56 lines
1.7 KiB
Rust
56 lines
1.7 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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use ops::Deref;
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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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unsafe impl<T> Zeroable for *const T {}
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unsafe impl<T> Zeroable for *mut T {}
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unsafe impl Zeroable for int {}
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unsafe impl Zeroable for uint {}
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unsafe impl Zeroable for i8 {}
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unsafe impl Zeroable for u8 {}
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unsafe impl Zeroable for i16 {}
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unsafe impl Zeroable for u16 {}
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unsafe impl Zeroable for i32 {}
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unsafe impl Zeroable for u32 {}
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unsafe impl Zeroable for i64 {}
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unsafe impl Zeroable for u64 {}
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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, Show)]
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#[experimental]
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pub struct NonZero<T: Zeroable>(T);
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impl<T: Zeroable> NonZero<T> {
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/// Create 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(always)]
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pub unsafe fn new(inner: T) -> NonZero<T> {
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NonZero(inner)
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}
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}
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impl<T: Zeroable> Deref for NonZero<T> {
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type Target = T;
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#[inline]
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fn deref<'a>(&'a self) -> &'a T {
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let NonZero(ref inner) = *self;
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inner
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}
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}
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