Struct bit_vec::BitVec
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pub struct BitVec<B = u32> { // some fields omitted }
The bitvector type.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_elem(10, false); // insert all primes less than 10 bv.set(2, true); bv.set(3, true); bv.set(5, true); bv.set(7, true); println!("{:?}", bv); println!("total bits set to true: {}", bv.iter().filter(|x| *x).count()); // flip all values in bitvector, producing non-primes less than 10 bv.negate(); println!("{:?}", bv); println!("total bits set to true: {}", bv.iter().filter(|x| *x).count()); // reset bitvector to empty bv.clear(); println!("{:?}", bv); println!("total bits set to true: {}", bv.iter().filter(|x| *x).count());
Methods
impl BitVec<u32>
fn new() -> Self
fn from_elem(nbits: usize, bit: bool) -> Self
Creates a BitVec
that holds nbits
elements, setting each element
to bit
.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_elem(10, false); assert_eq!(bv.len(), 10); for x in bv.iter() { assert_eq!(x, false); }
fn with_capacity(nbits: usize) -> Self
Constructs a new, empty BitVec
with the specified capacity.
The bitvector will be able to hold at least capacity
bits without
reallocating. If capacity
is 0, it will not allocate.
It is important to note that this function does not specify the length of the returned bitvector, but only the capacity.
fn from_bytes(bytes: &[u8]) -> Self
Transforms a byte-vector into a BitVec
. Each byte becomes eight bits,
with the most significant bits of each byte coming first. Each
bit becomes true
if equal to 1 or false
if equal to 0.
Examples
use bit_vec::BitVec; let bv = BitVec::from_bytes(&[0b10100000, 0b00010010]); assert!(bv.eq_vec(&[true, false, true, false, false, false, false, false, false, false, false, true, false, false, true, false]));
fn from_fn<F>(len: usize, f: F) -> Self where F: FnMut(usize) -> bool
Creates a BitVec
of the specified length where the value at each index
is f(index)
.
Examples
use bit_vec::BitVec; let bv = BitVec::from_fn(5, |i| { i % 2 == 0 }); assert!(bv.eq_vec(&[true, false, true, false, true]));
impl<B: BitBlock> BitVec<B>
fn blocks(&self) -> Blocks<B>
Iterator over the underlying blocks of data
fn storage(&self) -> &[B]
Exposes the raw block storage of this BitVec
Only really intended for BitSet.
unsafe fn storage_mut(&mut self) -> &mut Vec<B>
Exposes the raw block storage of this BitVec
Can probably cause unsafety. Only really intended for BitSet.
fn get(&self, i: usize) -> Option<bool>
Retrieves the value at index i
, or None
if the index is out of bounds.
Examples
use bit_vec::BitVec; let bv = BitVec::from_bytes(&[0b01100000]); assert_eq!(bv.get(0), Some(false)); assert_eq!(bv.get(1), Some(true)); assert_eq!(bv.get(100), None); // Can also use array indexing assert_eq!(bv[1], true);
fn set(&mut self, i: usize, x: bool)
Sets the value of a bit at an index i
.
Panics
Panics if i
is out of bounds.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_elem(5, false); bv.set(3, true); assert_eq!(bv[3], true);
fn set_all(&mut self)
Sets all bits to 1.
Examples
use bit_vec::BitVec; let before = 0b01100000; let after = 0b11111111; let mut bv = BitVec::from_bytes(&[before]); bv.set_all(); assert_eq!(bv, BitVec::from_bytes(&[after]));
fn negate(&mut self)
Flips all bits.
Examples
use bit_vec::BitVec; let before = 0b01100000; let after = 0b10011111; let mut bv = BitVec::from_bytes(&[before]); bv.negate(); assert_eq!(bv, BitVec::from_bytes(&[after]));
fn union(&mut self, other: &Self) -> bool
Calculates the union of two bitvectors. This acts like the bitwise or
function.
Sets self
to the union of self
and other
. Both bitvectors must be
the same length. Returns true
if self
changed.
Panics
Panics if the bitvectors are of different lengths.
Examples
use bit_vec::BitVec; let a = 0b01100100; let b = 0b01011010; let res = 0b01111110; let mut a = BitVec::from_bytes(&[a]); let b = BitVec::from_bytes(&[b]); assert!(a.union(&b)); assert_eq!(a, BitVec::from_bytes(&[res]));
fn intersect(&mut self, other: &Self) -> bool
Calculates the intersection of two bitvectors. This acts like the
bitwise and
function.
Sets self
to the intersection of self
and other
. Both bitvectors
must be the same length. Returns true
if self
changed.
Panics
Panics if the bitvectors are of different lengths.
Examples
use bit_vec::BitVec; let a = 0b01100100; let b = 0b01011010; let res = 0b01000000; let mut a = BitVec::from_bytes(&[a]); let b = BitVec::from_bytes(&[b]); assert!(a.intersect(&b)); assert_eq!(a, BitVec::from_bytes(&[res]));
fn difference(&mut self, other: &Self) -> bool
Calculates the difference between two bitvectors.
Sets each element of self
to the value of that element minus the
element of other
at the same index. Both bitvectors must be the same
length. Returns true
if self
changed.
