////////////////////////////////////// - -// HACK(japaric) needed for the implementation of `vec!` macro during testing -// N.B., see the `hack` module in this file for more details. -#[cfg(test)] -pub use hack::into_vec; - -// HACK(japaric) needed for the implementation of `Vec::clone` during testing -// N.B., see the `hack` module in this file for more details. -#[cfg(test)] -pub use hack::to_vec; - -// HACK(japaric): With cfg(test) `impl [T]` is not available, these three -// functions are actually methods that are in `impl [T]` but not in -// `core::slice::SliceExt` - we need to supply these functions for the -// `test_permutations` test -pub(crate) mod hack { - use core::alloc::Allocator; - - use crate::boxed::Box; - use crate::vec::Vec; - - // We shouldn't add inline attribute to this since this is used in - // `vec!` macro mostly and causes perf regression. See #71204 for - // discussion and perf results. - pub fn into_vec<T, A: Allocator>(b: Box<[T], A>) -> Vec<T, A> { - unsafe { - let len = b.len(); - let (b, alloc) = Box::into_raw_with_allocator(b); - Vec::from_raw_parts_in(b as *mut T, len, len, alloc) - } - } - - #[cfg(not(no_global_oom_handling))] - #[inline] - pub fn to_vec<T: ConvertVec, A: Allocator>(s: &[T], alloc: A) -> Vec<T, A> { - T::to_vec(s, alloc) - } - - #[cfg(not(no_global_oom_handling))] - pub trait ConvertVec { - fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A> - where - Self: Sized; - } - - #[cfg(not(no_global_oom_handling))] - impl<T: Clone> ConvertVec for T { - #[inline] - default fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A> { - struct DropGuard<'a, T, A: Allocator> { - vec: &'a mut Vec<T, A>, - num_init: usize, - } - impl<'a, T, A: Allocator> Drop for DropGuard<'a, T, A> { - #[inline] - fn drop(&mut self) { - // SAFETY: - // items were marked initialized in the loop below - unsafe { - self.vec.set_len(self.num_init); - } - } - } - let mut vec = Vec::with_capacity_in(s.len(), alloc); - let mut guard = DropGuard { vec: &mut vec, num_init: 0 }; - let slots = guard.vec.spare_capacity_mut(); - // .take(slots.len()) is necessary for LLVM to remove bounds checks - // and has better codegen than zip. - for (i, b) in s.iter().enumerate().take(slots.len()) { - guard.num_init = i; - slots[i].write(b.clone()); - } - core::mem::forget(guard); - // SAFETY: - // the vec was allocated and initialized above to at least this length. - unsafe { - vec.set_len(s.len()); - } - vec - } - } - - #[cfg(not(no_global_oom_handling))] - impl<T: Copy> ConvertVec for T { - #[inline] - fn to_vec<A: Allocator>(s: &[Self], alloc: A) -> Vec<Self, A> { - let mut v = Vec::with_capacity_in(s.len(), alloc); - // SAFETY: - // allocated above with the capacity of `s`, and initialize to `s.len()` in - // ptr::copy_to_non_overlapping below. - unsafe { - s.as_ptr().copy_to_nonoverlapping(v.as_mut_ptr(), s.len()); - v.set_len(s.len()); - } - v - } - } -} - -#[cfg(not(test))] -impl<T> [T] { - /// Sorts the slice. - /// - /// This sort is stable (i.e., does not reorder equal elements) and *O*(*n* \* log(*n*)) worst-case. - /// - /// When applicable, unstable sorting is preferred because it is generally faster than stable - /// sorting and it doesn't allocate auxiliary memory. - /// See [`sort_unstable`](slice::sort_unstable). - /// - /// # Current implementation - /// - /// The current algorithm is an adaptive, iterative merge sort inspired by - /// [timsort](https://en.wikipedia.org/wiki/Timsort). - /// It is designed to be very fast in cases where the slice is nearly sorted, or consists of - /// two or more sorted sequences concatenated one after another. - /// - /// Also, it allocates temporary storage half the size of `self`, but for short slices a - /// non-allocating insertion sort is used instead. - /// - /// # Examples - /// - /// ``` - /// let mut v = [-5, 4, 1, -3, 2]; - /// - /// v.sort(); - /// assert!(v == [-5, -3, 1, 2, 4]); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[rustc_allow_incoherent_impl] - #[stable(feature = "rust1", since = "1.0.0")] - #[inline] - pub fn sort(&mut self) - where - T: Ord, - { - stable_sort(self, T::lt); - } - - /// Sorts the slice with a comparator function. - /// - /// This sort is stable (i.e., does not reorder equal elements) and *O*(*n* \* log(*n*)) worst-case. - /// - /// The comparator function must define a total ordering for the elements in the slice. If - /// the ordering is not total, the order of the elements is unspecified. An order is a - /// total order if it is (for all `a`, `b` and `c`): - /// - /// * total and antisymmetric: exactly one of `a < b`, `a == b` or `a > b` is true, and - /// * transitive, `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`. - /// - /// For example, while [`f64`] doesn't implement [`Ord`] because `NaN != NaN`, we can use - /// `partial_cmp` as our sort function when we know the slice doesn't contain a `NaN`. - /// - /// ``` - /// let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0]; - /// floats.sort_by(|a, b| a.partial_cmp(b).unwrap()); - /// assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]); - /// ``` - /// - /// When applicable, unstable sorting is preferred because it is generally faster than stable - /// sorting and it doesn't allocate auxiliary memory. - /// See [`sort_unstable_by`](slice::sort_unstable_by). - /// - /// # Current implementation - /// - /// The current algorithm is an adaptive, iterative merge sort inspired by - /// [timsort](https://en.wikipedia.org/wiki/Timsort). - /// It is designed to be very fast in cases where the slice is nearly sorted, or consists of - /// two or more sorted sequences concatenated one after another. - /// - /// Also, it allocates temporary storage half the size of `self`, but for short slices a - /// non-allocating insertion sort is used instead. - /// - /// # Examples - /// - /// ``` - /// let mut v = [5, 4, 1, 3, 2]; - /// v.sort_by(|a, b| a.cmp(b)); - /// assert!(v == [1, 2, 3, 4, 5]); - /// - /// // reverse sorting - /// v.sort_by(|a, b| b.cmp(a)); - /// assert!(v == [5, 4, 3, 2, 1]); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[rustc_allow_incoherent_impl] - #[stable(feature = "rust1", since = "1.0.0")] - #[inline] - pub fn sort_by<F>(&mut self, mut compare: F) - where - F: FnMut(&T, &T) -> Ordering, - { - stable_sort(self, |a, b| compare(a, b) == Less); - } - - /// Sorts the slice with a key extraction function. - /// - /// This sort is stable (i.e., does not reorder equal elements) and *O*(*m* \* *n* \* log(*n*)) - /// worst-case, where the key function is *O*(*m*). - /// - /// For expensive key functions (e.g. functions that are not simple property accesses or - /// basic operations), [`sort_by_cached_key`](slice::sort_by_cached_key) is likely to be - /// significantly faster, as it does not recompute element keys. - /// - /// When applicable, unstable sorting is preferred because it is generally faster than stable - /// sorting and it doesn't allocate auxiliary memory. - /// See [`sort_unstable_by_key`](slice::sort_unstable_by_key). - /// - /// # Current implementation - /// - /// The current algorithm is an adaptive, iterative merge sort inspired by - /// [timsort](https://en.wikipedia.org/wiki/Timsort). - /// It is designed to be very fast in cases where the slice is nearly sorted, or consists of - /// two or more sorted sequences concatenated one after another. - /// - /// Also, it allocates temporary storage half the size of `self`, but for short slices a - /// non-allocating insertion sort is used instead. - /// - /// # Examples - /// - /// ``` - /// let mut v = [-5i32, 4, 1, -3, 2]; - /// - /// v.sort_by_key(|k| k.abs()); - /// assert!(v == [1, 2, -3, 4, -5]); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[rustc_allow_incoherent_impl] - #[stable(feature = "slice_sort_by_key", since = "1.7.0")] - #[inline] - pub fn sort_by_key<K, F>(&mut self, mut f: F) - where - F: FnMut(&T) -> K, - K: Ord, - { - stable_sort(self, |a, b| f(a).lt(&f(b))); - } - - /// Sorts the slice with a key extraction function. - /// - /// During sorting, the key function is called at most once per element, by using - /// temporary storage to remember the results of key evaluation. - /// The order of calls to the key function is unspecified and may change in future versions - /// of the standard library. - /// - /// This sort is stable (i.e., does not reorder equal elements) and *O*(*m* \* *n* + *n* \* log(*n*)) - /// worst-case, where the key function is *O*(*m*). - /// - /// For simple key functions (e.g., functions that are property accesses or - /// basic operations), [`sort_by_key`](slice::sort_by_key) is likely to be - /// faster. - /// - /// # Current implementation - /// - /// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters, - /// which combines the fast average case of randomized quicksort with the fast worst case of - /// heapsort, while achieving linear time on slices with certain patterns. It uses some - /// randomization to avoid degenerate cases, but with a fixed seed to always provide - /// deterministic behavior. - /// - /// In the worst case, the algorithm allocates temporary storage in a `Vec<(K, usize)>` the - /// length of the slice. - /// - /// # Examples - /// - /// ``` - /// let mut v = [-5i32, 4, 32, -3, 2]; - /// - /// v.sort_by_cached_key(|k| k.to_string()); - /// assert!(v == [-3, -5, 2, 32, 4]); - /// ``` - /// - /// [pdqsort]: https://github.com/orlp/pdqsort - #[cfg(not(no_global_oom_handling))] - #[rustc_allow_incoherent_impl] - #[stable(feature = "slice_sort_by_cached_key", since = "1.34.0")] - #[inline] - pub fn sort_by_cached_key<K, F>(&mut self, f: F) - where - F: FnMut(&T) -> K, - K: Ord, - { - // Helper macro for indexing our vector by the smallest possible type, to reduce allocation. - macro_rules! sort_by_key { - ($t:ty, $slice:ident, $f:ident) => {{ - let mut indices: Vec<_> = - $slice.iter().map($f).enumerate().map(|(i, k)| (k, i as $t)).collect(); - // The elements of `indices` are unique, as they are indexed, so any sort will be - // stable with respect to the original slice. We use `sort_unstable` here because - // it requires less memory allocation. - indices.sort_unstable(); - for i in 0..$slice.len() { - let mut index = indices[i].1; - while (index as usize) < i { - index = indices[index as usize].1; - } - indices[i].1 = index; - $slice.swap(i, index as usize); - } - }}; - } - - let sz_u8 = mem::size_of::<(K, u8)>(); - let sz_u16 = mem::size_of::<(K, u16)>(); - let sz_u32 = mem::size_of::<(K, u32)>(); - let sz_usize = mem::size_of::<(K, usize)>(); - - let len = self.len(); - if len < 2 { - return; - } - if sz_u8 < sz_u16 && len <= (u8::MAX as usize) { - return sort_by_key!(u8, self, f); - } - if sz_u16 < sz_u32 && len <= (u16::MAX as usize) { - return sort_by_key!(u16, self, f); - } - if sz_u32 < sz_usize && len <= (u32::MAX as usize) { - return sort_by_key!(u32, self, f); - } - sort_by_key!(usize, self, f) - } - - /// Copies `self` into a new `Vec`. - /// - /// # Examples - /// - /// ``` - /// let s = [10, 40, 30]; - /// let x = s.to_vec(); - /// // Here, `s` and `x` can be modified independently. - /// ``` - #[cfg(not(no_global_oom_handling))] - #[rustc_allow_incoherent_impl] - #[rustc_conversion_suggestion] - #[stable(feature = "rust1", since = "1.0.0")] - #[inline] - pub fn to_vec(&self) -> Vec<T> - where - T: Clone, - { - self.to_vec_in(Global) - } - - /// Copies `self` into a new `Vec` with an allocator. - /// - /// # Examples - /// - /// ``` - /// #![feature(allocator_api)] - /// - /// use std::alloc::System; - /// - /// let s = [10, 40, 30]; - /// let x = s.to_vec_in(System); - /// // Here, `s` and `x` can be modified independently. - /// ``` - #[cfg(not(no_global_oom_handling))] - #[rustc_allow_incoherent_impl] - #[inline] - #[unstable(feature = "allocator_api", issue = "32838")] - pub fn to_vec_in<A: Allocator>(&self, alloc: A) -> Vec<T, A> - where - T: Clone, - { - // N.B., see the `hack` module in this file for more details. - hack::to_vec(self, alloc) - } - - /// Converts `self` into a vector without clones or allocation. - /// - /// The resulting vector can be converted back into a box via - /// `Vec<T>`'s `into_boxed_slice` method. - /// - /// # Examples - /// - /// ``` - /// let s: Box<[i32]> = Box::new([10, 40, 30]); - /// let x = s.into_vec(); - /// // `s` cannot be used anymore because it has been converted into `x`. - /// - /// assert_eq!(x, vec![10, 40, 30]); - /// ``` - #[rustc_allow_incoherent_impl] - #[stable(feature = "rust1", since = "1.0.0")] - #[inline] - pub fn into_vec<A: Allocator>(self: Box<Self, A>) -> Vec<T, A> { - // N.B., see the `hack` module in this file for more details. - hack::into_vec(self) - } - - /// Creates a vector by copying a slice `n` times. - /// - /// # Panics - /// - /// This function will panic if the capacity would overflow. - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// assert_eq!([1, 2].repeat(3), vec![1, 2, 1, 2, 1, 2]); - /// ``` - /// - /// A panic upon overflow: - /// - /// ```should_panic - /// // this will panic at runtime - /// b"0123456789abcdef".repeat(usize::MAX); - /// ``` - #[rustc_allow_incoherent_impl] - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "repeat_generic_slice", since = "1.40.0")] - pub fn repeat(&self, n: usize) -> Vec<T> - where - T: Copy, - { - if n == 0 { - return Vec::new(); - } - - // If `n` is larger than zero, it can be split as - // `n = 2^expn + rem (2^expn > rem, expn >= 0, rem >= 0)`. - // `2^expn` is the number represented by the leftmost '1' bit of `n`, - // and `rem` is the remaining part of `n`. - - // Using `Vec` to access `set_len()`. - let capacity = self.len().checked_mul(n).expect("capacity overflow"); - let mut buf = Vec::with_capacity(capacity); - - // `2^expn` repetition is done by doubling `buf` `expn`-times. - buf.extend(self); - { - let mut m = n >> 1; - // If `m > 0`, there are remaining bits up to the leftmost '1'. - while m > 0 { - // `buf.extend(buf)`: - unsafe { - ptr::copy_nonoverlapping( - buf.as_ptr(), - (buf.as_mut_ptr() as *mut T).add(buf.len()), - buf.len(), - ); - // `buf` has capacity of `self.len() * n`. - let buf_len = buf.len(); - buf.set_len(buf_len * 2); - } - - m >>= 1; - } - } - - // `rem` (`= n - 2^expn`) repetition is done by copying - // first `rem` repetitions from `buf` itself. - let rem_len = capacity - buf.len(); // `self.len() * rem` - if rem_len > 0 { - // `buf.extend(buf[0 .. rem_len])`: - unsafe { - // This is non-overlapping since `2^expn > rem`. - ptr::copy_nonoverlapping( - buf.as_ptr(), - (buf.as_mut_ptr() as *mut T).add(buf.len()), - rem_len, - ); - // `buf.len() + rem_len` equals to `buf.capacity()` (`= self.len() * n`). - buf.set_len(capacity); - } - } - buf - } - - /// Flattens a slice of `T` into a single value `Self::Output`. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(["hello", "world"].concat(), "helloworld"); - /// assert_eq!([[1, 2], [3, 4]].concat(), [1, 2, 3, 4]); - /// ``` - #[rustc_allow_incoherent_impl] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn concat<Item: ?Sized>(&self) -> <Self as Concat<Item>>::Output - where - Self: Concat<Item>, - { - Concat::concat(self) - } - - /// Flattens a slice of `T` into a single value `Self::Output`, placing a - /// given separator between each. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(["hello", "world"].join(" "), "hello world"); - /// assert_eq!([[1, 2], [3, 4]].join(&0), [1, 2, 0, 3, 4]); - /// assert_eq!([[1, 2], [3, 4]].join(&[0, 0][..]), [1, 2, 0, 0, 3, 4]); - /// ``` - #[rustc_allow_incoherent_impl] - #[stable(feature = "rename_connect_to_join", since = "1.3.0")] - pub fn join<Separator>(&self, sep: Separator) -> <Self as Join<Separator>>::Output - where - Self: Join<Separator>, - { - Join::join(self, sep) - } - - /// Flattens a slice of `T` into a single value `Self::Output`, placing a - /// given separator between each. - /// - /// # Examples - /// - /// ``` - /// # #![allow(deprecated)] - /// assert_eq!(["hello", "world"].connect(" "), "hello world"); - /// assert_eq!([[1, 2], [3, 4]].connect(&0), [1, 2, 0, 3, 4]); - /// ``` - #[rustc_allow_incoherent_impl] - #[stable(feature = "rust1", since = "1.0.0")] - #[deprecated(since = "1.3.0", note = "renamed to join", suggestion = "join")] - pub fn connect<Separator>(&self, sep: Separator) -> <Self as Join<Separator>>::Output - where - Self: Join<Separator>, - { - Join::join(self, sep) - } -} - -#[cfg(not(test))] -impl [u8] { - /// Returns a vector containing a copy of this slice where each byte - /// is mapped to its ASCII upper case equivalent. - /// - /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', - /// but non-ASCII letters are unchanged. - /// - /// To uppercase the value in-place, use [`make_ascii_uppercase`]. - /// - /// [`make_ascii_uppercase`]: slice::make_ascii_uppercase - #[cfg(not(no_global_oom_handling))] - #[rustc_allow_incoherent_impl] - #[must_use = "this returns the uppercase bytes as a new Vec, \ - without modifying the original"] - #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")] - #[inline] - pub fn to_ascii_uppercase(&self) -> Vec<u8> { - let mut me = self.to_vec(); - me.make_ascii_uppercase(); - me - } - - /// Returns a vector containing a copy of this slice where each byte - /// is mapped to its ASCII lower case equivalent. - /// - /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', - /// but non-ASCII letters are unchanged. - /// - /// To lowercase the value in-place, use [`make_ascii_lowercase`]. - /// - /// [`make_ascii_lowercase`]: slice::make_ascii_lowercase - #[cfg(not(no_global_oom_handling))] - #[rustc_allow_incoherent_impl] - #[must_use = "this returns the lowercase bytes as a new Vec, \ - without modifying the original"] - #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")] - #[inline] - pub fn to_ascii_lowercase(&self) -> Vec<u8> { - let mut me = self.to_vec(); - me.make_ascii_lowercase(); - me - } -} - -//////////////////////////////////////////////////////////////////////////////// -// Extension traits for slices over specific kinds of data -//////////////////////////////////////////////////////////////////////////////// - -/// Helper trait for [`[T]::concat`](slice::concat). -/// -/// Note: the `Item` type parameter is not used in this trait, -/// but it allows impls to be more generic. -/// Without it, we get this error: -/// -/// ```error -/// error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predica -/// --> library/alloc/src/slice.rs:608:6 -/// | -/// 608 | impl<T: Clone, V: Borrow<[T]>> Concat for [V] { -/// | ^ unconstrained type parameter -/// ``` -/// -/// This is because there could exist `V` types with multiple `Borrow<[_]>` impls, -/// such that multiple `T` types would apply: -/// -/// ``` -/// # #[allow(dead_code)] -/// pub struct Foo(Vec<u32>, Vec<String>); -/// -/// impl std::borrow::Borrow<[u32]> for Foo { -/// fn borrow(&self) -> &[u32] { &self.0 } -/// } -/// -/// impl std::borrow::Borrow<[String]> for Foo { -/// fn borrow(&self) -> &[String] { &self.1 } -/// } -/// ``` -#[unstable(feature = "slice_concat_trait", issue = "27747")] -pub trait Concat<Item: ?Sized> { - #[unstable(feature = "slice_concat_trait", issue = "27747")] - /// The resulting type after concatenation - type Output; - - /// Implementation of [`[T]::concat`](slice::concat) - #[unstable(feature = "slice_concat_trait", issue = "27747")] - fn concat(slice: &Self) -> Self::Output; -} - -/// Helper trait for [`[T]::join`](slice::join) -#[unstable(feature = "slice_concat_trait", issue = "27747")] -pub trait Join<Separator> { - #[unstable(feature = "slice_concat_trait", issue = "27747")] - /// The resulting type after concatenation - type Output; - - /// Implementation of [`[T]::join`](slice::join) - #[unstable(feature = "slice_concat_trait", issue = "27747")] - fn join(slice: &Self, sep: Separator) -> Self::Output; -} - -#[cfg(not(no_global_oom_handling))] -#[unstable(feature = "slice_concat_ext", issue = "27747")] -impl<T: Clone, V: Borrow<[T]>> Concat<T> for [V] { - type Output = Vec<T>; - - fn concat(slice: &Self) -> Vec<T> { - let size = slice.iter().map(|slice| slice.borrow().len()).sum(); - let mut result = Vec::with_capacity(size); - for v in slice { - result.extend_from_slice(v.borrow()) - } - result - } -} - -#[cfg(not(no_global_oom_handling))] -#[unstable(feature = "slice_concat_ext", issue = "27747")] -impl<T: Clone, V: Borrow<[T]>> Join<&T> for [V] { - type Output = Vec<T>; - - fn join(slice: &Self, sep: &T) -> Vec<T> { - let mut iter = slice.iter(); - let first = match iter.next() { - Some(first) => first, - None => return vec![], - }; - let size = slice.iter().map(|v| v.borrow().len()).sum::<usize>() + slice.len() - 1; - let mut result = Vec::with_capacity(size); - result.extend_from_slice(first.borrow()); - - for v in iter { - result.push(sep.clone()); - result.extend_from_slice(v.borrow()) - } - result - } -} - -#[cfg(not(no_global_oom_handling))] -#[unstable(feature = "slice_concat_ext", issue = "27747")] -impl<T: Clone, V: Borrow<[T]>> Join<&[T]> for [V] { - type Output = Vec<T>; - - fn join(slice: &Self, sep: &[T]) -> Vec<T> { - let mut iter = slice.iter(); - let first = match iter.next() { - Some(first) => first, - None => return vec![], - }; - let size = - slice.iter().map(|v| v.borrow().len()).sum::<usize>() + sep.len() * (slice.len() - 1); - let mut result = Vec::with_capacity(size); - result.extend_from_slice(first.borrow()); - - for v in iter { - result.extend_from_slice(sep); - result.extend_from_slice(v.borrow()) - } - result - } -} - -//////////////////////////////////////////////////////////////////////////////// -// Standard trait implementations for slices -//////////////////////////////////////////////////////////////////////////////// - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> Borrow<[T]> for Vec<T, A> { - fn borrow(&self) -> &[T] { - &self[..] - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> BorrowMut<[T]> for Vec<T, A> { - fn borrow_mut(&mut self) -> &mut [T] { - &mut self[..] - } -} - -// Specializable trait for implementing ToOwned::clone_into. This is -// public in the crate and has the Allocator parameter so that -// vec::clone_from use it too. -#[cfg(not(no_global_oom_handling))] -pub(crate) trait SpecCloneIntoVec<T, A: Allocator> { - fn clone_into(&self, target: &mut Vec<T, A>); -} - -#[cfg(not(no_global_oom_handling))] -impl<T: Clone, A: Allocator> SpecCloneIntoVec<T, A> for [T] { - default fn clone_into(&self, target: &mut Vec<T, A>) { - // drop anything in target that will not be overwritten - target.truncate(self.len()); - - // target.len <= self.len due to the truncate above, so the - // slices here are always in-bounds. - let (init, tail) = self.split_at(target.len()); - - // reuse the contained values' allocations/resources. - target.clone_from_slice(init); - target.extend_from_slice(tail); - } -} - -#[cfg(not(no_global_oom_handling))] -impl<T: Copy, A: Allocator> SpecCloneIntoVec<T, A> for [T] { - fn clone_into(&self, target: &mut Vec<T, A>) { - target.clear(); - target.extend_from_slice(self); - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: Clone> ToOwned for [T] { - type Owned = Vec<T>; - #[cfg(not(test))] - fn to_owned(&self) -> Vec<T> { - self.to_vec() - } - - #[cfg(test)] - fn to_owned(&self) -> Vec<T> { - hack::to_vec(self, Global) - } - - fn clone_into(&self, target: &mut Vec<T>) { - SpecCloneIntoVec::clone_into(self, target); - } -} - -//////////////////////////////////////////////////////////////////////////////// -// Sorting -//////////////////////////////////////////////////////////////////////////////// - -#[inline] -#[cfg(not(no_global_oom_handling))] -fn stable_sort<T, F>(v: &mut [T], mut is_less: F) -where - F: FnMut(&T, &T) -> bool, -{ - if T::IS_ZST { - // Sorting has no meaningful behavior on zero-sized types. Do nothing. - return; - } - - let elem_alloc_fn = |len: usize| -> *mut T { - // SAFETY: Creating the layout is safe as long as merge_sort never calls this with len > - // v.len(). Alloc in general will only be used as 'shadow-region' to store temporary swap - // elements. - unsafe { alloc::alloc(alloc::Layout::array::<T>(len).unwrap_unchecked()) as *mut T } - }; - - let elem_dealloc_fn = |buf_ptr: *mut T, len: usize| { - // SAFETY: Creating the layout is safe as long as merge_sort never calls this with len > - // v.len(). The caller must ensure that buf_ptr was created by elem_alloc_fn with the same - // len. - unsafe { - alloc::dealloc(buf_ptr as *mut u8, alloc::Layout::array::<T>(len).unwrap_unchecked()); - } - }; - - let run_alloc_fn = |len: usize| -> *mut sort::TimSortRun { - // SAFETY: Creating the layout is safe as long as merge_sort never calls this with an - // obscene length or 0. - unsafe { - alloc::alloc(alloc::Layout::array::<sort::TimSortRun>(len).unwrap_unchecked()) - as *mut sort::TimSortRun - } - }; - - let run_dealloc_fn = |buf_ptr: *mut sort::TimSortRun, len: usize| { - // SAFETY: The caller must ensure that buf_ptr was created by elem_alloc_fn with the same - // len. - unsafe { - alloc::dealloc( - buf_ptr as *mut u8, - alloc::Layout::array::<sort::TimSortRun>(len).unwrap_unchecked(), - ); - } - }; - - sort::merge_sort(v, &mut is_less, elem_alloc_fn, elem_dealloc_fn, run_alloc_fn, run_dealloc_fn); -} diff --git a/rust/alloc/vec/drain.rs b/rust/alloc/vec/drain.rs deleted file mode 100644 index 78177a9e2a..0000000000 --- a/rust/alloc/vec/drain.rs +++ /dev/null @@ -1,255 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -use crate::alloc::{Allocator, Global}; -use core::fmt; -use core::iter::{FusedIterator, TrustedLen}; -use core::mem::{self, ManuallyDrop, SizedTypeProperties}; -use core::ptr::{self, NonNull}; -use core::slice::{self}; - -use super::Vec; - -/// A draining iterator for `Vec<T>`. -/// -/// This `struct` is created by [`Vec::drain`]. -/// See its documentation for more. -/// -/// # Example -/// -/// ``` -/// let mut v = vec![0, 1, 2]; -/// let iter: std::vec::Drain<'_, _> = v.drain(..); -/// ``` -#[stable(feature = "drain", since = "1.6.0")] -pub struct Drain< - 'a, - T: 'a, - #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + 'a = Global, -> { - /// Index of tail to preserve - pub(super) tail_start: usize, - /// Length of tail - pub(super) tail_len: usize, - /// Current remaining range to remove - pub(super) iter: slice::Iter<'a, T>, - pub(super) vec: NonNull<Vec<T, A>>, -} - -#[stable(feature = "collection_debug", since = "1.17.0")] -impl<T: fmt::Debug, A: Allocator> fmt::Debug for Drain<'_, T, A> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_tuple("Drain").field(&self.iter.as_slice()).finish() - } -} - -impl<'a, T, A: Allocator> Drain<'a, T, A> { - /// Returns the remaining items of this iterator as a slice. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec!['a', 'b', 'c']; - /// let mut drain = vec.drain(..); - /// assert_eq!(drain.as_slice(), &['a', 'b', 'c']); - /// let _ = drain.next().unwrap(); - /// assert_eq!(drain.as_slice(), &['b', 'c']); - /// ``` - #[must_use] - #[stable(feature = "vec_drain_as_slice", since = "1.46.0")] - pub fn as_slice(&self) -> &[T] { - self.iter.as_slice() - } - - /// Returns a reference to the underlying allocator. - #[unstable(feature = "allocator_api", issue = "32838")] - #[must_use] - #[inline] - pub fn allocator(&self) -> &A { - unsafe { self.vec.as_ref().allocator() } - } - - /// Keep unyielded elements in the source `Vec`. - /// - /// # Examples - /// - /// ``` - /// #![feature(drain_keep_rest)] - /// - /// let mut vec = vec!['a', 'b', 'c']; - /// let mut drain = vec.drain(..); - /// - /// assert_eq!(drain.next().unwrap(), 'a'); - /// - /// // This call keeps 'b' and 'c' in the vec. - /// drain.keep_rest(); - /// - /// // If we wouldn't call `keep_rest()`, - /// // `vec` would be empty. - /// assert_eq!(vec, ['b', 'c']); - /// ``` - #[unstable(feature = "drain_keep_rest", issue = "101122")] - pub fn keep_rest(self) { - // At this moment layout looks like this: - // - // [head] [yielded by next] [unyielded] [yielded by next_back] [tail] - // ^-- start \_________/-- unyielded_len \____/-- self.tail_len - // ^-- unyielded_ptr ^-- tail - // - // Normally `Drop` impl would drop [unyielded] and then move [tail] to the `start`. - // Here we want to - // 1. Move [unyielded] to `start` - // 2. Move [tail] to a new start at `start + len(unyielded)` - // 3. Update length of the original vec to `len(head) + len(unyielded) + len(tail)` - // a. In case of ZST, this is the only thing we want to do - // 4. Do *not* drop self, as everything is put in a consistent state already, there is nothing to do - let mut this = ManuallyDrop::new(self); - - unsafe { - let source_vec = this.vec.as_mut(); - - let start = source_vec.len(); - let tail = this.tail_start; - - let unyielded_len = this.iter.len(); - let unyielded_ptr = this.iter.as_slice().as_ptr(); - - // ZSTs have no identity, so we don't need to move them around. - if !T::IS_ZST { - let start_ptr = source_vec.as_mut_ptr().add(start); - - // memmove back unyielded elements - if unyielded_ptr != start_ptr { - let src = unyielded_ptr; - let dst = start_ptr; - - ptr::copy(src, dst, unyielded_len); - } - - // memmove back untouched tail - if tail != (start + unyielded_len) { - let src = source_vec.as_ptr().add(tail); - let dst = start_ptr.add(unyielded_len); - ptr::copy(src, dst, this.tail_len); - } - } - - source_vec.set_len(start + unyielded_len + this.tail_len); - } - } -} - -#[stable(feature = "vec_drain_as_slice", since = "1.46.0")] -impl<'a, T, A: Allocator> AsRef<[T]> for Drain<'a, T, A> { - fn as_ref(&self) -> &[T] { - self.as_slice() - } -} - -#[stable(feature = "drain", since = "1.6.0")] -unsafe impl<T: Sync, A: Sync + Allocator> Sync for Drain<'_, T, A> {} -#[stable(feature = "drain", since = "1.6.0")] -unsafe impl<T: Send, A: Send + Allocator> Send for Drain<'_, T, A> {} - -#[stable(feature = "drain", since = "1.6.0")] -impl<T, A: Allocator> Iterator for Drain<'_, T, A> { - type Item = T; - - #[inline] - fn next(&mut self) -> Option<T> { - self.iter.next().map(|elt| unsafe { ptr::read(elt as *const _) }) - } - - fn size_hint(&self) -> (usize, Option<usize>) { - self.iter.size_hint() - } -} - -#[stable(feature = "drain", since = "1.6.0")] -impl<T, A: Allocator> DoubleEndedIterator for Drain<'_, T, A> { - #[inline] - fn next_back(&mut self) -> Option<T> { - self.iter.next_back().map(|elt| unsafe { ptr::read(elt as *const _) }) - } -} - -#[stable(feature = "drain", since = "1.6.0")] -impl<T, A: Allocator> Drop for Drain<'_, T, A> { - fn drop(&mut self) { - /// Moves back the un-`Drain`ed elements to restore the original `Vec`. - struct DropGuard<'r, 'a, T, A: Allocator>(&'r mut Drain<'a, T, A>); - - impl<'r, 'a, T, A: Allocator> Drop for DropGuard<'r, 'a, T, A> { - fn drop(&mut self) { - if self.0.tail_len > 0 { - unsafe { - let source_vec = self.0.vec.as_mut(); - // memmove back untouched tail, update to new length - let start = source_vec.len(); - let tail = self.0.tail_start; - if tail != start { - let src = source_vec.as_ptr().add(tail); - let dst = source_vec.as_mut_ptr().add(start); - ptr::copy(src, dst, self.0.tail_len); - } - source_vec.set_len(start + self.0.tail_len); - } - } - } - } - - let iter = mem::take(&mut self.iter); - let drop_len = iter.len(); - - let mut vec = self.vec; - - if T::IS_ZST { - // ZSTs have no identity, so we don't need to move them around, we only need to drop the correct amount. - // this can be achieved by manipulating the Vec length instead of moving values out from `iter`. - unsafe { - let vec = vec.as_mut(); - let old_len = vec.len(); - vec.set_len(old_len + drop_len + self.tail_len); - vec.truncate(old_len + self.tail_len); - } - - return; - } - - // ensure elements are moved back into their appropriate places, even when drop_in_place panics - let _guard = DropGuard(self); - - if drop_len == 0 { - return; - } - - // as_slice() must only be called when iter.len() is > 0 because - // it also gets touched by vec::Splice which may turn it into a dangling pointer - // which would make it and the vec pointer point to different allocations which would - // lead to invalid pointer arithmetic below. - let drop_ptr = iter.as_slice().as_ptr(); - - unsafe { - // drop_ptr comes from a slice::Iter which only gives us a &[T] but for drop_in_place - // a pointer with mutable provenance is necessary. Therefore we must reconstruct - // it from the original vec but also avoid creating a &mut to the front since that could - // invalidate raw pointers to it which some unsafe code might rely on. - let vec_ptr = vec.as_mut().as_mut_ptr(); - let drop_offset = drop_ptr.sub_ptr(vec_ptr); - let to_drop = ptr::slice_from_raw_parts_mut(vec_ptr.add(drop_offset), drop_len); - ptr::drop_in_place(to_drop); - } - } -} - -#[stable(feature = "drain", since = "1.6.0")] -impl<T, A: Allocator> ExactSizeIterator for Drain<'_, T, A> { - fn is_empty(&self) -> bool { - self.iter.is_empty() - } -} - -#[unstable(feature = "trusted_len", issue = "37572")] -unsafe impl<T, A: Allocator> TrustedLen for Drain<'_, T, A> {} - -#[stable(feature = "fused", since = "1.26.0")] -impl<T, A: Allocator> FusedIterator for Drain<'_, T, A> {} diff --git a/rust/alloc/vec/extract_if.rs b/rust/alloc/vec/extract_if.rs deleted file mode 100644 index f314a51d4d..0000000000 --- a/rust/alloc/vec/extract_if.rs +++ /dev/null @@ -1,115 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -use crate::alloc::{Allocator, Global}; -use core::ptr; -use core::slice; - -use super::Vec; - -/// An iterator which uses a closure to determine if an element should be removed. -/// -/// This struct is created by [`Vec::extract_if`]. -/// See its documentation for more. -/// -/// # Example -/// -/// ``` -/// #![feature(extract_if)] -/// -/// let mut v = vec![0, 1, 2]; -/// let iter: std::vec::ExtractIf<'_, _, _> = v.extract_if(|x| *x % 2 == 0); -/// ``` -#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")] -#[derive(Debug)] -#[must_use = "iterators are lazy and do nothing unless consumed"] -pub struct ExtractIf< - 'a, - T, - F, - #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global, -> where - F: FnMut(&mut T) -> bool, -{ - pub(super) vec: &'a mut Vec<T, A>, - /// The index of the item that will be inspected by the next call to `next`. - pub(super) idx: usize, - /// The number of items that have been drained (removed) thus far. - pub(super) del: usize, - /// The original length of `vec` prior to draining. - pub(super) old_len: usize, - /// The filter test predicate. - pub(super) pred: F, -} - -impl<T, F, A: Allocator> ExtractIf<'_, T, F, A> -where - F: FnMut(&mut T) -> bool, -{ - /// Returns a reference to the underlying allocator. - #[unstable(feature = "allocator_api", issue = "32838")] - #[inline] - pub fn allocator(&self) -> &A { - self.vec.allocator() - } -} - -#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")] -impl<T, F, A: Allocator> Iterator for ExtractIf<'_, T, F, A> -where - F: FnMut(&mut T) -> bool, -{ - type Item = T; - - fn next(&mut self) -> Option<T> { - unsafe { - while self.idx < self.old_len { - let i = self.idx; - let v = slice::from_raw_parts_mut(self.vec.as_mut_ptr(), self.old_len); - let drained = (self.pred)(&mut v[i]); - // Update the index *after* the predicate is called. If the index - // is updated prior and the predicate panics, the element at this - // index would be leaked. - self.idx += 1; - if drained { - self.del += 1; - return Some(ptr::read(&v[i])); - } else if self.del > 0 { - let del = self.del; - let src: *const T = &v[i]; - let dst: *mut T = &mut v[i - del]; - ptr::copy_nonoverlapping(src, dst, 1); - } - } - None - } - } - - fn size_hint(&self) -> (usize, Option<usize>) { - (0, Some(self.old_len - self.idx)) - } -} - -#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")] -impl<T, F, A: Allocator> Drop for ExtractIf<'_, T, F, A> -where - F: FnMut(&mut T) -> bool, -{ - fn drop(&mut self) { - unsafe { - if self.idx < self.old_len && self.del > 0 { - // This is a pretty messed up state, and there isn't really an - // obviously right thing to do. We don't want to keep trying - // to execute `pred`, so we just backshift all the unprocessed - // elements and tell the vec that they still exist. The backshift - // is required to prevent a double-drop of the last successfully - // drained item prior to a panic in the predicate. - let ptr = self.vec.as_mut_ptr(); - let src = ptr.add(self.idx); - let dst = src.sub(self.del); - let tail_len = self.old_len - self.idx; - src.copy_to(dst, tail_len); - } - self.vec.set_len(self.old_len - self.del); - } - } -} diff --git a/rust/alloc/vec/into_iter.rs b/rust/alloc/vec/into_iter.rs deleted file mode 100644 index 136bfe94af..0000000000 --- a/rust/alloc/vec/into_iter.rs +++ /dev/null @@ -1,454 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -#[cfg(not(no_global_oom_handling))] -use super::AsVecIntoIter; -use crate::alloc::{Allocator, Global}; -#[cfg(not(no_global_oom_handling))] -use crate::collections::VecDeque; -use crate::raw_vec::RawVec; -use core::array; -use core::fmt; -use core::iter::{ - FusedIterator, InPlaceIterable, SourceIter, TrustedFused, TrustedLen, - TrustedRandomAccessNoCoerce, -}; -use core::marker::PhantomData; -use core::mem::{self, ManuallyDrop, MaybeUninit, SizedTypeProperties}; -use core::num::NonZeroUsize; -#[cfg(not(no_global_oom_handling))] -use core::ops::Deref; -use core::ptr::{self, NonNull}; -use core::slice::{self}; - -/// An iterator that moves out of a vector. -/// -/// This `struct` is created by the `into_iter` method on [`Vec`](super::Vec) -/// (provided by the [`IntoIterator`] trait). -/// -/// # Example -/// -/// ``` -/// let v = vec![0, 1, 2]; -/// let iter: std::vec::IntoIter<_> = v.into_iter(); -/// ``` -#[stable(feature = "rust1", since = "1.0.0")] -#[rustc_insignificant_dtor] -pub struct IntoIter< - T, - #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global, -> { - pub(super) buf: NonNull<T>, - pub(super) phantom: PhantomData<T>, - pub(super) cap: usize, - // the drop impl reconstructs a RawVec from buf, cap and alloc - // to avoid dropping the allocator twice we need to wrap it into ManuallyDrop - pub(super) alloc: ManuallyDrop<A>, - pub(super) ptr: *const T, - pub(super) end: *const T, // If T is a ZST, this is actually ptr+len. This encoding is picked so that - // ptr == end is a quick test for the Iterator being empty, that works - // for both ZST and non-ZST. -} - -#[stable(feature = "vec_intoiter_debug", since = "1.13.0")] -impl<T: fmt::Debug, A: Allocator> fmt::Debug for IntoIter<T, A> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_tuple("IntoIter").field(&self.as_slice()).finish() - } -} - -impl<T, A: Allocator> IntoIter<T, A> { - /// Returns the remaining items of this iterator as a slice. - /// - /// # Examples - /// - /// ``` - /// let vec = vec!['a', 'b', 'c']; - /// let mut into_iter = vec.into_iter(); - /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); - /// let _ = into_iter.next().unwrap(); - /// assert_eq!(into_iter.as_slice(), &['b', 'c']); - /// ``` - #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")] - pub fn as_slice(&self) -> &[T] { - unsafe { slice::from_raw_parts(self.ptr, self.len()) } - } - - /// Returns the remaining items of this iterator as a mutable slice. - /// - /// # Examples - /// - /// ``` - /// let vec = vec!['a', 'b', 'c']; - /// let mut into_iter = vec.into_iter(); - /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); - /// into_iter.as_mut_slice()[2] = 'z'; - /// assert_eq!(into_iter.next().unwrap(), 'a'); - /// assert_eq!(into_iter.next().unwrap(), 'b'); - /// assert_eq!(into_iter.next().unwrap(), 'z'); - /// ``` - #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")] - pub fn as_mut_slice(&mut self) -> &mut [T] { - unsafe { &mut *self.as_raw_mut_slice() } - } - - /// Returns a reference to the underlying allocator. - #[unstable(feature = "allocator_api", issue = "32838")] - #[inline] - pub fn allocator(&self) -> &A { - &self.alloc - } - - fn as_raw_mut_slice(&mut self) -> *mut [T] { - ptr::slice_from_raw_parts_mut(self.ptr as *mut T, self.len()) - } - - /// Drops remaining elements and relinquishes the backing allocation. - /// This method guarantees it won't panic before relinquishing - /// the backing allocation. - /// - /// This is roughly equivalent to the following, but more efficient - /// - /// ``` - /// # let mut into_iter = Vec::<u8>::with_capacity(10).into_iter(); - /// let mut into_iter = std::mem::replace(&mut into_iter, Vec::new().into_iter()); - /// (&mut into_iter).for_each(drop); - /// std::mem::forget(into_iter); - /// ``` - /// - /// This method is used by in-place iteration, refer to the vec::in_place_collect - /// documentation for an overview. - #[cfg(not(no_global_oom_handling))] - pub(super) fn forget_allocation_drop_remaining(&mut self) { - let remaining = self.as_raw_mut_slice(); - - // overwrite the individual fields instead of creating a new - // struct and then overwriting &mut self. - // this creates less assembly - self.cap = 0; - self.buf = unsafe { NonNull::new_unchecked(RawVec::NEW.ptr()) }; - self.ptr = self.buf.as_ptr(); - self.end = self.buf.as_ptr(); - - // Dropping the remaining elements can panic, so this needs to be - // done only after updating the other fields. - unsafe { - ptr::drop_in_place(remaining); - } - } - - /// Forgets to Drop the remaining elements while still allowing the backing allocation to be freed. - pub(crate) fn forget_remaining_elements(&mut self) { - // For th ZST case, it is crucial that we mutate `end` here, not `ptr`. - // `ptr` must stay aligned, while `end` may be unaligned. - self.end = self.ptr; - } - - #[cfg(not(no_global_oom_handling))] - #[inline] - pub(crate) fn into_vecdeque(self) -> VecDeque<T, A> { - // Keep our `Drop` impl from dropping the elements and the allocator - let mut this = ManuallyDrop::new(self); - - // SAFETY: This allocation originally came from a `Vec`, so it passes - // all those checks. We have `this.buf` ≤ `this.ptr` ≤ `this.end`, - // so the `sub_ptr`s below cannot wrap, and will produce a well-formed - // range. `end` ≤ `buf + cap`, so the range will be in-bounds. - // Taking `alloc` is ok because nothing else is going to look at it, - // since our `Drop` impl isn't going to run so there's no more code. - unsafe { - let buf = this.buf.as_ptr(); - let initialized = if T::IS_ZST { - // All the pointers are the same for ZSTs, so it's fine to - // say that they're all at the beginning of the "allocation". - 0..this.len() - } else { - this.ptr.sub_ptr(buf)..this.end.sub_ptr(buf) - }; - let cap = this.cap; - let alloc = ManuallyDrop::take(&mut this.alloc); - VecDeque::from_contiguous_raw_parts_in(buf, initialized, cap, alloc) - } - } -} - -#[stable(feature = "vec_intoiter_as_ref", since = "1.46.0")] -impl<T, A: Allocator> AsRef<[T]> for IntoIter<T, A> { - fn as_ref(&self) -> &[T] { - self.as_slice() - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -unsafe impl<T: Send, A: Allocator + Send> Send for IntoIter<T, A> {} -#[stable(feature = "rust1", since = "1.0.0")] -unsafe impl<T: Sync, A: Allocator + Sync> Sync for IntoIter<T, A> {} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> Iterator for IntoIter<T, A> { - type Item = T; - - #[inline] - fn next(&mut self) -> Option<T> { - if self.ptr == self.end { - None - } else if T::IS_ZST { - // `ptr` has to stay where it is to remain aligned, so we reduce the length by 1 by - // reducing the `end`. - self.end = self.end.wrapping_byte_sub(1); - - // Make up a value of this ZST. - Some(unsafe { mem::zeroed() }) - } else { - let old = self.ptr; - self.ptr = unsafe { self.ptr.add(1) }; - - Some(unsafe { ptr::read(old) }) - } - } - - #[inline] - fn size_hint(&self) -> (usize, Option<usize>) { - let exact = if T::IS_ZST { - self.end.addr().wrapping_sub(self.ptr.addr()) - } else { - unsafe { self.end.sub_ptr(self.ptr) } - }; - (exact, Some(exact)) - } - - #[inline] - fn advance_by(&mut self, n: usize) -> Result<(), NonZeroUsize> { - let step_size = self.len().min(n); - let to_drop = ptr::slice_from_raw_parts_mut(self.ptr as *mut T, step_size); - if T::IS_ZST { - // See `next` for why we sub `end` here. - self.end = self.end.wrapping_byte_sub(step_size); - } else { - // SAFETY: the min() above ensures that step_size is in bounds - self.ptr = unsafe { self.ptr.add(step_size) }; - } - // SAFETY: the min() above ensures that step_size is in bounds - unsafe { - ptr::drop_in_place(to_drop); - } - NonZeroUsize::new(n - step_size).map_or(Ok(()), Err) - } - - #[inline] - fn count(self) -> usize { - self.len() - } - - #[inline] - fn next_chunk<const N: usize>(&mut self) -> Result<[T; N], core::array::IntoIter<T, N>> { - let mut raw_ary = MaybeUninit::uninit_array(); - - let len = self.len(); - - if T::IS_ZST { - if len < N { - self.forget_remaining_elements(); - // Safety: ZSTs can be conjured ex nihilo, only the amount has to be correct - return Err(unsafe { array::IntoIter::new_unchecked(raw_ary, 0..len) }); - } - - self.end = self.end.wrapping_byte_sub(N); - // Safety: ditto - return Ok(unsafe { raw_ary.transpose().assume_init() }); - } - - if len < N { - // Safety: `len` indicates that this many elements are available and we just checked that - // it fits into the array. - unsafe { - ptr::copy_nonoverlapping(self.ptr, raw_ary.as_mut_ptr() as *mut T, len); - self.forget_remaining_elements(); - return Err(array::IntoIter::new_unchecked(raw_ary, 0..len)); - } - } - - // Safety: `len` is larger than the array size. Copy a fixed amount here to fully initialize - // the array. - return unsafe { - ptr::copy_nonoverlapping(self.ptr, raw_ary.as_mut_ptr() as *mut T, N); - self.ptr = self.ptr.add(N); - Ok(raw_ary.transpose().assume_init()) - }; - } - - unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> Self::Item - where - Self: TrustedRandomAccessNoCoerce, - { - // SAFETY: the caller must guarantee that `i` is in bounds of the - // `Vec<T>`, so `i` cannot overflow an `isize`, and the `self.ptr.add(i)` - // is guaranteed to pointer to an element of the `Vec<T>` and - // thus guaranteed to be valid to dereference. - // - // Also note the implementation of `Self: TrustedRandomAccess` requires - // that `T: Copy` so reading elements from the buffer doesn't invalidate - // them for `Drop`. - unsafe { if T::IS_ZST { mem::zeroed() } else { ptr::read(self.ptr.add(i)) } } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> { - #[inline] - fn next_back(&mut self) -> Option<T> { - if self.end == self.ptr { - None - } else if T::IS_ZST { - // See above for why 'ptr.offset' isn't used - self.end = self.end.wrapping_byte_sub(1); - - // Make up a value of this ZST. - Some(unsafe { mem::zeroed() }) - } else { - self.end = unsafe { self.end.sub(1) }; - - Some(unsafe { ptr::read(self.end) }) - } - } - - #[inline] - fn advance_back_by(&mut self, n: usize) -> Result<(), NonZeroUsize> { - let step_size = self.len().min(n); - if T::IS_ZST { - // SAFETY: same as for advance_by() - self.end = self.end.wrapping_byte_sub(step_size); - } else { - // SAFETY: same as for advance_by() - self.end = unsafe { self.end.sub(step_size) }; - } - let to_drop = ptr::slice_from_raw_parts_mut(self.end as *mut T, step_size); - // SAFETY: same as for advance_by() - unsafe { - ptr::drop_in_place(to_drop); - } - NonZeroUsize::new(n - step_size).map_or(Ok(()), Err) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> ExactSizeIterator for IntoIter<T, A> { - fn is_empty(&self) -> bool { - self.ptr == self.end - } -} - -#[stable(feature = "fused", since = "1.26.0")] -impl<T, A: Allocator> FusedIterator for IntoIter<T, A> {} - -#[doc(hidden)] -#[unstable(issue = "none", feature = "trusted_fused")] -unsafe impl<T, A: Allocator> TrustedFused for IntoIter<T, A> {} - -#[unstable(feature = "trusted_len", issue = "37572")] -unsafe impl<T, A: Allocator> TrustedLen for IntoIter<T, A> {} - -#[stable(feature = "default_iters", since = "1.70.0")] -impl<T, A> Default for IntoIter<T, A> -where - A: Allocator + Default, -{ - /// Creates an empty `vec::IntoIter`. - /// - /// ``` - /// # use std::vec; - /// let iter: vec::IntoIter<u8> = Default::default(); - /// assert_eq!