#[repr(C)]
pub struct BitVec<T = usize, O = Lsb0> where
    T: BitStore,
    O: BitOrder
{ /* fields omitted */ }
Expand description

Bit-Precision Dynamic Array

This is an analogue to Vec<bool> that stores its data using a compaction scheme to ensure that each bool takes exactly one bit of memory. It is similar to the C++ type std::vector<bool>, but uses bitvec’s type parameter system to provide more detailed control over the in-memory representation.

This is always a heap allocation. If you know your sizes at compile-time, you may prefer to use BitArray instead, which is able to store its data as an immediate value rather than through an indirection.

Documentation Practices

BitVec exactly replicates the API of the standard-library Vec type, including inherent methods, trait implementations, and relationships with the BitSlice slice analogue.

Items that are either direct ports, or renamed variants, of standard-library APIs will have a ## Original section that links to their standard-library documentation. Items that map to standard-library APIs but have a different API signature will also have an ## API Differences section that describes what the difference is, why it exists, and how to transform your code to fit it. For example:

Original

Vec<T>

API Differences

As with all bitvec data structures, this takes two type parameters <T, O> that govern the bit-vector’s storage representation in the underlying memory, and does not take a type parameter to govern what data type it stores (always bool)

Suggested Uses

BitVec is able to act as a compacted usize => bool dictionary, and is useful for holding large collections of truthiness. For instance, you might replace a Vec<Option<T>> with a (BitVec, Vec<MaybeUninit<T>>) to cut down on the resident size of the discriminant.

Through the BitField trait, BitVec is also able to act as a transport buffer for data that can be marshalled as integers. Serializing data to a narrower compacted form, or deserializing data from that form, can be easily accomplished by viewing subsets of a bit-vector and storing integers into, or loading integers out of, that subset. As an example, transporting four ten-bit integers can be done in five bytes instead of eight like so:

use bitvec::prelude::*;

let mut bv = bitvec![u8, Msb0; 0; 40];
bv[0 .. 10].store::<u16>(0x3A8);
bv[10 .. 20].store::<u16>(0x2F9);
bv[20 .. 30].store::<u16>(0x154);
bv[30 .. 40].store::<u16>(0x06D);

If you wish to use bit-field memory representations as struct fields rather than a transport buffer, consider BitArray instead: that type keeps its data as an immediate, and is more likely to act like a C struct with bitfields.

Examples

BitVec has exactly the same API as Vec<bool>, and even extends it with some of Vec<T>’s behaviors. As a brief tour:

Push and Pop

use bitvec::prelude::*;

let mut bv: BitVec = BitVec::new();
bv.push(false);
bv.push(true);

assert_eq!(bv.len(), 2);
assert_eq!(bv[0], false);

assert_eq!(bv.pop(), Some(true));
assert_eq!(bv.len(), 1);

Writing Into a Bit-Vector

The only Vec<bool> API that BitVec does not implement is IndexMut, because that is not yet possible. Instead, .get_mut() can produce a proxy reference, or .set() can take an index and a value to write.

use bitvec::prelude::*;

let mut bv: BitVec = BitVec::new();
bv.push(false);

*bv.get_mut(0).unwrap() = true;
assert!(bv[0]);
bv.set(0, false);
assert!(!bv[0]);

Macro Construction

Like Vec, BitVec also has a macro constructor: bitvec! takes a sequence of bit expressions and encodes them at compile-time into a suitable buffer. At run-time, this buffer is copied into the heap as a BitVec with no extra cost beyond the allocation.

use bitvec::prelude::*;

let bv = bitvec![0; 10];
let bv = bitvec![0, 1, 0, 0, 1];
let bv = bitvec![u16, Msb0; 1; 20];

Borrowing as BitSlice

BitVec lends its buffer as a BitSlice, so you can freely give permission to view or modify the contained data without affecting the allocation:

use bitvec::prelude::*;

fn read_bitslice(bits: &BitSlice) {
  // …
}

let bv = bitvec![0; 30];
read_bitslice(&bv);
let bs: &BitSlice = &bv;

Other Notes

The default type parameters are <usize, Lsb0>. This is the most performant pair when operating on memory, but likely does not match your needs if you are using BitVec to represent a transport buffer. See the user guide for more details on how the type parameters govern memory representation.

Applications, or single-purpose libraries, built atop bitvec will likely want to create a type alias with specific type parameters for their usage. bitvec is fully generic over the ordering/storage types, but this generality is rarely useful for client crates to propagate. <usize, Lsb0> is fastest; <u8, Msb0> matches what most debugger views of memory will print, and the rest are documented in the guide.

Safety

Unlike the other data structures in this crate, BitVec is uniquely able to hold uninitialized memory and produce pointers into it. As described in the BitAccess documentation, this crate is categorically unable to operate on uninitialized memory in any way. In particular, you may not allocate a buffer using ::with_capacity(), then use .as_mut_bitptr() to create a pointer used to write into the uninitialized buffer.

You must always initialize the buffer contents of a BitVec before attempting to view its contents. You can accomplish this through safe APIs such as .push(), .extend(), or .reserve(). These are all guaranteed to safely initialize the memory elements underlying the BitVec buffer without incurring undefined behavior in their operation.

Implementations

Port of the Vec<T> inherent API.

Constructs a new, empty, bit-vector.

This does not allocate until bits are .push()ed into it, or space is explicitly .reserve()d.

Original

Vec::new

Examples
use bitvec::prelude::*;

let bv = BitVec::<u8, Msb0>::new();
assert!(bv.is_empty());

Allocates a new, empty, bit-vector with space for at least capacity bits before reallocating.

Original

Vec::with_capacity

Panics

This panics if the requested capacity is longer than what the bit-vector can represent. See BitSlice::MAX_BITS.

Examples
use bitvec::prelude::*;

let mut bv: BitVec = BitVec::with_capacity(128);

assert!(bv.is_empty());
assert!(bv.capacity() >= 128);

for i in 0 .. 128 {
  bv.push(i & 0xC0 == i);
}
assert_eq!(bv.len(), 128);
assert!(bv.capacity() >= 128);

bv.push(false);
assert_eq!(bv.len(), 129);
assert!(bv.capacity() >= 129);

Constructs a bit-vector handle from its constituent fields.

Original

Vec::from_raw_parts

Safety

The only acceptable argument values for this function are those that were previously produced by calling .into_raw_parts(). Furthermore, you may only call this at most once on any set of arguments. Using the same arguments in more than one call to this function will result in a double- or use-after free error.

Attempting to conjure your own values and pass them into this function will break the allocator state.

Examples
use bitvec::prelude::*;

let bv = bitvec![0, 1, 0, 0, 1];
let (bitptr, len, capa) = bv.into_raw_parts();
let bv2 = unsafe {
  BitVec::from_raw_parts(bitptr, len, capa)
};
assert_eq!(bv2, bits![0, 1, 0, 0, 1]);

Decomposes a bit-vector into its constituent member fields.

This disarms the destructor. In order to prevent a memory leak, you must pass these exact values back into ::from_raw_parts().

Original

Vec::into_raw_parts

API Differences

This method is still unstable as of 1.54. It is provided here as a convenience, under the expectation that the standard-library method will stabilize as-is.

Gets the allocation capacity, measured in bits.

This counts how many total bits the bit-vector can store before it must perform a reällocation to acquire more memory.

If the capacity is not a multiple of 8, you should call .force_align().

Original

Vec::capacity

Examples
use bitvec::prelude::*;

let bv = bitvec![0, 1, 0, 0, 1];

Ensures that the bit-vector has allocation capacity for at least additional more bits to be appended to it.

For convenience, this method guarantees that the underlying memory for self[.. self.len() + additional] is initialized, and may be safely accessed directly without requiring use of .push() or .extend() to initialize it.

Newly-allocated memory is always initialized to zero. It is still dead until the bit-vector is grown (by .push(), .extend(), or .set_len()), but direct access will not trigger UB.

Original

Vec::reserve

Panics

This panics if the new capacity exceeds the bit-vector’s maximum.

Examples
use bitvec::prelude::*;

let mut bv: BitVec = BitVec::with_capacity(80);
assert!(bv.capacity() >= 80);
bv.reserve(800);
assert!(bv.capacity() >= 800);

Ensures that the bit-vector has allocation capacity for at least additional more bits to be appended to it.

This differs from .reserve() by requesting that the allocator provide the minimum capacity necessary, rather than a potentially larger amount that the allocator may find more convenient.

Remember that this is a request: the allocator provides what it provides, and you cannot rely on the new capacity to be exactly minimal. You should still prefer .reserve(), especially if you expect to append to the bit-vector in the future.

Original

Vec::reserve_exact

Panics

This panics if the new capacity exceeds the bit-vector’s maximum.

Examples
use bitvec::prelude::*;

let mut bv: BitVec = BitVec::with_capacity(80);
assert!(bv.capacity() >= 80);
bv.reserve_exact(800);
assert!(bv.capacity() >= 800);

Releases excess capacity back to the allocator.

Like .reserve_exact(), this is a request to the allocator, not a command. The allocator may reclaim excess memory or may not.

Original

Vec::reserve_exact

Examples
use bitvec::prelude::*;

let mut bv: BitVec = BitVec::with_capacity(1000);
bv.push(true);
bv.shrink_to_fit();
👎 Deprecated:

prefer `.into_boxed_bitslice() instead

Shortens the bit-vector, keeping the first new_len bits and discarding the rest.

If len is greater than the bit-vector’s current length, this has no effect.

The .drain() method can emulate .truncate(), except that it yields the excess bits rather than discarding them.

Note that this has no effect on the allocated capacity of the bit-vector, nor does it erase truncated memory. Bits in the allocated memory that are outside of the .as_bitslice() view are always considered to have initialized, but unspecified, values, and you cannot rely on them to be zero.