Panics
Panics if the bitvectors are of different length.
Examples
use bit_vec::BitVec; let a = 0b01100100; let b = 0b01011010; let a_b = 0b00100100; // a - b let b_a = 0b00011010; // b - a let mut bva = BitVec::from_bytes(&[a]); let bvb = BitVec::from_bytes(&[b]); assert!(bva.difference(&bvb)); assert_eq!(bva, BitVec::from_bytes(&[a_b])); let bva = BitVec::from_bytes(&[a]); let mut bvb = BitVec::from_bytes(&[b]); assert!(bvb.difference(&bva)); assert_eq!(bvb, BitVec::from_bytes(&[b_a]));
fn all(&self) -> bool
Returns true
if all bits are 1.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_elem(5, true); assert_eq!(bv.all(), true); bv.set(1, false); assert_eq!(bv.all(), false);
fn iter(&self) -> Iter<B>
Returns an iterator over the elements of the vector in order.
Examples
use bit_vec::BitVec; let bv = BitVec::from_bytes(&[0b01110100, 0b10010010]); assert_eq!(bv.iter().filter(|x| *x).count(), 7);
fn none(&self) -> bool
Returns true
if all bits are 0.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_elem(10, false); assert_eq!(bv.none(), true); bv.set(3, true); assert_eq!(bv.none(), false);
fn any(&self) -> bool
Returns true
if any bit is 1.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_elem(10, false); assert_eq!(bv.any(), false); bv.set(3, true); assert_eq!(bv.any(), true);
fn to_bytes(&self) -> Vec<u8>
Organises the bits into bytes, such that the first bit in the
BitVec
becomes the high-order bit of the first byte. If the
size of the BitVec
is not a multiple of eight then trailing bits
will be filled-in with false
.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_elem(3, true); bv.set(1, false); assert_eq!(bv.to_bytes(), [0b10100000]); let mut bv = BitVec::from_elem(9, false); bv.set(2, true); bv.set(8, true); assert_eq!(bv.to_bytes(), [0b00100000, 0b10000000]);
fn eq_vec(&self, v: &[bool]) -> bool
Compares a BitVec
to a slice of bool
s.
Both the BitVec
and slice must have the same length.
Panics
Panics if the BitVec
and slice are of different length.
Examples
use bit_vec::BitVec; let bv = BitVec::from_bytes(&[0b10100000]); assert!(bv.eq_vec(&[true, false, true, false, false, false, false, false]));
fn truncate(&mut self, len: usize)
Shortens a BitVec
, dropping excess elements.
If len
is greater than the vector's current length, this has no
effect.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_bytes(&[0b01001011]); bv.truncate(2); assert!(bv.eq_vec(&[false, true]));
fn reserve(&mut self, additional: usize)
Reserves capacity for at least additional
more bits to be inserted in the given
BitVec
. The collection may reserve more space to avoid frequent reallocations.
Panics
Panics if the new capacity overflows usize
.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_elem(3, false); bv.reserve(10); assert_eq!(bv.len(), 3); assert!(bv.capacity() >= 13);
fn reserve_exact(&mut self, additional: usize)
Reserves the minimum capacity for exactly additional
more bits to be inserted in the
given BitVec
. Does nothing if the capacity is already sufficient.
Note that the allocator may give the collection more space than it requests. Therefore
capacity can not be relied upon to be precisely minimal. Prefer reserve
if future
insertions are expected.
Panics
Panics if the new capacity overflows usize
.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_elem(3, false); bv.reserve(10); assert_eq!(bv.len(), 3); assert!(bv.capacity() >= 13);
fn capacity(&self) -> usize
Returns the capacity in bits for this bit vector. Inserting any element less than this amount will not trigger a resizing.
Examples
use bit_vec::BitVec; let mut bv = BitVec::new(); bv.reserve(10); assert!(bv.capacity() >= 10);
fn grow(&mut self, n: usize, value: bool)
Grows the BitVec
in-place, adding n
copies of value
to the BitVec
.
Panics
Panics if the new len overflows a usize
.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_bytes(&[0b01001011]); bv.grow(2, true); assert_eq!(bv.len(), 10); assert_eq!(bv.to_bytes(), [0b01001011, 0b11000000]);
fn pop(&mut self) -> Option<bool>
Removes the last bit from the BitVec, and returns it. Returns None if the BitVec is empty.
Examples
use bit_vec::BitVec; let mut bv = BitVec::from_bytes(&[0b01001001]); assert_eq!(bv.pop(), Some(true)); assert_eq!(bv.pop(), Some(false)); assert_eq!(bv.len(), 6);
fn push(&mut self, elem: bool)
Pushes a bool
onto the end.
Examples
use bit_vec::BitVec; let mut bv = BitVec::new(); bv.push(true); bv.push(false); assert!(bv.eq_vec(&[true, false]));
fn len(&self) -> usize
Returns the total number of bits in this vector
unsafe fn set_len(&mut self, len: usize)
Sets the number of bits that this BitVec considers initialized.
Almost certainly can cause bad stuff. Only really intended for BitSet.
fn is_empty(&self) -> bool
Returns true if there are no bits in this vector
fn clear(&mut self)
Clears all bits in this vector.