104 lines
3.3 KiB
Rust
104 lines
3.3 KiB
Rust
#[cfg(test)]
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pub(crate) use self::inner::AllocError;
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pub(crate) use self::inner::{do_alloc, Allocator, Global};
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// Nightly-case.
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// Use unstable `allocator_api` feature.
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// This is compatible with `allocator-api2` which can be enabled or not.
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// This is used when building for `std`.
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#[cfg(feature = "nightly")]
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mod inner {
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#[cfg(test)]
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pub use crate::alloc::alloc::AllocError;
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use crate::alloc::alloc::Layout;
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pub use crate::alloc::alloc::{Allocator, Global};
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use core::ptr::NonNull;
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#[allow(clippy::map_err_ignore)]
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pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<[u8]>, ()> {
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match alloc.allocate(layout) {
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Ok(ptr) => Ok(ptr),
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Err(_) => Err(()),
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}
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}
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}
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// Basic non-nightly case.
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// This uses `allocator-api2` enabled by default.
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// If any crate enables "nightly" in `allocator-api2`,
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// this will be equivalent to the nightly case,
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// since `allocator_api2::alloc::Allocator` would be re-export of
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// `core::alloc::Allocator`.
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#[cfg(all(not(feature = "nightly"), feature = "allocator-api2"))]
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mod inner {
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use crate::alloc::alloc::Layout;
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#[cfg(test)]
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pub use allocator_api2::alloc::AllocError;
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pub use allocator_api2::alloc::{Allocator, Global};
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use core::ptr::NonNull;
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#[allow(clippy::map_err_ignore)]
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pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<[u8]>, ()> {
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match alloc.allocate(layout) {
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Ok(ptr) => Ok(ptr),
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Err(_) => Err(()),
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}
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}
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}
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// No-defaults case.
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// When building with default-features turned off and
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// neither `nightly` nor `allocator-api2` is enabled,
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// this will be used.
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// Making it impossible to use any custom allocator with collections defined
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// in this crate.
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// Any crate in build-tree can enable `allocator-api2`,
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// or `nightly` without disturbing users that don't want to use it.
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#[cfg(not(any(feature = "nightly", feature = "allocator-api2")))]
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mod inner {
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use crate::alloc::alloc::{alloc, dealloc, Layout};
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use core::ptr::NonNull;
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#[allow(clippy::missing_safety_doc)] // not exposed outside of this crate
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pub unsafe trait Allocator {
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fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, ()>;
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unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout);
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}
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#[derive(Copy, Clone)]
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pub struct Global;
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unsafe impl Allocator for Global {
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#[inline]
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fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, ()> {
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match unsafe { NonNull::new(alloc(layout)) } {
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Some(data) => {
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// SAFETY: this is NonNull::slice_from_raw_parts.
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Ok(unsafe {
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NonNull::new_unchecked(core::ptr::slice_from_raw_parts_mut(
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data.as_ptr(),
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layout.size(),
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))
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})
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}
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None => Err(()),
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}
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}
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#[inline]
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unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
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dealloc(ptr.as_ptr(), layout);
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}
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}
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impl Default for Global {
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#[inline]
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fn default() -> Self {
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Global
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}
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}
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pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<[u8]>, ()> {
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alloc.allocate(layout)
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}
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}
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