Original

Vec::truncate

Examples

Truncating a five-bit vector to two bits:

use bitvec::prelude::*;

let mut bv = bitvec![0, 1, 0, 0, 1];
bv.truncate(2);
assert_eq!(bv.len(), 2);
assert!(bv.as_raw_slice()[0].count_ones() >= 2);

No truncation occurs when len is greater than the bit-vector’s current length:

👎 Deprecated:

use .as_bitslice() instead

👎 Deprecated:

use .as_mut_bitslice() instead

👎 Deprecated:

use .as_bitptr() instead

👎 Deprecated:

use .as_mut_bitptr() instead

Resizes a bit-vector to a new length.

Original

Vec::set_len

Safety

NOT ALL MEMORY IN THE ALLOCATION IS INITIALIZED!

Memory in a bit-vector’s allocation is only initialized when the bit-vector grows into it normally (through .push() or one of the various .extend*() methods). Setting the length to a value beyond what was previously initialized, but still within the allocation, is undefined behavior.

The caller is responsible for ensuring that all memory up to (but not including) the new length has already been initialized.

Panics

This panics if new_len exceeds the capacity as reported by .capacity().

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 1, 0, 0, 1];
unsafe {
  // The default storage type, `usize`, is at least 32 bits.
  bv.set_len(32);
}
assert_eq!(bv, bits![
  0, 1, 0, 0, 1, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0,
]);
//  `BitVec` guarantees that newly-initialized memory is zeroed.

Takes a bit out of the bit-vector.

The empty slot is filled with the last bit in the bit-vector, rather than shunting index + 1 .. self.len() down by one.

Original

Vec::swap_remove

Panics

This panics if index is out of bounds (self.len() or greater).

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 1, 0, 0, 1];
assert!(!bv.swap_remove(2));
assert_eq!(bv, bits![0, 1, 1, 0]);

Inserts a bit at a given position, shifting all bits after it one spot to the right.

index may be any value up to and including self.len(). If it is self.len(), it behaves equivalently to .push().

Original

Vec::insert

Panics

This panics if index is out of bounds (including self.len()).

Removes a bit at a given position, shifting all bits after it one spot to the left.

index may be any value up to, but not including, self.len().

Original

Vec::remove

Panics

This panics if index is out of bounds (excluding self.len()).

Retains only the bits that the predicate allows.

Bits are deleted from the vector when the predicate function returns false. This function is linear in self.len().

Original

Vec::retain

API Differences

The predicate receives both the index of the bit as well as its value, in order to allow the predicate to have more than one bit of keep/discard information.

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 1, 0, 0, 1];
bv.retain(|idx, _| idx % 2 == 0);
assert_eq!(bv, bits![0,    0,    1]);

Appends a single bit to the vector.

Original

Vec::push

Panics

This panics if the push would cause the bit-vector to exceed its maximum capacity.

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 0];
bv.push(true);
assert_eq!(bv.as_bitslice(), bits![0, 0, 1]);

Attempts to remove the trailing bit from the bit-vector.

This returns None if the bit-vector is empty.

Original

Vec::pop

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 1];
assert!(bv.pop().unwrap());
assert!(!bv.pop().unwrap());
assert!(bv.pop().is_none());

Moves all the bits out of other into the back of self.

The other bit-vector is emptied after this occurs.

Original

Vec::append

API Differences

This permits other to have different type parameters than self, and does not require that it be literally Self.

Panics

This panics if self.len() + other.len() exceeds the maximum capacity of a bit-vector.

Examples
use bitvec::prelude::*;

let mut bv1 = bitvec![u16, Msb0; 0; 10];
let mut bv2 = bitvec![u32, Lsb0; 1; 10];

bv1.append(&mut bv2);

assert_eq!(bv1.count_ones(), 10);
assert_eq!(bv1.count_zeros(), 10);
assert!(bv2.is_empty());

Iterates over a portion of the bit-vector, removing all yielded bits from it.

When the iterator drops, all bits in its coverage are removed from self, even if the iterator did not yield them. If the iterator is leaked or otherwise forgotten, and its destructor never runs, then the amount of un-yielded bits removed from the bit-vector is not specified.

Original

Vec::drain

Panics

This panics if range departs 0 .. self.len().

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 1, 0, 0, 1];
let bv2 = bv.drain(1 ..= 3).collect::<BitVec>();
assert_eq!(bv, bits![0,          1]);
assert_eq!(bv2, bits![1, 0, 0]);

// A full range clears the bit-vector.
bv.drain(..);
assert!(bv.is_empty());

Empties the bit-vector.

This does not affect the allocated capacity.

Original

Vec::clear

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 1, 0, 0, 1];
bv.clear();
assert!(bv.is_empty());

Gets the length of the bit-vector.

This is equivalent to BitSlice::len; it is provided as an inherent method here rather than relying on Deref forwarding so that you can write BitVec::len as a named function item.

Original

Vec::len

Tests if the bit-vector is empty.

This is equivalent to BitSlice::is_empty; it is provided as an inherent method here rather than relying on Deref forwarding so that you can write BitVec::is_empty as a named function item.

Original

Vec::is_empty

Splits the bit-vector in half at an index, moving self[at ..] out into a new bit-vector.

Original

Vec::split_off

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 1, 0, 0, 1];
let bv2 = bv.split_off(2);
assert_eq!((&*bv, &*bv2), (bits![0, 1], bits![0, 0, 1]));

Resizes the bit-vector to a new length, using a function to produce each inserted bit.

If new_len is less than self.len(), this is a truncate operation; if it is greater, then self is extended by repeatedly pushing func().

Original

Vec::resize_with

API Differences

The generator function receives the index into which its bit will be placed.

Examples
use bitvec::prelude::*;

let mut bv = bitvec![1; 2];
bv.resize_with(5, |idx| idx % 2 == 1);
assert_eq!(bv, bits![1, 1, 0, 1, 0]);

Destroys the BitVec handle without destroying the bit-vector allocation. The allocation is returned as an &mut BitSlice that lasts for the remaining program lifetime.

You may call BitBox::from_raw on this slice handle exactly once in order to reap the allocation before program exit. That function takes a mutable pointer, not a mutable reference, so you must ensure that the returned reference is never used again after restoring the allocation handle.

Original

Vec::len

Examples
use bitvec::prelude::*;

let bv = bitvec![0, 0, 1];
let static_bits: &'static mut BitSlice = bv.leak();
static_bits.set(0, true);
assert_eq!(static_bits, bits![1, 0, 1]);

let bb = unsafe { BitBox::from_raw(static_bits) };
// static_bits may no longer be used.
drop(bb); // explicitly reap memory before program exit

Resizes the bit-vector to a new length. New bits are initialized to value.

Original

Vec::resize

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0; 2];
bv.resize(5, true);
assert_eq!(bv, bits![0, 0, 1, 1, 1]);
👎 Deprecated:

use .extend_from_bitslice() or .extend_from_raw_slice() instead

Extends self by copying an internal range of its bit-slice as the region to append.

Original

Vec::extend_from_within

Panics

This panics if src is not within 0 .. self.len().

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 1, 0, 0, 1];
bv.extend_from_within(1 .. 4);
assert_eq!(bv, bits![0, 1, 0, 0, 1, 1, 0, 0]);

Modifies self.drain() so that the removed bit-slice is instead replaced with the contents of another bit-stream.

As with .drain(), the specified range is always removed from the bit-vector even if the splicer is not fully consumed, and the splicer does not specify how many bits are removed if it leaks.

The replacement source is only consumed when the splicer drops; however, it may be pulled before then. The replacement source cannot assume that there will be a delay between creation of the splicer and when it must begin producing bits.

This copies the Vec::splice implementation; see its documentation for more details about how the replacement should act.

Original

Vec::splice

Panics

This panics if range departs 0 .. self.len().

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 1, 1];
//                   a  b  c
let mut yank = bv.splice(
  .. 2,
  bits![static 1, 1, 0].iter().by_vals(),
//             d  e  f
);

assert!(!yank.next().unwrap()); // a
assert!(yank.next().unwrap()); // b
drop(yank);
assert_eq!(bv, bits![1, 1, 0, 1]);
//                   d  e  f  c

Constructors.

An empty bit-vector with no backing allocation.

Creates a new bit-vector by repeating a bit for the desired length.

Examples
use bitvec::prelude::*;

let zeros = BitVec::<u8, Msb0>::repeat(false, 50);
let ones = BitVec::<u16, Lsb0>::repeat(true, 50);

Copies the contents of a bit-slice into a new heap allocation.

This copies the raw underlying elements into a new allocation, and sets the produced bit-vector to use the same memory layout as the originating bit-slice. This means that it may begin at any bit in the first element, not just the zeroth bit. If you require this property, call .force_align().

Dead bits in the copied memory elements are guaranteed to be zeroed.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0, 1];
let bv = BitVec::from_bitslice(bits);
assert_eq!(bv, bits);

Constructs a new bit-vector from a single element.

This copies elem into a new heap allocation, and sets the bit-vector to cover it entirely.

Examples
use bitvec::prelude::*;

let bv = BitVec::<_, Msb0>::from_element(1u8);
assert!(bv[7]);

Constructs a new bit-vector from a slice of memory elements.

This copies slice into a new heap allocation, and sets the bit-vector to cover it entirely.

Panics

This panics if slice exceeds bit-vector capacity.

Examples
use bitvec::prelude::*;

let slice = &[0u8, 1, 2, 3];
let bv = BitVec::<_, Lsb0>::from_slice(slice);
assert_eq!(bv.len(), 32);

Fallibly constructs a new bit-vector from a slice of memory elements.

This fails early if slice exceeds bit-vector capacity. If it is not, then slice is copied into a new heap allocation and fully spanned by the returned bit-vector.

Examples
use bitvec::prelude::*;

let slice = &[0u8, 1, 2, 3];
let bv = BitVec::<_, Lsb0>::try_from_slice(slice).unwrap();
assert_eq!(bv.len(), 32);

Converts a regular vector in-place into a bit-vector.

The produced bit-vector spans every bit in the original vector. No reällocation occurs; this is purely a transform of the handle.

Panics

This panics if the source vector is too long to view as a bit-slice.

