Struct bitvec::array::BitArray

source · [−]
#[repr(transparent)]
pub struct BitArray<O = Lsb0, V = [usize; 1]> where
    O: BitOrder,
    V: BitView,  { /* private fields */ }
Expand description

An array of individual bits, able to be held by value on the stack.

This type is generic over all Sized implementors of the BitView trait. Due to limitations in the Rust language’s const-generics implementation (it is both unstable and incomplete), this must take an array type parameter directly, rather than register type and bit-count integer parameters. This makes it less convenient to use than C++’s std::bitset<N> array type. The bitarr! macro is capable of constructing both values and specific types of BitArray, and this macro should be preferred for most use.

The advantage of using this wrapper is that it implements Deref/Mut to BitSlice, as well as implementing all of BitSlices traits by forwarding to the BitSlice view of its contained data. This allows it to have BitSlice behavior by itself, without requiring explicit .as_bitslice() calls in user code.

Limitations

This does not track start or end indices of its BitSlice view, and so that view will always fully span the buffer. You cannot produce, for example, an array of twelve bits.

Type Parameters

  • O: The ordering of bits within memory registers.
  • V: Some buffer which can be used as the basis for a BitSlice view. This will usually be an array of [T: BitRegister; N].

Examples

This type is useful for marking that some value is always to be used as a BitSlice.

use bitvec::prelude::*;

struct HasBitfields {
  header: u32,
  // creates a type declaration.
  fields: bitarr!(for 20, in Msb0, u8),
}

impl HasBitfields {
  pub fn new() -> Self {
    Self {
      header: 0,
      // creates a value object.
      // the type paramaters must be repeated.
      fields: bitarr![Msb0, u8; 0; 20],
    }
  }

  /// Access a bit region directly
  pub fn get_subfield(&self) -> &BitSlice<Msb0, u8> {
    &self.fields[.. 4]
  }

  /// Read a 12-bit value out of a region
  pub fn read_value(&self) -> u16 {
    self.fields[4 .. 16].load()
  }

  /// Write a 12-bit value into a region
  pub fn set_value(&mut self, value: u16) {
    self.fields[4 .. 16].store(value);
  }
}

Eventual Obsolescence

When const-generics stabilize, this will be modified to have a signature more like BitArray<O, T, const N: usize>([T; elts::<T>(N)]);, to mirror the behavior of ordinary arrays [T; N] as they stand today.

Implementations

Constructs a new BitArray with its memory set to zero.

Wraps a buffer in a BitArray.

Examples
use bitvec::prelude::*;

let data = [0u8; 2];
let bits: BitArray<Msb0, _> = BitArray::new(data);
assert_eq!(bits.len(), 16);

Removes the BitArray wrapper, leaving the contained buffer.

Examples
use bitvec::prelude::*;

let bitarr = bitarr![Lsb0, usize; 0; 30];
let native: [usize; 1] = bitarr.value();

Views the array as a BitSlice.

Views the array as a mutable BitSlice.

Views the array as a slice of its underlying memory registers.

Views the array as a mutable slice of its underlying memory registers.

Views the interior buffer.

Mutably views the interior buffer.

Methods from Deref<Target = BitSlice<O, V::Store>>

Returns the number of bits in the slice.

Original

slice::len

Examples
use bitvec::prelude::*;

let a = bits![0, 0, 1];
assert_eq!(a.len(), 3);

Returns true if the slice has a length of 0.

Original

slice::is_empty

Examples
use bitvec::prelude::*;

let a = bits![0, 0, 1];
assert!(!a.is_empty());

Returns the first bit of the slice, or None if it is empty.

Original
Examples
use bitvec::prelude::*;

let v = bits![1, 0, 0];
assert_eq!(Some(&true), v.first().as_deref());

let w = bits![];
assert_eq!(None, w.first());

Returns a mutable pointer to the first bit of the slice, or None if it is empty.

Original

slice::first_mut

API Differences

This crate cannot manifest &mut bool references, and must use the BitRef proxy type where &mut bool exists in the standard library API. The proxy value must be bound as mut in order to write through it.

Examples
use bitvec::prelude::*;

let x = bits![mut 0, 1, 0];

if let Some(mut first) = x.first_mut() {
  *first = true;
}
assert_eq!(x, bits![1, 1, 0]);

Returns the first and all the rest of the bits of the slice, or None if it is empty.

Original

slice::split_first

Examples
use bitvec::prelude::*;

let x = bits![1, 0, 0];

if let Some((first, rest)) = x.split_first() {
  assert_eq!(first, &true);
  assert_eq!(rest, bits![0; 2]);
}

Returns the first and all the rest of the bits of the slice, or None if it is empty.

Original

slice::split_first_mut

API Differences

This crate cannot manifest &mut bool references, and must use the BitRef proxy type where &mut bool exists in the standard library API. The proxy value must be bound as mut in order to write through it.

Because the references are permitted to use the same memory address, they are marked as aliasing in order to satisfy Rust’s requirements about freedom from data races.

Examples
use bitvec::prelude::*;

let x = bits![mut 0, 0, 1];

if let Some((mut first, rest)) = x.split_first_mut() {
  *first = true;
  rest.set(0, true);
  rest.set(1, false);
}
assert_eq!(x, bits![1, 1, 0]);

Returns the last and all the rest of the bits of the slice, or None if it is empty.

Original

slice::split_last

Examples
use bitvec::prelude::*;

let x = bits![0, 0, 1];

if let Some((last, rest)) = x.split_last() {
  assert_eq!(last, &true);
  assert_eq!(rest, bits![0; 2]);
}

Returns the last and all the rest of the bits of the slice, or None if it is empty.

Original

slice::split_last_mut

API Differences

This crate cannot manifest &mut bool references, and must use the BitRef proxy type where &mut bool exists in the standard library API. The proxy value must be bound as mut in order to write through it.

Because the references are permitted to use the same memory address, they are marked as aliasing in order to satisfy Rust’s requirements about freedom from data races.

Examples
use bitvec::prelude::*;

let x = bits![mut 1, 0, 0];

if let Some((mut last, rest)) = x.split_last_mut() {
  *last = true;
  rest.set(0, false);
  rest.set(1, true);
}
assert_eq!(x, bits![0, 1, 1]);

Returns the last bit of the slice, or None if it is empty.

Original

slice::last

Examples
use bitvec::prelude::*;

let v = bits![0, 0, 1];
assert_eq!(Some(&true), v.last().as_deref());

let w = bits![];
assert_eq!(None, w.last());

Returns a mutable pointer to the last bit in the slice.

Original

slice::last_mut

API Differences

This crate cannot manifest &mut bool references, and must use the BitRef proxy type where &mut bool exists in the standard library API. The proxy value must be bound as mut in order to write through it.

Examples
use bitvec::prelude::*;

let x = bits![mut 0, 1, 0];

if let Some(mut last) = x.last_mut() {
  *last = true;
}
assert_eq!(x, bits![0, 1, 1]);

Returns a reference to a bit or subslice depending on the type of index.

  • If given a position, returns a reference to the bit at that position or None if out of bounds.
  • If given a range, returns the subslice corresponding to that range, or None if out of bounds.
Original

slice::get

Examples
use bitvec::prelude::*;

let v = bits![0, 1, 0];
assert_eq!(Some(&true), v.get(1).as_deref());
assert_eq!(Some(bits![0, 1]), v.get(0 .. 2));
assert_eq!(None, v.get(3));
assert_eq!(None, v.get(0 .. 4));

Returns a mutable reference to a bit or subslice depending on the type of index (see .get()) or None if the index is out of bounds.

Original

slice::get_mut

API Differences

This crate cannot manifest &mut bool references, and must use the BitRef proxy type where &mut bool exists in the standard library API. The proxy value must be bound as mut in order to write through it.

Examples
use bitvec::prelude::*;

let x = bits![mut 0, 0, 1];

if let Some(mut bit) = x.get_mut(1) {
  *bit = true;
}
assert_eq!(x, bits![0, 1, 1]);

Returns a reference to a bit or subslice, without doing bounds checking.

This is generally not recommended; use with caution! Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used. For a safe alternative, see .get().

