hashbrown/raw/
alloc.rs

1#[cfg(test)]
2pub(crate) use self::inner::AllocError;
3pub(crate) use self::inner::{do_alloc, Allocator, Global};
4
5// Nightly-case.
6// Use unstable `allocator_api` feature.
7// This is compatible with `allocator-api2` which can be enabled or not.
8// This is used when building for `std`.
9#[cfg(feature = "nightly")]
10mod inner {
11    #[cfg(test)]
12    pub use crate::alloc::alloc::AllocError;
13    use crate::alloc::alloc::Layout;
14    pub use crate::alloc::alloc::{Allocator, Global};
15    use core::ptr::NonNull;
16
17    #[allow(clippy::map_err_ignore)]
18    pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<[u8]>, ()> {
19        match alloc.allocate(layout) {
20            Ok(ptr) => Ok(ptr),
21            Err(_) => Err(()),
22        }
23    }
24}
25
26// Basic non-nightly case.
27// This uses `allocator-api2` enabled by default.
28// If any crate enables "nightly" in `allocator-api2`,
29// this will be equivalent to the nightly case,
30// since `allocator_api2::alloc::Allocator` would be re-export of
31// `core::alloc::Allocator`.
32#[cfg(all(not(feature = "nightly"), feature = "allocator-api2"))]
33mod inner {
34    use crate::alloc::alloc::Layout;
35    #[cfg(test)]
36    pub use allocator_api2::alloc::AllocError;
37    pub use allocator_api2::alloc::{Allocator, Global};
38    use core::ptr::NonNull;
39
40    #[allow(clippy::map_err_ignore)]
41    pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<[u8]>, ()> {
42        match alloc.allocate(layout) {
43            Ok(ptr) => Ok(ptr),
44            Err(_) => Err(()),
45        }
46    }
47}
48
49// No-defaults case.
50// When building with default-features turned off and
51// neither `nightly` nor `allocator-api2` is enabled,
52// this will be used.
53// Making it impossible to use any custom allocator with collections defined
54// in this crate.
55// Any crate in build-tree can enable `allocator-api2`,
56// or `nightly` without disturbing users that don't want to use it.
57#[cfg(not(any(feature = "nightly", feature = "allocator-api2")))]
58mod inner {
59    use crate::alloc::alloc::{alloc, dealloc, Layout};
60    use core::ptr::NonNull;
61
62    #[allow(clippy::missing_safety_doc)] // not exposed outside of this crate
63    pub unsafe trait Allocator {
64        fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, ()>;
65        unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout);
66    }
67
68    #[derive(Copy, Clone)]
69    pub struct Global;
70
71    unsafe impl Allocator for Global {
72        #[inline]
73        fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, ()> {
74            match unsafe { NonNull::new(alloc(layout)) } {
75                Some(data) => {
76                    // SAFETY: this is NonNull::slice_from_raw_parts.
77                    Ok(unsafe {
78                        NonNull::new_unchecked(core::ptr::slice_from_raw_parts_mut(
79                            data.as_ptr(),
80                            layout.size(),
81                        ))
82                    })
83                }
84                None => Err(()),
85            }
86        }
87        #[inline]
88        unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
89            dealloc(ptr.as_ptr(), layout);
90        }
91    }
92
93    impl Default for Global {
94        #[inline]
95        fn default() -> Self {
96            Global
97        }
98    }
99
100    pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<[u8]>, ()> {
101        alloc.allocate(layout)
102    }
103}
hashbrown/raw/alloc.rs

hashbrown/raw/
alloc.rs