Examples
use bitvec::prelude::*;

let v = vec![0u8, 1, 2, 3];
let bv = BitVec::<_, Msb0>::from_vec(v);
assert_eq!(bv.len(), 32);

Attempts to convert a regular vector in-place into a bit-vector.

This fails if the source vector is too long to view as a bit-slice. On success, the produced bit-vector spans every bit in the original vector. No reällocation occurs; this is purely a transform of the handle.

Examples
use bitvec::prelude::*;

let v = vec![0u8; 20];
assert_eq!(BitVec::<_, Msb0>::try_from_vec(v).unwrap().len(), 160);

It is not practical to allocate a vector that will fail this conversion.

Appends the contents of a bit-slice to a bit-vector.

This can extend from a bit-slice of any type parameters; it is not restricted to using the same parameters as self. However, when the type parameters do match, it is possible for this to use a batch-copy optimization to go faster than the individual-bit crawl that is necessary when they differ.

Until Rust provides extensive support for specialization in trait implementations, you should use this method whenever you are extending from a BitSlice proper, and only use the general .extend() implementation if you are required to use a generic bool source.

Original

Vec::extend_from_slice

Examples
use bitvec::prelude::*;

let mut bv = bitvec![0, 1];
bv.extend_from_bitslice(bits![0, 1, 0, 0, 1]);
assert_eq!(bv, bits![0, 1, 0, 1, 0, 0, 1]);

Appends a slice of T elements to a bit-vector.

The slice is viewed as a BitSlice<T, O>, then appended directly to the bit-vector.

Original

Vec::extend_from_slice

Converters.

Explicitly views the bit-vector as a bit-slice.

Explicitly views the bit-vector as a mutable bit-slice.

Views the bit-vector as a slice of its underlying memory elements.

Views the bit-vector as a mutable slice of its underlying memory elements.

Creates an unsafe shared bit-pointer to the start of the buffer.

Original

Vec::as_ptr

Safety

You must initialize the contents of the underlying buffer before accessing memory through this pointer. See the BitPtr documentation for more details.

Creates an unsafe writable bit-pointer to the start of the buffer.

Original

Vec::as_mut_ptr

Safety

You must initialize the contents of the underlying buffer before accessing memory through this pointer. See the BitPtr documentation for more details.

Converts a bit-vector into a boxed bit-slice.

This may cause a reällocation to drop any excess capacity.

Original

Vec::into_boxed_slice

Examples
use bitvec::prelude::*;

let bv = bitvec![0, 1, 0, 0, 1];
let bb = bv.into_boxed_bitslice();

Converts a bit-vector into a Vec of its underlying storage.

The produced vector contains all elements that contained live bits. Dead bits have an unspecified value; you should call .set_uninitialized() before converting into a vector.

This does not affect the allocated memory; it is purely a conversion of the handle.

Examples
use bitvec::prelude::*;

let bv = bitvec![u8, Msb0; 0, 1, 0, 0, 1];
let v = bv.into_vec();
assert_eq!(v[0] & 0xF8, 0b01001_000);

Utilities.

Overwrites each element (visible in .as_raw_mut_slice()) with a new bit-pattern.

This unconditionally writes element into each element in the backing slice, without altering the bit-vector’s length or capacity.

This guarantees that dead bits visible in .as_raw_slice() but not .as_bitslice() are initialized according to the bit-pattern of element. The elements not visible in the raw slice, but present in the allocation, do not specify a value. You may not rely on them being zeroed or being set to the element bit-pattern.

Parameters
  • &mut self
  • element: The bit-pattern with which each live element in the backing store is initialized.
Examples
use bitvec::prelude::*;

let mut bv = bitvec![u8, Msb0; 0; 20];
assert_eq!(bv.as_raw_slice(), [0; 3]);
bv.set_elements(0xA5);
assert_eq!(bv.as_raw_slice(), [0xA5; 3]);

Sets the uninitialized bits of a bit-vector to a known value.

This method modifies all bits that are observable in .as_raw_slice() but not observable in .as_bitslice() to a known value. Memory beyond the raw-slice view, but still within the allocation, is considered fully dead and will never be seen.

This can be used to zero the unused memory so that when viewed as a raw slice, unused bits have a consistent and predictable value.

Examples
use bitvec::prelude::*;

let mut bv = 0b1101_1100u8.view_bits::<Lsb0>().to_bitvec();
assert_eq!(bv.as_raw_slice()[0], 0b1101_1100u8);

bv.truncate(4);
assert_eq!(bv.count_ones(), 2);
assert_eq!(bv.as_raw_slice()[0], 0b1101_1100u8);

bv.set_uninitialized(false);
assert_eq!(bv.as_raw_slice()[0], 0b0000_1100u8);

bv.set_uninitialized(true);
assert_eq!(bv.as_raw_slice()[0], 0b1111_1100u8);

Ensures that the live region of the bit-vector’s contents begin at the front edge of the buffer.

BitVec has performance optimizations where it moves its view of its buffer contents in order to avoid needless moves of its data within the buffer. This can lead to unexpected contents of the raw memory values, so this method ensures that the semantic contents of the bit-vector match its in-memory storage.

Examples
use bitvec::prelude::*;

let data = 0b00_1111_00u8;
let bits = data.view_bits::<Msb0>();

let mut bv = bits[2 .. 6].to_bitvec();
assert_eq!(bv, bits![1; 4]);
assert_eq!(bv.as_raw_slice()[0], data);

bv.force_align();
assert_eq!(bv, bits![1; 4]);
// BitVec does not specify the value of dead bits in its buffer.
assert_eq!(bv.as_raw_slice()[0] & 0xF0, 0xF0);

Methods from Deref<Target = BitSlice<T, O>>

Gets the number of bits in the bit-slice.

Original

slice::len

Examples
use bitvec::prelude::*;

assert_eq!(bits![].len(), 0);
assert_eq!(bits![0; 10].len(), 10);

Tests if the bit-slice is empty (length zero).

Original

slice::is_empty

Examples
use bitvec::prelude::*;

assert!(bits![].is_empty());
assert!(!bits![0; 10].is_empty());

Gets a reference to the first bit of the bit-slice, or None if it is empty.

Original

slice::first

API Differences

bitvec uses a custom structure for both read-only and mutable references to bool.

Examples
use bitvec::prelude::*;

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

assert!(bits![].first().is_none());

Gets a mutable reference to the first bit of the bit-slice, or None if it is empty.

Original

slice::first_mut

API Differences

bitvec uses a custom structure for both read-only and mutable references to bool. This must be bound as mut in order to write through it.

Examples
use bitvec::prelude::*;

let bits = bits![mut 0; 3];
if let Some(mut first) = bits.first_mut() {
  *first = true;
}
assert_eq!(bits, bits![1, 0, 0]);

assert!(bits![mut].first_mut().is_none());

Splits the bit-slice into a reference to its first bit, and the rest of the bit-slice. Returns None when empty.

Original

slice::split_first

API Differences

bitvec uses a custom structure for both read-only and mutable references to bool.

Examples
use bitvec::prelude::*;

let bits = bits![1, 0, 0];
let (first, rest) = bits.split_first().unwrap();
assert_eq!(first, &true);
assert_eq!(rest, bits![0; 2]);

Splits the bit-slice into mutable references of its first bit, and the rest of the bit-slice. Returns None when empty.

Original

slice::split_first_mut

API Differences

bitvec uses a custom structure for both read-only and mutable references to bool. This must be bound as mut in order to write through it.

Examples
use bitvec::prelude::*;

let bits = bits![mut 0; 3];
if let Some((mut first, rest)) = bits.split_first_mut() {
  *first = true;
  assert_eq!(rest, bits![0; 2]);
}
assert_eq!(bits, bits![1, 0, 0]);

Splits the bit-slice into a reference to its last bit, and the rest of the bit-slice. Returns None when empty.

Original

slice::split_last

API Differences

bitvec uses a custom structure for both read-only and mutable references to bool.

Examples
use bitvec::prelude::*;

let bits = bits![0, 0, 1];
let (last, rest) = bits.split_last().unwrap();
assert_eq!(last, &true);
assert_eq!(rest, bits![0; 2]);

Splits the bit-slice into mutable references to its last bit, and the rest of the bit-slice. Returns None when empty.

Original

slice::split_last_mut

API Differences

bitvec uses a custom structure for both read-only and mutable references to bool. This must be bound as mut in order to write through it.

Examples
use bitvec::prelude::*;

let bits = bits![mut 0; 3];
if let Some((mut last, rest)) = bits.split_last_mut() {
  *last = true;
  assert_eq!(rest, bits![0; 2]);
}
assert_eq!(bits, bits![0, 0, 1]);

Gets a reference to the last bit of the bit-slice, or None if it is empty.

Original

slice::last

API Differences

bitvec uses a custom structure for both read-only and mutable references to bool.

Examples
use bitvec::prelude::*;

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

assert!(bits![].last().is_none());

Gets a mutable reference to the last bit of the bit-slice, or None if it is empty.

Original

slice::last_mut

API Differences

bitvec uses a custom structure for both read-only and mutable references to bool. This must be bound as mut in order to write through it.

Examples
use bitvec::prelude::*;

let bits = bits![mut 0; 3];
if let Some(mut last) = bits.last_mut() {
  *last = true;
}
assert_eq!(bits, bits![0, 0, 1]);

assert!(bits![mut].last_mut().is_none());

Gets a reference to a single bit or a subsection of the bit-slice, depending on the type of index.

  • If given a usize, this produces a reference structure to the bool at the position.
  • If given any form of range, this produces a smaller bit-slice.

This returns None if the index departs the bounds of self.

Original

slice::get

API Differences

BitSliceIndex uses discrete types for immutable and mutable references, rather than a single referent type.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0];
assert_eq!(bits.get(1).as_deref(), Some(&true));
assert_eq!(bits.get(0 .. 2), Some(bits![0, 1]));
assert!(bits.get(3).is_none());
assert!(bits.get(0 .. 4).is_none());

Gets a mutable reference to a single bit or a subsection of the bit-slice, depending on the type of index.

