112 lines
3.1 KiB
Rust
112 lines
3.1 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Exposes the NonZero lang item which provides optimization hints.
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#![unstable(feature = "nonzero", reason = "deprecated", issue = "49137")]
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#![rustc_deprecated(reason = "use `std::ptr::NonNull` or `std::num::NonZero*` instead",
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since = "1.26.0")]
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#![allow(deprecated)]
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use ops::CoerceUnsized;
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/// Unsafe trait to indicate what types are usable with the NonZero struct
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pub unsafe trait Zeroable {
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/// Whether this value is zero
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fn is_zero(&self) -> bool;
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}
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macro_rules! impl_zeroable_for_pointer_types {
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( $( $Ptr: ty )+ ) => {
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$(
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/// For fat pointers to be considered "zero", only the "data" part needs to be null.
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unsafe impl<T: ?Sized> Zeroable for $Ptr {
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#[inline]
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fn is_zero(&self) -> bool {
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(*self).is_null()
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}
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}
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)+
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}
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}
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macro_rules! impl_zeroable_for_integer_types {
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( $( $Int: ty )+ ) => {
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$(
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unsafe impl Zeroable for $Int {
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#[inline]
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fn is_zero(&self) -> bool {
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*self == 0
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}
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}
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)+
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}
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}
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impl_zeroable_for_pointer_types! {
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*const T
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*mut T
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}
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impl_zeroable_for_integer_types! {
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usize u8 u16 u32 u64 u128
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isize i8 i16 i32 i64 i128
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}
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/// A wrapper type for raw pointers and integers that will never be
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/// NULL or 0 that might allow certain optimizations.
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#[lang = "non_zero"]
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#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Debug, Hash)]
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pub struct NonZero<T: Zeroable>(pub(crate) T);
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impl<T: Zeroable> NonZero<T> {
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/// Creates an instance of NonZero with the provided value.
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/// You must indeed ensure that the value is actually "non-zero".
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#[inline]
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pub const unsafe fn new_unchecked(inner: T) -> Self {
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NonZero(inner)
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}
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/// Creates an instance of NonZero with the provided value.
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#[inline]
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pub fn new(inner: T) -> Option<Self> {
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if inner.is_zero() {
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None
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} else {
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Some(NonZero(inner))
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}
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}
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/// Gets the inner value.
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pub fn get(self) -> T {
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self.0
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}
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}
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impl<T: Zeroable+CoerceUnsized<U>, U: Zeroable> CoerceUnsized<NonZero<U>> for NonZero<T> {}
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impl<'a, T: ?Sized> From<&'a mut T> for NonZero<*mut T> {
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fn from(reference: &'a mut T) -> Self {
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NonZero(reference)
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}
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}
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impl<'a, T: ?Sized> From<&'a mut T> for NonZero<*const T> {
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fn from(reference: &'a mut T) -> Self {
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let ptr: *mut T = reference;
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NonZero(ptr)
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}
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}
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impl<'a, T: ?Sized> From<&'a T> for NonZero<*const T> {
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fn from(reference: &'a T) -> Self {
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NonZero(reference)
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}
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}
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