(iter.len(), 0); - /// assert_eq!(iter.as_slice(), &[]); - /// ``` - fn default() -> Self { - super::Vec::new_in(Default::default()).into_iter() - } -} - -#[doc(hidden)] -#[unstable(issue = "none", feature = "std_internals")] -#[rustc_unsafe_specialization_marker] -pub trait NonDrop {} - -// T: Copy as approximation for !Drop since get_unchecked does not advance self.ptr -// and thus we can't implement drop-handling -#[unstable(issue = "none", feature = "std_internals")] -impl<T: Copy> NonDrop for T {} - -#[doc(hidden)] -#[unstable(issue = "none", feature = "std_internals")] -// TrustedRandomAccess (without NoCoerce) must not be implemented because -// subtypes/supertypes of `T` might not be `NonDrop` -unsafe impl<T, A: Allocator> TrustedRandomAccessNoCoerce for IntoIter<T, A> -where - T: NonDrop, -{ - const MAY_HAVE_SIDE_EFFECT: bool = false; -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "vec_into_iter_clone", since = "1.8.0")] -impl<T: Clone, A: Allocator + Clone> Clone for IntoIter<T, A> { - #[cfg(not(test))] - fn clone(&self) -> Self { - self.as_slice().to_vec_in(self.alloc.deref().clone()).into_iter() - } - #[cfg(test)] - fn clone(&self) -> Self { - crate::slice::to_vec(self.as_slice(), self.alloc.deref().clone()).into_iter() - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -unsafe impl<#[may_dangle] T, A: Allocator> Drop for IntoIter<T, A> { - fn drop(&mut self) { - struct DropGuard<'a, T, A: Allocator>(&'a mut IntoIter<T, A>); - - impl<T, A: Allocator> Drop for DropGuard<'_, T, A> { - fn drop(&mut self) { - unsafe { - // `IntoIter::alloc` is not used anymore after this and will be dropped by RawVec - let alloc = ManuallyDrop::take(&mut self.0.alloc); - // RawVec handles deallocation - let _ = RawVec::from_raw_parts_in(self.0.buf.as_ptr(), self.0.cap, alloc); - } - } - } - - let guard = DropGuard(self); - // destroy the remaining elements - unsafe { - ptr::drop_in_place(guard.0.as_raw_mut_slice()); - } - // now `guard` will be dropped and do the rest - } -} - -// In addition to the SAFETY invariants of the following three unsafe traits -// also refer to the vec::in_place_collect module documentation to get an overview -#[unstable(issue = "none", feature = "inplace_iteration")] -#[doc(hidden)] -unsafe impl<T, A: Allocator> InPlaceIterable for IntoIter<T, A> { - const EXPAND_BY: Option<NonZeroUsize> = NonZeroUsize::new(1); - const MERGE_BY: Option<NonZeroUsize> = NonZeroUsize::new(1); -} - -#[unstable(issue = "none", feature = "inplace_iteration")] -#[doc(hidden)] -unsafe impl<T, A: Allocator> SourceIter for IntoIter<T, A> { - type Source = Self; - - #[inline] - unsafe fn as_inner(&mut self) -> &mut Self::Source { - self - } -} - -#[cfg(not(no_global_oom_handling))] -unsafe impl<T> AsVecIntoIter for IntoIter<T> { - type Item = T; - - fn as_into_iter(&mut self) -> &mut IntoIter<Self::Item> { - self - } -} diff --git a/rust/alloc/vec/is_zero.rs b/rust/alloc/vec/is_zero.rs deleted file mode 100644 index d928dcf90e..0000000000 --- a/rust/alloc/vec/is_zero.rs +++ /dev/null @@ -1,204 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -use core::num::{Saturating, Wrapping}; - -use crate::boxed::Box; - -#[rustc_specialization_trait] -pub(super) unsafe trait IsZero { - /// Whether this value's representation is all zeros, - /// or can be represented with all zeroes. - fn is_zero(&self) -> bool; -} - -macro_rules! impl_is_zero { - ($t:ty, $is_zero:expr) => { - unsafe impl IsZero for $t { - #[inline] - fn is_zero(&self) -> bool { - $is_zero(*self) - } - } - }; -} - -impl_is_zero!(i8, |x| x == 0); // It is needed to impl for arrays and tuples of i8. -impl_is_zero!(i16, |x| x == 0); -impl_is_zero!(i32, |x| x == 0); -impl_is_zero!(i64, |x| x == 0); -impl_is_zero!(i128, |x| x == 0); -impl_is_zero!(isize, |x| x == 0); - -impl_is_zero!(u8, |x| x == 0); // It is needed to impl for arrays and tuples of u8. -impl_is_zero!(u16, |x| x == 0); -impl_is_zero!(u32, |x| x == 0); -impl_is_zero!(u64, |x| x == 0); -impl_is_zero!(u128, |x| x == 0); -impl_is_zero!(usize, |x| x == 0); - -impl_is_zero!(bool, |x| x == false); -impl_is_zero!(char, |x| x == '\0'); - -impl_is_zero!(f32, |x: f32| x.to_bits() == 0); -impl_is_zero!(f64, |x: f64| x.to_bits() == 0); - -unsafe impl<T> IsZero for *const T { - #[inline] - fn is_zero(&self) -> bool { - (*self).is_null() - } -} - -unsafe impl<T> IsZero for *mut T { - #[inline] - fn is_zero(&self) -> bool { - (*self).is_null() - } -} - -unsafe impl<T: IsZero, const N: usize> IsZero for [T; N] { - #[inline] - fn is_zero(&self) -> bool { - // Because this is generated as a runtime check, it's not obvious that - // it's worth doing if the array is really long. The threshold here - // is largely arbitrary, but was picked because as of 2022-07-01 LLVM - // fails to const-fold the check in `vec![[1; 32]; n]` - // See https://github.com/rust-lang/rust/pull/97581#issuecomment-1166628022 - // Feel free to tweak if you have better evidence. - - N <= 16 && self.iter().all(IsZero::is_zero) - } -} - -// This is recursive macro. -macro_rules! impl_for_tuples { - // Stopper - () => { - // No use for implementing for empty tuple because it is ZST. - }; - ($first_arg:ident $(,$rest:ident)*) => { - unsafe impl <$first_arg: IsZero, $($rest: IsZero,)*> IsZero for ($first_arg, $($rest,)*){ - #[inline] - fn is_zero(&self) -> bool{ - // Destructure tuple to N references - // Rust allows to hide generic params by local variable names. - #[allow(non_snake_case)] - let ($first_arg, $($rest,)*) = self; - - $first_arg.is_zero() - $( && $rest.is_zero() )* - } - } - - impl_for_tuples!($($rest),*); - } -} - -impl_for_tuples!(A, B, C, D, E, F, G, H); - -// `Option<&T>` and `Option<Box<T>>` are guaranteed to represent `None` as null. -// For fat pointers, the bytes that would be the pointer metadata in the `Some` -// variant are padding in the `None` variant, so ignoring them and -// zero-initializing instead is ok. -// `Option<&mut T>` never implements `Clone`, so there's no need for an impl of -// `SpecFromElem`. - -unsafe impl<T: ?Sized> IsZero for Option<&T> { - #[inline] - fn is_zero(&self) -> bool { - self.is_none() - } -} - -unsafe impl<T: ?Sized> IsZero for Option<Box<T>> { - #[inline] - fn is_zero(&self) -> bool { - self.is_none() - } -} - -// `Option<num::NonZeroU32>` and similar have a representation guarantee that -// they're the same size as the corresponding `u32` type, as well as a guarantee -// that transmuting between `NonZeroU32` and `Option<num::NonZeroU32>` works. -// While the documentation officially makes it UB to transmute from `None`, -// we're the standard library so we can make extra inferences, and we know that -// the only niche available to represent `None` is the one that's all zeros. - -macro_rules! impl_is_zero_option_of_nonzero { - ($($t:ident,)+) => {$( - unsafe impl IsZero for Option<core::num::$t> { - #[inline] - fn is_zero(&self) -> bool { - self.is_none() - } - } - )+}; -} - -impl_is_zero_option_of_nonzero!( - NonZeroU8, - NonZeroU16, - NonZeroU32, - NonZeroU64, - NonZeroU128, - NonZeroI8, - NonZeroI16, - NonZeroI32, - NonZeroI64, - NonZeroI128, - NonZeroUsize, - NonZeroIsize, -); - -macro_rules! impl_is_zero_option_of_num { - ($($t:ty,)+) => {$( - unsafe impl IsZero for Option<$t> { - #[inline] - fn is_zero(&self) -> bool { - const { - let none: Self = unsafe { core::mem::MaybeUninit::zeroed().assume_init() }; - assert!(none.is_none()); - } - self.is_none() - } - } - )+}; -} - -impl_is_zero_option_of_num!(u8, u16, u32, u64, u128, i8, i16, i32, i64, i128, usize, isize,); - -unsafe impl<T: IsZero> IsZero for Wrapping<T> { - #[inline] - fn is_zero(&self) -> bool { - self.0.is_zero() - } -} - -unsafe impl<T: IsZero> IsZero for Saturating<T> { - #[inline] - fn is_zero(&self) -> bool { - self.0.is_zero() - } -} - -macro_rules! impl_for_optional_bool { - ($($t:ty,)+) => {$( - unsafe impl IsZero for $t { - #[inline] - fn is_zero(&self) -> bool { - // SAFETY: This is *not* a stable layout guarantee, but - // inside `core` we're allowed to rely on the current rustc - // behaviour that options of bools will be one byte with - // no padding, so long as they're nested less than 254 deep. - let raw: u8 = unsafe { core::mem::transmute(*self) }; - raw == 0 - } - } - )+}; -} -impl_for_optional_bool! { - Option<bool>, - Option<Option<bool>>, - Option<Option<Option<bool>>>, - // Could go further, but not worth the metadata overhead -} diff --git a/rust/alloc/vec/mod.rs b/rust/alloc/vec/mod.rs deleted file mode 100644 index 220fb9d6f4..0000000000 --- a/rust/alloc/vec/mod.rs +++ /dev/null @@ -1,3683 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -//! A contiguous growable array type with heap-allocated contents, written -//! `Vec<T>`. -//! -//! Vectors have *O*(1) indexing, amortized *O*(1) push (to the end) and -//! *O*(1) pop (from the end). -//! -//! Vectors ensure they never allocate more than `isize::MAX` bytes. -//! -//! # Examples -//! -//! You can explicitly create a [`Vec`] with [`Vec::new`]: -//! -//! ``` -//! let v: Vec<i32> = Vec::new(); -//! ``` -//! -//! ...or by using the [`vec!`] macro: -//! -//! ``` -//! let v: Vec<i32> = vec![]; -//! -//! let v = vec![1, 2, 3, 4, 5]; -//! -//! let v = vec![0; 10]; // ten zeroes -//! ``` -//! -//! You can [`push`] values onto the end of a vector (which will grow the vector -//! as needed): -//! -//! ``` -//! let mut v = vec![1, 2]; -//! -//! v.push(3); -//! ``` -//! -//! Popping values works in much the same way: -//! -//! ``` -//! let mut v = vec![1, 2]; -//! -//! let two = v.pop(); -//! ``` -//! -//! Vectors also support indexing (through the [`Index`] and [`IndexMut`] traits): -//! -//! ``` -//! let mut v = vec![1, 2, 3]; -//! let three = v[2]; -//! v[1] = v[1] + 5; -//! ``` -//! -//! [`push`]: Vec::push - -#![stable(feature = "rust1", since = "1.0.0")] - -#[cfg(not(no_global_oom_handling))] -use core::cmp; -use core::cmp::Ordering; -use core::fmt; -use core::hash::{Hash, Hasher}; -use core::iter; -use core::marker::PhantomData; -use core::mem::{self, ManuallyDrop, MaybeUninit, SizedTypeProperties}; -use core::ops::{self, Index, IndexMut, Range, RangeBounds}; -use core::ptr::{self, NonNull}; -use core::slice::{self, SliceIndex}; - -use crate::alloc::{Allocator, Global}; -#[cfg(not(no_borrow))] -use crate::borrow::{Cow, ToOwned}; -use crate::boxed::Box; -use crate::collections::{TryReserveError, TryReserveErrorKind}; -use crate::raw_vec::RawVec; - -#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")] -pub use self::extract_if::ExtractIf; - -mod extract_if; - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "vec_splice", since = "1.21.0")] -pub use self::splice::Splice; - -#[cfg(not(no_global_oom_handling))] -mod splice; - -#[stable(feature = "drain", since = "1.6.0")] -pub use self::drain::Drain; - -mod drain; - -#[cfg(not(no_borrow))] -#[cfg(not(no_global_oom_handling))] -mod cow; - -#[cfg(not(no_global_oom_handling))] -pub(crate) use self::in_place_collect::AsVecIntoIter; -#[stable(feature = "rust1", since = "1.0.0")] -pub use self::into_iter::IntoIter; - -mod into_iter; - -#[cfg(not(no_global_oom_handling))] -use self::is_zero::IsZero; - -#[cfg(not(no_global_oom_handling))] -mod is_zero; - -#[cfg(not(no_global_oom_handling))] -mod in_place_collect; - -mod partial_eq; - -#[cfg(not(no_global_oom_handling))] -use self::spec_from_elem::SpecFromElem; - -#[cfg(not(no_global_oom_handling))] -mod spec_from_elem; - -use self::set_len_on_drop::SetLenOnDrop; - -mod set_len_on_drop; - -#[cfg(not(no_global_oom_handling))] -use self::in_place_drop::{InPlaceDrop, InPlaceDstDataSrcBufDrop}; - -#[cfg(not(no_global_oom_handling))] -mod in_place_drop; - -#[cfg(not(no_global_oom_handling))] -use self::spec_from_iter_nested::SpecFromIterNested; - -#[cfg(not(no_global_oom_handling))] -mod spec_from_iter_nested; - -#[cfg(not(no_global_oom_handling))] -use self::spec_from_iter::SpecFromIter; - -#[cfg(not(no_global_oom_handling))] -mod spec_from_iter; - -#[cfg(not(no_global_oom_handling))] -use self::spec_extend::SpecExtend; - -use self::spec_extend::TrySpecExtend; - -mod spec_extend; - -/// A contiguous growable array type, written as `Vec<T>`, short for 'vector'. -/// -/// # Examples -/// -/// ``` -/// let mut vec = Vec::new(); -/// vec.push(1); -/// vec.push(2); -/// -/// assert_eq!(vec.len(), 2); -/// assert_eq!(vec[0], 1); -/// -/// assert_eq!(vec.pop(), Some(2)); -/// assert_eq!(vec.len(), 1); -/// -/// vec[0] = 7; -/// assert_eq!(vec[0], 7); -/// -/// vec.extend([1, 2, 3]); -/// -/// for x in &vec { -/// println!("{x}"); -/// } -/// assert_eq!(vec, [7, 1, 2, 3]); -/// ``` -/// -/// The [`vec!`] macro is provided for convenient initialization: -/// -/// ``` -/// let mut vec1 = vec![1, 2, 3]; -/// vec1.push(4); -/// let vec2 = Vec::from([1, 2, 3, 4]); -/// assert_eq!(vec1, vec2); -/// ``` -/// -/// It can also initialize each element of a `Vec<T>` with a given value. -/// This may be more efficient than performing allocation and initialization -/// in separate steps, especially when initializing a vector of zeros: -/// -/// ``` -/// let vec = vec![0; 5]; -/// assert_eq!(vec, [0, 0, 0, 0, 0]); -/// -/// // The following is equivalent, but potentially slower: -/// let mut vec = Vec::with_capacity(5); -/// vec.resize(5, 0); -/// assert_eq!(vec, [0, 0, 0, 0, 0]); -/// ``` -/// -/// For more information, see -/// [Capacity and Reallocation](#capacity-and-reallocation). -/// -/// Use a `Vec<T>` as an efficient stack: -/// -/// ``` -/// let mut stack = Vec::new(); -/// -/// stack.push(1); -/// stack.push(2); -/// stack.push(3); -/// -/// while let Some(top) = stack.pop() { -/// // Prints 3, 2, 1 -/// println!("{top}"); -/// } -/// ``` -/// -/// # Indexing -/// -/// The `Vec` type allows access to values by index, because it implements the -/// [`Index`] trait. An example will be more explicit: -/// -/// ``` -/// let v = vec![0, 2, 4, 6]; -/// println!("{}", v[1]); // it will display '2' -/// ``` -/// -/// However be careful: if you try to access an index which isn't in the `Vec`, -/// your software will panic! You cannot do this: -/// -/// ```should_panic -/// let v = vec![0, 2, 4, 6]; -/// println!("{}", v[6]); // it will panic! -/// ``` -/// -/// Use [`get`] and [`get_mut`] if you want to check whether the index is in -/// the `Vec`. -/// -/// # Slicing -/// -/// A `Vec` can be mutable. On the other hand, slices are read-only objects. -/// To get a [slice][prim@slice], use [`&`]. Example: -/// -/// ``` -/// fn read_slice(slice: &[usize]) { -/// // ... -/// } -/// -/// let v = vec![0, 1]; -/// read_slice(&v); -/// -/// // ... and that's all! -/// // you can also do it like this: -/// let u: &[usize] = &v; -/// // or like this: -/// let u: &[_] = &v; -/// ``` -/// -/// In Rust, it's more common to pass slices as arguments rather than vectors -/// when you just want to provide read access. The same goes for [`String`] and -/// [`&str`]. -/// -/// # Capacity and reallocation -/// -/// The capacity of a vector is the amount of space allocated for any future -/// elements that will be added onto the vector. This is not to be confused with -/// the *length* of a vector, which specifies the number of actual elements -/// within the vector. If a vector's length exceeds its capacity, its capacity -/// will automatically be increased, but its elements will have to be -/// reallocated. -/// -/// For example, a vector with capacity 10 and length 0 would be an empty vector -/// with space for 10 more elements. Pushing 10 or fewer elements onto the -/// vector will not change its capacity or cause reallocation to occur. However, -/// if the vector's length is increased to 11, it will have to reallocate, which -/// can be slow. For this reason, it is recommended to use [`Vec::with_capacity`] -/// whenever possible to specify how big the vector is expected to get. -/// -/// # Guarantees -/// -/// Due to its incredibly fundamental nature, `Vec` makes a lot of guarantees -/// about its design. This ensures that it's as low-overhead as possible in -/// the general case, and can be correctly manipulated in primitive ways -/// by unsafe code. Note that these guarantees refer to an unqualified `Vec<T>`. -/// If additional type parameters are added (e.g., to support custom allocators), -/// overriding their defaults may change the behavior. -/// -/// Most fundamentally, `Vec` is and always will be a (pointer, capacity, length) -/// triplet. No more, no less. The order of these fields is completely -/// unspecified, and you should use the appropriate methods to modify these. -/// The pointer will never be null, so this type is null-pointer-optimized. -/// -/// However, the pointer might not actually point to allocated memory. In particular, -/// if you construct a `Vec` with capacity 0 via [`Vec::new`], [`vec![]`][`vec!`], -/// [`Vec::with_capacity(0)`][`Vec::with_capacity`], or by calling [`shrink_to_fit`] -/// on an empty Vec, it will not allocate memory. Similarly, if you store zero-sized -/// types inside a `Vec`, it will not allocate space for them. *Note that in this case -/// the `Vec` might not report a [`capacity`] of 0*. `Vec` will allocate if and only -/// if <code>[mem::size_of::\<T>]\() * [capacity]\() > 0</code>. In general, `Vec`'s allocation -/// details are very subtle --- if you intend to allocate memory using a `Vec` -/// and use it for something else (either to pass to unsafe code, or to build your -/// own memory-backed collection), be sure to deallocate this memory by using -/// `from_raw_parts` to recover the `Vec` and then dropping it. -/// -/// If a `Vec` *has* allocated memory, then the memory it points to is on the heap -/// (as defined by the allocator Rust is configured to use by default), and its -/// pointer points to [`len`] initialized, contiguous elements in order (what -/// you would see if you coerced it to a slice), followed by <code>[capacity] - [len]</code> -/// logically uninitialized, contiguous elements. -/// -/// A vector containing the elements `'a'` and `'b'` with capacity 4 can be -/// visualized as below. The top part is the `Vec` struct, it contains a -/// pointer to the head of the allocation in the heap, length and capacity. -/// The bottom part is the allocation on the heap, a contiguous memory block. -/// -/// ```text -/// ptr len capacity -/// +--------+--------+--------+ -/// | 0x0123 | 2 | 4 | -/// +--------+--------+--------+ -/// | -/// v -/// Heap +--------+--------+--------+--------+ -/// | 'a' | 'b' | uninit | uninit | -/// +--------+--------+--------+--------+ -/// ``` -/// -/// - **uninit** represents memory that is not initialized, see [`MaybeUninit`]. -/// - Note: the ABI is not stable and `Vec` makes no guarantees about its memory -/// layout (including the order of fields). -/// -/// `Vec` will never perform a "small optimization" where elements are actually -/// stored on the stack for two reasons: -/// -/// * It would make it more difficult for unsafe code to correctly manipulate -/// a `Vec`. The contents of a `Vec` wouldn't have a stable address if it were -/// only moved, and it would be more difficult to determine if a `Vec` had -/// actually allocated memory. -/// -/// * It would penalize the general case, incurring an additional branch -/// on every access. -/// -/// `Vec` will never automatically shrink itself, even if completely empty. This -/// ensures no unnecessary allocations or deallocations occur. Emptying a `Vec` -/// and then filling it back up to the same [`len`] should incur no calls to -/// the allocator. If you wish to free up unused memory, use -/// [`shrink_to_fit`] or [`shrink_to`]. -/// -/// [`push`] and [`insert`] will never (re)allocate if the reported capacity is -/// sufficient. [`push`] and [`insert`] *will* (re)allocate if -/// <code>[len] == [capacity]</code>. That is, the reported capacity is completely -/// accurate, and can be relied on. It can even be used to manually free the memory -/// allocated by a `Vec` if desired. Bulk insertion methods *may* reallocate, even -/// when not necessary. -/// -/// `Vec` does not guarantee any particular growth strategy when reallocating -/// when full, nor when [`reserve`] is called. The current strategy is basic -/// and it may prove desirable to use a non-constant growth factor. Whatever -/// strategy is used will of course guarantee *O*(1) amortized [`push`]. -/// -/// `vec![x; n]`, `vec![a, b, c, d]`, and -/// [`Vec::with_capacity(n)`][`Vec::with_capacity`], will all produce a `Vec` -/// with exactly the requested capacity. If <code>[len] == [capacity]</code>, -/// (as is the case for the [`vec!