  • If given a usize, this produces a reference structure to the bool at the position.
  • If given any form of range, this produces a smaller bit-slice.

This returns None if the index departs the bounds of self.

Original

slice::get_mut

API Differences

BitSliceIndex uses discrete types for immutable and mutable references, rather than a single referent type.

Examples
use bitvec::prelude::*;

let bits = bits![mut 0; 3];

*bits.get_mut(0).unwrap() = true;
bits.get_mut(1 ..).unwrap().fill(true);
assert_eq!(bits, bits![1; 3]);

Gets a reference to a single bit or to a subsection of the bit-slice, without bounds checking.

This has the same arguments and behavior as .get(), except that it does not check that index is in bounds.

Original

slice::get_unchecked

Safety

You must ensure that index is within bounds (within the range 0 .. self.len()), or this method will introduce memory safety and/or undefined behavior.

It is library-level undefined behavior to index beyond the length of any bit-slice, even if you know that the offset remains within an allocation as measured by Rust or LLVM.

Examples
use bitvec::prelude::*;

let data = 0b0001_0010u8;
let bits = &data.view_bits::<Lsb0>()[.. 3];

unsafe {
  assert!(bits.get_unchecked(1));
  assert!(bits.get_unchecked(4));
}

Gets a mutable reference to a single bit or a subsection of the bit-slice, depending on the type of index.

This has the same arguments and behavior as .get_mut(), except that it does not check that index is in bounds.

Original

slice::get_unchecked_mut

Safety

You must ensure that index is within bounds (within the range 0 .. self.len()), or this method will introduce memory safety and/or undefined behavior.

It is library-level undefined behavior to index beyond the length of any bit-slice, even if you know that the offset remains within an allocation as measured by Rust or LLVM.

Examples
use bitvec::prelude::*;

let mut data = 0u8;
let bits = &mut data.view_bits_mut::<Lsb0>()[.. 3];

unsafe {
  bits.get_unchecked_mut(1).commit(true);
  bits.get_unchecked_mut(4 .. 6).fill(true);
}
assert_eq!(data, 0b0011_0010);
👎 Deprecated:

use .as_bitptr() instead

👎 Deprecated:

use .as_mut_bitptr() instead

Produces a range of bit-pointers to each bit in the bit-slice.

This is a standard-library range, which has no real functionality for pointer types. You should prefer .as_bitptr_range() instead, as it produces a custom structure that provides expected ranging functionality.

Original

slice::as_ptr_range

Produces a range of mutable bit-pointers to each bit in the bit-slice.

This is a standard-library range, which has no real functionality for pointer types. You should prefer .as_mut_bitptr_range() instead, as it produces a custom structure that provides expected ranging functionality.

Original

slice::as_mut_ptr_range

Exchanges the bit values at two indices.

Original

slice::swap

Panics

This panics if either a or b are out of bounds.

Examples
use bitvec::prelude::*;

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

Reverses the order of bits in a bit-slice.

Original

slice::reverse

Examples
use bitvec::prelude::*;

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

Produces an iterator over each bit in the bit-slice.

Original

slice::iter

API Differences

This iterator yields proxy-reference structures, not &bool. It can be adapted to yield &bool with the .by_refs() method, or bool with .by_vals().

This iterator, and its adapters, are fast. Do not try to be more clever than them by abusing .as_bitptr_range().

Examples
use bitvec::prelude::*;

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

assert!(!iter.next().unwrap());
assert!( iter.next().unwrap());
assert!( iter.next_back().unwrap());
assert!(!iter.next_back().unwrap());
assert!( iter.next().is_none());

Produces a mutable iterator over each bit in the bit-slice.

Original

slice::iter_mut

API Differences

This iterator yields proxy-reference structures, not &mut bool. In addition, it marks each proxy as alias-tainted.

If you are using this in an ordinary loop and not keeping multiple yielded proxy-references alive at the same scope, you may use the .remove_alias() adapter to undo the alias marking.

This iterator is fast. Do not try to be more clever than it by abusing .as_mut_bitptr_range().

Examples
use bitvec::prelude::*;

let bits = bits![mut 0; 4];
let mut iter = bits.iter_mut();

iter.nth(1).unwrap().commit(true); // index 1
iter.next_back().unwrap().commit(true); // index 3

assert!(iter.next().is_some()); // index 2
assert!(iter.next().is_none()); // complete
assert_eq!(bits, bits![0, 1, 0, 1]);

Iterates over consecutive windowing subslices in a bit-slice.

Windows are overlapping views of the bit-slice. Each window advances one bit from the previous, so in a bit-slice [A, B, C, D, E], calling .windows(3) will yield [A, B, C], [B, C, D], and [C, D, E].

Original

slice::windows

Panics

This panics if size is 0.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0, 1];
let mut iter = bits.windows(3);

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

Iterates over non-overlapping subslices of a bit-slice.

Unlike .windows(), the subslices this yields do not overlap with each other. If self.len() is not an even multiple of chunk_size, then the last chunk yielded will be shorter.

Original

slice::chunks

Sibling Methods
  • .chunks_mut() has the same division logic, but each yielded bit-slice is mutable.
  • .chunks_exact() does not yield the final chunk if it is shorter than chunk_size.
  • .rchunks() iterates from the back of the bit-slice to the front, with the final, possibly-shorter, segment at the front edge.
Panics

This panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0, 1];
let mut iter = bits.chunks(2);

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

Iterates over non-overlapping mutable subslices of a bit-slice.

Iterators do not require that each yielded item is destroyed before the next is produced. This means that each bit-slice yielded must be marked as aliased. If you are using this in a loop that does not collect multiple yielded subslices for the same scope, then you can remove the alias marking by calling the (unsafe) method .remove_alias() on the iterator.

Original

slice::chunks_mut

Sibling Methods
  • .chunks() has the same division logic, but each yielded bit-slice is immutable.
  • .chunks_exact_mut() does not yield the final chunk if it is shorter than chunk_size.
  • .rchunks_mut() iterates from the back of the bit-slice to the front, with the final, possibly-shorter, segment at the front edge.
Panics

This panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let bits = bits![mut u8, Msb0; 0; 5];

for (idx, chunk) in unsafe {
  bits.chunks_mut(2).remove_alias()
}.enumerate() {
  chunk.store(idx + 1);
}
assert_eq!(bits, bits![0, 1, 1, 0, 1]);
//                     ^^^^  ^^^^  ^

Iterates over non-overlapping subslices of a bit-slice.

If self.len() is not an even multiple of chunk_size, then the last few bits are not yielded by the iterator at all. They can be accessed with the .remainder() method if the iterator is bound to a name.

Original

slice::chunks_exact

Sibling Methods
  • .chunks() yields any leftover bits at the end as a shorter chunk during iteration.
  • .chunks_exact_mut() has the same division logic, but each yielded bit-slice is mutable.
  • .rchunks_exact() iterates from the back of the bit-slice to the front, with the unyielded remainder segment at the front edge.
Panics

This panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0, 1];
let mut iter = bits.chunks_exact(2);

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

Iterates over non-overlapping mutable subslices of a bit-slice.

If self.len() is not an even multiple of chunk_size, then the last few bits are not yielded by the iterator at all. They can be accessed with the .into_remainder() method if the iterator is bound to a name.

Iterators do not require that each yielded item is destroyed before the next is produced. This means that each bit-slice yielded must be marked as aliased. If you are using this in a loop that does not collect multiple yielded subslices for the same scope, then you can remove the alias marking by calling the (unsafe) method .remove_alias() on the iterator.

Original

slice::chunks_exact_mut

Sibling Methods
  • .chunks_mut() yields any leftover bits at the end as a shorter chunk during iteration.
  • .chunks_exact() has the same division logic, but each yielded bit-slice is immutable.
  • .rchunks_exact_mut() iterates from the back of the bit-slice forwards, with the unyielded remainder segment at the front edge.
Panics

This panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let bits = bits![mut u8, Msb0; 0; 5];
let mut iter = bits.chunks_exact_mut(2);

for (idx, chunk) in iter.by_ref().enumerate() {
  chunk.store(idx + 1);
}
iter.into_remainder().store(1u8);

assert_eq!(bits, bits![0, 1, 1, 0, 1]);
//                       remainder ^

Iterates over non-overlapping subslices of a bit-slice, from the back edge.

Unlike .chunks(), this aligns its chunks to the back edge of self. If self.len() is not an even multiple of chunk_size, then the leftover partial chunk is self[0 .. len % chunk_size].

Original

slice::rchunks

Sibling Methods
  • .rchunks_mut() has the same division logic, but each yielded bit-slice is mutable.
  • .rchunks_exact() does not yield the final chunk if it is shorter than chunk_size.
  • .chunks() iterates from the front of the bit-slice to the back, with the final, possibly-shorter, segment at the back edge.
Panics

This panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0, 1];
let mut iter = bits.rchunks(2);

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

Iterates over non-overlapping mutable subslices of a bit-slice, from the back edge.

Unlike .chunks_mut(), this aligns its chunks to the back edge of self. If self.len() is not an even multiple of chunk_size, then the leftover partial chunk is self[0 .. len % chunk_size].

Iterators do not require that each yielded item is destroyed before the next is produced. This means that each bit-slice yielded must be marked as aliased. If you are using this in a loop that does not collect multiple yielded values for the same scope, then you can remove the alias marking by calling the (unsafe) method .remove_alias() on the iterator.

Original

slice::rchunks_mut

Sibling Methods
  • .rchunks() has the same division logic, but each yielded bit-slice is immutable.
  • .rchunks_exact_mut() does not yield the final chunk if it is shorter than chunk_size.
  • .chunks_mut() iterates from the front of the bit-slice to the back, with the final, possibly-shorter, segment at the back edge.
Examples
use bitvec::prelude::*;

let bits = bits![mut u8, Msb0; 0; 5];
for (idx, chunk) in unsafe {
  bits.rchunks_mut(2).remove_alias()
}.enumerate() {
  chunk.store(idx + 1);
}
assert_eq!(bits, bits![1, 1, 0, 0, 1]);
//           remainder ^  ^^^^  ^^^^

Iterates over non-overlapping subslices of a bit-slice, from the back edge.