Original

slice::get_unchecked

Examples
use bitvec::prelude::*;

let x = bits![0, 1, 0];

unsafe {
  assert_eq!(x.get_unchecked(1), &true);
}

Returns a mutable reference to a bit or subslice, without doing bounds checking.

This is generally not recommended; use with caution! Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used. For a safe alternative, see [.get_mut()].

Original

slice::get_unchecked_mut

API Differences

This crate cannot manifest &mut bool references, and must use the BitRef proxy type where &mut bool exists in the standard library API. The proxy value must be bound as mut in order to write through it.

Examples
use bitvec::prelude::*;

let x = bits![mut 0; 3];
unsafe {
  let mut bit = x.get_unchecked_mut(1);
  *bit = true;
}
assert_eq!(x, bits![0, 1, 0]);

Swaps two bits in the slice.

Original

slice::swap

Arguments
  • a: The index of the first bit
  • b: The index of the second bit
Panics

Panics if a or b are out of bounds.

Examples
use bitvec::prelude::*;

let v = bits![mut 0, 1, 1, 0];
v.swap(1, 3);
assert_eq!(v, bits![0, 0, 1, 1]);

Reverses the order of bits in the slice, in place.

Original

slice::reverse

Examples
use bitvec::prelude::*;

let v = bits![mut 0, 1, 1];
v.reverse();
assert_eq!(v, bits![1, 1, 0]);

Returns an iterator over the slice.

Original

slice::iter

API Differences

This iterator yields BitRef proxy references, rather than &bool ordinary references. It does so in order to promote consistency in the crate, and make switching between immutable and mutable single-bit access easier.

The produced iterator has a by_ref adapter that yields &bool references, and a by_val adapter that yields bool values. Use these methods to fit this iterator into APIs that expect ordinary bool inputs.

Examples
use bitvec::prelude::*;

let x = bits![0, 0, 1];
let mut iterator = x.iter();

assert_eq!(iterator.next().as_deref(), Some(&false));
assert_eq!(iterator.next().as_deref(), Some(&false));
assert_eq!(iterator.next().as_deref(), Some(&true));
assert_eq!(iterator.next().as_deref(), None);

Returns an iterator that allows modifying each bit.

Original

slice::iter_mut

API Differences

This crate cannot manifest &mut bool references, and must use the BitRef proxy type where &mut bool exists in the standard library API. The proxy value must be bound as mut in order to write through it.

This iterator marks each yielded item as aliased, as iterators can be used to yield multiple items into the same scope. If you are using the iterator in a manner that ensures that all yielded items have disjoint lifetimes, you can use the .remove_alias() adapter on it to remove the alias marker from the yielded subslices.

Examples
use bitvec::prelude::*;

let x = bits![mut 0, 0, 1];
for mut bit in x.iter_mut() {
  *bit = !*bit;
}
assert_eq!(x, bits![1, 1, 0]);

Returns an iterator over all contiguous windows of length size. The windows overlap. If the slice is shorter than size, the iterator returns no values.

Original

slice::windows

Panics

Panics if size is 0.

Examples
use bitvec::prelude::*;

let slice = bits![0, 0, 1, 1];
let mut iter = slice.windows(2);
assert_eq!(iter.next().unwrap(), bits![0; 2]);
assert_eq!(iter.next().unwrap(), bits![0, 1]);
assert_eq!(iter.next().unwrap(), bits![1; 2]);
assert!(iter.next().is_none());

If the slice is shorter than size:

use bitvec::prelude::*;

let slice = bits![0; 3];
let mut iter = slice.windows(4);
assert!(iter.next().is_none());

Returns an iterator over chunk_size bits of the slice at a time, starting at the beginning of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last chunk will not have length chunk_size.

See .chunks_exact() for a variant of this iterator that returns chunks of always exactly chunk_size bits, and .rchunks() for the same iterator but starting at the end of the slice.

Original

slice::chunks

Panics

Panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let slice = bits![0, 1, 0, 0, 1];
let mut iter = slice.chunks(2);
assert_eq!(iter.next().unwrap(), bits![0, 1]);
assert_eq!(iter.next().unwrap(), bits![0, 0]);
assert_eq!(iter.next().unwrap(), bits![1]);
assert!(iter.next().is_none());

Returns an iterator over chunk_size bits of the slice at a time, starting at the beginning of the slice.

The chunks are mutable slices, and do not overlap. If chunk_size does not divide the length of the slice, then the last chunk will not have length chunk_size.

See .chunks_exact_mut() for a variant of this iterator that returns chunks of always exactly chunk_size bits, and .rchunks_mut() for the same iterator but starting at the end of the slice.

Original

slice::chunks_mut

API Differences

This iterator marks each yielded item as aliased, as iterators can be used to yield multiple items into the same scope. If you are using the iterator in a manner that ensures that all yielded items have disjoint lifetimes, you can use the .remove_alias() adapter on it to remove the alias marker from the yielded subslices.

Panics

Panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let v = bits![mut 0; 5];
let mut count = 1;

for chunk in v.chunks_mut(2) {
  for mut bit in chunk.iter_mut() {
    *bit = count % 2 == 0;
  }
  count += 1;
}
assert_eq!(v, bits![0, 0, 1, 1, 0]);

Returns an iterator over chunk_size bits of the slice at a time, starting at the beginning of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 bits will be omitted and can be retrieved from the .remainder() method of the iterator.

Due to each chunk having exactly chunk_size bits, the compiler may be able to optimize the resulting code better than in the case of .chunks().

See .chunks() for a variant of this iterator that also returns the remainder as a smaller chunk, and .rchunks_exact() for the same iterator but starting at the end of the slice.

Original

slice::chunks_exact

Panics

Panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let slice = bits![0, 1, 1, 0, 0];
let mut iter = slice.chunks_exact(2);
assert_eq!(iter.next().unwrap(), bits![0, 1]);
assert_eq!(iter.next().unwrap(), bits![1, 0]);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), bits![0]);

Returns an iterator over chunk_size bits of the slice at a time, starting at the beginning of the slice.

The chunks are mutable slices, and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 bits will be omitted and can be retrieved from the .into_remainder() method of the iterator.

Due to each chunk having exactly chunk_size bits, the compiler may be able to optimize the resulting code better than in the case of .chunks_mut().

See .chunks_mut() for a variant of this iterator that also returns the remainder as a smaller chunk, and .rchunks_exact_mut() for the same iterator but starting at the end of the slice.

Original

slice::chunks_exact_mut

API Differences

This iterator marks each yielded item as aliased, as iterators can be used to yield multiple items into the same scope. If you are using the iterator in a manner that ensures that all yielded items have disjoint lifetimes, you can use the .remove_alias() adapter on it to remove the alias marker from the yielded subslices.

Panics

Panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let v = bits![mut 0; 5];

for chunk in v.chunks_exact_mut(2) {
  chunk.set_all(true);
}
assert_eq!(v, bits![1, 1, 1, 1, 0]);

Returns an iterator over chunk_size bits of the slice at a time, starting at the end of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last chunk will not have length chunk_size.

See .rchunks_exact() for a variant of this iterator that returns chunks of always exactly chunk_size bits, and .chunks() for the same iterator but starting at the beginning of the slice.

Original

slice::rchunks

Panics

Panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let slice = bits![0, 1, 0, 0, 1];
let mut iter = slice.rchunks(2);
assert_eq!(iter.next().unwrap(), bits![0, 1]);
assert_eq!(iter.next().unwrap(), bits![1, 0]);
assert_eq!(iter.next().unwrap(), bits![0]);
assert!(iter.next().is_none());

Returns an iterator over chunk_size bits of the slice at a time, starting at the end of the slice.

The chunks are mutable slices, and do not overlap. If chunk_size does not divide the length of the slice, then the last chunk will not have length chunk_size.

See .rchunks_exact_mut() for a variant of this iterator that returns chunks of always exactly chunk_size bits, and .chunks_mut() for the same iterator but starting at the beginning of the slice.

Original

slice::rchunks_mut

API Differences

This iterator marks each yielded item as aliased, as iterators can be used to yield multiple items into the same scope. If you are using the iterator in a manner that ensures that all yielded items have disjoint lifetimes, you can use the .remove_alias() adapter on it to remove the alias marker from the yielded subslices.