`] macro), then a `Vec<T>` can be converted to -/// and from a [`Box<[T]>`][owned slice] without reallocating or moving the elements. -/// -/// `Vec` will not specifically overwrite any data that is removed from it, -/// but also won't specifically preserve it. Its uninitialized memory is -/// scratch space that it may use however it wants. It will generally just do -/// whatever is most efficient or otherwise easy to implement. Do not rely on -/// removed data to be erased for security purposes. Even if you drop a `Vec`, its -/// buffer may simply be reused by another allocation. Even if you zero a `Vec`'s memory -/// first, that might not actually happen because the optimizer does not consider -/// this a side-effect that must be preserved. There is one case which we will -/// not break, however: using `unsafe` code to write to the excess capacity, -/// and then increasing the length to match, is always valid. -/// -/// Currently, `Vec` does not guarantee the order in which elements are dropped. -/// The order has changed in the past and may change again. -/// -/// [`get`]: slice::get -/// [`get_mut`]: slice::get_mut -/// [`String`]: crate::string::String -/// [`&str`]: type@str -/// [`shrink_to_fit`]: Vec::shrink_to_fit -/// [`shrink_to`]: Vec::shrink_to -/// [capacity]: Vec::capacity -/// [`capacity`]: Vec::capacity -/// [mem::size_of::\<T>]: core::mem::size_of -/// [len]: Vec::len -/// [`len`]: Vec::len -/// [`push`]: Vec::push -/// [`insert`]: Vec::insert -/// [`reserve`]: Vec::reserve -/// [`MaybeUninit`]: core::mem::MaybeUninit -/// [owned slice]: Box -#[stable(feature = "rust1", since = "1.0.0")] -#[cfg_attr(not(test), rustc_diagnostic_item = "Vec")] -#[rustc_insignificant_dtor] -pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> { - buf: RawVec<T, A>, - len: usize, -} - -//////////////////////////////////////////////////////////////////////////////// -// Inherent methods -//////////////////////////////////////////////////////////////////////////////// - -impl<T> Vec<T> { - /// Constructs a new, empty `Vec<T>`. - /// - /// The vector will not allocate until elements are pushed onto it. - /// - /// # Examples - /// - /// ``` - /// # #![allow(unused_mut)] - /// let mut vec: Vec<i32> = Vec::new(); - /// ``` - #[inline] - #[rustc_const_stable(feature = "const_vec_new", since = "1.39.0")] - #[stable(feature = "rust1", since = "1.0.0")] - #[must_use] - pub const fn new() -> Self { - Vec { buf: RawVec::NEW, len: 0 } - } - - /// Constructs a new, empty `Vec<T>` with at least the specified capacity. - /// - /// The vector will be able to hold at least `capacity` elements without - /// reallocating. This method is allowed to allocate for more elements than - /// `capacity`. If `capacity` is 0, the vector will not allocate. - /// - /// It is important to note that although the returned vector has the - /// minimum *capacity* specified, the vector will have a zero *length*. For - /// an explanation of the difference between length and capacity, see - /// *[Capacity and reallocation]*. - /// - /// If it is important to know the exact allocated capacity of a `Vec`, - /// always use the [`capacity`] method after construction. - /// - /// For `Vec<T>` where `T` is a zero-sized type, there will be no allocation - /// and the capacity will always be `usize::MAX`. - /// - /// [Capacity and reallocation]: #capacity-and-reallocation - /// [`capacity`]: Vec::capacity - /// - /// # Panics - /// - /// Panics if the new capacity exceeds `isize::MAX` bytes. - /// - /// # Examples - /// - /// ``` - /// let mut vec = Vec::with_capacity(10); - /// - /// // The vector contains no items, even though it has capacity for more - /// assert_eq!(vec.len(), 0); - /// assert!(vec.capacity() >= 10); - /// - /// // These are all done without reallocating... - /// for i in 0..10 { - /// vec.push(i); - /// } - /// assert_eq!(vec.len(), 10); - /// assert!(vec.capacity() >= 10); - /// - /// // ...but this may make the vector reallocate - /// vec.push(11); - /// assert_eq!(vec.len(), 11); - /// assert!(vec.capacity() >= 11); - /// - /// // A vector of a zero-sized type will always over-allocate, since no - /// // allocation is necessary - /// let vec_units = Vec::<()>::with_capacity(10); - /// assert_eq!(vec_units.capacity(), usize::MAX); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[inline] - #[stable(feature = "rust1", since = "1.0.0")] - #[must_use] - pub fn with_capacity(capacity: usize) -> Self { - Self::with_capacity_in(capacity, Global) - } - - /// Tries to construct a new, empty `Vec<T>` with at least the specified capacity. - /// - /// The vector will be able to hold at least `capacity` elements without - /// reallocating. This method is allowed to allocate for more elements than - /// `capacity`. If `capacity` is 0, the vector will not allocate. - /// - /// It is important to note that although the returned vector has the - /// minimum *capacity* specified, the vector will have a zero *length*. For - /// an explanation of the difference between length and capacity, see - /// *[Capacity and reallocation]*. - /// - /// If it is important to know the exact allocated capacity of a `Vec`, - /// always use the [`capacity`] method after construction. - /// - /// For `Vec<T>` where `T` is a zero-sized type, there will be no allocation - /// and the capacity will always be `usize::MAX`. - /// - /// [Capacity and reallocation]: #capacity-and-reallocation - /// [`capacity`]: Vec::capacity - /// - /// # Examples - /// - /// ``` - /// let mut vec = Vec::try_with_capacity(10).unwrap(); - /// - /// // The vector contains no items, even though it has capacity for more - /// assert_eq!(vec.len(), 0); - /// assert!(vec.capacity() >= 10); - /// - /// // These are all done without reallocating... - /// for i in 0..10 { - /// vec.push(i); - /// } - /// assert_eq!(vec.len(), 10); - /// assert!(vec.capacity() >= 10); - /// - /// // ...but this may make the vector reallocate - /// vec.push(11); - /// assert_eq!(vec.len(), 11); - /// assert!(vec.capacity() >= 11); - /// - /// let mut result = Vec::try_with_capacity(usize::MAX); - /// assert!(result.is_err()); - /// - /// // A vector of a zero-sized type will always over-allocate, since no - /// // allocation is necessary - /// let vec_units = Vec::<()>::try_with_capacity(10).unwrap(); - /// assert_eq!(vec_units.capacity(), usize::MAX); - /// ``` - #[inline] - #[stable(feature = "kernel", since = "1.0.0")] - pub fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> { - Self::try_with_capacity_in(capacity, Global) - } - - /// Creates a `Vec<T>` directly from a pointer, a capacity, and a length. - /// - /// # Safety - /// - /// This is highly unsafe, due to the number of invariants that aren't - /// checked: - /// - /// * `ptr` must have been allocated using the global allocator, such as via - /// the [`alloc::alloc`] function. - /// * `T` needs to have the same alignment as what `ptr` was allocated with. - /// (`T` having a less strict alignment is not sufficient, the alignment really - /// needs to be equal to satisfy the [`dealloc`] requirement that memory must be - /// allocated and deallocated with the same layout.) - /// * The size of `T` times the `capacity` (ie. the allocated size in bytes) needs - /// to be the same size as the pointer was allocated with. (Because similar to - /// alignment, [`dealloc`] must be called with the same layout `size`.) - /// * `length` needs to be less than or equal to `capacity`. - /// * The first `length` values must be properly initialized values of type `T`. - /// * `capacity` needs to be the capacity that the pointer was allocated with. - /// * The allocated size in bytes must be no larger than `isize::MAX`. - /// See the safety documentation of [`pointer::offset`]. - /// - /// These requirements are always upheld by any `ptr` that has been allocated - /// via `Vec<T>`. Other allocation sources are allowed if the invariants are - /// upheld. - /// - /// Violating these may cause problems like corrupting the allocator's - /// internal data structures. For example it is normally **not** safe - /// to build a `Vec<u8>` from a pointer to a C `char` array with length - /// `size_t`, doing so is only safe if the array was initially allocated by - /// a `Vec` or `String`. - /// It's also not safe to build one from a `Vec<u16>` and its length, because - /// the allocator cares about the alignment, and these two types have different - /// alignments. The buffer was allocated with alignment 2 (for `u16`), but after - /// turning it into a `Vec<u8>` it'll be deallocated with alignment 1. To avoid - /// these issues, it is often preferable to do casting/transmuting using - /// [`slice::from_raw_parts`] instead. - /// - /// The ownership of `ptr` is effectively transferred to the - /// `Vec<T>` which may then deallocate, reallocate or change the - /// contents of memory pointed to by the pointer at will. Ensure - /// that nothing else uses the pointer after calling this - /// function. - /// - /// [`String`]: crate::string::String - /// [`alloc::alloc`]: crate::alloc::alloc - /// [`dealloc`]: crate::alloc::GlobalAlloc::dealloc - /// - /// # Examples - /// - /// ``` - /// use std::ptr; - /// use std::mem; - /// - /// let v = vec![1, 2, 3]; - /// - // FIXME Update this when vec_into_raw_parts is stabilized - /// // Prevent running `v`'s destructor so we are in complete control - /// // of the allocation. - /// let mut v = mem::ManuallyDrop::new(v); - /// - /// // Pull out the various important pieces of information about `v` - /// let p = v.as_mut_ptr(); - /// let len = v.len(); - /// let cap = v.capacity(); - /// - /// unsafe { - /// // Overwrite memory with 4, 5, 6 - /// for i in 0..len { - /// ptr::write(p.add(i), 4 + i); - /// } - /// - /// // Put everything back together into a Vec - /// let rebuilt = Vec::from_raw_parts(p, len, cap); - /// assert_eq!(rebuilt, [4, 5, 6]); - /// } - /// ``` - /// - /// Using memory that was allocated elsewhere: - /// - /// ```rust - /// use std::alloc::{alloc, Layout}; - /// - /// fn main() { - /// let layout = Layout::array::<u32>(16).expect("overflow cannot happen"); - /// - /// let vec = unsafe { - /// let mem = alloc(layout).cast::<u32>(); - /// if mem.is_null() { - /// return; - /// } - /// - /// mem.write(1_000_000); - /// - /// Vec::from_raw_parts(mem, 1, 16) - /// }; - /// - /// assert_eq!(vec, &[1_000_000]); - /// assert_eq!(vec.capacity(), 16); - /// } - /// ``` - #[inline] - #[stable(feature = "rust1", since = "1.0.0")] - pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Self { - unsafe { Self::from_raw_parts_in(ptr, length, capacity, Global) } - } -} - -impl<T, A: Allocator> Vec<T, A> { - /// Constructs a new, empty `Vec<T, A>`. - /// - /// The vector will not allocate until elements are pushed onto it. - /// - /// # Examples - /// - /// ``` - /// #![feature(allocator_api)] - /// - /// use std::alloc::System; - /// - /// # #[allow(unused_mut)] - /// let mut vec: Vec<i32, _> = Vec::new_in(System); - /// ``` - #[inline] - #[unstable(feature = "allocator_api", issue = "32838")] - pub const fn new_in(alloc: A) -> Self { - Vec { buf: RawVec::new_in(alloc), len: 0 } - } - - /// Constructs a new, empty `Vec<T, A>` with at least the specified capacity - /// with the provided allocator. - /// - /// The vector will be able to hold at least `capacity` elements without - /// reallocating. This method is allowed to allocate for more elements than - /// `capacity`. If `capacity` is 0, the vector will not allocate. - /// - /// It is important to note that although the returned vector has the - /// minimum *capacity* specified, the vector will have a zero *length*. For - /// an explanation of the difference between length and capacity, see - /// *[Capacity and reallocation]*. - /// - /// If it is important to know the exact allocated capacity of a `Vec`, - /// always use the [`capacity`] method after construction. - /// - /// For `Vec<T, A>` where `T` is a zero-sized type, there will be no allocation - /// and the capacity will always be `usize::MAX`. - /// - /// [Capacity and reallocation]: #capacity-and-reallocation - /// [`capacity`]: Vec::capacity - /// - /// # Panics - /// - /// Panics if the new capacity exceeds `isize::MAX` bytes. - /// - /// # Examples - /// - /// ``` - /// #![feature(allocator_api)] - /// - /// use std::alloc::System; - /// - /// let mut vec = Vec::with_capacity_in(10, System); - /// - /// // The vector contains no items, even though it has capacity for more - /// assert_eq!(vec.len(), 0); - /// assert!(vec.capacity() >= 10); - /// - /// // These are all done without reallocating... - /// for i in 0..10 { - /// vec.push(i); - /// } - /// assert_eq!(vec.len(), 10); - /// assert!(vec.capacity() >= 10); - /// - /// // ...but this may make the vector reallocate - /// vec.push(11); - /// assert_eq!(vec.len(), 11); - /// assert!(vec.capacity() >= 11); - /// - /// // A vector of a zero-sized type will always over-allocate, since no - /// // allocation is necessary - /// let vec_units = Vec::<(), System>::with_capacity_in(10, System); - /// assert_eq!(vec_units.capacity(), usize::MAX); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[inline] - #[unstable(feature = "allocator_api", issue = "32838")] - pub fn with_capacity_in(capacity: usize, alloc: A) -> Self { - Vec { buf: RawVec::with_capacity_in(capacity, alloc), len: 0 } - } - - /// Tries to construct a new, empty `Vec<T, A>` with at least the specified capacity - /// with the provided allocator. - /// - /// The vector will be able to hold at least `capacity` elements without - /// reallocating. This method is allowed to allocate for more elements than - /// `capacity`. If `capacity` is 0, the vector will not allocate. - /// - /// It is important to note that although the returned vector has the - /// minimum *capacity* specified, the vector will have a zero *length*. For - /// an explanation of the difference between length and capacity, see - /// *[Capacity and reallocation]*. - /// - /// If it is important to know the exact allocated capacity of a `Vec`, - /// always use the [`capacity`] method after construction. - /// - /// For `Vec<T, A>` where `T` is a zero-sized type, there will be no allocation - /// and the capacity will always be `usize::MAX`. - /// - /// [Capacity and reallocation]: #capacity-and-reallocation - /// [`capacity`]: Vec::capacity - /// - /// # Examples - /// - /// ``` - /// #![feature(allocator_api)] - /// - /// use std::alloc::System; - /// - /// let mut vec = Vec::try_with_capacity_in(10, System).unwrap(); - /// - /// // The vector contains no items, even though it has capacity for more - /// assert_eq!(vec.len(), 0); - /// assert!(vec.capacity() >= 10); - /// - /// // These are all done without reallocating... - /// for i in 0..10 { - /// vec.push(i); - /// } - /// assert_eq!(vec.len(), 10); - /// assert!(vec.capacity() >= 10); - /// - /// // ...but this may make the vector reallocate - /// vec.push(11); - /// assert_eq!(vec.len(), 11); - /// assert!(vec.capacity() >= 11); - /// - /// let mut result = Vec::try_with_capacity_in(usize::MAX, System); - /// assert!(result.is_err()); - /// - /// // A vector of a zero-sized type will always over-allocate, since no - /// // allocation is necessary - /// let vec_units = Vec::<(), System>::try_with_capacity_in(10, System).unwrap(); - /// assert_eq!(vec_units.capacity(), usize::MAX); - /// ``` - #[inline] - #[stable(feature = "kernel", since = "1.0.0")] - pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> { - Ok(Vec { buf: RawVec::try_with_capacity_in(capacity, alloc)?, len: 0 }) - } - - /// Creates a `Vec<T, A>` directly from a pointer, a capacity, a length, - /// and an allocator. - /// - /// # Safety - /// - /// This is highly unsafe, due to the number of invariants that aren't - /// checked: - /// - /// * `ptr` must be [*currently allocated*] via the given allocator `alloc`. - /// * `T` needs to have the same alignment as what `ptr` was allocated with. - /// (`T` having a less strict alignment is not sufficient, the alignment really - /// needs to be equal to satisfy the [`dealloc`] requirement that memory must be - /// allocated and deallocated with the same layout.) - /// * The size of `T` times the `capacity` (ie. the allocated size in bytes) needs - /// to be the same size as the pointer was allocated with. (Because similar to - /// alignment, [`dealloc`] must be called with the same layout `size`.) - /// * `length` needs to be less than or equal to `capacity`. - /// * The first `length` values must be properly initialized values of type `T`. - /// * `capacity` needs to [*fit*] the layout size that the pointer was allocated with. - /// * The allocated size in bytes must be no larger than `isize::MAX`. - /// See the safety documentation of [`pointer::offset`]. - /// - /// These requirements are always upheld by any `ptr` that has been allocated - /// via `Vec<T, A>`. Other allocation sources are allowed if the invariants are - /// upheld. - /// - /// Violating these may cause problems like corrupting the allocator's - /// internal data structures. For example it is **not** safe - /// to build a `Vec<u8>` from a pointer to a C `char` array with length `size_t`. - /// It's also not safe to build one from a `Vec<u16>` and its length, because - /// the allocator cares about the alignment, and these two types have different - /// alignments. The buffer was allocated with alignment 2 (for `u16`), but after - /// turning it into a `Vec<u8>` it'll be deallocated with alignment 1. - /// - /// The ownership of `ptr` is effectively transferred to the - /// `Vec<T>` which may then deallocate, reallocate or change the - /// contents of memory pointed to by the pointer at will. Ensure - /// that nothing else uses the pointer after calling this - /// function. - /// - /// [`String`]: crate::string::String - /// [`dealloc`]: crate::alloc::GlobalAlloc::dealloc - /// [*currently allocated*]: crate::alloc::Allocator#currently-allocated-memory - /// [*fit*]: crate::alloc::Allocator#memory-fitting - /// - /// # Examples - /// - /// ``` - /// #![feature(allocator_api)] - /// - /// use std::alloc::System; - /// - /// use std::ptr; - /// use std::mem; - /// - /// let mut v = Vec::with_capacity_in(3, System); - /// v.push(1); - /// v.push(2); - /// v.push(3); - /// - // FIXME Update this when vec_into_raw_parts is stabilized - /// // Prevent running `v`'s destructor so we are in complete control - /// // of the allocation. - /// let mut v = mem::ManuallyDrop::new(v); - /// - /// // Pull out the various important pieces of information about `v` - /// let p = v.as_mut_ptr(); - /// let len = v.len(); - /// let cap = v.capacity(); - /// let alloc = v.allocator(); - /// - /// unsafe { - /// // Overwrite memory with 4, 5, 6 - /// for i in 0..len { - /// ptr::write(p.add(i), 4 + i); - /// } - /// - /// // Put everything back together into a Vec - /// let rebuilt = Vec::from_raw_parts_in(p, len, cap, alloc.clone()); - /// assert_eq!(rebuilt, [4, 5, 6]); - /// } - /// ``` - /// - /// Using memory that was allocated elsewhere: - /// - /// ```rust - /// #![feature(allocator_api)] - /// - /// use std::alloc::{AllocError, Allocator, Global, Layout}; - /// - /// fn main() { - /// let layout = Layout::array::<u32>(16).expect("overflow cannot happen"); - /// - /// let vec = unsafe { - /// let mem = match Global.allocate(layout) { - /// Ok(mem) => mem.cast::<u32>().as_ptr(), - /// Err(AllocError) => return, - /// }; - /// - /// mem.write(1_000_000); - /// - /// Vec::from_raw_parts_in(mem, 1, 16, Global) - /// }; - /// - /// assert_eq!(vec, &[1_000_000]); - /// assert_eq!(vec.capacity(), 16); - /// } - /// ``` - #[inline] - #[unstable(feature = "allocator_api", issue = "32838")] - pub unsafe fn from_raw_parts_in(ptr: *mut T, length: usize, capacity: usize, alloc: A) -> Self { - unsafe { Vec { buf: RawVec::from_raw_parts_in(ptr, capacity, alloc), len: length } } - } - - /// Decomposes a `Vec<T>` into its raw components. - /// - /// Returns the raw pointer to the underlying data, the length of - /// the vector (in elements), and the allocated capacity of the - /// data (in elements). These are the same arguments in the same - /// order as the arguments to [`from_raw_parts`]. - /// - /// After calling this function, the caller is responsible for the - /// memory previously managed by the `Vec`. The only way to do - /// this is to convert the raw pointer, length, and capacity back - /// into a `Vec` with the [`from_raw_parts`] function, allowing - /// the destructor to perform the cleanup. - /// - /// [`from_raw_parts`]: Vec::from_raw_parts - /// - /// # Examples - /// - /// ``` - /// #![feature(vec_into_raw_parts)] - /// let v: Vec<i32> = vec![-1, 0, 1]; - /// - /// let (ptr, len, cap) = v.into_raw_parts(); - /// - /// let rebuilt = unsafe { - /// // We can now make changes to the components, such as - /// // transmuting the raw pointer to a compatible type. - /// let ptr = ptr as *mut u32; - /// - /// Vec::from_raw_parts(ptr, len, cap) - /// }; - /// assert_eq!