If self.len() is not an even multiple of chunk_size, then the first few bits are not yielded by the iterator at all. They can be accessed with the .remainder() method if the iterator is bound to a name.

Original

slice::rchunks_exact

Sibling Methods
  • .rchunks() yields any leftover bits at the front as a shorter chunk during iteration.
  • .rchunks_exact_mut() has the same division logic, but each yielded bit-slice is mutable.
  • .chunks_exact() iterates from the front of the bit-slice to the back, with the unyielded remainder segment at the back edge.
Panics

This panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0, 1];
let mut iter = bits.rchunks_exact(2);

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

Iterates over non-overlapping mutable subslices of a bit-slice, from the back edge.

If self.len() is not an even multiple of chunk_size, then the first few bits are not yielded by the iterator at all. They can be accessed with the .into_remainder() method if the iterator is bound to a name.

Iterators do not require that each yielded item is destroyed before the next is produced. This means that each bit-slice yielded must be marked as aliased. If you are using this in a loop that does not collect multiple yielded subslices for the same scope, then you can remove the alias marking by calling the (unsafe) method .remove_alias() on the iterator.

Sibling Methods
  • .rchunks_mut() yields any leftover bits at the front as a shorter chunk during iteration.
  • .rchunks_exact() has the same division logic, but each yielded bit-slice is immutable.
  • .chunks_exact_mut() iterates from the front of the bit-slice backwards, with the unyielded remainder segment at the back edge.
Panics

This panics if chunk_size is 0.

Examples
use bitvec::prelude::*;

let bits = bits![mut u8, Msb0; 0; 5];
let mut iter = bits.rchunks_exact_mut(2);

for (idx, chunk) in iter.by_ref().enumerate() {
  chunk.store(idx + 1);
}
iter.into_remainder().store(1u8);

assert_eq!(bits, bits![1, 1, 0, 0, 1]);
//           remainder ^

Splits a bit-slice in two parts at an index.

The returned bit-slices are self[.. mid] and self[mid ..]. mid is included in the right bit-slice, not the left.

If mid is 0 then the left bit-slice is empty; if it is self.len() then the right bit-slice is empty.

This method guarantees that even when either partition is empty, the encoded bit-pointer values of the bit-slice references is &self[0] and &self[mid].

Original

slice::split_at

Panics

This panics if mid is greater than self.len(). It is allowed to be equal to the length, in which case the right bit-slice is simply empty.

Examples
use bitvec::prelude::*;

let bits = bits![0, 0, 0, 1, 1, 1];
let base = bits.as_bitptr();

let (a, b) = bits.split_at(0);
assert_eq!(unsafe { a.as_bitptr().offset_from(base) }, 0);
assert_eq!(unsafe { b.as_bitptr().offset_from(base) }, 0);

let (a, b) = bits.split_at(6);
assert_eq!(unsafe { b.as_bitptr().offset_from(base) }, 6);

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

Splits a mutable bit-slice in two parts at an index.

The returned bit-slices are self[.. mid] and self[mid ..]. mid is included in the right bit-slice, not the left.

If mid is 0 then the left bit-slice is empty; if it is self.len() then the right bit-slice is empty.

This method guarantees that even when either partition is empty, the encoded bit-pointer values of the bit-slice references is &self[0] and &self[mid].

Original

slice::split_at_mut

API Differences

The end bits of the left half and the start bits of the right half might be stored in the same memory element. In order to avoid breaking bitvec’s memory-safety guarantees, both bit-slices are marked as T::Alias. This marking allows them to be used without interfering with each other when they interact with memory.

Panics

This panics if mid is greater than self.len(). It is allowed to be equal to the length, in which case the right bit-slice is simply empty.

Examples
use bitvec::prelude::*;

let bits = bits![mut u8, Msb0; 0; 6];
let base = bits.as_mut_bitptr();

let (a, b) = bits.split_at_mut(0);
assert_eq!(unsafe { a.as_mut_bitptr().offset_from(base) }, 0);
assert_eq!(unsafe { b.as_mut_bitptr().offset_from(base) }, 0);

let (a, b) = bits.split_at_mut(6);
assert_eq!(unsafe { b.as_mut_bitptr().offset_from(base) }, 6);

let (a, b) = bits.split_at_mut(3);
a.store(3);
b.store(5);

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

Iterates over subslices separated by bits that match a predicate. The matched bit is not contained in the yielded bit-slices.

Original

slice::split

API Differences

The predicate function receives the index being tested as well as the bit value at that index. This allows the predicate to have more than one bit of information about the bit-slice being traversed.

Sibling Methods
  • .split_mut() has the same splitting logic, but each yielded bit-slice is mutable.
  • .split_inclusive() includes the matched bit in the yielded bit-slice.
  • .rsplit() iterates from the back of the bit-slice instead of the front.
  • .splitn() times out after n yields.
Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 1, 0];
//                     ^
let mut iter = bits.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, then an empty bit-slice will be the first item yielded by the iterator. Similarly, if the last bit in the bit-slice matches, then an empty bit-slice will be the last item yielded.

use bitvec::prelude::*;

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

assert_eq!(iter.next().unwrap(), bits![0; 2]);
assert!(iter.next().unwrap().is_empty());
assert!(iter.next().is_none());

If two matched bits are directly adjacent, then an empty bit-slice will be yielded between them:

use bitvec::prelude::*;

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

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

Iterates over mutable subslices separated by bits that match a predicate. The matched bit is not contained in the yielded bit-slices.

Iterators do not require that each yielded item is destroyed before the next is produced. This means that each bit-slice yielded must be marked as aliased. If you are using this in a loop that does not collect multiple yielded subslices for the same scope, then you can remove the alias marking by calling the (unsafe) method .remove_alias() on the iterator.

Original

slice::split_mut

API Differences

The predicate function receives the index being tested as well as the bit value at that index. This allows the predicate to have more than one bit of information about the bit-slice being traversed.

Sibling Methods
Examples
use bitvec::prelude::*;

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

Iterates over subslices separated by bits that match a predicate. Unlike .split(), this does include the matching bit as the last bit in the yielded bit-slice.

Original

slice::split_inclusive

API Differences

The predicate function receives the index being tested as well as the bit value at that index. This allows the predicate to have more than one bit of information about the bit-slice being traversed.

Sibling Methods
  • .split_inclusive_mut() has the same splitting logic, but each yielded bit-slice is mutable.
  • .split() does not include the matched bit in the yielded bit-slice.
Examples
use bitvec::prelude::*;

let bits = bits![0, 0, 1, 0, 1];
//                     ^     ^
let mut iter = bits.split_inclusive(|_pos, bit| *bit);

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

Iterates over mutable subslices separated by bits that match a predicate. Unlike .split_mut(), this does include the matching bit as the last bit in the bit-slice.

Iterators do not require that each yielded item is destroyed before the next is produced. This means that each bit-slice yielded must be marked as aliased. If you are using this in a loop that does not collect multiple yielded subslices for the same scope, then you can remove the alias marking by calling the (unsafe) method .remove_alias() on the iterator.

Original

slice::split_inclusive_mut

API Differences

The predicate function receives the index being tested as well as the bit value at that index. This allows the predicate to have more than one bit of information about the bit-slice being traversed.

Sibling Methods
  • .split_inclusive() has the same splitting logic, but each yielded bit-slice is immutable.
  • .split_mut() does not include the matched bit in the yielded bit-slice.
Examples
use bitvec::prelude::*;

let bits = bits![mut 0, 0, 0, 0, 0];
//                         ^
for group in bits.split_inclusive_mut(|pos, _bit| pos % 3 == 2) {
  group.set(0, true);
}
assert_eq!(bits, bits![1, 0, 0, 1, 0]);

Iterates over subslices separated by bits that match a predicate, from the back edge. The matched bit is not contained in the yielded bit-slices.

Original

slice::rsplit

API Differences

The predicate function receives the index being tested as well as the bit value at that index. This allows the predicate to have more than one bit of information about the bit-slice being traversed.

Sibling Methods
  • .rsplit_mut() has the same splitting logic, but each yielded bit-slice is mutable.
  • .split() iterates from the front of the bit-slice instead of the back.
  • .rsplitn() times out after n yields.
Examples
use bitvec::prelude::*;

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

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

If the last bit is matched, then an empty bit-slice will be the first item yielded by the iterator. Similarly, if the first bit in the bit-slice matches, then an empty bit-slice will be the last item yielded.

use bitvec::prelude::*;

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

assert!(iter.next().unwrap().is_empty());
assert_eq!(iter.next().unwrap(), bits![0; 2]);
assert!(iter.next().is_none());

If two yielded bits are directly adjacent, then an empty bit-slice will be yielded between them:

use bitvec::prelude::*;

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

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

Iterates over mutable subslices separated by bits that match a predicate, from the back. The matched bit is not contained in the yielded bit-slices.

Iterators do not require that each yielded item is destroyed before the next is produced. This means that each bit-slice yielded must be marked as aliased. If you are using this in a loop that does not collect multiple yielded subslices for the same scope, then you can remove the alias marking by calling the (unsafe) method .remove_alias() on the iterator.

Original

slice::rsplit_mut

API Differences

The predicate function receives the index being tested as well as the bit value at that index. This allows the predicate to have more than one bit of information about the bit-slice being traversed.

Sibling Methods
  • .rsplit() has the same splitting logic, but each yielded bit-slice is immutable.
  • .split_mut() iterates from the front of the bit-slice to the back.
  • .rsplitn_mut() iterates from the front of the bit-slice to the back.
Examples
use bitvec::prelude::*;

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

Iterates over subslices separated by bits that match a predicate, giving up after yielding n times. The nth yield contains the rest of the bit-slice. As with .split(), the yielded bit-slices do not contain the matched bit.