Panics

Panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let v = bits![mut 0; 5];
let mut count = 1;

for chunk in v.rchunks_mut(2) {
  for mut bit in chunk.iter_mut() {
    *bit = count % 2 == 0;
  }
  count += 1;
}
assert_eq!(v, bits![0, 1, 1, 0, 0]);

Returns an iterator over chunk_size bits of the slice at a time, starting at the end of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 bits will be omitted and can be retrieved from the .remainder() method of the iterator.

Due to each chunk having exactly chunk_size bits, the compiler may be able to optimize the resulting code better than in the case of .rchunks().

See .rchunks() for a variant of this iterator that also returns the remainder as a smaller chunk, and .chunks_exact() for the same iterator but starting at the beginning of the slice.

Original

slice::rchunks_exact

Panics

Panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let slice = bits![0, 0, 1, 1, 0];
let mut iter = slice.rchunks_exact(2);
assert_eq!(iter.next().unwrap(), bits![1, 0]);
assert_eq!(iter.next().unwrap(), bits![0, 1]);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), bits![0]);

Returns an iterator over chunk_size bits of the slice at a time, starting at the end of the slice.

The chunks are mutable slices, and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 bits will be omitted and can be retrieved from the .into_remainder() method of the iterator.

Due to each chunk having exactly chunk_size bits, the compiler may be able to optimize the resulting code better than in the case of .rchunks_mut().

See .rchunks_mut() for a variant of this iterator that also returns the remainder as a smaller chunk, and .chunks_exact_mut() for the same iterator but starting at the beginning of the slice.

Original

slice::rchunks_exact_mut

API Differences

This iterator marks each yielded item as aliased, as iterators can be used to yield multiple items into the same scope. If you are using the iterator in a manner that ensures that all yielded items have disjoint lifetimes, you can use the .remove_alias() adapter on it to remove the alias marker from the yielded subslices.

Panics

Panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let v = bits![mut 0; 5];

for chunk in v.rchunks_exact_mut(2) {
  chunk.set_all(true);
}
assert_eq!(v, bits![0, 1, 1, 1, 1]);

Divides one slice into two at an index.

The first will contain all indices from [0, mid) (excluding the index mid itself) and the second will contain all indices from [mid, len) (excluding the index len itself).

Original

slice::split_at

Panics

Panics if mid > len.

Behavior

When mid is 0 or self.len(), then the left or right return values, respectively, are empty slices. Empty slice references produced by this method are specified to have the address information you would expect: a left empty slice has the same base address and start bit as self, and a right empty slice will have its address raised by self.len().

Examples
use bitvec::prelude::*;

let v = bits![0, 0, 0, 1, 1, 1];

{
  let (left, right) = v.split_at(0);
  assert_eq!(left, bits![]);
  assert_eq!(right, v);
}

{
  let (left, right) = v.split_at(2);
  assert_eq!(left, bits![0, 0]);
  assert_eq!(right, bits![0, 1, 1, 1]);
}

{
  let (left, right) = v.split_at(6);
  assert_eq!(left, v);
  assert_eq!(right, bits![]);
}

Divides one mutable slice into two at an index.

The first will contain all indices from [0, mid) (excluding the index mid itself) and the second will contain all indices from [mid, len) (excluding the index len itself).

Original

slice::split_at_mut

API Differences

The partition index mid may occur anywhere in the slice, and as a result the two returned slices may both have write access to the memory address containing mid. As such, the returned slices must be marked with T::Alias in order to correctly manage memory access going forward.

This marking is applied to all memory accesses in both slices, regardless of whether any future accesses actually require it. To limit the alias marking to only the addresses that need it, use [.bit_domain()] or [.bit_domain_mut()] to split either slice into its aliased and unaliased subslices.

Panics

Panics if mid > len.

Behavior

When mid is 0 or self.len(), then the left or right return values, respectively, are empty slices. Empty slice references produced by this method are specified to have the address information you would expect: a left empty slice has the same base address and start bit as self, and a right empty slice will have its address raised by self.len().

Examples
use bitvec::prelude::*;

let v = bits![mut 0, 0, 0, 1, 1, 1];
// scoped to restrict the lifetime of the borrows
{
  let (left, right) = v.split_at_mut(2);
  assert_eq!(left, bits![0, 0]);
  assert_eq!(right, bits![0, 1, 1, 1]);

  left.set(1, true);
  right.set(1, false);
}
assert_eq!(v, bits![0, 1, 0, 0, 1, 1]);

Returns an iterator over subslices separated by bits that match pred. The matched bit is not contained in the subslices.

Original

slice::split

API Differences

In order to allow more than one bit of information for the split decision, the predicate receives the index of each bit, as well as its value.

Examples
use bitvec::prelude::*;

let slice = bits![0, 1, 1, 0];
let mut iter = slice.split(|pos, _bit| pos % 3 == 2);

assert_eq!(iter.next().unwrap(), bits![0, 1]);
assert_eq!(iter.next().unwrap(), bits![0]);
assert!(iter.next().is_none());

If the first bit is matched, an empty slice will be the first item returned by the iterator. Similarly, if the last bit in the slice is matched, an empty slice will be the last item returned by the iterator:

use bitvec::prelude::*;

let slice = bits![0, 0, 1];
let mut iter = slice.split(|_pos, bit| *bit);

assert_eq!(iter.next().unwrap(), bits![0, 0]);
assert_eq!(iter.next().unwrap(), bits![]);
assert!(iter.next().is_none());

If two matched bits are directly adjacent, an empty slice will be present between them:

use bitvec::prelude::*;

let slice = bits![1, 0, 0, 1];
let mut iter = slice.split(|_pos, bit| !*bit);

assert_eq!(iter.next().unwrap(), bits![1]);
assert_eq!(iter.next().unwrap(), bits![]);
assert_eq!(iter.next().unwrap(), bits![1]);
assert!(iter.next().is_none());

Returns an iterator over mutable subslices separated by bits that match pred. The matched bit is not contained in the subslices.

Original

slice::split_mut

API Differences

In order to allow more than one bit of information for the split decision, the predicate receives the index of each bit, as well as its value.

This iterator marks each yielded item as aliased, as iterators can be used to yield multiple items into the same scope. If you are using the iterator in a manner that ensures that all yielded items have disjoint lifetimes, you can use the .remove_alias() adapter on it to remove the alias marker from the yielded subslices.

Examples
use bitvec::prelude::*;

let v = bits![mut 0, 0, 1, 0, 1, 0];
for group in v.split_mut(|_pos, bit| *bit) {
  group.set(0, true);
}
assert_eq!(v, bits![1, 0, 1, 1, 1, 1]);

Returns an iterator over subslices separated by bits that match pred, starting at the end of the slice and working backwards. The matched bit is not contained in the subslices.

Original

slice::rsplit

API Differences

In order to allow more than one bit of information for the split decision, the predicate receives the index of each bit, as well as its value.

Examples
use bitvec::prelude::*;

let slice = bits![1, 1, 1, 0, 1, 1];
let mut iter = slice.rsplit(|_pos, bit| !*bit);

assert_eq!(iter.next().unwrap(), bits![1; 2]);
assert_eq!(iter.next().unwrap(), bits![1; 3]);
assert!(iter.next().is_none());

As with .split(), if the first or last bit is matched, an empty slice will be the first (or last) item returned by the iterator.

use bitvec::prelude::*;

let v = bits![1, 0, 0, 1, 0, 0, 1];
let mut it = v.rsplit(|_pos, bit| *bit);
assert_eq!(it.next().unwrap(), bits![]);
assert_eq!(it.next().unwrap(), bits![0; 2]);
assert_eq!(it.next().unwrap(), bits![0; 2]);
assert_eq!(it.next().unwrap(), bits![]);
assert!(it.next().is_none());

Returns an iterator over mutable subslices separated by bits that match pred, starting at the end of the slice and working backwards. The matched bit is not contained in the subslices.

Original

slice::rsplit_mut

API Differences

In order to allow more than one bit of information for the split decision, the predicate receives the index of each bit, as well as its value.

This iterator marks each yielded item as aliased, as iterators can be used to yield multiple items into the same scope. If you are using the iterator in a manner that ensures that all yielded items have disjoint lifetimes, you can use the .remove_alias() adapter on it to remove the alias marker from the yielded subslices.

