1pub(crate) use self::inner::{do_alloc, Allocator, Global};
2
3// Nightly-case.
4// Use unstable `allocator_api` feature.
5// This is compatible with `allocator-api2` which can be enabled or not.
6// This is used when building for `std`.
7#[cfg(feature = "nightly")]
8mod inner {
9 use crate::alloc::alloc::Layout;
10 pub use crate::alloc::alloc::{Allocator, Global};
11 use core::ptr::NonNull;
12
13 #[allow(clippy::map_err_ignore)]
14 pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
15 match alloc.allocate(layout) {
16 Ok(ptr: NonNull<[u8]>) => Ok(ptr.as_non_null_ptr()),
17 Err(_) => Err(()),
18 }
19 }
20}
21
22// Basic non-nightly case.
23// This uses `allocator-api2` enabled by default.
24// If any crate enables "nightly" in `allocator-api2`,
25// this will be equivalent to the nightly case,
26// since `allocator_api2::alloc::Allocator` would be re-export of
27// `core::alloc::Allocator`.
28#[cfg(all(not(feature = "nightly"), feature = "allocator-api2"))]
29mod inner {
30 use crate::alloc::alloc::Layout;
31 pub use allocator_api2::alloc::{Allocator, Global};
32 use core::ptr::NonNull;
33
34 #[allow(clippy::map_err_ignore)]
35 pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
36 match alloc.allocate(layout) {
37 Ok(ptr) => Ok(ptr.cast()),
38 Err(_) => Err(()),
39 }
40 }
41}
42
43// No-defaults case.
44// When building with default-features turned off and
45// neither `nightly` nor `allocator-api2` is enabled,
46// this will be used.
47// Making it impossible to use any custom allocator with collections defined
48// in this crate.
49// Any crate in build-tree can enable `allocator-api2`,
50// or `nightly` without disturbing users that don't want to use it.
51#[cfg(not(any(feature = "nightly", feature = "allocator-api2")))]
52mod inner {
53 use crate::alloc::alloc::{alloc, dealloc, Layout};
54 use core::ptr::NonNull;
55
56 #[allow(clippy::missing_safety_doc)] // not exposed outside of this crate
57 pub unsafe trait Allocator {
58 fn allocate(&self, layout: Layout) -> Result<NonNull<u8>, ()>;
59 unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout);
60 }
61
62 #[derive(Copy, Clone)]
63 pub struct Global;
64
65 unsafe impl Allocator for Global {
66 #[inline]
67 fn allocate(&self, layout: Layout) -> Result<NonNull<u8>, ()> {
68 unsafe { NonNull::new(alloc(layout)).ok_or(()) }
69 }
70 #[inline]
71 unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
72 dealloc(ptr.as_ptr(), layout);
73 }
74 }
75
76 impl Default for Global {
77 #[inline]
78 fn default() -> Self {
79 Global
80 }
81 }
82
83 pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
84 alloc.allocate(layout)
85 }
86}
87