#[repr(C, align(8))]pub struct BitRef<'a, M = Const, T = usize, O = Lsb0>{ /* private fields */ }
Expand description
§Proxy Bit-Reference
This structure simulates &/mut bool
within BitSlice
regions. It is analogous
to the C++ type std::bitset<N>::reference
.
This type wraps a BitPtr
and caches a bool
in one of the remaining padding
bytes. It is then able to freely give out references to its cached bool
, and
commits the cached value back to the proxied location when dropped.
§Original
This is semantically equivalent to &'a bool
or &'a mut bool
.
§Quirks
Because this type has both a lifetime and a destructor, it can introduce an
uncommon syntax error condition in Rust. When an expression that produces this
type is in the final expression of a block, including if that expression is used
as a condition in a match
, if let
, or if
, then the compiler will attempt
to extend the drop scope of this type to the outside of the block. This causes a
lifetime mismatch error if the source region from which this proxy is produced
begins its lifetime inside the block.
If you get a compiler error that this type causes something to be dropped while borrowed, you can end the borrow by putting any expression-ending syntax element after the offending expression that produces this type, including a semicolon or an item definition.
§Examples
use bitvec::prelude::*;
let bits = bits![mut 0; 2];
let (left, right) = bits.split_at_mut(1);
let mut first = left.get_mut(0).unwrap();
let second = right.get_mut(0).unwrap();
// Writing through a dereference requires a `mut` binding.
*first = true;
// Writing through the explicit method call does not.
second.commit(true);
drop(first); // It’s not a reference, so NLL does not apply!
assert_eq!(bits, bits![1; 2]);
Implementations§
Source§impl<M, T, O> BitRef<'_, M, T, O>
impl<M, T, O> BitRef<'_, M, T, O>
Sourcepub unsafe fn from_bitptr(bitptr: BitPtr<M, T, O>) -> Self
pub unsafe fn from_bitptr(bitptr: BitPtr<M, T, O>) -> Self
Converts a bit-pointer into a proxy bit-reference.
This reads through the pointer in order to cache the current bit value in the proxy.
§Original
The syntax unsafe { &* ptr }
.
§Safety
This is equivalent to (and is!) dereferencing a raw pointer. The pointer must be well-constructed, refer to a live memory location in the program context, and not be aliased beyond its typing indicators.
Sourcepub fn into_bitptr(self) -> BitPtr<M, T, O>
pub fn into_bitptr(self) -> BitPtr<M, T, O>
Source§impl<T, O> BitRef<'_, Mut, T, O>
impl<T, O> BitRef<'_, Mut, T, O>
Trait Implementations§
Source§impl<'a, M, T1, T2, O1, O2> Extend<BitRef<'a, M, T2, O2>> for BitVec<T1, O1>
impl<'a, M, T1, T2, O1, O2> Extend<BitRef<'a, M, T2, O2>> for BitVec<T1, O1>
§Bit-Vector Extension by Proxy References
DO NOT use this. You clearly have a bit-slice. Use
.extend_from_bitslice()
instead!
Iterating over a bit-slice requires loading from memory and constructing a proxy reference for each bit. This is needlessly slow; the specialized method is able to avoid this per-bit cost and possibly even use batched operations.
Source§fn extend<I>(&mut self, iter: I)where
I: IntoIterator<Item = BitRef<'a, M, T2, O2>>,
fn extend<I>(&mut self, iter: I)where
I: IntoIterator<Item = BitRef<'a, M, T2, O2>>,
Source§fn extend_one(&mut self, item: A)
fn extend_one(&mut self, item: A)
extend_one
)Source§fn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one
)Source§impl<'a, M, T1, T2, O1, O2> FromIterator<BitRef<'a, M, T2, O2>> for BitVec<T1, O1>
impl<'a, M, T1, T2, O1, O2> FromIterator<BitRef<'a, M, T2, O2>> for BitVec<T1, O1>
§Bit-Vector Collection from Proxy References
DO NOT use this. You clearly have a bit-slice. Use
::from_bitslice()
instead!
Iterating over a bit-slice requires loading from memory and constructing a proxy reference for each bit. This is needlessly slow; the specialized method is able to avoid this per-bit cost and possibly even use batched operations.
Source§impl<M, T, O> Ord for BitRef<'_, M, T, O>
impl<M, T, O> Ord for BitRef<'_, M, T, O>
Source§impl<M, T, O> PartialOrd<&bool> for BitRef<'_, M, T, O>
impl<M, T, O> PartialOrd<&bool> for BitRef<'_, M, T, O>
Source§impl<M1, M2, O1, O2, T1, T2> PartialOrd<BitRef<'_, M2, T2, O2>> for BitRef<'_, M1, T1, O1>
impl<M1, M2, O1, O2, T1, T2> PartialOrd<BitRef<'_, M2, T2, O2>> for BitRef<'_, M1, T1, O1>
Source§impl<M, T, O> PartialOrd<bool> for BitRef<'_, M, T, O>
impl<M, T, O> PartialOrd<bool> for BitRef<'_, M, T, O>
impl<M, T, O> Eq for BitRef<'_, M, T, O>
impl<M, T, O> Send for BitRef<'_, M, T, O>
impl<M, T, O> Sync for BitRef<'_, M, T, O>
Auto Trait Implementations§
impl<'a, M, T, O> Freeze for BitRef<'a, M, T, O>where
M: Freeze,
impl<'a, M = Const, T = usize, O = Lsb0> !RefUnwindSafe for BitRef<'a, M, T, O>
impl<'a, M, T, O> Unpin for BitRef<'a, M, T, O>
impl<'a, M = Const, T = usize, O = Lsb0> !UnwindSafe for BitRef<'a, M, T, O>
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