Examples
use bitvec::prelude::*;

let v = bits![mut 0, 0, 1, 0, 1, 0];
for group in v.rsplit_mut(|_pos, bit| *bit) {
  group.set(0, true);
}
assert_eq!(v, bits![1, 0, 1, 1, 1, 1]);

Returns an iterator over subslices separated by bits that match pred, limited to returning at most n items. The matched bit is not contained in the subslices.

The last item returned, if any, will contain the remainder of the slice.

Original

slice::splitn

API Differences

In order to allow more than one bit of information for the split decision, the predicate receives the index of each bit, as well as its value.

Examples

Print the slice split once by set bits (i.e., [0, 0,], [0, 1, 0]):

use bitvec::prelude::*;

let v = bits![0, 0, 1, 0, 1, 0];

for group in v.splitn(2, |_pos, bit| *bit) {
  println!("{:b}", group);
}

Returns an iterator over subslices separated by bits that match pred, limited to returning at most n items. The matched bit is not contained in the subslices.

The last item returned, if any, will contain the remainder of the slice.

Original

slice::splitn_mut

API Differences

In order to allow more than one bit of information for the split decision, the predicate receives the index of each bit, as well as its value.

This iterator marks each yielded item as aliased, as iterators can be used to yield multiple items into the same scope. If you are using the iterator in a manner that ensures that all yielded items have disjoint lifetimes, you can use the .remove_alias() adapter on it to remove the alias marker from the yielded subslices.

Examples
use bitvec::prelude::*;

let v = bits![mut 0, 0, 1, 0, 1, 0];

for group in v.splitn_mut(2, |_pos, bit| *bit) {
  group.set(0, true);
}
assert_eq!(v, bits![1, 0, 1, 1, 1, 0]);

Returns an iterator over subslices separated by bits that match pred, limited to returning at most n items. This starts at the end of the slice and works backwards. The matched bit is not contained in the subslices.

The last item returned, if any, will contain the remainder of the slice.

Original

slice::rsplitn

API Differences

In order to allow more than one bit of information for the split decision, the predicate receives the index of each bit, as well as its value.

Examples

Print the slice split once, starting from the end, by set bits (i.e., [0], [0, 0, 1, 0]):

use bitvec::prelude::*;

let v = bits![0, 0, 1, 0, 1, 0];

for group in v.rsplitn(2, |_pos, bit| *bit) {
  println!("{:b}", group);
}

Returns an iterator over subslices separated by bits that match pred, limited to returning at most n items. This starts at the end of the slice and works backwards. The matched bit is not contained in the subslices.

The last item returned, if any, will contain the remainder of the slice.

Original

slice::rsplitn_mut

API Differences

In order to allow more than one bit of information for the split decision, the predicate receives the index of each bit, as well as its value.

This iterator marks each yielded item as aliased, as iterators can be used to yield multiple items into the same scope. If you are using the iterator in a manner that ensures that all yielded items have disjoint lifetimes, you can use the .remove_alias() adapter on it to remove the alias marker from the yielded subslices.

Examples
use bitvec::prelude::*;

let v = bits![mut 0, 0, 1, 0, 1, 0];

for group in v.rsplitn_mut(2, |_pos, bit| *bit) {
  group.set(0, true);
}
assert_eq!(v, bits![1, 0, 1, 0, 1, 1]);

Returns true if the slice contains a subslice that matches the given span.

Original

slice::contains

API Differences

This searches for a matching subslice (allowing different type parameters) rather than for a specific bit. Searching for a contained element with a given value is not as useful on a collection of bool.

Furthermore, BitSlice defines any and not_all, which are optimized searchers for any true or false bit, respectively, in a sequence.

Examples
use bitvec::prelude::*;

let data = 0b0101_1010u8;
let bits_msb = data.view_bits::<Msb0>();
let bits_lsb = data.view_bits::<Lsb0>();
assert!(bits_msb.contains(&bits_lsb[1 .. 5]));

This example uses a palindrome pattern to demonstrate that the slice being searched for does not need to have the same type parameters as the slice being searched.

Returns true if needle is a prefix of the slice.

Original

slice::starts_with

Examples
use bitvec::prelude::*;

let v = bits![0, 1, 0, 0];
assert!(v.starts_with(bits![0]));
assert!(v.starts_with(bits![0, 1]));
assert!(!v.starts_with(bits![1]));
assert!(!v.starts_with(bits![1, 0]));

Always returns true if needle is an empty slice:

use bitvec::prelude::*;

let v = bits![0, 1, 0];
assert!(v.starts_with(bits![]));
let v = bits![];
assert!(v.starts_with(bits![]));

Returns true if needle is a suffix of the slice.

Original

slice::ends_with

Examples
use bitvec::prelude::*;

let v = bits![0, 1, 0, 0];
assert!(v.ends_with(bits![0]));
assert!(v.ends_with(bits![0; 2]));
assert!(!v.ends_with(bits![1]));
assert!(!v.ends_with(bits![1, 0]));

Always returns true if needle is an empty slice:

use bitvec::prelude::*;

let v = bits![0, 1, 0];
assert!(v.ends_with(bits![]));
let v = bits![];
assert!(v.ends_with(bits![]));

Rotates the slice in-place such that the first by bits of the slice move to the end while the last self.len() - by bits move to the front. After calling .rotate_left(), the bit previously at index by will become the first bit in the slice.

Original

slice::rotate_left

Panics

This function will panic if by is greater than the length of the slice. Note that by == self.len() does not panic and is a noöp.

Complexity

Takes linear (in self.len()) time.

Examples
use bitvec::prelude::*;

let a = bits![mut 0, 0, 1, 0, 1, 0];
a.rotate_left(2);
assert_eq!(a, bits![1, 0, 1, 0, 0, 0]);

Rotating a subslice:

use bitvec::prelude::*;

let a = bits![mut 0, 0, 1, 0, 1, 1];
a[1 .. 5].rotate_left(1);
assert_eq!(a, bits![0, 1, 0, 1, 0, 1]);

Rotates the slice in-place such that the first self.len() - by bits of the slice move to the end while the last by bits move to the front. After calling .rotate_right(), the bit previously at index `self.len()

  • by` will become the first bit in the slice.
Original

slice::rotate_right

Panics

This function will panic if by is greater than the length of the slice. Note that by == self.len() does not panic and is a noöp.

Complexity

Takes linear (in self.len()) time.

Examples
use bitvec::prelude::*;

let a = bits![mut 0, 0, 1, 1, 1, 0];
a.rotate_right(2);
assert_eq!(a, bits![1, 0, 0, 0, 1, 1]);

Rotating a subslice:

use bitvec::prelude::*;

let a = bits![mut 0, 0, 1, 0, 1, 1];
a[1 .. 5].rotate_right(1);
assert_eq!(a, bits![0, 1, 0, 1, 0, 1]);

Copies bits from one part of the slice to another part of itself.

src is the range within self to copy from. dest is the starting index of the range within self to copy to, which will have the same length as src. The two ranges may overlap. The ends of the two ranges must be less than or equal to self.len().

Original

slice::copy_within

Panics

This function will panic if either range exceeds the end of the slice, or if the end of src is before the start.

Examples

Copying four bits within a slice:

use bitvec::prelude::*;

let bits = bits![mut 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0];

bits.copy_within(1 .. 5, 8);

assert_eq!(bits, bits![1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0]);

Transmute the bit-slice to a bit-slice of another type, ensuring alignment of the types is maintained.

Original

slice::align_to

API Differences

Type U is required to have the same BitStore type family as type T. If T is a fundamental integer, so must U be; if T is an ::Alias type, then so must U. Changing the type family with this method is unsound and strictly forbidden. Unfortunately, this cannot be encoded in the type system, so you are required to abide by this limitation yourself.

Implementation

The algorithm used to implement this function attempts to create the widest possible span for the middle slice. However, the slice divisions must abide by the Domain restrictions: the left and right slices produced by this function will include the head and tail elements of the domain (if present), as well as the left and right subslices (if any) produced by calling slice::align_to on the domain body (if present).

The standard library implementation currently maximizes the width of the center slice, but its API does not guarantee this property, and retains the right to produce pessimal slices. As such, this function cannot guarantee maximal center slice width either, and you cannot rely on this behavior for correctness of your work; it is only a possible performance improvement.

