summaryrefslogtreecommitdiffstats
path: root/vendor/hashbrown/src/raw/alloc.rs
blob: 15299e7b09941da31345b0b7a027a2717c084c0e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
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)
    }
}