ring/
polyfill.rs

1// Copyright 2015-2016 Brian Smith.
2//
3// Permission to use, copy, modify, and/or distribute this software for any
4// purpose with or without fee is hereby granted, provided that the above
5// copyright notice and this permission notice appear in all copies.
6//
7// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
8// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
10// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
14
15//! Polyfills for functionality that will (hopefully) be added to Rust's
16//! standard library soon.
17
18#[cfg(any(target_pointer_width = "32", target_pointer_width = "64"))]
19#[inline(always)]
20pub const fn u64_from_usize(x: usize) -> u64 {
21    x as u64
22}
23
24#[cfg(any(target_pointer_width = "32", target_pointer_width = "64"))]
25pub fn usize_from_u32(x: u32) -> usize {
26    x as usize
27}
28
29#[cfg(all(target_arch = "aarch64", target_pointer_width = "64"))]
30#[allow(clippy::cast_possible_truncation)]
31pub fn usize_from_u64(x: u64) -> usize {
32    x as usize
33}
34
35/// const-capable `x.try_into().unwrap_or(usize::MAX)`
36#[allow(clippy::cast_possible_truncation)]
37#[inline(always)]
38pub const fn usize_from_u64_saturated(x: u64) -> usize {
39    const USIZE_MAX: u64 = u64_from_usize(usize::MAX);
40    if x < USIZE_MAX {
41        x as usize
42    } else {
43        usize::MAX
44    }
45}
46
47mod array_flat_map;
48mod array_flatten;
49mod array_split_map;
50
51#[cfg(feature = "alloc")]
52mod leading_zeros_skipped;
53
54#[cfg(test)]
55mod test;
56
57mod unwrap_const;
58
59pub use self::{
60    array_flat_map::ArrayFlatMap, array_flatten::ArrayFlatten, array_split_map::ArraySplitMap,
61    unwrap_const::unwrap_const,
62};
63
64#[cfg(feature = "alloc")]
65pub use leading_zeros_skipped::LeadingZerosStripped;
66
67#[cfg(test)]
68mod tests {
69    use super::*;
70    #[test]
71    fn test_usize_from_u64_saturated() {
72        const USIZE_MAX: u64 = u64_from_usize(usize::MAX);
73        assert_eq!(usize_from_u64_saturated(u64::MIN), usize::MIN);
74        assert_eq!(usize_from_u64_saturated(USIZE_MAX), usize::MAX);
75        assert_eq!(usize_from_u64_saturated(USIZE_MAX - 1), usize::MAX - 1);
76
77        #[cfg(not(target_pointer_width = "64"))]
78        {
79            assert_eq!(usize_from_u64_saturated(USIZE_MAX + 1), usize::MAX);
80        }
81    }
82}
ring/polyfill.rs

ring/
polyfill.rs