Safety

This method is essentially a mem::transmute with respect to the memory region in the retured middle slice, so all of the usual caveats pertaining to mem::transmute::<T, U> also apply here.

Examples

Basic usage:

use bitvec::prelude::*;

unsafe {
  let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
  let bits = bytes.view_bits::<LocalBits>();
  let (prefix, shorts, suffix) = bits.align_to::<u16>();
  match prefix.len() {
    0 => {
      assert_eq!(shorts, bits[.. 48]);
      assert_eq!(suffix, bits[48 ..]);
    },
    8 => {
      assert_eq!(prefix, bits[.. 8]);
      assert_eq!(shorts, bits[8 ..]);
    },
    _ => unreachable!("This case will not occur")
  }
}

Transmute the bit-slice to a bit-slice of another type, ensuring alignment of the types is maintained.

Original

slice::align_to_mut

API Differences

Type U is required to have the same BitStore type family as type T. If T is a fundamental integer, so must U be; if T is an ::Alias type, then so must U. Changing the type family with this method is unsound and strictly forbidden. Unfortunately, this cannot be encoded in the type system, so you are required to abide by this limitation yourself.

Implementation

The algorithm used to implement this function attempts to create the widest possible span for the middle slice. However, the slice divisions must abide by the DomainMut restrictions: the left and right slices produced by this function will include the head and tail elements of the domain (if present), as well as the left and right subslices (if any) produced by calling slice::align_to_mut on the domain body (if present).

The standard library implementation currently maximizes the width of the center slice, but its API does not guarantee this property, and retains the right to produce pessimal slices. As such, this function cannot guarantee maximal center slice width either, and you cannot rely on this behavior for correctness of your work; it is only a possible performance improvement.

Safety

This method is essentially a mem::transmute with respect to the memory region in the retured middle slice, so all of the usual caveats pertaining to mem::transmute::<T, U> also apply here.

Examples

Basic usage:

use bitvec::prelude::*;

unsafe {
  let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
  let bits = bytes.view_bits_mut::<LocalBits>();
  let (prefix, shorts, suffix) = bits.align_to_mut::<u16>();
  //  same access and behavior as in `align_to`
}

Creates a vector by repeating a slice n times.

Original

slice::repeat

Panics

This function will panic if the capacity would overflow.

Examples

Basic usage:

use bitvec::prelude::*;

assert_eq!(bits![0, 1].repeat(3), bits![0, 1, 0, 1, 0, 1]);

A panic upon overflow:

ⓘ
use bitvec::prelude::*;

// this will panic at runtime
bits![0, 1].repeat(BitSlice::<LocalBits, usize>::MAX_BITS);

Writes a new bit at a given index.

Parameters
  • &mut self
  • index: The bit index at which to write. It must be in the range 0 .. self.len().
  • value: The value to be written; true for 1 or false for 0.
Effects

If index is valid, then the bit to which it refers is set to value.

Panics

This method panics if index is not less than self.len().

Examples
use bitvec::prelude::*;

let bits = bits![mut 0];

assert!(!bits[0]);
bits.set(0, true);
assert!(bits[0]);

This example panics when it attempts to set a bit that is out of bounds.

ⓘ
use bitvec::prelude::*;

let bits = bits![mut 0];
bits.set(1, false);

Writes a new bit at a given index.

This method supports writing through a shared reference to a bit that may be observed by other BitSlice handles. It is only present when the T type parameter supports such shared mutation (measured by the Radium trait).

Parameters
  • &self
  • index: The bit index at which to write. It must be in the range 0 .. self.len().
  • value: The value to be written; true for 1 or false for 0.
Effects

If index is valid, then the bit to which it refers is set to value. If T is an atomic, this will lock the memory bus for the referent address, and may cause stalls.

Panics

This method panics if index is not less than self.len().

Examples
use bitvec::prelude::*;
use core::cell::Cell;

let byte = Cell::new(0u8);
let bits = byte.view_bits::<Msb0>();
let bits_2 = bits;

bits.set_aliased(1, true);
assert!(bits_2[1]);

This example panics when it attempts to set a bit that is out of bounds.

ⓘ
use bitvec::prelude::*;
use core::cell::Cell;

let byte = Cell::new(0u8);
let bits = byte.view_bits::<Lsb0>();
bits.set_aliased(8, false);

Tests if any bit in the slice is set (logical ∨).

Truth Table
0 0 => 0
0 1 => 1
1 0 => 1
1 1 => 1
Parameters
  • &self
Returns

Whether any bit in the slice domain is set. The empty slice returns false.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0];
assert!(bits[.. 2].any());
assert!(!bits[2 ..].any());

Tests if all bits in the slice domain are set (logical ∧).

Truth Table
0 0 => 0
0 1 => 0
1 0 => 0
1 1 => 1
Parameters
  • &self
Returns

Whether all bits in the slice domain are set. The empty slice returns true.

Examples
use bitvec::prelude::*;

let bits = bits![1, 1, 0, 1];
assert!(bits[.. 2].all());
assert!(!bits[2 ..].all());

Tests if all bits in the slice are unset (logical ¬∨).

Truth Table
0 0 => 1
0 1 => 0
1 0 => 0
1 1 => 0
Parameters
  • &self
Returns

Whether all bits in the slice domain are unset.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0];
assert!(!bits[.. 2].not_any());
assert!(bits[2 ..].not_any());

Tests if any bit in the slice is unset (logical ¬∧).

Truth Table
0 0 => 1
0 1 => 1
1 0 => 1
1 1 => 0
Parameters
  • &self
Returns

Whether any bit in the slice domain is unset.

Examples
use bitvec::prelude::*;

let bits = bits![1, 1, 0, 1];
assert!(!bits[.. 2].not_all());
assert!(bits[2 ..].not_all());

Tests whether the slice has some, but not all, bits set and some, but not all, bits unset.

This is false if either .all() or .not_any() are true.

Truth Table
0 0 => 0
0 1 => 1
1 0 => 1
1 1 => 0
Parameters
  • &self
Returns

Whether the slice domain has mixed content. The empty slice returns false.

Examples
use bitvec::prelude::*;

let data = 0b111_000_10u8;
let bits = bits![1, 1, 0, 0, 1, 0];

assert!(!bits[.. 2].some());
assert!(!bits[2 .. 4].some());
assert!(bits.some());

Counts the number of bits set to 1 in the slice contents.

Parameters
  • &self
Returns

The number of bits in the slice domain that are set to 1.

Examples

Basic usage:

use bitvec::prelude::*;

let bits = bits![1, 1, 0, 0];
assert_eq!(bits[.. 2].count_ones(), 2);
assert_eq!(bits[2 ..].count_ones(), 0);

Counts the number of bits cleared to 0 in the slice contents.

Parameters
  • &self
Returns

The number of bits in the slice domain that are cleared to 0.

Examples

Basic usage:

use bitvec::prelude::*;

let bits = bits![1, 1, 0, 0];
assert_eq!(bits[.. 2].count_zeros(), 0);
assert_eq!(bits[2 ..].count_zeros(), 2);

Enumerates all bits in a BitSlice that are set to 1.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0, 1, 0, 0, 0, 1];
let mut indices = [1, 4, 8].iter().copied();

let mut iter_ones = bits.iter_ones();
let mut compose = bits.iter()
  .copied()
  .enumerate()
  .filter_map(|(idx, bit)| if bit { Some(idx) } else { None });

for ((a, b), c) in iter_ones.zip(compose).zip(indices) {
  assert_eq!(a, b);
  assert_eq!(b, c);
}

Enumerates all bits in a BitSlice that are cleared to 0.

Examples
use bitvec::prelude::*;

let bits = bits![1, 0, 1, 1, 0, 1, 1, 1, 0];
let mut indices = [1, 4, 8].iter().copied();

let mut iter_zeros = bits.iter_zeros();
let mut compose = bits.iter()
  .copied()
  .enumerate()
  .filter_map(|(idx, bit)| if !bit { Some(idx) } else { None });

for ((a, b), c) in iter_zeros.zip(compose).zip(indices) {
  assert_eq!(a, b);
  assert_eq!(b, c);
}

Gets the index of the first bit in the bit-slice set to 1.