(rebuilt, [4294967295, 0, 1]); - /// ``` - #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")] - pub fn into_raw_parts(self) -> (*mut T, usize, usize) { - let mut me = ManuallyDrop::new(self); - (me.as_mut_ptr(), me.len(), me.capacity()) - } - - /// Decomposes a `Vec<T>` into its raw components. - /// - /// Returns the raw pointer to the underlying data, the length of the vector (in elements), - /// the allocated capacity of the data (in elements), and the allocator. These are the same - /// arguments in the same order as the arguments to [`from_raw_parts_in`]. - /// - /// After calling this function, the caller is responsible for the - /// memory previously managed by the `Vec`. The only way to do - /// this is to convert the raw pointer, length, and capacity back - /// into a `Vec` with the [`from_raw_parts_in`] function, allowing - /// the destructor to perform the cleanup. - /// - /// [`from_raw_parts_in`]: Vec::from_raw_parts_in - /// - /// # Examples - /// - /// ``` - /// #![feature(allocator_api, vec_into_raw_parts)] - /// - /// use std::alloc::System; - /// - /// let mut v: Vec<i32, System> = Vec::new_in(System); - /// v.push(-1); - /// v.push(0); - /// v.push(1); - /// - /// let (ptr, len, cap, alloc) = v.into_raw_parts_with_alloc(); - /// - /// let rebuilt = unsafe { - /// // We can now make changes to the components, such as - /// // transmuting the raw pointer to a compatible type. - /// let ptr = ptr as *mut u32; - /// - /// Vec::from_raw_parts_in(ptr, len, cap, alloc) - /// }; - /// assert_eq!(rebuilt, [4294967295, 0, 1]); - /// ``` - #[unstable(feature = "allocator_api", issue = "32838")] - // #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")] - pub fn into_raw_parts_with_alloc(self) -> (*mut T, usize, usize, A) { - let mut me = ManuallyDrop::new(self); - let len = me.len(); - let capacity = me.capacity(); - let ptr = me.as_mut_ptr(); - let alloc = unsafe { ptr::read(me.allocator()) }; - (ptr, len, capacity, alloc) - } - - /// Returns the total number of elements the vector can hold without - /// reallocating. - /// - /// # Examples - /// - /// ``` - /// let mut vec: Vec<i32> = Vec::with_capacity(10); - /// vec.push(42); - /// assert!(vec.capacity() >= 10); - /// ``` - #[inline] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn capacity(&self) -> usize { - self.buf.capacity() - } - - /// Reserves capacity for at least `additional` more elements to be inserted - /// in the given `Vec<T>`. The collection may reserve more space to - /// speculatively avoid frequent reallocations. After calling `reserve`, - /// capacity will be greater than or equal to `self.len() + additional`. - /// Does nothing if capacity is already sufficient. - /// - /// # Panics - /// - /// Panics if the new capacity exceeds `isize::MAX` bytes. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1]; - /// vec.reserve(10); - /// assert!(vec.capacity() >= 11); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn reserve(&mut self, additional: usize) { - self.buf.reserve(self.len, additional); - } - - /// Reserves the minimum capacity for at least `additional` more elements to - /// be inserted in the given `Vec<T>`. Unlike [`reserve`], this will not - /// deliberately over-allocate to speculatively avoid frequent allocations. - /// After calling `reserve_exact`, capacity will be greater than or equal to - /// `self.len() + additional`. Does nothing if the capacity is already - /// sufficient. - /// - /// Note that the allocator may give the collection more space than it - /// requests. Therefore, capacity can not be relied upon to be precisely - /// minimal. Prefer [`reserve`] if future insertions are expected. - /// - /// [`reserve`]: Vec::reserve - /// - /// # Panics - /// - /// Panics if the new capacity exceeds `isize::MAX` bytes. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1]; - /// vec.reserve_exact(10); - /// assert!(vec.capacity() >= 11); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn reserve_exact(&mut self, additional: usize) { - self.buf.reserve_exact(self.len, additional); - } - - /// Tries to reserve capacity for at least `additional` more elements to be inserted - /// in the given `Vec<T>`. The collection may reserve more space to speculatively avoid - /// frequent reallocations. After calling `try_reserve`, capacity will be - /// greater than or equal to `self.len() + additional` if it returns - /// `Ok(())`. Does nothing if capacity is already sufficient. This method - /// preserves the contents even if an error occurs. - /// - /// # Errors - /// - /// If the capacity overflows, or the allocator reports a failure, then an error - /// is returned. - /// - /// # Examples - /// - /// ``` - /// use std::collections::TryReserveError; - /// - /// fn process_data(data: &[u32]) -> Result<Vec<u32>, TryReserveError> { - /// let mut output = Vec::new(); - /// - /// // Pre-reserve the memory, exiting if we can't - /// output.try_reserve(data.len())?; - /// - /// // Now we know this can't OOM in the middle of our complex work - /// output.extend(data.iter().map(|&val| { - /// val * 2 + 5 // very complicated - /// })); - /// - /// Ok(output) - /// } - /// # process_data(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?"); - /// ``` - #[stable(feature = "try_reserve", since = "1.57.0")] - pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> { - self.buf.try_reserve(self.len, additional) - } - - /// Tries to reserve the minimum capacity for at least `additional` - /// elements to be inserted in the given `Vec<T>`. Unlike [`try_reserve`], - /// this will not deliberately over-allocate to speculatively avoid frequent - /// allocations. After calling `try_reserve_exact`, capacity will be greater - /// than or equal to `self.len() + additional` if it returns `Ok(())`. - /// Does nothing if the capacity is already sufficient. - /// - /// Note that the allocator may give the collection more space than it - /// requests. Therefore, capacity can not be relied upon to be precisely - /// minimal. Prefer [`try_reserve`] if future insertions are expected. - /// - /// [`try_reserve`]: Vec::try_reserve - /// - /// # Errors - /// - /// If the capacity overflows, or the allocator reports a failure, then an error - /// is returned. - /// - /// # Examples - /// - /// ``` - /// use std::collections::TryReserveError; - /// - /// fn process_data(data: &[u32]) -> Result<Vec<u32>, TryReserveError> { - /// let mut output = Vec::new(); - /// - /// // Pre-reserve the memory, exiting if we can't - /// output.try_reserve_exact(data.len())?; - /// - /// // Now we know this can't OOM in the middle of our complex work - /// output.extend(data.iter().map(|&val| { - /// val * 2 + 5 // very complicated - /// })); - /// - /// Ok(output) - /// } - /// # process_data(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?"); - /// ``` - #[stable(feature = "try_reserve", since = "1.57.0")] - pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> { - self.buf.try_reserve_exact(self.len, additional) - } - - /// Shrinks the capacity of the vector as much as possible. - /// - /// It will drop down as close as possible to the length but the allocator - /// may still inform the vector that there is space for a few more elements. - /// - /// # Examples - /// - /// ``` - /// let mut vec = Vec::with_capacity(10); - /// vec.extend([1, 2, 3]); - /// assert!(vec.capacity() >= 10); - /// vec.shrink_to_fit(); - /// assert!(vec.capacity() >= 3); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn shrink_to_fit(&mut self) { - // The capacity is never less than the length, and there's nothing to do when - // they are equal, so we can avoid the panic case in `RawVec::shrink_to_fit` - // by only calling it with a greater capacity. - if self.capacity() > self.len { - self.buf.shrink_to_fit(self.len); - } - } - - /// Shrinks the capacity of the vector with a lower bound. - /// - /// The capacity will remain at least as large as both the length - /// and the supplied value. - /// - /// If the current capacity is less than the lower limit, this is a no-op. - /// - /// # Examples - /// - /// ``` - /// let mut vec = Vec::with_capacity(10); - /// vec.extend([1, 2, 3]); - /// assert!(vec.capacity() >= 10); - /// vec.shrink_to(4); - /// assert!(vec.capacity() >= 4); - /// vec.shrink_to(0); - /// assert!(vec.capacity() >= 3); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "shrink_to", since = "1.56.0")] - pub fn shrink_to(&mut self, min_capacity: usize) { - if self.capacity() > min_capacity { - self.buf.shrink_to_fit(cmp::max(self.len, min_capacity)); - } - } - - /// Converts the vector into [`Box<[T]>`][owned slice]. - /// - /// If the vector has excess capacity, its items will be moved into a - /// newly-allocated buffer with exactly the right capacity. - /// - /// [owned slice]: Box - /// - /// # Examples - /// - /// ``` - /// let v = vec![1, 2, 3]; - /// - /// let slice = v.into_boxed_slice(); - /// ``` - /// - /// Any excess capacity is removed: - /// - /// ``` - /// let mut vec = Vec::with_capacity(10); - /// vec.extend([1, 2, 3]); - /// - /// assert!(vec.capacity() >= 10); - /// let slice = vec.into_boxed_slice(); - /// assert_eq!(slice.into_vec().capacity(), 3); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn into_boxed_slice(mut self) -> Box<[T], A> { - unsafe { - self.shrink_to_fit(); - let me = ManuallyDrop::new(self); - let buf = ptr::read(&me.buf); - let len = me.len(); - buf.into_box(len).assume_init() - } - } - - /// Shortens the vector, keeping the first `len` elements and dropping - /// the rest. - /// - /// If `len` is greater or equal to the vector's current length, this has - /// no effect. - /// - /// The [`drain`] method can emulate `truncate`, but causes the excess - /// elements to be returned instead of dropped. - /// - /// Note that this method has no effect on the allocated capacity - /// of the vector. - /// - /// # Examples - /// - /// Truncating a five element vector to two elements: - /// - /// ``` - /// let mut vec = vec![1, 2, 3, 4, 5]; - /// vec.truncate(2); - /// assert_eq!(vec, [1, 2]); - /// ``` - /// - /// No truncation occurs when `len` is greater than the vector's current - /// length: - /// - /// ``` - /// let mut vec = vec![1, 2, 3]; - /// vec.truncate(8); - /// assert_eq!(vec, [1, 2, 3]); - /// ``` - /// - /// Truncating when `len == 0` is equivalent to calling the [`clear`] - /// method. - /// - /// ``` - /// let mut vec = vec![1, 2, 3]; - /// vec.truncate(0); - /// assert_eq!(vec, []); - /// ``` - /// - /// [`clear`]: Vec::clear - /// [`drain`]: Vec::drain - #[stable(feature = "rust1", since = "1.0.0")] - pub fn truncate(&mut self, len: usize) { - // This is safe because: - // - // * the slice passed to `drop_in_place` is valid; the `len > self.len` - // case avoids creating an invalid slice, and - // * the `len` of the vector is shrunk before calling `drop_in_place`, - // such that no value will be dropped twice in case `drop_in_place` - // were to panic once (if it panics twice, the program aborts). - unsafe { - // Note: It's intentional that this is `>` and not `>=`. - // Changing it to `>=` has negative performance - // implications in some cases. See #78884 for more. - if len > self.len { - return; - } - let remaining_len = self.len - len; - let s = ptr::slice_from_raw_parts_mut(self.as_mut_ptr().add(len), remaining_len); - self.len = len; - ptr::drop_in_place(s); - } - } - - /// Extracts a slice containing the entire vector. - /// - /// Equivalent to `&s[..]`. - /// - /// # Examples - /// - /// ``` - /// use std::io::{self, Write}; - /// let buffer = vec![1, 2, 3, 5, 8]; - /// io::sink().write(buffer.as_slice()).unwrap(); - /// ``` - #[inline] - #[stable(feature = "vec_as_slice", since = "1.7.0")] - pub fn as_slice(&self) -> &[T] { - self - } - - /// Extracts a mutable slice of the entire vector. - /// - /// Equivalent to `&mut s[..]`. - /// - /// # Examples - /// - /// ``` - /// use std::io::{self, Read}; - /// let mut buffer = vec![0; 3]; - /// io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap(); - /// ``` - #[inline] - #[stable(feature = "vec_as_slice", since = "1.7.0")] - pub fn as_mut_slice(&mut self) -> &mut [T] { - self - } - - /// Returns a raw pointer to the vector's buffer, or a dangling raw pointer - /// valid for zero sized reads if the vector didn't allocate. - /// - /// The caller must ensure that the vector outlives the pointer this - /// function returns, or else it will end up pointing to garbage. - /// Modifying the vector may cause its buffer to be reallocated, - /// which would also make any pointers to it invalid. - /// - /// The caller must also ensure that the memory the pointer (non-transitively) points to - /// is never written to (except inside an `UnsafeCell`) using this pointer or any pointer - /// derived from it. If you need to mutate the contents of the slice, use [`as_mut_ptr`]. - /// - /// This method guarantees that for the purpose of the aliasing model, this method - /// does not materialize a reference to the underlying slice, and thus the returned pointer - /// will remain valid when mixed with other calls to [`as_ptr`] and [`as_mut_ptr`]. - /// Note that calling other methods that materialize mutable references to the slice, - /// or mutable references to specific elements you are planning on accessing through this pointer, - /// as well as writing to those elements, may still invalidate this pointer. - /// See the second example below for how this guarantee can be used. - /// - /// - /// # Examples - /// - /// ``` - /// let x = vec![1, 2, 4]; - /// let x_ptr = x.as_ptr(); - /// - /// unsafe { - /// for i in 0..x.len() { - /// assert_eq!(*x_ptr.add(i), 1 << i); - /// } - /// } - /// ``` - /// - /// Due to the aliasing guarantee, the following code is legal: - /// - /// ```rust - /// unsafe { - /// let mut v = vec![0, 1, 2]; - /// let ptr1 = v.as_ptr(); - /// let _ = ptr1.read(); - /// let ptr2 = v.as_mut_ptr().offset(2); - /// ptr2.write(2); - /// // Notably, the write to `ptr2` did *not* invalidate `ptr1` - /// // because it mutated a different element: - /// let _ = ptr1.read(); - /// } - /// ``` - /// - /// [`as_mut_ptr`]: Vec::as_mut_ptr - /// [`as_ptr`]: Vec::as_ptr - #[stable(feature = "vec_as_ptr", since = "1.37.0")] - #[rustc_never_returns_null_ptr] - #[inline] - pub fn as_ptr(&self) -> *const T { - // We shadow the slice method of the same name to avoid going through - // `deref`, which creates an intermediate reference. - self.buf.ptr() - } - - /// Returns an unsafe mutable pointer to the vector's buffer, or a dangling - /// raw pointer valid for zero sized reads if the vector didn't allocate. - /// - /// The caller must ensure that the vector outlives the pointer this - /// function returns, or else it will end up pointing to garbage. - /// Modifying the vector may cause its buffer to be reallocated, - /// which would also make any pointers to it invalid. - /// - /// This method guarantees that for the purpose of the aliasing model, this method - /// does not materialize a reference to the underlying slice, and thus the returned pointer - /// will remain valid when mixed with other calls to [`as_ptr`] and [`as_mut_ptr`]. - /// Note that calling other methods that materialize references to the slice, - /// or references to specific elements you are planning on accessing through this pointer, - /// may still invalidate this pointer. - /// See the second example below for how this guarantee can be used. - /// - /// - /// # Examples - /// - /// ``` - /// // Allocate vector big enough for 4 elements. - /// let size = 4; - /// let mut x: Vec<i32> = Vec::with_capacity(size); - /// let x_ptr = x.as_mut_ptr(); - /// - /// // Initialize elements via raw pointer writes, then set length. - /// unsafe { - /// for i in 0..size { - /// *x_ptr.add(i) = i as i32; - /// } - /// x.set_len(size); - /// } - /// assert_eq!(&*x, &[0, 1, 2, 3]); - /// ``` - /// - /// Due to the aliasing guarantee, the following code is legal: - /// - /// ```rust - /// unsafe { - /// let mut v = vec![0]; - /// let ptr1 = v.as_mut_ptr(); - /// ptr1.write(1); - /// let ptr2 = v.as_mut_ptr(); - /// ptr2.write(2); - /// // Notably, the write to `ptr2` did *not* invalidate `ptr1`: - /// ptr1.write(3); - /// } - /// ``` - /// - /// [`as_mut_ptr`]: Vec::as_mut_ptr - /// [`as_ptr`]: Vec::as_ptr - #[stable(feature = "vec_as_ptr", since = "1.37.0")] - #[rustc_never_returns_null_ptr] - #[inline] - pub fn as_mut_ptr(&mut self) -> *mut T { - // We shadow the slice method of the same name to avoid going through - // `deref_mut`, which creates an intermediate reference. - self.buf.ptr() - } - - /// Returns a reference to the underlying allocator. - #[unstable(feature = "allocator_api", issue = "32838")] - #[inline] - pub fn allocator(&self) -> &A { - self.buf.allocator() - } - - /// Forces the length of the vector to `new_len`. - /// - /// This is a low-level operation that maintains none of the normal - /// invariants of the type. Normally changing the length of a vector - /// is done using one of the safe operations instead, such as - /// [`truncate`], [`resize`], [`extend`], or [`clear`]. - /// - /// [`truncate`]: Vec::truncate - /// [`resize`]: Vec::resize - /// [`extend`]: Extend::extend - /// [`clear`]: Vec::clear - /// - /// # Safety - /// - /// - `new_len` must be less than or equal to [`capacity()`]. - /// - The elements at `old_len..new_len` must be initialized. - /// - /// [`capacity()`]: Vec::capacity - /// - /// # Examples - /// - /// This method can be useful for situations in which the vector - /// is serving as a buffer for other code, particularly over FFI: - /// - /// ```no_run - /// # #![allow(dead_code)] - /// # // This is just a minimal skeleton for the doc example; - /// # // don't use this as a starting point for a real library. - /// # pub struct StreamWrapper { strm: *mut std::ffi::c_void } - /// # const Z_OK: i32 = 0; - /// # extern "C" { - /// # fn deflateGetDictionary( - /// # strm: *mut std::ffi::c_void, - /// # dictionary: *mut u8, - /// # dictLength: *mut usize, - /// # ) -> i32; - /// # } - /// # impl StreamWrapper { - /// pub fn get_dictionary(&self) -> Option<Vec<u8>> { - /// // Per the FFI method's docs, "32768 bytes is always enough". - /// let mut dict = Vec::with_capacity(32_768); - /// let mut dict_length = 0; - /// // SAFETY: When `deflateGetDictionary` returns `Z_OK`, it holds that: - /// // 1. `dict_length` elements were initialized. - /// // 2. `dict_length` <= the capacity (32_768) - /// // which makes `set_len` safe to call. - /// unsafe { - /// // Make the FFI call... - /// let r = deflateGetDictionary(self.strm, dict.as_mut_ptr(), &mut dict_length); - /// if r == Z_OK { - /// // ...and update the length to what was initialized. - /// dict.set_len(dict_length); - /// Some(dict) - /// } else { - /// None - /// } - /// } - /// } - /// # } - /// ``` - /// - /// While the following example is sound, there is a memory leak since - /// the inner vectors were not freed prior to the `set_len` call: - /// - /// ``` - /// let mut vec = vec![vec![1, 0, 0], - /// vec![0, 1, 0], - /// vec![0, 0, 1]]; - /// // SAFETY: - /// // 1. `old_len..0` is empty so no elements need to be initialized. - /// // 2. `0 <= capacity` always holds whatever `capacity` is. - /// unsafe { - /// vec.set_len(0); - /// } - /// ``` - /// - /// Normally, here, one would use [`clear`] instead to correctly drop - /// the contents and thus not leak memory. - #[inline] - #[stable(feature = "rust1", since = "1.0.0")] - pub unsafe fn set_len(&mut self, new_len: usize) { - debug_assert!(new_len <= self.capacity()); - - self.len = new_len; - } - - /// Removes an element from the vector and returns it. - /// - /// The removed element is replaced by the last element of the vector. - /// - /// This does not preserve ordering, but is *O*(1). - /// If you need to preserve the element order, use [`remove`] instead. - /// - /// [`remove`]: Vec::remove - /// - /// # Panics - /// - /// Panics if `index` is out of bounds. - /// - /// # Examples - /// - /// ``` - /// let mut v = vec!["foo", "bar", "baz", "qux"]; - /// - /// assert_eq!(v.swap_remove(1), "bar"); - /// assert_eq!(v, ["foo", "qux", "baz"]); - /// - /// assert_eq!(v.swap_remove(0), "foo"); - /// assert_eq!(v, ["baz", "qux"]); - /// ``` - #[inline] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn swap_remove(&mut self, index: usize) -> T { - #[cold] - #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] - #[track_caller] - fn assert_failed(index: usize, len: usize) -> ! { - panic!("swap_remove index (is {index}) should be < len (is {len})"); - } - - let len = self.len(); - if index >= len { - assert_failed(index, len); - } - unsafe { - // We replace self[index] with the last element. Note that if the - // bounds check above succeeds there must be a last element (which - // can be self[index] itself). - let value = ptr::read(self.as_ptr().add(index)); - let base_ptr = self.as_mut_ptr(); - ptr::copy(base_ptr.add(len - 1), base_ptr.add(index), 1); - self.set_len(len - 1); - value - } - } - - /// Inserts an element at position `index` within the vector, shifting all - /// elements after it to the right. - /// - /// # Panics - /// - /// Panics if `index > len`. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1, 2, 3]; - /// vec.insert(1, 4); - /// assert_eq!(vec, [1, 4, 2, 3]); - /// vec.insert(4, 5); - /// assert_eq!(vec, [1, 4, 2, 3, 5]); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn insert(&mut self, index: usize, element: T) { - #[cold] - #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] - #[track_caller] - fn assert_failed(index: usize, len: usize) -> ! { - panic!("insertion index (is {index}) should be <= len (is {len})"); - } - - let len = self.len(); - - // space for the new element - if len == self.buf.capacity() { - self.reserve(1); - } - - unsafe { - // infallible - // The spot to put the new value - { - let p = self.as_mut_ptr().add(index); - if index < len { - // Shift everything over to make space. (Duplicating the - // `index`th element into two consecutive places.) - ptr::copy(p, p.add(1), len - index); - } else if index == len { - // No elements need shifting. - } else { - assert_failed(index, len); - } - // Write it in, overwriting the first copy of the `index`th - // element. - ptr::write(p, element); - } - self.set_len(len + 1); - } - } - - /// Removes and returns the element at position `index` within the vector, - /// shifting all elements after it to the left. - /// - /// Note: Because this shifts over the remaining elements, it has a - /// worst-case performance of *O*(*n*). If you don't need the order of elements - /// to be preserved, use [`swap_remove`] instead. If you'd like to remove - /// elements from the beginning of the `Vec`, consider using - /// [`VecDeque::pop_front`] instead. - /// - /// [`swap_remove`]: Vec::swap_remove - /// [`VecDeque::pop_front`]: crate::collections::VecDeque::pop_front - /// - /// # Panics - /// - /// Panics if `index` is out of bounds. - /// - /// # Examples - /// - /// ``` - /// let mut v = vec![1, 2, 3]; - /// assert_eq!