Original

slice::splitn

API Differences

The predicate function receives the index being tested as well as the bit value at that index. This allows the predicate to have more than one bit of information about the bit-slice being traversed.

Sibling Methods
  • .splitn_mut() has the same splitting logic, but each yielded bit-slice is mutable.
  • .rsplitn() iterates from the back of the bit-slice instead of the front.
  • .split() has the same splitting logic, but never times out.
Examples
use bitvec::prelude::*;

let bits = bits![0, 0, 1, 0, 1, 0];
let mut iter = bits.splitn(2, |_pos, bit| *bit);

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

Iterates over mutable subslices separated by bits that match a predicate, giving up after yielding n times. The nth yield contains the rest of the bit-slice. As with .split_mut(), the yielded bit-slices do not contain the matched bit.

Iterators do not require that each yielded item is destroyed before the next is produced. This means that each bit-slice yielded must be marked as aliased. If you are using this in a loop that does not collect multiple yielded subslices for the same scope, then you can remove the alias marking by calling the (unsafe) method .remove_alias() on the iterator.

Original

slice::splitn_mut

API Differences

The predicate function receives the index being tested as well as the bit value at that index. This allows the predicate to have more than one bit of information about the bit-slice being traversed.

Sibling Methods
  • .splitn() has the same splitting logic, but each yielded bit-slice is immutable.
  • .rsplitn_mut() iterates from the back of the bit-slice instead of the front.
  • .split_mut() has the same splitting logic, but never times out.
Examples
use bitvec::prelude::*;

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

Iterates over mutable subslices separated by bits that match a predicate from the back edge, giving up after yielding n times. The nth yield contains the rest of the bit-slice. As with .split_mut(), the yielded bit-slices do not contain the matched bit.

Original

slice::rsplitn

API Differences

The predicate function receives the index being tested as well as the bit value at that index. This allows the predicate to have more than one bit of information about the bit-slice being traversed.

Sibling Methods
  • .rsplitn_mut() has the same splitting logic, but each yielded bit-slice is mutable.
  • .splitn(): iterates from the front of the bit-slice instead of the back.
  • .rsplit() has the same splitting logic, but never times out.
Examples
use bitvec::prelude::*;

let bits = bits![0, 0, 1, 1, 0];
//                        ^
let mut iter = bits.rsplitn(2, |_pos, bit| *bit);

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

Iterates over mutable subslices separated by bits that match a predicate from the back edge, giving up after yielding n times. The nth yield contains the rest of the bit-slice. As with .split_mut(), the yielded bit-slices do not contain the matched bit.

Iterators do not require that each yielded item is destroyed before the next is produced. This means that each bit-slice yielded must be marked as aliased. If you are using this in a loop that does not collect multiple yielded subslices for the same scope, then you can remove the alias marking by calling the (unsafe) method .remove_alias() on the iterator.

Original

slice::rsplitn_mut

API Differences

The predicate function receives the index being tested as well as the bit value at that index. This allows the predicate to have more than one bit of information about the bit-slice being traversed.

Sibling Methods
  • .rsplitn() has the same splitting logic, but each yielded bit-slice is immutable.
  • .splitn_mut() iterates from the front of the bit-slice instead of the back.
  • .rsplit_mut() has the same splitting logic, but never times out.
Examples
use bitvec::prelude::*;

let bits = bits![mut 0, 0, 1, 0, 0, 1, 0, 0, 0];
for group in bits.rsplitn_mut(2, |_idx, bit| *bit) {
  group.set(0, true);
}
assert_eq!(bits, bits![1, 0, 1, 0, 0, 1, 1, 0, 0]);
//                     ^ group 2         ^ group 1

Tests if the bit-slice contains the given sequence anywhere within it.

This scans over self.windows(other.len()) until one of the windows matches. The search key does not need to share type parameters with the bit-slice being tested, as the comparison is bit-wise. However, sharing type parameters will accelerate the comparison.

Original

slice::contains

Examples
use bitvec::prelude::*;

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

Tests if the bit-slice begins with the given sequence.

The search key does not need to share type parameters with the bit-slice being tested, as the comparison is bit-wise. However, sharing type parameters will accelerate the comparison.

Original

slice::starts_with

Examples
use bitvec::prelude::*;

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

This always returns true if the needle is empty:

use bitvec::prelude::*;

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

Tests if the bit-slice ends with the given sequence.

The search key does not need to share type parameters with the bit-slice being tested, as the comparison is bit-wise. However, sharing type parameters will accelerate the comparison.

Original

slice::ends_with

Examples
use bitvec::prelude::*;

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

This always returns true if the needle is empty:

use bitvec::prelude::*;

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

Removes a prefix bit-slice, if present.

Like .starts_with(), the search key does not need to share type parameters with the bit-slice being stripped. If self.starts_with(suffix), then this returns Some(&self[prefix.len() ..]), otherwise it returns None.

Original

slice::strip_prefix

API Differences

BitSlice does not support pattern searches; instead, it permits self and prefix to differ in type parameters.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0, 1, 0, 1, 1, 0];
assert_eq!(bits.strip_prefix(bits![0, 1]).unwrap(), bits[2 ..]);
assert_eq!(bits.strip_prefix(bits![0, 1, 0, 0,]).unwrap(), bits[4 ..]);
assert!(bits.strip_prefix(bits![1, 0]).is_none());

Removes a suffix bit-slice, if present.

Like .ends_with(), the search key does not need to share type parameters with the bit-slice being stripped. If self.ends_with(suffix), then this returns Some(&self[.. self.len() - suffix.len()]), otherwise it returns None.

Original

slice::strip_suffix

API Differences

BitSlice does not support pattern searches; instead, it permits self and suffix to differ in type parameters.

Examples
use bitvec::prelude::*;

let bits = bits![0, 1, 0, 0, 1, 0, 1, 1, 0];
assert_eq!(bits.strip_suffix(bits![1, 0]).unwrap(), bits[.. 7]);
assert_eq!(bits.strip_suffix(bits![0, 1, 1, 0]).unwrap(), bits[.. 5]);
assert!(bits.strip_suffix(bits![0, 1]).is_none());

Rotates the contents of a bit-slice to the left (towards the zero index).

This essentially splits the bit-slice at by, then exchanges the two pieces. self[.. by] becomes the first section, and is then followed by self[.. by].

The implementation is batch-accelerated where possible. It should have a runtime complexity much lower than O(by).

Original

slice::rotate_left

Examples
use bitvec::prelude::*;

let bits = bits![mut 0, 0, 1, 0, 1, 0];
//      split occurs here ^
bits.rotate_left(2);
assert_eq!(bits, bits![1, 0, 1, 0, 0, 0]);

Rotates the contents of a bit-slice to the right (away from the zero index).

This essentially splits the bit-slice at self.len() - by, then exchanges the two pieces. self[len - by ..] becomes the first section, and is then followed by self[.. len - by].

The implementation is batch-accelerated where possible. It should have a runtime complexity much lower than O(by).

Original

slice::rotate_right

Examples
use bitvec::prelude::*;

let bits = bits![mut 0, 0, 1, 1, 1, 0];
//            split occurs here ^
bits.rotate_right(2);
assert_eq!(bits, bits![1, 0, 0, 0, 1, 1]);

Fills the bit-slice with a given bit.

This is a recent stabilization in the standard library. bitvec previously offered this behavior as the novel API .set_all(). That method name is now removed in favor of this standard-library analogue.

Original

slice::fill

Examples
use bitvec::prelude::*;

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

Fills the bit-slice with bits produced by a generator function.

Original

slice::fill_with

API Differences

The generator function receives the index of the bit being initialized as an argument.

Examples
use bitvec::prelude::*;

let bits = bits![mut 0; 5];
bits.fill_with(|idx| idx % 2 == 0);
assert_eq!(bits, bits![1, 0, 1, 0, 1]);
👎 Deprecated:

use .clone_from_bitslice() instead

👎 Deprecated:

use .copy_from_bitslice() instead

Copies a span of bits to another location in the bit-slice.

src is the range of bit-indices in the bit-slice to copy, and dest is the starting index of the destination range. srcanddest .. dest + src.len()are permitted to overlap; the copy will automatically detect and manage this. However, bothsrcanddest .. dest + src.len()**must** fall within the bounds ofself`.

Original

slice::copy_within

Panics

This panics if either the source or destination range exceed self.len().

Examples
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);
//                        v  v  v  v
assert_eq!(bits, bits![1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0]);
//                                             ^  ^  ^  ^
👎 Deprecated:

use .swap_with_bitslice() instead

Produces bit-slice view(s) with different underlying storage types.

This may have unexpected effects, and you cannot assume that before[idx] == after[idx]! Consult the tables in the manual for information about memory layouts.

Original

slice::align_to

Notes

Unlike the standard library documentation, this explicitly guarantees that the middle bit-slice will have maximal size. You may rely on this property.

Safety

You may not use this to cast away alias protections. Rust does not have support for higher-kinded types, so this cannot express the relation Outer<T> -> Outer<U> where Outer: BitStoreContainer, but memory safety does require that you respect this rule. Reälign integers to integers, Cells to Cells, and atomics to atomics, but do not cross these boundaries.

Examples
use bitvec::prelude::*;

let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let bits = bytes.view_bits::<Lsb0>();
let (pfx, mid, sfx) = unsafe {
  bits.align_to::<u16>()
};
assert!(pfx.len() <= 8);
assert_eq!(mid.len(), 48);
assert!(sfx.len() <= 8);

Produces bit-slice view(s) with different underlying storage types.

This may have unexpected effects, and you cannot assume that before[idx] == after[idx]! Consult the tables in the manual for information about memory layouts.

Original

slice::align_to_mut

Notes

Unlike the standard library documentation, this explicitly guarantees that the middle bit-slice will have maximal size. You may rely on this property.