Examples
use bitvec::prelude::*;

assert!(bits![].first_one().is_none());
assert_eq!(bits![0, 0, 1].first_one().unwrap(), 2);

Gets the index of the first bit in the bit-slice set to 0.

Examples
use bitvec::prelude::*;

assert!(bits![].first_zero().is_none());
assert_eq!(bits![1, 1, 0].first_zero().unwrap(), 2);

Gets the index of the last bit in the bit-slice set to 1.

Examples
use bitvec::prelude::*;

assert!(bits![].last_one().is_none());
assert_eq!(bits![1, 0, 0, 1].last_one().unwrap(), 3);

Gets the index of the last bit in the bit-slice set to 0.

Examples
use bitvec::prelude::*;

assert!(bits![].last_zero().is_none());
assert_eq!(bits![0, 1, 1, 0].last_zero().unwrap(), 3);

Counts the number of bits from the start of the bit-slice to the first bit set to 0.

This returns 0 if the bit-slice is empty.

Examples
use bitvec::prelude::*;

assert_eq!(bits![].leading_ones(), 0);
assert_eq!(bits![0].leading_ones(), 0);
assert_eq!(bits![1, 0, 1, 1].leading_ones(), 1);
assert_eq!(bits![1, 1, 1, 1].leading_ones(), 4);

Counts the number of bits from the start of the bit-slice to the first bit set to 1.

This returns 0 if the bit-slice is empty.

Examples
use bitvec::prelude::*;

assert_eq!(bits![].leading_zeros(), 0);
assert_eq!(bits![1].leading_zeros(), 0);
assert_eq!(bits![0, 1, 0, 0].leading_zeros(), 1);
assert_eq!(bits![0, 0, 0, 0].leading_zeros(), 4);

Counts the number of bits from the end of the bit-slice to the last bit set to 0.

This returns 0 if the bit-slice is empty.

Examples
use bitvec::prelude::*;

assert_eq!(bits![].trailing_ones(), 0);
assert_eq!(bits![0].trailing_ones(), 0);
assert_eq!(bits![1, 0, 1, 1].trailing_ones(), 2);

Counts the number of bits from the end of the bit-slice to the last bit set to 1.

This returns 0 if the bit-slice is empty.

Examples
use bitvec::prelude::*;

assert_eq!(bits![].trailing_zeros(), 0);
assert_eq!(bits![1].trailing_zeros(), 0);
assert_eq!(bits![0, 1, 0, 0].trailing_zeros(), 2);

Copies the bits from src into self.

The length of src must be the same as `self.

If src has the same type arguments as self, it can be more performant to use .copy_from_bitslice().

Original

slice::clone_from_bitslice

API Differences

This method is renamed, as it takes a bit slice rather than an element slice.

Panics

This function will panic if the two slices have different lengths.

Examples

Cloning two bits from a slice into another:

use bitvec::prelude::*;

let src = bits![Msb0, u16; 1; 4];
let dst = bits![mut Lsb0, u8; 0; 2];

dst.clone_from_bitslice(&src[2 ..]);
assert_eq!(dst, bits![1; 2]);

Rust enforces that there can only be one mutable reference with no immutable references to a particular piece of data in a particular scope. Because of this, attempting to use clone_from_slice on a single slice will result in a compile failure:

ⓘ
use bitvec::prelude::*;

let slice = bits![mut 0, 0, 0, 1, 1];
slice[.. 2].clone_from_bitslice(&slice[3 ..]); // compile fail!

To work around this, we can use .split_at_mut() to create two distinct sub-slices from a slice:

use bitvec::prelude::*;

let slice = bits![mut 0, 0, 0, 1, 1];

{
  let (left, right) = slice.split_at_mut(2);
  left.clone_from_bitslice(&right[1 ..]);
}

assert_eq!(slice, bits![1, 1, 0, 1, 1]);
Performance

If self and src use the same type arguments, this specializes to .copy_from_bitslice(); if you know statically that this is the case, prefer to call that method directly and avoid the cost of detection at runtime. Otherwise, this is a bit-by-bit crawl across both slices, which is a slow process.

Copies all bits from src into self, using a memcpy wherever possible.

The length of src must be same as self.

If src does not use the same type arguments as self, use .clone_from_bitslice().

Original

slice::copy_from_slice

API Differences

This method is renamed, as it takes a bit slice rather than an element slice.

Panics

This function will panic if the two slices have different lengths.

Examples

Copying two bits from a slice into another:

use bitvec::prelude::*;

let src = bits![1; 4];
let dst = bits![mut 0; 2];

// Because the slices have to be the same length,
// we slice the source slice from four bits to
// two. It will panic if we don't do this.
dst.clone_from_bitslice(&src[2..]);

Rust enforces that there can only be one mutable reference with no immutable references to a particular piece of data in a particular scope. Because of this, attempting to use [.copy_from_slice()] on a single slice will result in a compile failure:

ⓘ
use bitvec::prelude::*;

let slice = bits![mut 0, 0, 0, 1, 1];

slice[.. 2].copy_from_bitslice(&bits[3 ..]); // compile fail!

To work around this, we can use .split_at_mut() to create two distinct sub-slices from a slice:

use bitvec::prelude::*;

let slice = bits![mut 0, 0, 0, 1, 1];

{
  let (left, right) = slice.split_at_mut(2);
  left.copy_from_bitslice(&right[1 ..]);
}

assert_eq!(slice, bits![1, 1, 0, 1, 1]);

Swaps all bits in self with those in other.

The length of other must be the same as self.

Original

slice::swap_with_slice

API Differences

This method is renamed, as it takes a bit slice rather than an element slice.

Panics

This function will panic if the two slices have different lengths.

Examples
use bitvec::prelude::*;

let mut one = [0xA5u8, 0x69];
let mut two = 0x1234u16;
let one_bits = one.view_bits_mut::<Msb0>();
let two_bits = two.view_bits_mut::<Lsb0>();

one_bits.swap_with_bitslice(two_bits);

assert_eq!(one, [0x2C, 0x48]);
assert_eq!(two, 0x96A5);

Shifts the contents of a bit-slice left (towards index 0).

This moves the contents of the slice from by .. down to 0 .. len - by, and erases len - by .. to 0. As this is a destructive (and linearly expensive) operation, you may prefer instead to use range subslicing.

Parameters
  • &mut self
  • by: The distance by which to shift the slice contents.
Panics

This panics if by is not less than self.len().

Examples
use bitvec::prelude::*;

let bits = bits![mut 1; 6];
bits.shift_left(2);
assert_eq!(bits, bits![1, 1, 1, 1, 0, 0]);

Shifts the contents of a bit-slice right (towards index self.len()).

This moves the contents of the slice from .. len - by up to by .., and erases .. by to 0. As this is a destructive (and linearly expensive) operation, you may prefer instead to use range subslicing.

Parameters
  • &mut self
  • by: The distance by which to shift the slice contents.
Panics

This panics if by is not less than self.len().

Examples
use bitvec::prelude::*;

let bits = bits![mut 1; 6];
bits.shift_right(2);
assert_eq!(bits, bits![0, 0, 1, 1, 1, 1]);

Sets all bits in the slice to a value.

Parameters
  • &mut self
  • value: The bit value to which all bits in the slice will be set.
Examples
use bitvec::prelude::*;

let mut src = 0u8;
let bits = src.view_bits_mut::<Msb0>();
bits[2 .. 6].set_all(true);
assert_eq!(bits.as_slice(), &[0b0011_1100]);
bits[3 .. 5].set_all(false);
assert_eq!(bits.as_slice(), &[0b0010_0100]);
bits[.. 1].set_all(true);
assert_eq!(bits.as_slice(), &[0b1010_0100]);

Applies a function to each bit in the slice.

BitSlice cannot implement IndexMut, as it cannot manifest &mut bool references, and the BitRef proxy reference has an unavoidable overhead. This method bypasses both problems, by applying a function to each pair of index and value in the slice, without constructing a proxy reference. Benchmarks indicate that this method is about 2–4 times faster than the .iter_mut().enumerate() equivalent.

Parameters
  • &mut self
  • func: A function which receives two arguments, index: usize and value: bool, and returns a bool.
Effects

For each index in the slice, the result of invoking func with the index number and current bit value is written into the slice.

