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/*! `BitVec` structure
This module holds the main working type of the library. Clients can use
`BitSlice` directly, but `BitVec` is much more useful for most work.
The `BitSlice` module discusses the design decisions for the separation between
slice and vector types.
!*/
#![cfg(feature = "alloc")]
use core::{
borrow::{
Borrow,
BorrowMut,
},
clone::Clone,
cmp::{
Eq,
Ord,
Ordering,
PartialEq,
PartialOrd,
},
convert::{
AsMut,
AsRef,
From,
},
default::Default,
fmt::{
self,
Debug,
Display,
Formatter,
},
hash::{
Hash,
Hasher,
},
iter::{
DoubleEndedIterator,
ExactSizeIterator,
Extend,
FromIterator,
Iterator,
IntoIterator,
},
marker::PhantomData,
mem,
ops::{
Add,
AddAssign,
BitAnd,
BitAndAssign,
BitOr,
BitOrAssign,
BitXor,
BitXorAssign,
Deref,
DerefMut,
Drop,
Index,
Neg,
Not,
Shl,
ShlAssign,
Shr,
ShrAssign,
Sub,
SubAssign,
},
ptr,
};
#[cfg(all(feature = "alloc", not(feature = "std")))]
use alloc::{
borrow::ToOwned,
boxed::Box,
vec::Vec,
};
#[cfg(feature = "std")]
use std::borrow::ToOwned;
/** A compact `Vec` of bits, whose cursor and storage type can be customized.
`BitVec` is a newtype wrapper over `Vec`, and as such is exactly three words in
size on the stack.
**IMPORTANT NOTE:** It is **horrifically** unsafe to use `mem::transmute`
between `Vec<T>` and `BitVec<_, T>`, because `BitVec` achieves its size by using
the length field of the underlying `Vec` to count bits, rather than elements.
This means that it has a fixed maximum bit width regardless of element type, and
the length field will always be horrifically wrong to be treated as a `Vec`.
Safe methods exist to move between `Vec` and `BitVec` – **USE THEM**.
`BitVec` takes two type parameters.
- `C: Cursor` must be an implementor of the `Cursor` trait. `BitVec` takes a
`PhantomData` marker for access to the associated functions, and will never
make use of an instance of the trait. The default implementations,
`LittleEndian` and `BigEndian`, are zero-sized, and any further
implementations should be as well, as the invoked functions will never receive
state.
- `T: Bits` must be a primitive type. Rust decided long ago to not provide a
unifying trait over the primitives, so `Bits` provides access to just enough
properties of the primitives for `BitVec` to use. This trait is sealed against
downstream implementation, and can only be implemented in this crate.
**/
#[repr(transparent)]
pub struct BitVec<C = crate::BigEndian, T = u8>
where C: crate::Cursor, T: crate::Bits {
_cursor: PhantomData<C>,
inner: Vec<T>,
}
impl<C, T> BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Constructs a new, empty, `BitVec<C, T>`.
///
/// The vector will not allocate until bits are pushed onto it.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv: BitVec = BitVec::new();
/// assert!(bv.is_empty());
/// assert_eq!(bv.capacity(), 0);
/// ```
pub fn new() -> Self {
Self {
_cursor: PhantomData,
inner: Vec::new(),
}
}
/// Constructs a new, empty `BitVec<T>` with the specified capacity.
///
/// The vector will be able to hold exactly `capacity` elements without
/// reallocating. If `capacity` is 0, the vector will not allocate.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv: BitVec = BitVec::with_capacity(10);
/// assert!(bv.is_empty());
/// assert!(bv.capacity() >= 2);
/// ```
pub fn with_capacity(capacity: usize) -> Self {
let (elts, bits) = T::split(capacity);
let cap = elts + if bits > 0 { 1 } else { 0 };
Self {
inner: Vec::with_capacity(cap),
_cursor: PhantomData,
}
}
/// Returns the number of bits the vector can hold without reallocating.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv: BitVec = BitVec::with_capacity(10);
/// assert!(bv.is_empty());
/// assert!(bv.capacity() >= 2);
/// ```
pub fn capacity(&self) -> usize {
assert!(self.inner.capacity() <= T::MAX_ELT, "Capacity overflow");
self.inner.capacity() << T::BITS
}
/// Appends a bit to the collection.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv: BitVec = BitVec::new();
/// assert!(bv.is_empty());
/// bv.push(true);
/// assert_eq!(bv.len(), 1);
/// assert!(bv[0]);
/// ```
pub fn push(&mut self, value: bool) {
assert!(self.len() < core::usize::MAX, "Vector will overflow!");
let bit = self.bits();
// Get a cursor to the bit that matches the semantic count.
let cursor = C::curr::<T>(bit);
// Insert `value` at the current cursor.
self.do_with_tail(|elt| elt.set(cursor, value));
// If the cursor is at the *end* of an element, this bit will finish it
// and the element count needs to be incremented.
if bit == T::MASK {
let elts = self.elts();
assert!(elts <= T::MAX_ELT, "Elements will overflow");
unsafe { self.set_elts(elts + 1) };
}
// Increment the bit counter, wrapping if need be.
unsafe { self.set_bits((bit + 1) & T::MASK); }
}
/// Removes the last bit from the collection.