(v.remove(1), 2); - /// assert_eq!(v, [1, 3]); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - #[track_caller] - pub fn remove(&mut self, index: usize) -> T { - #[cold] - #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] - #[track_caller] - fn assert_failed(index: usize, len: usize) -> ! { - panic!("removal index (is {index}) should be < len (is {len})"); - } - - let len = self.len(); - if index >= len { - assert_failed(index, len); - } - unsafe { - // infallible - let ret; - { - // the place we are taking from. - let ptr = self.as_mut_ptr().add(index); - // copy it out, unsafely having a copy of the value on - // the stack and in the vector at the same time. - ret = ptr::read(ptr); - - // Shift everything down to fill in that spot. - ptr::copy(ptr.add(1), ptr, len - index - 1); - } - self.set_len(len - 1); - ret - } - } - - /// Retains only the elements specified by the predicate. - /// - /// In other words, remove all elements `e` for which `f(&e)` returns `false`. - /// This method operates in place, visiting each element exactly once in the - /// original order, and preserves the order of the retained elements. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1, 2, 3, 4]; - /// vec.retain(|&x| x % 2 == 0); - /// assert_eq!(vec, [2, 4]); - /// ``` - /// - /// Because the elements are visited exactly once in the original order, - /// external state may be used to decide which elements to keep. - /// - /// ``` - /// let mut vec = vec![1, 2, 3, 4, 5]; - /// let keep = [false, true, true, false, true]; - /// let mut iter = keep.iter(); - /// vec.retain(|_| *iter.next().unwrap()); - /// assert_eq!(vec, [2, 3, 5]); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn retain<F>(&mut self, mut f: F) - where - F: FnMut(&T) -> bool, - { - self.retain_mut(|elem| f(elem)); - } - - /// Retains only the elements specified by the predicate, passing a mutable reference to it. - /// - /// In other words, remove all elements `e` such that `f(&mut e)` returns `false`. - /// This method operates in place, visiting each element exactly once in the - /// original order, and preserves the order of the retained elements. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1, 2, 3, 4]; - /// vec.retain_mut(|x| if *x <= 3 { - /// *x += 1; - /// true - /// } else { - /// false - /// }); - /// assert_eq!(vec, [2, 3, 4]); - /// ``` - #[stable(feature = "vec_retain_mut", since = "1.61.0")] - pub fn retain_mut<F>(&mut self, mut f: F) - where - F: FnMut(&mut T) -> bool, - { - let original_len = self.len(); - // Avoid double drop if the drop guard is not executed, - // since we may make some holes during the process. - unsafe { self.set_len(0) }; - - // Vec: [Kept, Kept, Hole, Hole, Hole, Hole, Unchecked, Unchecked] - // |<- processed len ->| ^- next to check - // |<- deleted cnt ->| - // |<- original_len ->| - // Kept: Elements which predicate returns true on. - // Hole: Moved or dropped element slot. - // Unchecked: Unchecked valid elements. - // - // This drop guard will be invoked when predicate or `drop` of element panicked. - // It shifts unchecked elements to cover holes and `set_len` to the correct length. - // In cases when predicate and `drop` never panick, it will be optimized out. - struct BackshiftOnDrop<'a, T, A: Allocator> { - v: &'a mut Vec<T, A>, - processed_len: usize, - deleted_cnt: usize, - original_len: usize, - } - - impl<T, A: Allocator> Drop for BackshiftOnDrop<'_, T, A> { - fn drop(&mut self) { - if self.deleted_cnt > 0 { - // SAFETY: Trailing unchecked items must be valid since we never touch them. - unsafe { - ptr::copy( - self.v.as_ptr().add(self.processed_len), - self.v.as_mut_ptr().add(self.processed_len - self.deleted_cnt), - self.original_len - self.processed_len, - ); - } - } - // SAFETY: After filling holes, all items are in contiguous memory. - unsafe { - self.v.set_len(self.original_len - self.deleted_cnt); - } - } - } - - let mut g = BackshiftOnDrop { v: self, processed_len: 0, deleted_cnt: 0, original_len }; - - fn process_loop<F, T, A: Allocator, const DELETED: bool>( - original_len: usize, - f: &mut F, - g: &mut BackshiftOnDrop<'_, T, A>, - ) where - F: FnMut(&mut T) -> bool, - { - while g.processed_len != original_len { - // SAFETY: Unchecked element must be valid. - let cur = unsafe { &mut *g.v.as_mut_ptr().add(g.processed_len) }; - if !f(cur) { - // Advance early to avoid double drop if `drop_in_place` panicked. - g.processed_len += 1; - g.deleted_cnt += 1; - // SAFETY: We never touch this element again after dropped. - unsafe { ptr::drop_in_place(cur) }; - // We already advanced the counter. - if DELETED { - continue; - } else { - break; - } - } - if DELETED { - // SAFETY: `deleted_cnt` > 0, so the hole slot must not overlap with current element. - // We use copy for move, and never touch this element again. - unsafe { - let hole_slot = g.v.as_mut_ptr().add(g.processed_len - g.deleted_cnt); - ptr::copy_nonoverlapping(cur, hole_slot, 1); - } - } - g.processed_len += 1; - } - } - - // Stage 1: Nothing was deleted. - process_loop::<F, T, A, false>(original_len, &mut f, &mut g); - - // Stage 2: Some elements were deleted. - process_loop::<F, T, A, true>(original_len, &mut f, &mut g); - - // All item are processed. This can be optimized to `set_len` by LLVM. - drop(g); - } - - /// Removes all but the first of consecutive elements in the vector that resolve to the same - /// key. - /// - /// If the vector is sorted, this removes all duplicates. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![10, 20, 21, 30, 20]; - /// - /// vec.dedup_by_key(|i| *i / 10); - /// - /// assert_eq!(vec, [10, 20, 30, 20]); - /// ``` - #[stable(feature = "dedup_by", since = "1.16.0")] - #[inline] - pub fn dedup_by_key<F, K>(&mut self, mut key: F) - where - F: FnMut(&mut T) -> K, - K: PartialEq, - { - self.dedup_by(|a, b| key(a) == key(b)) - } - - /// Removes all but the first of consecutive elements in the vector satisfying a given equality - /// relation. - /// - /// The `same_bucket` function is passed references to two elements from the vector and - /// must determine if the elements compare equal. The elements are passed in opposite order - /// from their order in the slice, so if `same_bucket(a, b)` returns `true`, `a` is removed. - /// - /// If the vector is sorted, this removes all duplicates. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"]; - /// - /// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b)); - /// - /// assert_eq!(vec, ["foo", "bar", "baz", "bar"]); - /// ``` - #[stable(feature = "dedup_by", since = "1.16.0")] - pub fn dedup_by<F>(&mut self, mut same_bucket: F) - where - F: FnMut(&mut T, &mut T) -> bool, - { - let len = self.len(); - if len <= 1 { - return; - } - - // Check if we ever want to remove anything. - // This allows to use copy_non_overlapping in next cycle. - // And avoids any memory writes if we don't need to remove anything. - let mut first_duplicate_idx: usize = 1; - let start = self.as_mut_ptr(); - while first_duplicate_idx != len { - let found_duplicate = unsafe { - // SAFETY: first_duplicate always in range [1..len) - // Note that we start iteration from 1 so we never overflow. - let prev = start.add(first_duplicate_idx.wrapping_sub(1)); - let current = start.add(first_duplicate_idx); - // We explicitly say in docs that references are reversed. - same_bucket(&mut *current, &mut *prev) - }; - if found_duplicate { - break; - } - first_duplicate_idx += 1; - } - // Don't need to remove anything. - // We cannot get bigger than len. - if first_duplicate_idx == len { - return; - } - - /* INVARIANT: vec.len() > read > write > write-1 >= 0 */ - struct FillGapOnDrop<'a, T, A: core::alloc::Allocator> { - /* Offset of the element we want to check if it is duplicate */ - read: usize, - - /* Offset of the place where we want to place the non-duplicate - * when we find it. */ - write: usize, - - /* The Vec that would need correction if `same_bucket` panicked */ - vec: &'a mut Vec<T, A>, - } - - impl<'a, T, A: core::alloc::Allocator> Drop for FillGapOnDrop<'a, T, A> { - fn drop(&mut self) { - /* This code gets executed when `same_bucket` panics */ - - /* SAFETY: invariant guarantees that `read - write` - * and `len - read` never overflow and that the copy is always - * in-bounds. */ - unsafe { - let ptr = self.vec.as_mut_ptr(); - let len = self.vec.len(); - - /* How many items were left when `same_bucket` panicked. - * Basically vec[read..].len() */ - let items_left = len.wrapping_sub(self.read); - - /* Pointer to first item in vec[write..write+items_left] slice */ - let dropped_ptr = ptr.add(self.write); - /* Pointer to first item in vec[read..] slice */ - let valid_ptr = ptr.add(self.read); - - /* Copy `vec[read..]` to `vec[write..write+items_left]`. - * The slices can overlap, so `copy_nonoverlapping` cannot be used */ - ptr::copy(valid_ptr, dropped_ptr, items_left); - - /* How many items have been already dropped - * Basically vec[read..write].len() */ - let dropped = self.read.wrapping_sub(self.write); - - self.vec.set_len(len - dropped); - } - } - } - - /* Drop items while going through Vec, it should be more efficient than - * doing slice partition_dedup + truncate */ - - // Construct gap first and then drop item to avoid memory corruption if `T::drop` panics. - let mut gap = - FillGapOnDrop { read: first_duplicate_idx + 1, write: first_duplicate_idx, vec: self }; - unsafe { - // SAFETY: we checked that first_duplicate_idx in bounds before. - // If drop panics, `gap` would remove this item without drop. - ptr::drop_in_place(start.add(first_duplicate_idx)); - } - - /* SAFETY: Because of the invariant, read_ptr, prev_ptr and write_ptr - * are always in-bounds and read_ptr never aliases prev_ptr */ - unsafe { - while gap.read < len { - let read_ptr = start.add(gap.read); - let prev_ptr = start.add(gap.write.wrapping_sub(1)); - - // We explicitly say in docs that references are reversed. - let found_duplicate = same_bucket(&mut *read_ptr, &mut *prev_ptr); - if found_duplicate { - // Increase `gap.read` now since the drop may panic. - gap.read += 1; - /* We have found duplicate, drop it in-place */ - ptr::drop_in_place(read_ptr); - } else { - let write_ptr = start.add(gap.write); - - /* read_ptr cannot be equal to write_ptr because at this point - * we guaranteed to skip at least one element (before loop starts). - */ - ptr::copy_nonoverlapping(read_ptr, write_ptr, 1); - - /* We have filled that place, so go further */ - gap.write += 1; - gap.read += 1; - } - } - - /* Technically we could let `gap` clean up with its Drop, but - * when `same_bucket` is guaranteed to not panic, this bloats a little - * the codegen, so we just do it manually */ - gap.vec.set_len(gap.write); - mem::forget(gap); - } - } - - /// Appends an element to the back of a collection. - /// - /// # Panics - /// - /// Panics if the new capacity exceeds `isize::MAX` bytes. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1, 2]; - /// vec.push(3); - /// assert_eq!(vec, [1, 2, 3]); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[inline] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn push(&mut self, value: T) { - // This will panic or abort if we would allocate > isize::MAX bytes - // or if the length increment would overflow for zero-sized types. - if self.len == self.buf.capacity() { - self.buf.reserve_for_push(self.len); - } - unsafe { - let end = self.as_mut_ptr().add(self.len); - ptr::write(end, value); - self.len += 1; - } - } - - /// Tries to append an element to the back of a collection. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1, 2]; - /// vec.try_push(3).unwrap(); - /// assert_eq!(vec, [1, 2, 3]); - /// ``` - #[inline] - #[stable(feature = "kernel", since = "1.0.0")] - pub fn try_push(&mut self, value: T) -> Result<(), TryReserveError> { - if self.len == self.buf.capacity() { - self.buf.try_reserve_for_push(self.len)?; - } - unsafe { - let end = self.as_mut_ptr().add(self.len); - ptr::write(end, value); - self.len += 1; - } - Ok(()) - } - - /// Appends an element if there is sufficient spare capacity, otherwise an error is returned - /// with the element. - /// - /// Unlike [`push`] this method will not reallocate when there's insufficient capacity. - /// The caller should use [`reserve`] or [`try_reserve`] to ensure that there is enough capacity. - /// - /// [`push`]: Vec::push - /// [`reserve`]: Vec::reserve - /// [`try_reserve`]: Vec::try_reserve - /// - /// # Examples - /// - /// A manual, panic-free alternative to [`FromIterator`]: - /// - /// ``` - /// #![feature(vec_push_within_capacity)] - /// - /// use std::collections::TryReserveError; - /// fn from_iter_fallible<T>(iter: impl Iterator<Item=T>) -> Result<Vec<T>, TryReserveError> { - /// let mut vec = Vec::new(); - /// for value in iter { - /// if let Err(value) = vec.push_within_capacity(value) { - /// vec.try_reserve(1)?; - /// // this cannot fail, the previous line either returned or added at least 1 free slot - /// let _ = vec.push_within_capacity(value); - /// } - /// } - /// Ok(vec) - /// } - /// assert_eq!(from_iter_fallible(0..100), Ok(Vec::from_iter(0..100))); - /// ``` - #[inline] - #[unstable(feature = "vec_push_within_capacity", issue = "100486")] - pub fn push_within_capacity(&mut self, value: T) -> Result<(), T> { - if self.len == self.buf.capacity() { - return Err(value); - } - unsafe { - let end = self.as_mut_ptr().add(self.len); - ptr::write(end, value); - self.len += 1; - } - Ok(()) - } - - /// Removes the last element from a vector and returns it, or [`None`] if it - /// is empty. - /// - /// If you'd like to pop the first element, consider using - /// [`VecDeque::pop_front`] instead. - /// - /// [`VecDeque::pop_front`]: crate::collections::VecDeque::pop_front - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1, 2, 3]; - /// assert_eq!(vec.pop(), Some(3)); - /// assert_eq!(vec, [1, 2]); - /// ``` - #[inline] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn pop(&mut self) -> Option<T> { - if self.len == 0 { - None - } else { - unsafe { - self.len -= 1; - core::intrinsics::assume(self.len < self.capacity()); - Some(ptr::read(self.as_ptr().add(self.len()))) - } - } - } - - /// Moves all the elements of `other` into `self`, leaving `other` empty. - /// - /// # Panics - /// - /// Panics if the new capacity exceeds `isize::MAX` bytes. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1, 2, 3]; - /// let mut vec2 = vec![4, 5, 6]; - /// vec.append(&mut vec2); - /// assert_eq!(vec, [1, 2, 3, 4, 5, 6]); - /// assert_eq!(vec2, []); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[inline] - #[stable(feature = "append", since = "1.4.0")] - pub fn append(&mut self, other: &mut Self) { - unsafe { - self.append_elements(other.as_slice() as _); - other.set_len(0); - } - } - - /// Appends elements to `self` from other buffer. - #[cfg(not(no_global_oom_handling))] - #[inline] - unsafe fn append_elements(&mut self, other: *const [T]) { - let count = unsafe { (*other).len() }; - self.reserve(count); - let len = self.len(); - unsafe { ptr::copy_nonoverlapping(other as *const T, self.as_mut_ptr().add(len), count) }; - self.len += count; - } - - /// Tries to append elements to `self` from other buffer. - #[inline] - unsafe fn try_append_elements(&mut self, other: *const [T]) -> Result<(), TryReserveError> { - let count = unsafe { (*other).len() }; - self.try_reserve(count)?; - let len = self.len(); - unsafe { ptr::copy_nonoverlapping(other as *const T, self.as_mut_ptr().add(len), count) }; - self.len += count; - Ok(()) - } - - /// Removes the specified range from the vector in bulk, returning all - /// removed elements as an iterator. If the iterator is dropped before - /// being fully consumed, it drops the remaining removed elements. - /// - /// The returned iterator keeps a mutable borrow on the vector to optimize - /// its implementation. - /// - /// # Panics - /// - /// Panics if the starting point is greater than the end point or if - /// the end point is greater than the length of the vector. - /// - /// # Leaking - /// - /// If the returned iterator goes out of scope without being dropped (due to - /// [`mem::forget`], for example), the vector may have lost and leaked - /// elements arbitrarily, including elements outside the range. - /// - /// # Examples - /// - /// ``` - /// let mut v = vec![1, 2, 3]; - /// let u: Vec<_> = v.drain(1..).collect(); - /// assert_eq!(v, &[1]); - /// assert_eq!(u, &[2, 3]); - /// - /// // A full range clears the vector, like `clear()` does - /// v.drain(..); - /// assert_eq!(v, &[]); - /// ``` - #[stable(feature = "drain", since = "1.6.0")] - pub fn drain<R>(&mut self, range: R) -> Drain<'_, T, A> - where - R: RangeBounds<usize>, - { - // Memory safety - // - // When the Drain is first created, it shortens the length of - // the source vector to make sure no uninitialized or moved-from elements - // are accessible at all if the Drain's destructor never gets to run. - // - // Drain will ptr::read out the values to remove. - // When finished, remaining tail of the vec is copied back to cover - // the hole, and the vector length is restored to the new length. - // - let len = self.len(); - let Range { start, end } = slice::range(range, ..len); - - unsafe { - // set self.vec length's to start, to be safe in case Drain is leaked - self.set_len(start); - let range_slice = slice::from_raw_parts(self.as_ptr().add(start), end - start); - Drain { - tail_start: end, - tail_len: len - end, - iter: range_slice.iter(), - vec: NonNull::from(self), - } - } - } - - /// Clears the vector, removing all values. - /// - /// Note that this method has no effect on the allocated capacity - /// of the vector. - /// - /// # Examples - /// - /// ``` - /// let mut v = vec![1, 2, 3]; - /// - /// v.clear(); - /// - /// assert!(v.is_empty()); - /// ``` - #[inline] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn clear(&mut self) { - let elems: *mut [T] = self.as_mut_slice(); - - // SAFETY: - // - `elems` comes directly from `as_mut_slice` and is therefore valid. - // - Setting `self.len` before calling `drop_in_place` means that, - // if an element's `Drop` impl panics, the vector's `Drop` impl will - // do nothing (leaking the rest of the elements) instead of dropping - // some twice. - unsafe { - self.len = 0; - ptr::drop_in_place(elems); - } - } - - /// Returns the number of elements in the vector, also referred to - /// as its 'length'. - /// - /// # Examples - /// - /// ``` - /// let a = vec![1, 2, 3]; - /// assert_eq!(a.len(), 3); - /// ``` - #[inline] - #[stable(feature = "rust1", since = "1.0.0")] - pub fn len(&self) -> usize { - self.len - } - - /// Returns `true` if the vector contains no elements. - /// - /// # Examples - /// - /// ``` - /// let mut v = Vec::new(); - /// assert!(v.is_empty()); - /// - /// v.push(1); - /// assert!(!v.is_empty()); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn is_empty(&self) -> bool { - self.len() == 0 - } - - /// Splits the collection into two at the given index. - /// - /// Returns a newly allocated vector containing the elements in the range - /// `[at, len)`. After the call, the original vector will be left containing - /// the elements `[0, at)` with its previous capacity unchanged. - /// - /// # Panics - /// - /// Panics if `at > len`. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1, 2, 3]; - /// let vec2 = vec.split_off(1); - /// assert_eq!(vec, [1]); - /// assert_eq!(vec2, [2, 3]); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[inline] - #[must_use = "use `.truncate()` if you don't need the other half"] - #[stable(feature = "split_off", since = "1.4.0")] - pub fn split_off(&mut self, at: usize) -> Self - where - A: Clone, - { - #[cold] - #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] - #[track_caller] - fn assert_failed(at: usize, len: usize) -> ! { - panic!("`at` split index (is {at}) should be <= len (is {len})"); - } - - if at > self.len() { - assert_failed(at, self.len()); - } - - if at == 0 { - // the new vector can take over the original buffer and avoid the copy - return mem::replace( - self, - Vec::with_capacity_in(self.capacity(), self.allocator().clone()), - ); - } - - let other_len = self.len - at; - let mut other = Vec::with_capacity_in(other_len, self.allocator().clone()); - - // Unsafely `set_len` and copy items to `other`. - unsafe { - self.set_len(at); - other.set_len(other_len); - - ptr::copy_nonoverlapping(self.as_ptr().add(at), other.as_mut_ptr(), other.len()); - } - other - } - - /// Resizes the `Vec` in-place so that `len` is equal to `new_len`. - /// - /// If `new_len` is greater than `len`, the `Vec` is extended by the - /// difference, with each additional slot filled with the result of - /// calling the closure `f`. The return values from `f` will end up - /// in the `Vec` in the order they have been generated. - /// - /// If `new_len` is less than `len`, the `Vec` is simply truncated. - /// - /// This method uses a closure to create new values on every push. If - /// you'd rather [`Clone`] a given value, use [`Vec::resize`]. If you - /// want to use the [`Default`] trait to generate values, you can - /// pass [`Default::default`] as the second argument. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1, 2, 3]; - /// vec.resize_with(5, Default::default); - /// assert_eq!(vec, [1, 2, 3, 0, 0]); - /// - /// let mut vec = vec![]; - /// let mut p = 1; - /// vec.resize_with(4, || { p *= 2; p }); - /// assert_eq!(vec, [2, 4, 8, 16]); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "vec_resize_with", since = "1.33.0")] - pub fn resize_with<F>(&mut self, new_len: usize, f: F) - where - F: FnMut() -> T, - { - let len = self.len(); - if new_len > len { - self.extend_trusted(iter::repeat_with(f).take(new_len - len)); - } else { - self.truncate(new_len); - } - } - - /// Consumes and leaks the `Vec`, returning a mutable reference to the contents, - /// `&'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`. - /// - /// As of Rust 1.57, this method does not reallocate or shrink the `Vec`, - /// so the leaked allocation may include unused capacity that is not part - /// of the returned slice. - /// - /// 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. - /// - /// # Examples - /// - /// Simple usage: - /// - /// ``` - /// let x = vec![1, 2, 3]; - /// let static_ref: &'static mut [usize] = x.leak(); - /// static_ref[0] += 1; - /// assert_eq!