Examples
use bitvec::prelude::*;

let mut data = 0u8;
let bits = data.view_bits_mut::<Msb0>();
bits.for_each(|idx, _bit| idx % 3 == 0);
assert_eq!(data, 0b100_100_10);

Produces the absolute offset in bits between two slice heads.

While this method is sound for any two arbitrary bit slices, the answer it produces is meaningful only when one argument is a strict subslice of the other. If the two slices are created from different buffers entirely, a comparison is undefined; if the two slices are disjoint regions of the same buffer, then the semantically correct distance is between the tail of the lower and the head of the upper, which this does not measure.

Visual Description

Consider the following sequence of bits:

[ 0 1 2 3 4 5 6 7 8 9 a b ]
  |       ^^^^^^^       |
  ^^^^^^^^^^^^^^^^^^^^^^^

It does not matter whether there are bits between the tail of the smaller and the larger slices. The offset is computed from the bit distance between the two heads.

Behavior

This function computes the semantic distance between the heads, rather than the *electrical. It does not take into account the BitOrder implementation of the slice.

Safety and Soundness

One of self or other must contain the other for this comparison to be meaningful.

Parameters
  • &self
  • other: Another bit slice. This must be either a strict subregion or a strict superregion of self.
Returns

The distance in (semantic) bits betwen the heads of each region. The value is positive when other is higher in the address space than self, and negative when other is lower in the address space than self.

Writes a new bit at a given index, without doing bounds checking.

This is generally not recommended; use with caution! Calling this method with an out-of-bounds index is undefined behavior. For a safe alternative, see .set().

Parameters
  • &mut self
  • index: The bit index at which to write. It must be in the range 0 .. self.len().
  • value: The value to be written; true for 1 or false for 0.
Effects

The bit at index is set to value. If index is out of bounds, then the memory access is incorrect, and its behavior is unspecified.

Safety

This method is not safe. It performs raw pointer arithmetic to seek from the start of the slice to the requested index, and set the bit there. It does not inspect the length of self, and it is free to perform out-of-bounds memory write access.

Use this method only when you have already performed the bounds check, and can guarantee that the call occurs with a safely in-bounds index.

Examples

This example uses a bit slice of length 2, and demonstrates out-of-bounds access to the last bit in the element.

use bitvec::prelude::*;

let bits = bits![mut 0; 2];
let (first, _) = bits.split_at_mut(1);

unsafe {
  first.set_unchecked(1, true);
}

assert_eq!(bits, bits![0, 1]);

Writes a new bit at a given index, without doing bounds checking.

This method supports writing through a shared reference to a bit that may be observed by other BitSlice handles. It is only present when the T type parameter supports such shared mutation (measured by the Radium trait).

Effects

The bit at index is set to value. If index is out of bounds, then the memory access is incorrect, and its behavior is unspecified. If T is an atomic, this will lock the memory bus for the referent address, and may cause stalls.

Safety

This method is not safe. It performs raw pointer arithmetic to seek from the start of the slice to the requested index, and set the bit there. It does not inspect the length of self, and it is free to perform out-of-bounds memory write access.

Use this method only when you have already performed the bounds check, and can guarantee that the call occurs with a safely in-bounds index.

Examples
use bitvec::prelude::*;
use core::cell::Cell;

let byte = Cell::new(0u8);
let bits = byte.view_bits::<Msb0>();
let bits_2 = bits;

let (first, _) = bits.split_at(1);
assert_eq!(first.len(), 1);
unsafe { first.set_aliased_unchecked(2, true); }

assert!(bits_2[2]);

Swaps two bits in the slice.

See .swap().

Safety

a and b must both be less than self.len().

Divides one slice into two at an index, without performing any bounds checking.

See .split_at().

Safety

mid must not be greater than self.len(). If this condition is violated, the function behavior is unspecified.

Examples
use bitvec::prelude::*;

let bits = bits![0, 0, 0, 1, 1, 1];
let (l, r) = unsafe { bits.split_at_unchecked(3) };
assert!(l.not_any());
assert!(r.all());

let (l, r) = unsafe { bits.split_at_unchecked(6) };
assert_eq!(l, bits);
assert!(r.is_empty());

Divides one mutable slice into two at an index.

See .split_at_mut().

Safety

mid must not be greater than self.len().

Copies bits from one part of the slice to another part of itself, without doing bounds checks.

The ranges are allowed to overlap.

Parameters
  • &mut self
  • src: The range within self from which to copy.
  • dst: The starting index within self at which to paste.
Effects

self[src] is copied to self[dest .. dest + src.end() - src.start()].

Safety

src and dest .. dest + src.len() must be entirely within self.len().

Returns a raw bit-pointer to the base of the bit-slice’s region.

The caller must ensure that the bit-slice outlives the bit-pointer this function returns, or else it will end up pointing to garbage.

The caller must also ensure that the memory the bit-pointer (non-transitively) points to is never written to using this bit-pointer or any bit-pointer derived from it. If you need to mutate the contents of the slice, use .as_mut_bitptr().

Modifying the container referenced by this bit-slice may cause its buffer to be reällocated, which would also make any bit-pointers to it invalid.

Original

slice::as_ptr

API Differences

This returns a structure, BitPtr, rather than an actual raw pointer *Bit. The information required to address a bit within a memory element cannot be encoded into a single pointer.

This structure can be converted back into a &BitSlice with the function from_raw_parts.

Examples
use bitvec::prelude::*;

let x = bits![0, 0, 1];
let x_ptr = x.as_ptr();

unsafe {
  for i in 0 .. x.len() {
    assert_eq!(*x.get_unchecked(i), (&*x)[i]);
  }
}

Returns an unsafe mutable bit-pointer to the bit-slice’s region.

The caller must ensure that the bit-slice outlives the bit-pointer this function returns, or else it will end up pointing to garbage.

Modifying the container referenced by this bit-slice may cause its buffer to be reällocated, which would also make any bit-pointers to it invalid.

Original

slice::as_mut_ptr

API Differences

This returns *mut BitSlice, which is the equivalont of *mut [T] instead of *mut T. The pointer encoding used requires more than one CPU word of space to address a single bit, so there is no advantage to removing the length information from the encoded pointer value.

Examples
use bitvec::prelude::*;

let bits = bits![mut Lsb0, u8; 0; 8];
let bits_ptr = bits.as_mut_ptr();

for i in 0 .. bits.len() {
  unsafe {
    bits_ptr.add(i).write(i % 3 == 0);
  }
}
assert_eq!(bits.as_slice()[0], 0b0100_1001);

Returns the two raw bit-pointers spanning the bit-slice.

The returned range is half-open, which means that the end bit-pointer points one past the last bit of the bit-slice. This way, an empty bit-slice is represented by two equal bit-pointers, and the difference between the two bit-pointers represents the size of the bit-slice.

See as_bitptr for warnings on using these bit-pointers. The end bit-pointer requires extra caution, as it does not point to a valid bit in the bit-slice.

This function allows a more direct access to bit-pointers, without paying the cost of encoding into a *BitSlice, at the cost of no longer fitting into ordinary Rust interfaces.

Original

slice::as_ptr_range

API Differences

This returns a dedicated structure, rather than a range of BitPtrs, because the traits needed for non-core types to correctly operate in ranges are still unstable. The structure can be converted into a range, but that range will not be an iterator.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0, 1];
let mid_ptr = bits.get(2).unwrap().into_bitptr();
let mut range = bits.as_bitptr_range();
assert!(range.contains(&mid_ptr));
unsafe {
  assert!(!range.next().unwrap().read());
  assert!(range.next_back().unwrap().read())
}

Returns the two unsafe mutable bit-pointers spanning the bit-slice.

The returned range is half-open, which means that the end bit-pointer points one past the last bitt of the bit-slice. This way, an empty bit-slice is represented by two equal bit-pointers, and the difference between the two bit-pointers represents the size of the bit-slice.

See as_mut_bitptr for warnings on using these bit-pointers. The end bit-pointer requires extra caution, as it does not point to a valid bit in the bit-slice.

