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// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
//! `Box<[T]>` slice allocation helpers on [`Arena`].
//!
//! Public docs live on [`Arena`] itself.
use allocator_api2::alloc::{AllocError, Allocator};
use super::{AllocFlavor, Arena, expect_alloc};
use crate::r#box::Box;
impl<A: Allocator + Clone> Arena<A> {
/// Copy `slice` into the arena and return a [`Box<[T], A>`](crate::Box).
///
/// The returned smart pointer is owned and mutable; its `Drop` runs
/// `T::drop` on each element immediately when the smart pointer is
/// dropped.
///
/// Available only with the `dst` Cargo feature, which pulls in the
/// `ptr_meta` crate to polyfill stable `core::ptr::metadata`.
///
/// # Panics
///
/// Panics if the underlying allocator fails or if the `align_of::<T>()` is at least 32 KiB.
/// Use [`Self::try_alloc_slice_copy_box`] for a fallible variant.
#[must_use]
#[inline]
pub fn alloc_slice_copy_box<T: Copy>(&self, slice: impl AsRef<[T]>) -> Box<[T], A> {
let slice = slice.as_ref();
let ptr = expect_alloc(self.try_alloc_slice_local_copy::<_, true>(slice, AllocFlavor::Box));
// SAFETY: helper initialized the slice and bumped the refcount for this Box.
Box::from_owned_in_chunk_unsized(unsafe { crate::internal::owned_in_chunk::OwnedInLocalChunk::from_raw_alloc(ptr) })
}
/// Fallible variant of [`Self::alloc_slice_copy_box`].
///
/// # Errors
///
/// Returns [`AllocError`] if the backing allocator fails or if the data alignment
/// is at least 32 KiB.
#[inline]
pub fn try_alloc_slice_copy_box<T: Copy>(&self, slice: impl AsRef<[T]>) -> Result<Box<[T], A>, AllocError> {
let slice = slice.as_ref();
let ptr = self.try_alloc_slice_local_copy::<_, false>(slice, AllocFlavor::Box)?;
// SAFETY: helper initialized the slice and bumped the refcount for this Box.
Ok(Box::from_owned_in_chunk_unsized(unsafe {
crate::internal::owned_in_chunk::OwnedInLocalChunk::from_raw_alloc(ptr)
}))
}
/// Clone every element of `slice` into the arena and return an
/// owned, mutable [`Box<[T], A>`](crate::Box).
///
/// Available only with the `dst` Cargo feature.
///
/// # Panics
///
/// Panics if the underlying allocator fails or if the `align_of::<T>()` is at least 32 KiB.
/// Use [`Self::try_alloc_slice_clone_box`] for a fallible variant.
///
/// May panic if `T::clone` panics; already-cloned elements are dropped before the
/// panic propagates.
#[inline]
pub fn alloc_slice_clone_box<T: Clone>(&self, slice: impl AsRef<[T]>) -> Box<[T], A> {
let ptr = expect_alloc(self.try_alloc_slice_local_clone_inner::<_, true>(slice.as_ref(), AllocFlavor::Box));
// SAFETY: helper initialized the slice and bumped the refcount for this Box.
Box::from_owned_in_chunk_unsized(unsafe { crate::internal::owned_in_chunk::OwnedInLocalChunk::from_raw_alloc(ptr) })
}
/// Fallible variant of [`Self::alloc_slice_clone_box`].
///
/// # Errors
///
/// Returns [`AllocError`] if the backing allocator fails or if the data alignment
/// is at least 32 KiB.
///
/// # Panics
///
/// May panic if `T::clone` panics; already-cloned elements are
/// dropped before the panic propagates.
#[inline]
pub fn try_alloc_slice_clone_box<T: Clone>(&self, slice: impl AsRef<[T]>) -> Result<Box<[T], A>, AllocError> {
let ptr = self.try_alloc_slice_local_clone_inner::<_, false>(slice.as_ref(), AllocFlavor::Box)?;
// SAFETY: helper initialized the slice and bumped the refcount for this Box.
Ok(Box::from_owned_in_chunk_unsized(unsafe {
crate::internal::owned_in_chunk::OwnedInLocalChunk::from_raw_alloc(ptr)
}))
}
/// Allocate a slice of `len` elements, with element `i` produced by `f(i)`.
///
/// Returns an owned, mutable [`Box<[T], A>`](crate::Box).
///
/// Available only with the `dst` Cargo feature.
///
/// # Panics
///
/// Panics if the underlying allocator fails or if the `align_of::<T>()` is at least 32 KiB.
/// Use [`Self::try_alloc_slice_fill_with_box`] for a fallible variant.
///
/// If `f` panics, already-initialized elements are dropped (drop guard) and the
/// panic propagates.