(static_ref, &[2, 2, 3]); - /// ``` - #[stable(feature = "vec_leak", since = "1.47.0")] - #[inline] - pub fn leak<'a>(self) -> &'a mut [T] - where - A: 'a, - { - let mut me = ManuallyDrop::new(self); - unsafe { slice::from_raw_parts_mut(me.as_mut_ptr(), me.len) } - } - - /// Returns the remaining spare capacity of the vector as a slice of - /// `MaybeUninit<T>`. - /// - /// The returned slice can be used to fill the vector with data (e.g. by - /// reading from a file) before marking the data as initialized using the - /// [`set_len`] method. - /// - /// [`set_len`]: Vec::set_len - /// - /// # Examples - /// - /// ``` - /// // Allocate vector big enough for 10 elements. - /// let mut v = Vec::with_capacity(10); - /// - /// // Fill in the first 3 elements. - /// let uninit = v.spare_capacity_mut(); - /// uninit[0].write(0); - /// uninit[1].write(1); - /// uninit[2].write(2); - /// - /// // Mark the first 3 elements of the vector as being initialized. - /// unsafe { - /// v.set_len(3); - /// } - /// - /// assert_eq!(&v, &[0, 1, 2]); - /// ``` - #[stable(feature = "vec_spare_capacity", since = "1.60.0")] - #[inline] - pub fn spare_capacity_mut(&mut self) -> &mut [MaybeUninit<T>] { - // Note: - // This method is not implemented in terms of `split_at_spare_mut`, - // to prevent invalidation of pointers to the buffer. - unsafe { - slice::from_raw_parts_mut( - self.as_mut_ptr().add(self.len) as *mut MaybeUninit<T>, - self.buf.capacity() - self.len, - ) - } - } - - /// Returns vector content as a slice of `T`, along with the remaining spare - /// capacity of the vector as a slice of `MaybeUninit<T>`. - /// - /// The returned spare capacity slice can be used to fill the vector with data - /// (e.g. by reading from a file) before marking the data as initialized using - /// the [`set_len`] method. - /// - /// [`set_len`]: Vec::set_len - /// - /// Note that this is a low-level API, which should be used with care for - /// optimization purposes. If you need to append data to a `Vec` - /// you can use [`push`], [`extend`], [`extend_from_slice`], - /// [`extend_from_within`], [`insert`], [`append`], [`resize`] or - /// [`resize_with`], depending on your exact needs. - /// - /// [`push`]: Vec::push - /// [`extend`]: Vec::extend - /// [`extend_from_slice`]: Vec::extend_from_slice - /// [`extend_from_within`]: Vec::extend_from_within - /// [`insert`]: Vec::insert - /// [`append`]: Vec::append - /// [`resize`]: Vec::resize - /// [`resize_with`]: Vec::resize_with - /// - /// # Examples - /// - /// ``` - /// #![feature(vec_split_at_spare)] - /// - /// let mut v = vec![1, 1, 2]; - /// - /// // Reserve additional space big enough for 10 elements. - /// v.reserve(10); - /// - /// let (init, uninit) = v.split_at_spare_mut(); - /// let sum = init.iter().copied().sum::<u32>(); - /// - /// // Fill in the next 4 elements. - /// uninit[0].write(sum); - /// uninit[1].write(sum * 2); - /// uninit[2].write(sum * 3); - /// uninit[3].write(sum * 4); - /// - /// // Mark the 4 elements of the vector as being initialized. - /// unsafe { - /// let len = v.len(); - /// v.set_len(len + 4); - /// } - /// - /// assert_eq!(&v, &[1, 1, 2, 4, 8, 12, 16]); - /// ``` - #[unstable(feature = "vec_split_at_spare", issue = "81944")] - #[inline] - pub fn split_at_spare_mut(&mut self) -> (&mut [T], &mut [MaybeUninit<T>]) { - // SAFETY: - // - len is ignored and so never changed - let (init, spare, _) = unsafe { self.split_at_spare_mut_with_len() }; - (init, spare) - } - - /// Safety: changing returned .2 (&mut usize) is considered the same as calling `.set_len(_)`. - /// - /// This method provides unique access to all vec parts at once in `extend_from_within`. - unsafe fn split_at_spare_mut_with_len( - &mut self, - ) -> (&mut [T], &mut [MaybeUninit<T>], &mut usize) { - let ptr = self.as_mut_ptr(); - // SAFETY: - // - `ptr` is guaranteed to be valid for `self.len` elements - // - but the allocation extends out to `self.buf.capacity()` elements, possibly - // uninitialized - let spare_ptr = unsafe { ptr.add(self.len) }; - let spare_ptr = spare_ptr.cast::<MaybeUninit<T>>(); - let spare_len = self.buf.capacity() - self.len; - - // SAFETY: - // - `ptr` is guaranteed to be valid for `self.len` elements - // - `spare_ptr` is pointing one element past the buffer, so it doesn't overlap with `initialized` - unsafe { - let initialized = slice::from_raw_parts_mut(ptr, self.len); - let spare = slice::from_raw_parts_mut(spare_ptr, spare_len); - - (initialized, spare, &mut self.len) - } - } -} - -impl<T: Clone, A: Allocator> Vec<T, A> { - /// Resizes the `Vec` in-place so that `len` is equal to `new_len`. - /// - /// If `new_len` is greater than `len`, the `Vec` is extended by the - /// difference, with each additional slot filled with `value`. - /// If `new_len` is less than `len`, the `Vec` is simply truncated. - /// - /// This method requires `T` to implement [`Clone`], - /// in order to be able to clone the passed value. - /// If you need more flexibility (or want to rely on [`Default`] instead of - /// [`Clone`]), use [`Vec::resize_with`]. - /// If you only need to resize to a smaller size, use [`Vec::truncate`]. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec!["hello"]; - /// vec.resize(3, "world"); - /// assert_eq!(vec, ["hello", "world", "world"]); - /// - /// let mut vec = vec![1, 2, 3, 4]; - /// vec.resize(2, 0); - /// assert_eq!(vec, [1, 2]); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "vec_resize", since = "1.5.0")] - pub fn resize(&mut self, new_len: usize, value: T) { - let len = self.len(); - - if new_len > len { - self.extend_with(new_len - len, value) - } else { - self.truncate(new_len); - } - } - - /// Tries to resize the `Vec` in-place so that `len` is equal to `new_len`. - /// - /// If `new_len` is greater than `len`, the `Vec` is extended by the - /// difference, with each additional slot filled with `value`. - /// If `new_len` is less than `len`, the `Vec` is simply truncated. - /// - /// This method requires `T` to implement [`Clone`], - /// in order to be able to clone the passed value. - /// If you need more flexibility (or want to rely on [`Default`] instead of - /// [`Clone`]), use [`Vec::resize_with`]. - /// If you only need to resize to a smaller size, use [`Vec::truncate`]. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec!["hello"]; - /// vec.try_resize(3, "world").unwrap(); - /// assert_eq!(vec, ["hello", "world", "world"]); - /// - /// let mut vec = vec![1, 2, 3, 4]; - /// vec.try_resize(2, 0).unwrap(); - /// assert_eq!(vec, [1, 2]); - /// - /// let mut vec = vec![42]; - /// let result = vec.try_resize(usize::MAX, 0); - /// assert!(result.is_err()); - /// ``` - #[stable(feature = "kernel", since = "1.0.0")] - pub fn try_resize(&mut self, new_len: usize, value: T) -> Result<(), TryReserveError> { - let len = self.len(); - - if new_len > len { - self.try_extend_with(new_len - len, value) - } else { - self.truncate(new_len); - Ok(()) - } - } - - /// Clones and appends all elements in a slice to the `Vec`. - /// - /// Iterates over the slice `other`, clones each element, and then appends - /// it to this `Vec`. The `other` slice is traversed in-order. - /// - /// Note that this function is same as [`extend`] except that it is - /// specialized to work with slices instead. If and when Rust gets - /// specialization this function will likely be deprecated (but still - /// available). - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1]; - /// vec.extend_from_slice(&[2, 3, 4]); - /// assert_eq!(vec, [1, 2, 3, 4]); - /// ``` - /// - /// [`extend`]: Vec::extend - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "vec_extend_from_slice", since = "1.6.0")] - pub fn extend_from_slice(&mut self, other: &[T]) { - self.spec_extend(other.iter()) - } - - /// Tries to clone and append all elements in a slice to the `Vec`. - /// - /// Iterates over the slice `other`, clones each element, and then appends - /// it to this `Vec`. The `other` slice is traversed in-order. - /// - /// Note that this function is same as [`extend`] except that it is - /// specialized to work with slices instead. If and when Rust gets - /// specialization this function will likely be deprecated (but still - /// available). - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1]; - /// vec.try_extend_from_slice(&[2, 3, 4]).unwrap(); - /// assert_eq!(vec, [1, 2, 3, 4]); - /// ``` - /// - /// [`extend`]: Vec::extend - #[stable(feature = "kernel", since = "1.0.0")] - pub fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError> { - self.try_spec_extend(other.iter()) - } - - /// Copies elements from `src` range to the end of the vector. - /// - /// # Panics - /// - /// Panics if the starting point is greater than the end point or if - /// the end point is greater than the length of the vector. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![0, 1, 2, 3, 4]; - /// - /// vec.extend_from_within(2..); - /// assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4]); - /// - /// vec.extend_from_within(..2); - /// assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4, 0, 1]); - /// - /// vec.extend_from_within(4..8); - /// assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4, 0, 1, 4, 2, 3, 4]); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[stable(feature = "vec_extend_from_within", since = "1.53.0")] - pub fn extend_from_within<R>(&mut self, src: R) - where - R: RangeBounds<usize>, - { - let range = slice::range(src, ..self.len()); - self.reserve(range.len()); - - // SAFETY: - // - `slice::range` guarantees that the given range is valid for indexing self - unsafe { - self.spec_extend_from_within(range); - } - } -} - -impl<T, A: Allocator, const N: usize> Vec<[T; N], A> { - /// Takes a `Vec<[T; N]>` and flattens it into a `Vec<T>`. - /// - /// # Panics - /// - /// Panics if the length of the resulting vector would overflow a `usize`. - /// - /// This is only possible when flattening a vector of arrays of zero-sized - /// types, and thus tends to be irrelevant in practice. If - /// `size_of::<T>() > 0`, this will never panic. - /// - /// # Examples - /// - /// ``` - /// #![feature(slice_flatten)] - /// - /// let mut vec = vec![[1, 2, 3], [4, 5, 6], [7, 8, 9]]; - /// assert_eq!(vec.pop(), Some([7, 8, 9])); - /// - /// let mut flattened = vec.into_flattened(); - /// assert_eq!(flattened.pop(), Some(6)); - /// ``` - #[unstable(feature = "slice_flatten", issue = "95629")] - pub fn into_flattened(self) -> Vec<T, A> { - let (ptr, len, cap, alloc) = self.into_raw_parts_with_alloc(); - let (new_len, new_cap) = if T::IS_ZST { - (len.checked_mul(N).expect("vec len overflow"), usize::MAX) - } else { - // SAFETY: - // - `cap * N` cannot overflow because the allocation is already in - // the address space. - // - Each `[T; N]` has `N` valid elements, so there are `len * N` - // valid elements in the allocation. - unsafe { (len.unchecked_mul(N), cap.unchecked_mul(N)) } - }; - // SAFETY: - // - `ptr` was allocated by `self` - // - `ptr` is well-aligned because `[T; N]` has the same alignment as `T`. - // - `new_cap` refers to the same sized allocation as `cap` because - // `new_cap * size_of::<T>()` == `cap * size_of::<[T; N]>()` - // - `len` <= `cap`, so `len * N` <= `cap * N`. - unsafe { Vec::<T, A>::from_raw_parts_in(ptr.cast(), new_len, new_cap, alloc) } - } -} - -impl<T: Clone, A: Allocator> Vec<T, A> { - #[cfg(not(no_global_oom_handling))] - /// Extend the vector by `n` clones of value. - fn extend_with(&mut self, n: usize, value: T) { - self.reserve(n); - - unsafe { - let mut ptr = self.as_mut_ptr().add(self.len()); - // Use SetLenOnDrop to work around bug where compiler - // might not realize the store through `ptr` through self.set_len() - // don't alias. - let mut local_len = SetLenOnDrop::new(&mut self.len); - - // Write all elements except the last one - for _ in 1..n { - ptr::write(ptr, value.clone()); - ptr = ptr.add(1); - // Increment the length in every step in case clone() panics - local_len.increment_len(1); - } - - if n > 0 { - // We can write the last element directly without cloning needlessly - ptr::write(ptr, value); - local_len.increment_len(1); - } - - // len set by scope guard - } - } - - /// Try to extend the vector by `n` clones of value. - fn try_extend_with(&mut self, n: usize, value: T) -> Result<(), TryReserveError> { - self.try_reserve(n)?; - - unsafe { - let mut ptr = self.as_mut_ptr().add(self.len()); - // Use SetLenOnDrop to work around bug where compiler - // might not realize the store through `ptr` through self.set_len() - // don't alias. - let mut local_len = SetLenOnDrop::new(&mut self.len); - - // Write all elements except the last one - for _ in 1..n { - ptr::write(ptr, value.clone()); - ptr = ptr.add(1); - // Increment the length in every step in case clone() panics - local_len.increment_len(1); - } - - if n > 0 { - // We can write the last element directly without cloning needlessly - ptr::write(ptr, value); - local_len.increment_len(1); - } - - // len set by scope guard - Ok(()) - } - } -} - -impl<T: PartialEq, A: Allocator> Vec<T, A> { - /// Removes consecutive repeated elements in the vector according to the - /// [`PartialEq`] trait implementation. - /// - /// If the vector is sorted, this removes all duplicates. - /// - /// # Examples - /// - /// ``` - /// let mut vec = vec![1, 2, 2, 3, 2]; - /// - /// vec.dedup(); - /// - /// assert_eq!(vec, [1, 2, 3, 2]); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - #[inline] - pub fn dedup(&mut self) { - self.dedup_by(|a, b| a == b) - } -} - -//////////////////////////////////////////////////////////////////////////////// -// Internal methods and functions -//////////////////////////////////////////////////////////////////////////////// - -#[doc(hidden)] -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> { - <T as SpecFromElem>::from_elem(elem, n, Global) -} - -#[doc(hidden)] -#[cfg(not(no_global_oom_handling))] -#[unstable(feature = "allocator_api", issue = "32838")] -pub fn from_elem_in<T: Clone, A: Allocator>(elem: T, n: usize, alloc: A) -> Vec<T, A> { - <T as SpecFromElem>::from_elem(elem, n, alloc) -} - -#[cfg(not(no_global_oom_handling))] -trait ExtendFromWithinSpec { - /// # Safety - /// - /// - `src` needs to be valid index - /// - `self.capacity() - self.len()` must be `>= src.len()` - unsafe fn spec_extend_from_within(&mut self, src: Range<usize>); -} - -#[cfg(not(no_global_oom_handling))] -impl<T: Clone, A: Allocator> ExtendFromWithinSpec for Vec<T, A> { - default unsafe fn spec_extend_from_within(&mut self, src: Range<usize>) { - // SAFETY: - // - len is increased only after initializing elements - let (this, spare, len) = unsafe { self.split_at_spare_mut_with_len() }; - - // SAFETY: - // - caller guarantees that src is a valid index - let to_clone = unsafe { this.get_unchecked(src) }; - - iter::zip(to_clone, spare) - .map(|(src, dst)| dst.write(src.clone())) - // Note: - // - Element was just initialized with `MaybeUninit::write`, so it's ok to increase len - // - len is increased after each element to prevent leaks (see issue #82533) - .for_each(|_| *len += 1); - } -} - -#[cfg(not(no_global_oom_handling))] -impl<T: Copy, A: Allocator> ExtendFromWithinSpec for Vec<T, A> { - unsafe fn spec_extend_from_within(&mut self, src: Range<usize>) { - let count = src.len(); - { - let (init, spare) = self.split_at_spare_mut(); - - // SAFETY: - // - caller guarantees that `src` is a valid index - let source = unsafe { init.get_unchecked(src) }; - - // SAFETY: - // - Both pointers are created from unique slice references (`&mut [_]`) - // so they are valid and do not overlap. - // - Elements are :Copy so it's OK to copy them, without doing - // anything with the original values - // - `count` is equal to the len of `source`, so source is valid for - // `count` reads - // - `.reserve(count)` guarantees that `spare.len() >= count` so spare - // is valid for `count` writes - unsafe { ptr::copy_nonoverlapping(source.as_ptr(), spare.as_mut_ptr() as _, count) }; - } - - // SAFETY: - // - The elements were just initialized by `copy_nonoverlapping` - self.len += count; - } -} - -//////////////////////////////////////////////////////////////////////////////// -// Common trait implementations for Vec -//////////////////////////////////////////////////////////////////////////////// - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> ops::Deref for Vec<T, A> { - type Target = [T]; - - #[inline] - fn deref(&self) -> &[T] { - unsafe { slice::from_raw_parts(self.as_ptr(), self.len) } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> ops::DerefMut for Vec<T, A> { - #[inline] - fn deref_mut(&mut self) -> &mut [T] { - unsafe { slice::from_raw_parts_mut(self.as_mut_ptr(), self.len) } - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: Clone, A: Allocator + Clone> Clone for Vec<T, A> { - #[cfg(not(test))] - fn clone(&self) -> Self { - let alloc = self.allocator().clone(); - <[T]>::to_vec_in(&**self, alloc) - } - - // HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is - // required for this method definition, is not available. Instead use the - // `slice::to_vec` function which is only available with cfg(test) - // NB see the slice::hack module in slice.rs for more information - #[cfg(test)] - fn clone(&self) -> Self { - let alloc = self.allocator().clone(); - crate::slice::to_vec(&**self, alloc) - } - - fn clone_from(&mut self, other: &Self) { - crate::slice::SpecCloneIntoVec::clone_into(other.as_slice(), self); - } -} - -/// The hash of a vector is the same as that of the corresponding slice, -/// as required by the `core::borrow::Borrow` implementation. -/// -/// ``` -/// use std::hash::BuildHasher; -/// -/// let b = std::hash::RandomState::new(); -/// let v: Vec<u8> = vec![0xa8, 0x3c, 0x09]; -/// let s: &[u8] = &[0xa8, 0x3c, 0x09]; -/// assert_eq!(b.hash_one(v), b.hash_one(s)); -/// ``` -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: Hash, A: Allocator> Hash for Vec<T, A> { - #[inline] - fn hash<H: Hasher>(&self, state: &mut H) { - Hash::hash(&**self, state) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -#[rustc_on_unimplemented( - message = "vector indices are of type `usize` or ranges of `usize`", - label = "vector indices are of type `usize` or ranges of `usize`" -)] -impl<T, I: SliceIndex<[T]>, A: Allocator> Index<I> for Vec<T, A> { - type Output = I::Output; - - #[inline] - fn index(&self, index: I) -> &Self::Output { - Index::index(&**self, index) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -#[rustc_on_unimplemented( - message = "vector indices are of type `usize` or ranges of `usize`", - label = "vector indices are of type `usize` or ranges of `usize`" -)] -impl<T, I: SliceIndex<[T]>, A: Allocator> IndexMut<I> for Vec<T, A> { - #[inline] - fn index_mut(&mut self, index: I) -> &mut Self::Output { - IndexMut::index_mut(&mut **self, index) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -impl<T> FromIterator<T> for Vec<T> { - #[inline] - fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Vec<T> { - <Self as SpecFromIter<T, I::IntoIter>>::from_iter(iter.into_iter()) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> IntoIterator for Vec<T, A> { - type Item = T; - type IntoIter = IntoIter<T, A>; - - /// Creates a consuming iterator, that is, one that moves each value out of - /// the vector (from start to end). The vector cannot be used after calling - /// this. - /// - /// # Examples - /// - /// ``` - /// let v = vec!["a".to_string(), "b".to_string()]; - /// let mut v_iter = v.into_iter(); - /// - /// let first_element: Option<String> = v_iter.next(); - /// - /// assert_eq!(first_element, Some("a".to_string())); - /// assert_eq!(v_iter.next(), Some("b".to_string())); - /// assert_eq!(v_iter.next(), None); - /// ``` - #[inline] - fn into_iter(self) -> Self::IntoIter { - unsafe { - let mut me = ManuallyDrop::new(self); - let alloc = ManuallyDrop::new(ptr::read(me.allocator())); - let begin = me.as_mut_ptr(); - let end = if T::IS_ZST { - begin.wrapping_byte_add(me.len()) - } else { - begin.add(me.len()) as *const T - }; - let cap = me.buf.capacity(); - IntoIter { - buf: NonNull::new_unchecked(begin), - phantom: PhantomData, - cap, - alloc, - ptr: begin, - end, - } - } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<'a, T, A: Allocator> IntoIterator for &'a Vec<T, A> { - type Item = &'a T; - type IntoIter = slice::Iter<'a, T>; - - fn into_iter(self) -> Self::IntoIter { - self.iter() - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<'a, T, A: Allocator> IntoIterator for &'a mut Vec<T, A> { - type Item = &'a mut T; - type IntoIter = slice::IterMut<'a, T>; - - fn into_iter(self) -> Self::IntoIter { - self.iter_mut() - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> Extend<T> for Vec<T, A> { - #[inline] - fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) { - <Self as SpecExtend<T, I::IntoIter>>::spec_extend(self, iter.into_iter()) - } - - #[inline] - fn extend_one(&mut self, item: T) { - self.push(item); - } - - #[inline] - fn extend_reserve(&mut self, additional: usize) { - self.reserve(additional); - } -} - -impl<T, A: Allocator> Vec<T, A> { - // leaf method to which various SpecFrom/SpecExtend implementations delegate when - // they have no further optimizations to apply - #[cfg(not(no_global_oom_handling))] - fn extend_desugared<I: Iterator<Item = T>>(&mut self, mut iterator: I) { - // This is the case for a general iterator. - // - // This function should be the moral equivalent of: - // - // for item in iterator { - // self.push(item); - // } - while let Some(element) = iterator.next() { - let len = self.len(); - if len == self.capacity() { - let (lower, _) = iterator.size_hint(); - self.reserve(lower.saturating_add(1)); - } - unsafe { - ptr::write(self.as_mut_ptr().add(len), element); - // Since next() executes user code which can panic we have to bump the length - // after each step. - // NB can't overflow since we would have had to alloc the address space - self.set_len(len + 1); - } - } - } - - // leaf method to which various SpecFrom/SpecExtend implementations delegate when - // they have no further optimizations to apply - fn try_extend_desugared<I: Iterator<Item = T>>(&mut self, mut iterator: I) -> Result<(), TryReserveError> { - // This is the case for a general iterator. - // - // This function should be the moral equivalent of: - // - // for item in iterator { - // self.push(item); - // } - while let Some(element) = iterator.next() { - let len = self.len(); - if len == self.capacity() { - let (lower, _) = iterator.size_hint(); - self.try_reserve(lower.saturating_add(1))?; - } - unsafe { - ptr::write(self.as_mut_ptr().add(len), element); - // Since next() executes user code which can panic we have to bump the length - // after each step. - // NB can't overflow since we would have had to alloc the address space - self.set_len(len + 1); - } - } - - Ok(()) - } - - // specific extend for `TrustedLen` iterators, called both by the specializations - // and internal places where resolving specialization makes compilation slower - #[cfg(not(no_global_oom_handling))] - fn extend_trusted(&mut self, iterator: impl iter::TrustedLen<Item = T>) { - let (low, high) = iterator.size_hint(); - if let Some(additional) = high { - debug_assert_eq!