Original

slice::as_mut_ptr_range

API Differences

This returns a dedicated structure, rather than a range of BitPtrs, because the traits needed for non-core types to correctly operate in ranges are still unstable. The structure can be converted into a range, but that range will not be an iterator.

Examples
use bitvec::prelude::*;
use bitvec::ptr as bv_ptr;

let mut data = 0u8;
let bits = data.view_bits_mut::<Msb0>();
for mut bitptr in bits.as_mut_bitptr_range() {
  unsafe { bv_ptr::write(bitptr, true); }
}
assert_eq!(data, !0);

Splits the slice into subslices at alias boundaries.

This splits self into the memory locations that it partially fills and the memory locations that it completely fills. The locations that are completely filled may be accessed without any bitvec-imposed alias conditions, while the locations that are only partially filled are left unchanged.

You can read more about the BitDomain splitting in its documentation.

Examples
use bitvec::prelude::*;

let mut data = [0u16; 3];
let all = data.view_bits_mut::<Msb0>();
let (_, rest) = all.split_at_mut(8);
let bits: &BitSlice<Msb0, <u16 as BitStore>::Alias> = &rest[.. 32];

let (head, body, tail) = bits
  .bit_domain()
  .region()
  .unwrap();
assert_eq!(head.len(), 8);
assert_eq!(tail.len(), 8);
let _: &BitSlice<Msb0, <u16 as BitStore>::Alias> = head;
let _: &BitSlice<Msb0, <u16 as BitStore>::Alias> = tail;
let _: &BitSlice<Msb0, u16> = body;

Splits the slice into subslices at alias boundaries.

This splits self into the memory locations that it partially fills and the memory locations that it completely fills. The locations that are completely filled may be accessed without any bitvec-imposed alias conditions, while the locations that are only partially filled are left unchanged.

You can read more about the BitDomainMut splitting in its documentation.

Examples
use bitvec::prelude::*;

let mut data = [0u16; 3];
let all = data.view_bits_mut::<Msb0>();
let (_, rest) = all.split_at_mut(8);
let bits: &mut BitSlice<Msb0, <u16 as BitStore>::Alias>
  = &mut rest[.. 32];

let (head, body, tail) = bits
  .bit_domain_mut()
  .region()
  .unwrap();
assert_eq!(head.len(), 8);
assert_eq!(tail.len(), 8);
let _: &mut BitSlice<Msb0, <u16 as BitStore>::Alias> = head;
let _: &mut BitSlice<Msb0, <u16 as BitStore>::Alias> = tail;
let _: &mut BitSlice<Msb0, u16> = body;

Views the underlying memory containing the slice, split at alias boundaries.

This splits self into the memory locations that it partially fills and the memory locatinos that it completely fills. The locations that are completely filled may be accessed without any bitvec-imposed alias conditions, while the locations that are only partially filled are left unchanged.

You can read more about the Domain splitting in its documentation.

Examples
use bitvec::prelude::*;

let mut data = [0u16; 3];
let all = data.view_bits_mut::<Msb0>();
let (_, rest) = all.split_at_mut(8);
let bits: &BitSlice<Msb0, <u16 as BitStore>::Alias> = &rest[.. 32];

let (head, body, tail) = bits
  .domain()
  .region()
  .unwrap();
assert_eq!(body.len(), 1);

let _: &<u16 as BitStore>::Alias = head.unwrap().1;
let _: &<u16 as BitStore>::Alias = tail.unwrap().0;
let _: &[u16] = body;

Views the underlying memory containing the slice, split at alias boundaries.

This splits self into the memory locations that it partially fills and the memory locations that it completely fills. The locations that are completely filled may be accessed without any bitvec-imposed alias conditions, while the locations that are only partially filled are left unchanged.

You can read more about the DomainMut splitting in its documentation.

Examples
use bitvec::prelude::*;

let mut data = [0u16; 3];
let all = data.view_bits_mut::<Msb0>();
let (_, rest) = all.split_at_mut(8);
let bits: &mut BitSlice<Msb0, <u16 as BitStore>::Alias> = &mut rest[.. 32];

let (head, body, tail) = bits
  .domain_mut()
  .region()
  .unwrap();
assert_eq!(body.len(), 1);

let _: &<<u16 as BitStore>::Alias as BitStore>::Access = head.unwrap().1;
let _: &<<u16 as BitStore>::Alias as BitStore>::Access = tail.unwrap().0;
let _: &mut [u16] = body;

Views the underlying memory containing the slice.

The returned slice handle views all elements touched by self, and marks them all with self’s current aliasing state. For a more precise view, or one that permits mutation, use .domain() or .domain_mut().

Splits a mutable slice at some mid-point.

This method has the same behavior as .split_at_mut(), except that it does not apply an aliasing marker to the partitioned subslices.

Safety

Because this method is defined only on BitSlices whose T type is alias-safe, the subslices do not need to be additionally marked.

Copies self into a new BitVec.

This resets any alias markings from self, since the returned buffer is known to be newly allocated and thus unaliased.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 1];
let bv = bits.to_bitvec();
assert_eq!(bits, bv);

Trait Implementations

Performs the conversion.

Performs the conversion.

Formats the value using the given formatter.

The resulting type after applying the & operator.

Performs the & operation. Read more

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Loads from self, using little-endian element T ordering. Read more

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Stores into self, using little-endian element ordering. Read more

Stores into self, using big-endian element ordering. Read more

Loads the bits in the self region into a local value. Read more

Stores a sequence of bits from the user into the domain of self. Read more

The resulting type after applying the | operator.

Performs the | operation. Read more

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The resulting type after applying the ^ operator.

Performs the ^ operation. Read more

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Dereferences the value.

Mutably dereferences the value.

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Feeds this value into the given Hasher. Read more

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The returned type after indexing.

Performs the indexing (container[index]) operation. Read more

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Which kind of iterator are we turning this into?

The type of the elements being iterated over.

Creates an iterator from a value. Read more

Which kind of iterator are we turning this into?

The type of the elements being iterated over.

Creates an iterator from a value. Read more

Which kind of iterator are we turning this into?

The type of the elements being iterated over.

Creates an iterator from a value. Read more

Formats the value using the given formatter.

The resulting type after applying the ! operator.

Performs the unary ! operation. Read more

Formats the value using the given formatter.

This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

Restrict a value to a certain interval. Read more

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

This method returns an ordering between self and other values if one exists. Read more

This method tests less than (for self and other) and is used by the < operator. Read more

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

This method tests greater than (for self and other) and is used by the > operator. Read more

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

This method returns an ordering between self and other values if one exists. Read more

This method tests less than (for self and other) and is used by the < operator. Read more

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

This method tests greater than (for self and other) and is used by the > operator. Read more

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

Formats the value using the given formatter.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Converts self into T using Into<T>. Read more

Converts self into a target type. Read more

Causes self to use its Binary implementation when Debug-formatted.

Causes self to use its Display implementation when Debug-formatted. Read more

Causes self to use its LowerExp implementation when Debug-formatted. Read more

Causes self to use its LowerHex implementation when Debug-formatted. Read more

Causes self to use its Octal implementation when Debug-formatted.

Causes self to use its Pointer implementation when Debug-formatted. Read more

Causes self to use its UpperExp implementation when Debug-formatted. Read more

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Performs the conversion.

Performs the conversion.

Performs the conversion.

Pipes by value. This is generally the method you want to use. Read more

Borrows self and passes that borrow into the pipe function. Read more

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Calls .tap() only in debug builds, and is erased in release builds.

Calls .tap_mut() only in debug builds, and is erased in release builds. Read more

Calls .tap_borrow() only in debug builds, and is erased in release builds. Read more

Calls .tap_borrow_mut() only in debug builds, and is erased in release builds. Read more

Calls .tap_ref() only in debug builds, and is erased in release builds. Read more

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Provides immutable access for inspection. Read more

Calls tap in debug builds, and does nothing in release builds.

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Calls tap_mut in debug builds, and does nothing in release builds.

Provides immutable access to the reference for inspection.

Calls tap_ref in debug builds, and does nothing in release builds.

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Calls tap_ref_mut in debug builds, and does nothing in release builds.

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Calls tap_borrow_mut in debug builds, and does nothing in release builds. Read more

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Calls tap_deref in debug builds, and does nothing in release builds.

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Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

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Performs the conversion.

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