Safety

You may not use this to cast away alias protections. Rust does not have support for higher-kinded types, so this cannot express the relation Outer<T> -> Outer<U> where Outer: BitStoreContainer, but memory safety does require that you respect this rule. Reälign integers to integers, Cells to Cells, and atomics to atomics, but do not cross these boundaries.

Examples
use bitvec::prelude::*;

let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let bits = bytes.view_bits_mut::<Lsb0>();
let (pfx, mid, sfx) = unsafe {
  bits.align_to_mut::<u16>()
};
assert!(pfx.len() <= 8);
assert_eq!(mid.len(), 48);
assert!(sfx.len() <= 8);
👎 Deprecated:

use .to_bitvec() instead

Creates a bit-vector by repeating a bit-slice n times.

Original

slice::repeat

Panics

This method panics if self.len() * n exceeds the BitVec capacity.

Examples
use bitvec::prelude::*;

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

This panics by exceeding bit-vector maximum capacity:

use bitvec::prelude::*;

bits![0, 1].repeat(BitSlice::<usize, Lsb0>::MAX_BITS);

Gets a raw pointer to the zeroth bit of the bit-slice.

Original

slice::as_ptr

API Differences

This is renamed in order to indicate that it is returning a bitvec structure, not a raw pointer.

Gets a raw, write-capable pointer to the zeroth bit of the bit-slice.

Original

slice::as_mut_ptr

API Differences

This is renamed in order to indicate that it is returning a bitvec structure, not a raw pointer.

Views the bit-slice as a half-open range of bit-pointers, to its first bit in the bit-slice and first bit beyond it.

Original

slice::as_ptr_range

API Differences

This is renamed to indicate that it returns a bitvec structure, rather than an ordinary Range.

Notes

BitSlice does define a .as_ptr_range(), which returns a Range<BitPtr>. BitPtrRange has additional capabilities that Range<*const T> and Range<BitPtr> do not.

Views the bit-slice as a half-open range of write-capable bit-pointers, to its first bit in the bit-slice and the first bit beyond it.

Original

slice::as_mut_ptr_range

API Differences

This is renamed to indicate that it returns a bitvec structure, rather than an ordinary Range.

Notes

BitSlice does define a [.as_mut_ptr_range()], which returns a Range<BitPtr>. BitPtrRange has additional capabilities that Range<*mut T> and Range<BitPtr> do not.

Copies the bits from src into self.

self and src must have the same length.

Performance

If src has the same type arguments as self, it will use the same implementation as .copy_from_bitslice(); if you know that this will always be the case, you should prefer to use that method directly.

Only .copy_from_bitslice() is able to perform acceleration; this method is always required to perform a bit-by-bit crawl over both bit-slices.

Original

slice::clone_from_slice

API Differences

This is renamed to reflect that it copies from another bit-slice, not from an element slice.

In order to support general usage, it allows src to have different type parameters than self, at the cost of performance optimizations.

Panics

This panics if the two bit-slices have different lengths.

Examples
use bitvec::prelude::*;

Copies all bits from src into self, using batched acceleration when possible.

self and src must have the same length.

Original

slice::copy_from_slice

Panics

This panics if the two bit-slices have different lengths.

Examples
use bitvec::prelude::*;

Swaps the contents of two bit-slices.

self and other must have the same length.

Original

slice::swap_with_slice

API Differences

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

Panics

This panics if the two bit-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);

Writes a new value into a single bit.

This is the replacement for *slice[index] = value;, as bitvec is not able to express that under the current IndexMut API signature.

Parameters
  • &mut self
  • index: The bit-index to set. It must be in 0 .. self.len().
  • value: The new bit-value to write into the bit at index.
Panics

This panics if index is out of bounds.

Examples
use bitvec::prelude::*;

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

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

Writes a new value into a single bit, without bounds checking.

Parameters
  • &mut self
  • index: The bit-index to set. It must be in 0 .. self.len().
  • value: The new bit-value to write into the bit at index.
Safety

You must ensure that index is in the range 0 .. self.len().

This performs bit-pointer offset arithmetic without doing any bounds checks. If index is out of bounds, then this will issue an out-of-bounds access and will trigger memory unsafety.

Examples
use bitvec::prelude::*;

let mut data = 0u8;
let bits = &mut data.view_bits_mut::<Lsb0>()[.. 2];
assert_eq!(bits.len(), 2);
unsafe {
  bits.set_unchecked(3, true);
}
assert_eq!(data, 8);

Writes a new value into a bit, and returns its previous value.

Panics

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

Examples
use bitvec::prelude::*;

let bits = bits![mut 0];
assert!(!bits.replace(0, true));
assert!(bits[0]);

Writes a new value into a bit, returning the previous value, without bounds checking.

Safety

index must be less than self.len().

Examples
use bitvec::prelude::*;

let bits = bits![mut 0, 0];
let old = unsafe {
  let a = &mut bits[.. 1];
  a.replace_unchecked(1, true)
};
assert!(!old);
assert!(bits[1]);

Swaps two bits in a bit-slice, without bounds checking.

See .swap() for documentation.

Safety

You must ensure that a and b are both in the range 0 .. self.len().

This method performs bit-pointer offset arithmetic without doing any bounds checks. If a or b are out of bounds, then this will issue an out-of-bounds access and will trigger memory unsafety.

Splits a bit-slice at an index, without bounds checking.

See .split_at() for documentation.

Safety

You must ensure that mid is in the range 0 ..= self.len().

This method produces new bit-slice references. If mid is out of bounds, its behavior is library-level undefined. You must conservatively assume that an out-of-bounds split point produces compiler-level UB.

Splits a mutable bit-slice at an index, without bounds checking.

See .split_at_mut() for documentation.

Safety

You must ensure that mid is in the range 0 ..= self.len().

This method produces new bit-slice references. If mid is out of bounds, its behavior is library-level undefined. You must conservatively assume that an out-of-bounds split point produces compiler-level UB.

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

The regions 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.len()]. The bits of self[src] are in an unspecified, but initialized, state.

Safety

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

Examples
use bitvec::prelude::*;

let mut data = 0b1011_0000u8;
let bits = data.view_bits_mut::<Msb0>();

unsafe {
  bits.copy_within_unchecked(.. 4, 2);
}
assert_eq!(data, 0b1010_1100);

Partitions a bit-slice into maybe-contended and known-uncontended parts.

The documentation of BitDomain goes into this in more detail. In short, this produces a &BitSlice that is as large as possible without requiring alias protection, as well as any bits that were not able to be included in the unaliased bit-slice.

Partitions a mutable bit-slice into maybe-contended and known-uncontended parts.

The documentation of BitDomain goes into this in more detail. In short, this produces a &mut BitSlice that is as large as possible without requiring alias protection, as well as any bits that were not able to be included in the unaliased bit-slice.

Views the underlying memory of a bit-slice, removing alias protections where possible.

The documentation of Domain goes into this in more detail. In short, this produces a &[T] slice with alias protections removed, covering all elements that self completely fills. Partially-used elements on either the front or back edge of the slice are returned separately.

Views the underlying memory of a bit-slice, removing alias protections where possible.

The documentation of Domain goes into this in more detail. In short, this produces a &mut [T] slice with alias protections removed, covering all elements that self completely fills. Partially-used elements on the front or back edge of the slice are returned separately.

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

Examples
use bitvec::prelude::*;

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

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

Examples
use bitvec::prelude::*;

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

Enumerates the index of each bit in a bit-slice set to 1.

This is a shorthand for a .enumerate().filter_map() iterator that selects the index of each true bit; however, its implementation is eligible for optimizations that the individual-bit iterator is not.

Specializations for the Lsb0 and Msb0 orderings allow processors with instructions that seek particular bits within an element to operate on whole elements, rather than on each bit individually.

Examples

This example uses .iter_ones(), a .filter_map() that finds the index of each set bit, and the known indices, in order to show that they have equivalent behavior.

use bitvec::prelude::*;

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

let iter_ones = bits.iter_ones();
let known_indices = [1, 4, 8].iter().copied();
let filter = bits.iter()
  .by_vals()
  .enumerate()
  .filter_map(|(idx, bit)| if bit { Some(idx) } else { None });
let all = iter_ones.zip(known_indices).zip(filter);

for ((iter_one, known), filtered) in all {
  assert_eq!(iter_one, known);
  assert_eq!(known, filtered);
}

Enumerates the index of each bit in a bit-slice cleared to 0.

This is a shorthand for a .enumerate().filter_map() iterator that selects the index of each false bit; however, its implementation is eligible for optimizations that the individual-bit iterator is not.

Specializations for the Lsb0 and Msb0 orderings allow processors with instructions that seek particular bits within an element to operate on whole elements, rather than on each bit individually.

Examples

This example uses .iter_zeros(), a .filter_map() that finds the index of each cleared bit, and the known indices, in order to show that they have equivalent behavior.

use bitvec::prelude::*;

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

let iter_zeros = bits.iter_zeros();
let known_indices = [1, 4, 8].iter().copied();
let filter = bits.iter()
  .by_vals()
  .enumerate()
  .filter_map(|(idx, bit)| if !bit { Some(idx) } else { None });
let all = iter_zeros.zip(known_indices).zip(filter);

for ((iter_zero, known), filtered) in all {
  assert_eq!(iter_zero, known);
  assert_eq!(known, filtered);
}

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

Returns None if there is no true bit in the bit-slice.

Examples
use bitvec::prelude::*;

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

Finds the index of the first bit in the bit-slice cleared to 0.

Returns None if there is no false bit in the bit-slice.

Examples
use bitvec::prelude::*;

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

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

Returns None if there is no true bit in the bit-slice.

Examples
use bitvec::prelude::*;

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

Finds the index of the last bit in the bit-slice cleared to 0.

Returns None if there is no false bit in the bit-slice.

Examples
use bitvec::prelude::*;

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

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].leading_ones(), 1);

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].leading_zeros(), 1);

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![0, 1].trailing_ones(), 1);

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![1, 0].trailing_zeros(), 1);

Tests if there is at least one bit set to 1 in the bit-slice.