#[inline]
pub fn alloc_slice_fill_with_box<T, F: FnMut(usize) -> T>(&self, len: usize, f: F) -> Box<[T], A> {
let ptr = expect_alloc(self.try_alloc_slice_local_fill_with_inner::<_, _, true>(len, AllocFlavor::Box, f));
// SAFETY: helper initialized the slice and bumped the refcount for this Box.
Box::from_owned_in_chunk_unsized(unsafe { crate::internal::owned_in_chunk::OwnedInLocalChunk::from_raw_alloc(ptr) })
}
/// Fallible variant of [`Self::alloc_slice_fill_with_box`].
///
/// # Errors
///
/// Returns [`AllocError`] if the backing allocator fails or if the data alignment
/// is at least 32 KiB.
///
/// # Panics
///
/// If `f` panics, already-initialized elements are dropped and the
/// panic propagates.
#[inline]
pub fn try_alloc_slice_fill_with_box<T, F: FnMut(usize) -> T>(&self, len: usize, f: F) -> Result<Box<[T], A>, AllocError> {
let ptr = self.try_alloc_slice_local_fill_with_inner::<_, _, false>(len, AllocFlavor::Box, f)?;
// SAFETY: helper initialized the slice and bumped the refcount for this Box.
Ok(Box::from_owned_in_chunk_unsized(unsafe {
crate::internal::owned_in_chunk::OwnedInLocalChunk::from_raw_alloc(ptr)
}))
}
/// Allocate a slice and fill it with values pulled from `iter`.
///
/// Returns an owned, mutable [`Box<[T], A>`](crate::Box).
///
/// # Panics
///
/// Panics if the underlying allocator fails or if the `align_of::<T>()` is at least 32 KiB.
/// Use [`Self::try_alloc_slice_fill_iter_box`] for a fallible variant.
///
/// May also panic if the iterator yields fewer elements than its
/// `ExactSizeIterator::len()` reported.
#[inline]
pub fn alloc_slice_fill_iter_box<T, I>(&self, iter: I) -> Box<[T], A>
where
I: IntoIterator<Item = T>,
I::IntoIter: ExactSizeIterator,
{
let ptr = expect_alloc(self.try_alloc_slice_local_fill_iter_inner::<_, _, true>(iter, AllocFlavor::Box));
// SAFETY: helper initialized the slice and bumped the refcount for this Box.
Box::from_owned_in_chunk_unsized(unsafe { crate::internal::owned_in_chunk::OwnedInLocalChunk::from_raw_alloc(ptr) })
}
/// Fallible variant of [`Self::alloc_slice_fill_iter_box`].
///
/// # Errors
///
/// Returns [`AllocError`] if the backing allocator fails or if the data alignment
/// is at least 32 KiB.
///
/// # Panics
///
/// Panics if the iterator yields fewer elements than its
/// `ExactSizeIterator::len()` reported.
#[inline]
pub fn try_alloc_slice_fill_iter_box<T, I>(&self, iter: I) -> Result<Box<[T], A>, AllocError>
where
I: IntoIterator<Item = T>,
I::IntoIter: ExactSizeIterator,
{
let ptr = self.try_alloc_slice_local_fill_iter_inner::<_, _, false>(iter, AllocFlavor::Box)?;
// SAFETY: helper initialized the slice and bumped the refcount for this Box.
Ok(Box::from_owned_in_chunk_unsized(unsafe {
crate::internal::owned_in_chunk::OwnedInLocalChunk::from_raw_alloc(ptr)
}))
}
}
impl<A: Allocator + Clone> Arena<A> {
/// Allocate `len` slots and fill each via `f(i)`, returning a
/// [`Pin<Box<[T], A>>`](core::pin::Pin). Each element is pinned
/// to its slot.
///
/// # Panics
///
/// See [`Self::alloc_slice_fill_with_box`].
#[must_use]
#[inline]
pub fn alloc_slice_fill_with_box_pin<T, F: FnMut(usize) -> T>(&self, len: usize, f: F) -> core::pin::Pin<Box<[T], A>>
where
A: 'static,
{
crate::r#box::Box::into_pin(self.alloc_slice_fill_with_box(len, f))
}
/// Fallible variant of [`Self::alloc_slice_fill_with_box_pin`].
///
/// # Errors
///
/// See [`Self::try_alloc_slice_fill_with_box`].
#[inline]
pub fn try_alloc_slice_fill_with_box_pin<T, F: FnMut(usize) -> T>(
&self,
len: usize,
f: F,
) -> Result<core::pin::Pin<Box<[T], A>>, AllocError>
where
A: 'static,
{
self.try_alloc_slice_fill_with_box(len, f).map(crate::r#box::Box::into_pin)
}
}