( - low, - additional, - "TrustedLen iterator's size hint is not exact: {:?}", - (low, high) - ); - self.reserve(additional); - unsafe { - let ptr = self.as_mut_ptr(); - let mut local_len = SetLenOnDrop::new(&mut self.len); - iterator.for_each(move |element| { - ptr::write(ptr.add(local_len.current_len()), element); - // Since the loop executes user code which can panic we have to update - // the length every step to correctly drop what we've written. - // NB can't overflow since we would have had to alloc the address space - local_len.increment_len(1); - }); - } - } else { - // Per TrustedLen contract a `None` upper bound means that the iterator length - // truly exceeds usize::MAX, which would eventually lead to a capacity overflow anyway. - // Since the other branch already panics eagerly (via `reserve()`) we do the same here. - // This avoids additional codegen for a fallback code path which would eventually - // panic anyway. - panic!("capacity overflow"); - } - } - - // specific extend for `TrustedLen` iterators, called both by the specializations - // and internal places where resolving specialization makes compilation slower - fn try_extend_trusted(&mut self, iterator: impl iter::TrustedLen<Item = T>) -> Result<(), TryReserveError> { - let (low, high) = iterator.size_hint(); - if let Some(additional) = high { - debug_assert_eq!( - low, - additional, - "TrustedLen iterator's size hint is not exact: {:?}", - (low, high) - ); - self.try_reserve(additional)?; - unsafe { - let ptr = self.as_mut_ptr(); - let mut local_len = SetLenOnDrop::new(&mut self.len); - iterator.for_each(move |element| { - ptr::write(ptr.add(local_len.current_len()), element); - // Since the loop executes user code which can panic we have to update - // the length every step to correctly drop what we've written. - // NB can't overflow since we would have had to alloc the address space - local_len.increment_len(1); - }); - } - Ok(()) - } else { - Err(TryReserveErrorKind::CapacityOverflow.into()) - } - } - - /// Creates a splicing iterator that replaces the specified range in the vector - /// with the given `replace_with` iterator and yields the removed items. - /// `replace_with` does not need to be the same length as `range`. - /// - /// `range` is removed even if the iterator is not consumed until the end. - /// - /// It is unspecified how many elements are removed from the vector - /// if the `Splice` value is leaked. - /// - /// The input iterator `replace_with` is only consumed when the `Splice` value is dropped. - /// - /// This is optimal if: - /// - /// * The tail (elements in the vector after `range`) is empty, - /// * or `replace_with` yields fewer or equal elements than `range`’s length - /// * or the lower bound of its `size_hint()` is exact. - /// - /// Otherwise, a temporary vector is allocated and the tail is moved twice. - /// - /// # Panics - /// - /// Panics if the starting point is greater than the end point or if - /// the end point is greater than the length of the vector. - /// - /// # Examples - /// - /// ``` - /// let mut v = vec![1, 2, 3, 4]; - /// let new = [7, 8, 9]; - /// let u: Vec<_> = v.splice(1..3, new).collect(); - /// assert_eq!(v, &[1, 7, 8, 9, 4]); - /// assert_eq!(u, &[2, 3]); - /// ``` - #[cfg(not(no_global_oom_handling))] - #[inline] - #[stable(feature = "vec_splice", since = "1.21.0")] - pub fn splice<R, I>(&mut self, range: R, replace_with: I) -> Splice<'_, I::IntoIter, A> - where - R: RangeBounds<usize>, - I: IntoIterator<Item = T>, - { - Splice { drain: self.drain(range), replace_with: replace_with.into_iter() } - } - - /// Creates an iterator which uses a closure to determine if an element should be removed. - /// - /// If the closure returns true, then the element is removed and yielded. - /// If the closure returns false, the element will remain in the vector and will not be yielded - /// by the iterator. - /// - /// If the returned `ExtractIf` is not exhausted, e.g. because it is dropped without iterating - /// or the iteration short-circuits, then the remaining elements will be retained. - /// Use [`retain`] with a negated predicate if you do not need the returned iterator. - /// - /// [`retain`]: Vec::retain - /// - /// Using this method is equivalent to the following code: - /// - /// ``` - /// # let some_predicate = |x: &mut i32| { *x == 2 || *x == 3 || *x == 6 }; - /// # let mut vec = vec![1, 2, 3, 4, 5, 6]; - /// let mut i = 0; - /// while i < vec.len() { - /// if some_predicate(&mut vec[i]) { - /// let val = vec.remove(i); - /// // your code here - /// } else { - /// i += 1; - /// } - /// } - /// - /// # assert_eq!(vec, vec![1, 4, 5]); - /// ``` - /// - /// But `extract_if` is easier to use. `extract_if` is also more efficient, - /// because it can backshift the elements of the array in bulk. - /// - /// Note that `extract_if` also lets you mutate every element in the filter closure, - /// regardless of whether you choose to keep or remove it. - /// - /// # Examples - /// - /// Splitting an array into evens and odds, reusing the original allocation: - /// - /// ``` - /// #![feature(extract_if)] - /// let mut numbers = vec![1, 2, 3, 4, 5, 6, 8, 9, 11, 13, 14, 15]; - /// - /// let evens = numbers.extract_if(|x| *x % 2 == 0).collect::<Vec<_>>(); - /// let odds = numbers; - /// - /// assert_eq!(evens, vec![2, 4, 6, 8, 14]); - /// assert_eq!(odds, vec![1, 3, 5, 9, 11, 13, 15]); - /// ``` - #[unstable(feature = "extract_if", reason = "recently added", issue = "43244")] - pub fn extract_if<F>(&mut self, filter: F) -> ExtractIf<'_, T, F, A> - where - F: FnMut(&mut T) -> bool, - { - let old_len = self.len(); - - // Guard against us getting leaked (leak amplification) - unsafe { - self.set_len(0); - } - - ExtractIf { vec: self, idx: 0, del: 0, old_len, pred: filter } - } -} - -/// Extend implementation that copies elements out of references before pushing them onto the Vec. -/// -/// This implementation is specialized for slice iterators, where it uses [`copy_from_slice`] to -/// append the entire slice at once. -/// -/// [`copy_from_slice`]: slice::copy_from_slice -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "extend_ref", since = "1.2.0")] -impl<'a, T: Copy + 'a, A: Allocator> Extend<&'a T> for Vec<T, A> { - fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) { - self.spec_extend(iter.into_iter()) - } - - #[inline] - fn extend_one(&mut self, &item: &'a T) { - self.push(item); - } - - #[inline] - fn extend_reserve(&mut self, additional: usize) { - self.reserve(additional); - } -} - -/// Implements comparison of vectors, [lexicographically](Ord#lexicographical-comparison). -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A1, A2> PartialOrd<Vec<T, A2>> for Vec<T, A1> -where - T: PartialOrd, - A1: Allocator, - A2: Allocator, -{ - #[inline] - fn partial_cmp(&self, other: &Vec<T, A2>) -> Option<Ordering> { - PartialOrd::partial_cmp(&**self, &**other) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: Eq, A: Allocator> Eq for Vec<T, A> {} - -/// Implements ordering of vectors, [lexicographically](Ord#lexicographical-comparison). -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: Ord, A: Allocator> Ord for Vec<T, A> { - #[inline] - fn cmp(&self, other: &Self) -> Ordering { - Ord::cmp(&**self, &**other) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -unsafe impl<#[may_dangle] T, A: Allocator> Drop for Vec<T, A> { - fn drop(&mut self) { - unsafe { - // use drop for [T] - // use a raw slice to refer to the elements of the vector as weakest necessary type; - // could avoid questions of validity in certain cases - ptr::drop_in_place(ptr::slice_from_raw_parts_mut(self.as_mut_ptr(), self.len)) - } - // RawVec handles deallocation - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T> Default for Vec<T> { - /// Creates an empty `Vec<T>`. - /// - /// The vector will not allocate until elements are pushed onto it. - fn default() -> Vec<T> { - Vec::new() - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: fmt::Debug, A: Allocator> fmt::Debug for Vec<T, A> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> AsRef<Vec<T, A>> for Vec<T, A> { - fn as_ref(&self) -> &Vec<T, A> { - self - } -} - -#[stable(feature = "vec_as_mut", since = "1.5.0")] -impl<T, A: Allocator> AsMut<Vec<T, A>> for Vec<T, A> { - fn as_mut(&mut self) -> &mut Vec<T, A> { - self - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> AsRef<[T]> for Vec<T, A> { - fn as_ref(&self) -> &[T] { - self - } -} - -#[stable(feature = "vec_as_mut", since = "1.5.0")] -impl<T, A: Allocator> AsMut<[T]> for Vec<T, A> { - fn as_mut(&mut self) -> &mut [T] { - self - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: Clone> From<&[T]> for Vec<T> { - /// Allocate a `Vec<T>` and fill it by cloning `s`'s items. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(Vec::from(&[1, 2, 3][..]), vec![1, 2, 3]); - /// ``` - #[cfg(not(test))] - fn from(s: &[T]) -> Vec<T> { - s.to_vec() - } - #[cfg(test)] - fn from(s: &[T]) -> Vec<T> { - crate::slice::to_vec(s, Global) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "vec_from_mut", since = "1.19.0")] -impl<T: Clone> From<&mut [T]> for Vec<T> { - /// Allocate a `Vec<T>` and fill it by cloning `s`'s items. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(Vec::from(&mut [1, 2, 3][..]), vec![1, 2, 3]); - /// ``` - #[cfg(not(test))] - fn from(s: &mut [T]) -> Vec<T> { - s.to_vec() - } - #[cfg(test)] - fn from(s: &mut [T]) -> Vec<T> { - crate::slice::to_vec(s, Global) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "vec_from_array_ref", since = "1.74.0")] -impl<T: Clone, const N: usize> From<&[T; N]> for Vec<T> { - /// Allocate a `Vec<T>` and fill it by cloning `s`'s items. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(Vec::from(&[1, 2, 3]), vec![1, 2, 3]); - /// ``` - fn from(s: &[T; N]) -> Vec<T> { - Self::from(s.as_slice()) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "vec_from_array_ref", since = "1.74.0")] -impl<T: Clone, const N: usize> From<&mut [T; N]> for Vec<T> { - /// Allocate a `Vec<T>` and fill it by cloning `s`'s items. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(Vec::from(&mut [1, 2, 3]), vec![1, 2, 3]); - /// ``` - fn from(s: &mut [T; N]) -> Vec<T> { - Self::from(s.as_mut_slice()) - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "vec_from_array", since = "1.44.0")] -impl<T, const N: usize> From<[T; N]> for Vec<T> { - /// Allocate a `Vec<T>` and move `s`'s items into it. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(Vec::from([1, 2, 3]), vec![1, 2, 3]); - /// ``` - #[cfg(not(test))] - fn from(s: [T; N]) -> Vec<T> { - <[T]>::into_vec(Box::new(s)) - } - - #[cfg(test)] - fn from(s: [T; N]) -> Vec<T> { - crate::slice::into_vec(Box::new(s)) - } -} - -#[cfg(not(no_borrow))] -#[stable(feature = "vec_from_cow_slice", since = "1.14.0")] -impl<'a, T> From<Cow<'a, [T]>> for Vec<T> -where - [T]: ToOwned<Owned = Vec<T>>, -{ - /// Convert a clone-on-write slice into a vector. - /// - /// If `s` already owns a `Vec<T>`, it will be returned directly. - /// If `s` is borrowing a slice, a new `Vec<T>` will be allocated and - /// filled by cloning `s`'s items into it. - /// - /// # Examples - /// - /// ``` - /// # use std::borrow::Cow; - /// let o: Cow<'_, [i32]> = Cow::Owned(vec![1, 2, 3]); - /// let b: Cow<'_, [i32]> = Cow::Borrowed(&[1, 2, 3]); - /// assert_eq!(Vec::from(o), Vec::from(b)); - /// ``` - fn from(s: Cow<'a, [T]>) -> Vec<T> { - s.into_owned() - } -} - -// note: test pulls in std, which causes errors here -#[cfg(not(test))] -#[stable(feature = "vec_from_box", since = "1.18.0")] -impl<T, A: Allocator> From<Box<[T], A>> for Vec<T, A> { - /// Convert a boxed slice into a vector by transferring ownership of - /// the existing heap allocation. - /// - /// # Examples - /// - /// ``` - /// let b: Box<[i32]> = vec![1, 2, 3].into_boxed_slice(); - /// assert_eq!(Vec::from(b), vec![1, 2, 3]); - /// ``` - fn from(s: Box<[T], A>) -> Self { - s.into_vec() - } -} - -// note: test pulls in std, which causes errors here -#[cfg(not(no_global_oom_handling))] -#[cfg(not(test))] -#[stable(feature = "box_from_vec", since = "1.20.0")] -impl<T, A: Allocator> From<Vec<T, A>> for Box<[T], A> { - /// Convert a vector into a boxed slice. - /// - /// If `v` has excess capacity, its items will be moved into a - /// newly-allocated buffer with exactly the right capacity. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(Box::from(vec![1, 2, 3]), vec![1, 2, 3].into_boxed_slice()); - /// ``` - /// - /// Any excess capacity is removed: - /// ``` - /// let mut vec = Vec::with_capacity(10); - /// vec.extend([1, 2, 3]); - /// - /// assert_eq!(Box::from(vec), vec![1, 2, 3].into_boxed_slice()); - /// ``` - fn from(v: Vec<T, A>) -> Self { - v.into_boxed_slice() - } -} - -#[cfg(not(no_global_oom_handling))] -#[stable(feature = "rust1", since = "1.0.0")] -impl From<&str> for Vec<u8> { - /// Allocate a `Vec<u8>` and fill it with a UTF-8 string. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(Vec::from("123"), vec![b'1', b'2', b'3']); - /// ``` - fn from(s: &str) -> Vec<u8> { - From::from(s.as_bytes()) - } -} - -#[stable(feature = "array_try_from_vec", since = "1.48.0")] -impl<T, A: Allocator, const N: usize> TryFrom<Vec<T, A>> for [T; N] { - type Error = Vec<T, A>; - - /// Gets the entire contents of the `Vec<T>` as an array, - /// if its size exactly matches that of the requested array. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(vec![1, 2, 3].try_into(), Ok([1, 2, 3])); - /// assert_eq!(<Vec<i32>>::new().try_into(), Ok([])); - /// ``` - /// - /// If the length doesn't match, the input comes back in `Err`: - /// ``` - /// let r: Result<[i32; 4], _> = (0..10).collect::<Vec<_>>().try_into(); - /// assert_eq!(r, Err(vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9])); - /// ``` - /// - /// If you're fine with just getting a prefix of the `Vec<T>`, - /// you can call [`.truncate(N)`](Vec::truncate) first. - /// ``` - /// let mut v = String::from("hello world").into_bytes(); - /// v.sort(); - /// v.truncate(2); - /// let [a, b]: [_; 2] = v.try_into().unwrap(); - /// assert_eq!(a, b' '); - /// assert_eq!(b, b'd'); - /// ``` - fn try_from(mut vec: Vec<T, A>) -> Result<[T; N], Vec<T, A>> { - if vec.len() != N { - return Err(vec); - } - - // SAFETY: `.set_len(0)` is always sound. - unsafe { vec.set_len(0) }; - - // SAFETY: A `Vec`'s pointer is always aligned properly, and - // the alignment the array needs is the same as the items. - // We checked earlier that we have sufficient items. - // The items will not double-drop as the `set_len` - // tells the `Vec` not to also drop them. - let array = unsafe { ptr::read(vec.as_ptr() as *const [T; N]) }; - Ok(array) - } -} diff --git a/rust/alloc/vec/partial_eq.rs b/rust/alloc/vec/partial_eq.rs deleted file mode 100644 index 10ad4e4922..0000000000 --- a/rust/alloc/vec/partial_eq.rs +++ /dev/null @@ -1,49 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -use crate::alloc::Allocator; -#[cfg(not(no_global_oom_handling))] -use crate::borrow::Cow; - -use super::Vec; - -macro_rules! __impl_slice_eq1 { - ([$($vars:tt)*] $lhs:ty, $rhs:ty $(where $ty:ty: $bound:ident)?, #[$stability:meta]) => { - #[$stability] - impl<T, U, $($vars)*> PartialEq<$rhs> for $lhs - where - T: PartialEq<U>, - $($ty: $bound)? - { - #[inline] - fn eq(&self, other: &$rhs) -> bool { self[..] == other[..] } - #[inline] - fn ne(&self, other: &$rhs) -> bool { self[..] != other[..] } - } - } -} - -__impl_slice_eq1! { [A1: Allocator, A2: Allocator] Vec<T, A1>, Vec<U, A2>, #[stable(feature = "rust1", since = "1.0.0")] } -__impl_slice_eq1! { [A: Allocator] Vec<T, A>, &[U], #[stable(feature = "rust1", since = "1.0.0")] } -__impl_slice_eq1! { [A: Allocator] Vec<T, A>, &mut [U], #[stable(feature = "rust1", since = "1.0.0")] } -__impl_slice_eq1! { [A: Allocator] &[T], Vec<U, A>, #[stable(feature = "partialeq_vec_for_ref_slice", since = "1.46.0")] } -__impl_slice_eq1! { [A: Allocator] &mut [T], Vec<U, A>, #[stable(feature = "partialeq_vec_for_ref_slice", since = "1.46.0")] } -__impl_slice_eq1! { [A: Allocator] Vec<T, A>, [U], #[stable(feature = "partialeq_vec_for_slice", since = "1.48.0")] } -__impl_slice_eq1! { [A: Allocator] [T], Vec<U, A>, #[stable(feature = "partialeq_vec_for_slice", since = "1.48.0")] } -#[cfg(not(no_global_oom_handling))] -__impl_slice_eq1! { [A: Allocator] Cow<'_, [T]>, Vec<U, A> where T: Clone, #[stable(feature = "rust1", since = "1.0.0")] } -#[cfg(not(no_global_oom_handling))] -__impl_slice_eq1! { [] Cow<'_, [T]>, &[U] where T: Clone, #[stable(feature = "rust1", since = "1.0.0")] } -#[cfg(not(no_global_oom_handling))] -__impl_slice_eq1! { [] Cow<'_, [T]>, &mut [U] where T: Clone, #[stable(feature = "rust1", since = "1.0.0")] } -__impl_slice_eq1! { [A: Allocator, const N: usize] Vec<T, A>, [U; N], #[stable(feature = "rust1", since = "1.0.0")] } -__impl_slice_eq1! { [A: Allocator, const N: usize] Vec<T, A>, &[U; N], #[stable(feature = "rust1", since = "1.0.0")] } - -// NOTE: some less important impls are omitted to reduce code bloat -// FIXME(Centril): Reconsider this? -//__impl_slice_eq1! { [const N: usize] Vec<A>, &mut [B; N], } -//__impl_slice_eq1! { [const N: usize] [A; N], Vec<B>, } -//__impl_slice_eq1! { [const N: usize] &[A; N], Vec<B>, } -//__impl_slice_eq1! { [const N: usize] &mut [A; N], Vec<B>, } -//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, [B; N], } -//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &[B; N], } -//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &mut [B; N], } diff --git a/rust/alloc/vec/set_len_on_drop.rs b/rust/alloc/vec/set_len_on_drop.rs deleted file mode 100644 index d3c7297b80..0000000000 --- a/rust/alloc/vec/set_len_on_drop.rs +++ /dev/null @@ -1,35 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -// Set the length of the vec when the `SetLenOnDrop` value goes out of scope. -// -// The idea is: The length field in SetLenOnDrop is a local variable -// that the optimizer will see does not alias with any stores through the Vec's data -// pointer. This is a workaround for alias analysis issue #32155 -pub(super) struct SetLenOnDrop<'a> { - len: &'a mut usize, - local_len: usize, -} - -impl<'a> SetLenOnDrop<'a> { - #[inline] - pub(super) fn new(len: &'a mut usize) -> Self { - SetLenOnDrop { local_len: *len, len } - } - - #[inline] - pub(super) fn increment_len(&mut self, increment: usize) { - self.local_len += increment; - } - - #[inline] - pub(super) fn current_len(&self) -> usize { - self.local_len - } -} - -impl Drop for SetLenOnDrop<'_> { - #[inline] - fn drop(&mut self) { - *self.len = self.local_len; - } -} diff --git a/rust/alloc/vec/spec_extend.rs b/rust/alloc/vec/spec_extend.rs deleted file mode 100644 index ada9195374..0000000000 --- a/rust/alloc/vec/spec_extend.rs +++ /dev/null @@ -1,119 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -use crate::alloc::Allocator; -use crate::collections::TryReserveError; -use core::iter::TrustedLen; -use core::slice::{self}; - -use super::{IntoIter, Vec}; - -// Specialization trait used for Vec::extend -#[cfg(not(no_global_oom_handling))] -pub(super) trait SpecExtend<T, I> { - fn spec_extend(&mut self, iter: I); -} - -// Specialization trait used for Vec::try_extend -pub(super) trait TrySpecExtend<T, I> { - fn try_spec_extend(&mut self, iter: I) -> Result<(), TryReserveError>; -} - -#[cfg(not(no_global_oom_handling))] -impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A> -where - I: Iterator<Item = T>, -{ - default fn spec_extend(&mut self, iter: I) { - self.extend_desugared(iter) - } -} - -impl<T, I, A: Allocator> TrySpecExtend<T, I> for Vec<T, A> -where - I: Iterator<Item = T>, -{ - default fn try_spec_extend(&mut self, iter: I) -> Result<(), TryReserveError> { - self.try_extend_desugared(iter) - } -} - -#[cfg(not(no_global_oom_handling))] -impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A> -where - I: TrustedLen<Item = T>, -{ - default fn spec_extend(&mut self, iterator: I) { - self.extend_trusted(iterator) - } -} - -impl<T, I, A: Allocator> TrySpecExtend<T, I> for Vec<T, A> -where - I: TrustedLen<Item = T>, -{ - default fn try_spec_extend(&mut self, iterator: I) -> Result<(), TryReserveError> { - self.try_extend_trusted(iterator) - } -} - -#[cfg(not(no_global_oom_handling))] -impl<T, A: Allocator> SpecExtend<T, IntoIter<T>> for Vec<T, A> { - fn spec_extend(&mut self, mut iterator: IntoIter<T>) { - unsafe { - self.append_elements(iterator.as_slice() as _); - } - iterator.forget_remaining_elements(); - } -} - -impl<T, A: Allocator> TrySpecExtend<T, IntoIter<T>> for Vec<T, A> { - fn try_spec_extend(&mut self, mut iterator: IntoIter<T>) -> Result<(), TryReserveError> { - unsafe { - self.try_append_elements(iterator.as_slice() as _)?; - } - iterator.forget_remaining_elements(); - Ok(()) - } -} - -#[cfg(not(no_global_oom_handling))] -impl<'a, T: 'a, I, A: Allocator> SpecExtend<&'a T, I> for Vec<T, A> -where - I: Iterator<Item = &'a T>, - T: Clone, -{ - default fn spec_extend(&mut self, iterator: I) { - self.spec_extend(iterator.cloned()) - } -} - -impl<'a, T: 'a, I, A: Allocator> TrySpecExtend<&'a T, I> for Vec<T, A> -where - I: Iterator<Item = &'a T>, - T: Clone, -{ - default fn try_spec_extend(&mut self, iterator: I) -> Result<(), TryReserveError> { - self.try_spec_extend(iterator.cloned()) - } -} - -#[cfg(not(no_global_oom_handling))] -impl<'a, T: 'a, A: Allocator> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A> -where - T: Copy, -{ - fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) { - let slice = iterator.as_slice(); - unsafe { self.append_elements(slice) }; - } -} - -impl<'a, T: 'a, A: Allocator> TrySpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A> -where - T: Copy, -{ - fn try_spec_extend(&mut self, iterator: slice::Iter<'a, T>) -> Result<(), TryReserveError> { - let slice = iterator.as_slice(); - unsafe { self.try_append_elements(slice) } - } -} |