Returns false when self is empty.

Examples
use bitvec::prelude::*;

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

Tests if every bit is set to 1 in the bit-slice.

Returns true when self is empty.

Examples
use bitvec::prelude::*;

assert!( bits![].all());
assert!(!bits![0].all());
assert!( bits![1].all());

Tests if every bit is cleared to 0 in the bit-slice.

Returns true when self is empty.

Examples
use bitvec::prelude::*;

assert!( bits![].not_any());
assert!(!bits![1].not_any());
assert!( bits![0].not_any());

Tests if at least one bit is cleared to 0 in the bit-slice.

Returns false when self is empty.

Examples
use bitvec::prelude::*;

assert!(!bits![].not_all());
assert!(!bits![1].not_all());
assert!( bits![0].not_all());

Tests if at least one bit is set to 1, and at least one bit is cleared to 0, in the bit-slice.

Returns false when self is empty.

Examples
use bitvec::prelude::*;

assert!(!bits![].some());
assert!(!bits![0].some());
assert!(!bits![1].some());
assert!( bits![0, 1].some());

Shifts the contents of a bit-slice down (towards the zero-index), clearing the top bits to 0.

This is a more-expensive version of taking &bits[by ..]; unless you want to directly affect the memory representation, you should use that instead.

Has no effect when by is 0.

Panics

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

Examples
use bitvec::prelude::*;

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

Shifts the contents of a bit-slice up (away from the zero-index), clearing the bottom bits to 0.

This is a more-expensive version of taking &bits[.. bits.len() - by]; unless you want to directly affect the memory representation, you should just use that instead.

Has no effect when by is 0.

Panics

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

Examples
use bitvec::prelude::*;

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

Writes a new value into a single bit, using alias-safe operations.

This is equivalent to .set(), except that it does not require an &mut reference, and allows bit-slices with alias-safe storage to share write permissions.

Parameters
  • &self: This method only exists on bit-slices with alias-safe storage, and so does not require exclusive access.
  • index: The bit index to set. It must be in 0 .. self.len().
  • value: The new bit-value to write into the bit at index.
Panics

This panics if index is out of bounds.

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

let bits: &BitSlice<_, _> = bits![Cell<usize>, Lsb0; 0, 1];
bits.set_aliased(0, true);
bits.set_aliased(1, false);

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

Writes a new value into a single bit, using alias-safe operations and without bounds checking.

This is equivalent to .set_unchecked(), except that it does not require an &mut reference, and allows bit-slices with alias-safe storage to share write permissions.

Parameters
  • &self: This method only exists on bit-slices with alias-safe storage, and so does not require exclusive access.
  • index: The bit index to set. It must be in 0 .. self.len().
  • value: The new bit-value to write into the bit at index.
Safety

The caller must ensure that index is not out of bounds.

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

let data = Cell::new(0u8);
let bits = &data.view_bits::<Lsb0>()[.. 2];
unsafe {
  bits.set_aliased_unchecked(3, true);
}
assert_eq!(data.get(), 8);

Copies a bit-slice into an owned bit-vector.

Since the new vector is freshly owned, this gets marked as ::Unalias to remove any guards that may have been inserted by the bit-slice’s history.

It does not use the underlying memory type, so that a BitSlice<_, Cell<_>> will produce a BitVec<_, Cell<_>>.

Original

slice::to_vec

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.

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

Performs the &= operation. Read more

Performs the &= operation. Read more

Performs the &= operation. Read more

Little-Endian Integer Loading Read more

Big-Endian Integer Loading Read more

Little-Endian Integer Storing Read more

Big-Endian Integer Storing Read more

Integer Loading Read more

Integer Storing Read more

The resulting type after applying the | operator.

Performs the | operation. Read more

Performs the |= operation. Read more

Performs the |= operation. Read more

Performs the |= operation. Read more

The resulting type after applying the ^ operator.

Performs the ^ operation. Read more

Performs the ^= operation. Read more

Performs the ^= operation. Read more

Performs the ^= operation. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Returns the “default value” for a type. Read more

The resulting type after dereferencing.

Dereferences the value.

Mutably dereferences the value.

Deserialize this value from the given Serde deserializer. Read more

Formats the value using the given formatter. Read more

Executes the destructor for this type. Read more

Extends a collection with the contents of an iterator. Read more

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

Extends a collection with exactly one element.

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

Reserves capacity in a collection for the given number of additional elements. Read more

Extends a collection with the contents of an iterator. Read more

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

Extends a collection with exactly one element.

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

Reserves capacity in a collection for the given number of additional elements. Read more

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.

Extends a collection with the contents of an iterator. Read more

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

Extends a collection with exactly one element.

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

Reserves capacity in a collection for the given number of additional elements. Read more

Extends a collection with the contents of an iterator. Read more

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

Extends a collection with exactly one element.

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

Reserves capacity in a collection for the given number of additional elements. Read more

Bit-Vector Extension

This extends a bit-vector from anything that produces individual bits.

Original

impl<T> Extend<T> for Vec<T>

Notes

This .extend() call is the second-slowest possible way to append bits into a bit-vector, faster only than calling iter.for_each(|bit| bv.push(bit)). DO NOT use this if you have any other choice.

If you are extending a bit-vector from the contents of a bit-slice, then you should use .extend_from_bitslice() instead. That method is specialized to perform upfront allocation and, where possible, use a batch copy rather than copying each bit individually from the source into the bit-vector.

Extends a collection with the contents of an iterator. Read more

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

Extends a collection with exactly one element.

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

Reserves capacity in a collection for the given number of additional elements. Read more

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Creates a value from an iterator. Read more

Creates a value from an iterator. Read more

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.

Creates a value from an iterator. Read more

Creates a value from an iterator. Read more

Bit-Vector Collection

This collects a bit-vector from anything that produces individual bits.

Original

impl<T> FromIterator<T> for Vec<T>

Notes

This .collect() call is the second-slowest possible way to collect bits into a bit-vector, faster only than calling iter.for_each(|bit| bv.push(bit)). DO NOT use this if you have any other choice.

If you are collecting a bit-vector from the contents of a bit-slice, then you should use ::from_bitslice() instead. That method is specialized to perform upfront allocation and, where possible, use a batch copy rather than copying each bit individually from the source into the bit-vector.

Creates a value from an iterator. Read more

Feeds this value into the given Hasher. Read more

Feeds a slice of this type into the given Hasher. Read more

The returned type after indexing.

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

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

Bit-Vector Iteration

Bit-vectors have the advantage that iteration consumes the whole structure, so they can simply freeze the allocation into a bit-box, then use its iteration and destructor.

Original

impl<T> IntoIterator for Vec<T>

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.

This implementation inverts all elements in the live buffer. You cannot rely on the value of bits in the buffer that are outside the domain of BitVec::as_mut_bitslice.

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 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

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

Formats the value using the given formatter.

Reading From a Bit-Vector

The implementation loads bytes out of the reference bit-vector until either the destination buffer is filled or the source has no more bytes to provide. When .read() returns, the provided bit-vector will have its contents shifted down so that it begins at the first bit after the last byte copied out into buf.

Note that the return value of .read() is always the number of bytes of buf filled!

API Differences

The standard library does not impl Read for Vec<u8>. It is provided here as a courtesy.

Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more

Like read, except that it reads into a slice of buffers. Read more

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

Determines if this Reader has an efficient read_vectored implementation. Read more

Read all bytes until EOF in this source, placing them into buf. Read more

Read all bytes until EOF in this source, appending them to buf. Read more

Read the exact number of bytes required to fill buf. Read more

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

Pull some bytes from this source into the specified buffer. Read more

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

Read the exact number of bytes required to fill buf. Read more

Creates a “by reference” adaptor for this instance of Read. Read more

Transforms this Read instance to an Iterator over its bytes. Read more

Creates an adapter which will chain this stream with another. Read more

Creates an adapter which will read at most limit bytes from it. Read more

Serialize this value into the given Serde serializer. Read more

The type returned in the event of a conversion error.

Performs the conversion.

Formats the value using the given formatter.

Writing Into a Bit-Vector

The implementation appends bytes to the referenced bit-vector until the source buffer is exhausted.

Note that the return value of .write() is always the number of bytes of buf consumed!

The implementation uses BitField::store_be to fill bytes. Note that unlike the standard library, it is implemented on bit-vectors of any underlying element type. However, using a BitVec<_, u8> is still likely to be fastest.

Original

impl Write for Vec<u8>

Write a buffer into this writer, returning how many bytes were written. Read more

Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more

Like write, except that it writes from a slice of buffers. Read more

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

Determines if this Writer has an efficient write_vectored implementation. Read more

Attempts to write an entire buffer into this writer. Read more

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

Attempts to write multiple buffers into this writer. Read more

Writes a formatted string into this writer, returning any error encountered. Read more

Creates a “by reference” adapter for this instance of Write. Read more

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

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

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. Read more

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

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

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

Formats each item in a sequence. Read more

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

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

Borrows self, then passes self.borrow() into the pipe function. Read more

Mutably borrows self, then passes self.borrow_mut() into the pipe function. Read more

Borrows self, then passes self.as_ref() into the pipe function.

Mutably borrows self, then passes self.as_mut() into the pipe function. Read more

Borrows self, then passes self.deref() into the pipe function.

Mutably borrows self, then passes self.deref_mut() into the pipe function. Read more

Immutable access to a value. Read more

Mutable access to a value. Read more

Immutable access to the Borrow<B> of a value. Read more

Mutable access to the BorrowMut<B> of a value. Read more

Immutable access to the AsRef<R> view of a value. Read more

Mutable access to the AsMut<R> view of a value. Read more

Immutable access to the Deref::Target of a value. Read more

Mutable access to the Deref::Target of a value. Read more

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

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

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

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

The resulting type after obtaining ownership.

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

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

Uses borrowed data to replace owned data, usually by cloning. Read more

Converts the given value to a String. Read more

Attempts to convert self into T using TryInto<T>. 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.