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pub(crate) use self::inner::{do_alloc, Allocator, Global};
// Nightly-case.
// Use unstable `allocator_api` feature.
// This is compatible with `allocator-api2` which can be enabled or not.
// This is used when building for `std`.
#[cfg(feature = "nightly")]
mod inner {
use crate::alloc::alloc::Layout;
pub use crate::alloc::alloc::{Allocator, Global};
use core::ptr::NonNull;
#[allow(clippy::map_err_ignore)]
pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
match alloc.allocate(layout) {
Ok(ptr) => Ok(ptr.as_non_null_ptr()),
Err(_) => Err(()),
}
}
}
// Basic non-nightly case.
// This uses `allocator-api2` enabled by default.
// If any crate enables "nightly" in `allocator-api2`,
// this will be equivalent to the nightly case,
// since `allocator_api2::alloc::Allocator` would be re-export of
// `core::alloc::Allocator`.
#[cfg(all(not(feature = "nightly"), feature = "allocator-api2"))]
mod inner {
use crate::alloc::alloc::Layout;
pub use allocator_api2::alloc::{Allocator, Global};
use core::ptr::NonNull;
#[allow(clippy::map_err_ignore)]
pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
match alloc.allocate(layout) {
Ok(ptr) => Ok(ptr.cast()),
Err(_) => Err(()),
}
}
}
// No-defaults case.
// When building with default-features turned off and
// neither `nightly` nor `allocator-api2` is enabled,
// this will be used.
// Making it impossible to use any custom allocator with collections defined
// in this crate.
// Any crate in build-tree can enable `allocator-api2`,
// or `nightly` without disturbing users that don't want to use it.
#[cfg(not(any(feature = "nightly", feature = "allocator-api2")))]
mod inner {
use crate::alloc::alloc::{alloc, dealloc, Layout};
use core::ptr::NonNull;
#[allow(clippy::missing_safety_doc)] // not exposed outside of this crate
pub unsafe trait Allocator {
fn allocate(&self, layout: Layout) -> Result<NonNull<u8>, ()>;
unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout);
}
#[derive(Copy, Clone)]
pub struct Global;
unsafe impl Allocator for Global {
#[inline]
fn allocate(&self, layout: Layout) -> Result<NonNull<u8>, ()> {
unsafe { NonNull::new(alloc(layout)).ok_or(()) }
}
#[inline]
unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
dealloc(ptr.as_ptr(), layout);
}
}
impl Default for Global {
#[inline]
fn default() -> Self {
Global
}
}
pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
alloc.allocate(layout)
}
}
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