///
/// Returns `None` if the collection is empty.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv: BitVec = BitVec::new();
/// assert!(bv.is_empty());
/// bv.push(true);
/// assert_eq!(bv.len(), 1);
/// assert!(bv[0]);
///
/// assert!(bv.pop().unwrap());
/// assert!(bv.is_empty());
/// assert!(bv.pop().is_none());
/// ```
pub fn pop(&mut self) -> Option<bool> {
if self.inner.is_empty() {
return None;
}
// Vec.pop never calls the allocator, it just decrements the length
// counter. Similarly, this just decrements the length counter and
// yields the bit underneath it.
let cur = self.len() - 1;
let ret = self.get(cur);
unsafe { self.inner.set_len(cur); }
Some(ret)
}
/// Empties out the `BitVec`, resetting it to length zero.
///
/// This does not affect the memory store! It will not zero the raw memory
/// nor will it deallocate.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv = bitvec![1; 30];
/// assert_eq!(bv.len(), 30);
/// assert!(bv.iter().all(|b| b));
/// bv.clear();
/// assert!(bv.is_empty());
/// ```
///
/// After `clear()`, `bv` will no longer show raw memory, so the above test
/// cannot show that the underlying memory is untouched. This is also an
/// implementation detail on which you should not rely.
pub fn clear(&mut self) {
self.do_with_vec(Vec::<T>::clear);
}
/// Reserves capacity for additional bits.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv = bitvec![1; 5];
/// let cap = bv.capacity();
/// bv.reserve(10);
/// assert!(bv.capacity() >= cap + 10);
/// ```
pub fn reserve(&mut self, additional: usize) {
let (cur_elts, cur_bits) = T::split(self.raw_len());
let (new_elts, new_bits) = T::split(additional);
let (elts, bits) = (cur_elts + new_elts, cur_bits + new_bits);
let extra = elts + if bits > 0 { 1 } else { 0 };
assert!(self.raw_len() + extra <= T::MAX_ELT, "Capacity would overflow");
self.do_with_vec(|v| v.reserve(extra));
}
/// Shrinks the capacity to fit at least as much as is needed, but with as
/// little or as much excess as the allocator chooses.
///
/// This may or may not deallocate tail space, as the allocator sees fit.
/// This does not zero the abandoned memory.
pub fn shrink_to_fit(&mut self) {
self.do_with_vec(Vec::<T>::shrink_to_fit);
}
/// Shrinks the `BitVec` to the given size, dropping all excess storage.
///
/// This does not affect the memory store! It will not zero the raw memory
/// nor will it deallocate.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv = bitvec![1; 30];
/// assert_eq!(bv.len(), 30);
/// let cap = bv.capacity();
/// bv.truncate(10);
/// assert_eq!(bv.len(), 10);
/// assert_eq!(bv.capacity(), cap);
/// ```
pub fn truncate(&mut self, len: usize) {
let (elts, bits) = T::split(len);
let trunc = elts + if bits > 0 { 1 } else { 0 };
self.do_with_vec(|v| v.truncate(trunc));
unsafe { self.set_len(len); }
}
/// Converts the `BitVec` into a boxed slice of storage elements. This drops
/// all `BitVec` management semantics, including partial fill status of the
/// trailing element or endianness, and gives ownership the raw storage.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv: BitVec<BigEndian, u8> = bitvec![1; 64];
/// let bytes: Box<[u8]> = bv.into_boxed_slice();
/// assert_eq!(bytes.len(), 8);
/// for byte in bytes.iter() {
/// assert_eq!(*byte, !0);
/// }
/// ```
pub fn into_boxed_slice(self) -> Box<[T]> {
let raw = self.raw_len();
let buf = unsafe {
let mut buf = ptr::read(&self.inner);
mem::forget(self);
buf.set_len(raw);
buf
};
buf.into_boxed_slice()
}
/// Sets the backing storage to the provided element.
///
/// This unconditionally sets each element in the backing storage to the
/// provided value, without altering the `BitVec` length or capacity. It
/// operates an the underlying `Vec` directly, and will ignore any partial
/// bounds on the tail.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv = bitvec![0; 10];
/// assert_eq!(bv.as_ref(), &[0, 0]);
/// bv.set_store(0xA5);
/// assert_eq!(bv.as_ref(), &[0xA5, 0xA5]);
/// ```
pub fn set_store(&mut self, element: T) {
self.do_with_vec(|v| {
let len = v.len();
let cap = v.capacity();
unsafe { v.set_len(cap); }
for elt in v.iter_mut() {
*elt = element;
}
unsafe { v.set_len(len); }
});
}
/// Sets the bit count to a new value.
///
/// This utility function unconditionally sets the bottom `T::BITS` bits of
/// `inner.len` to reflect how many bits of the tail are live. It should
/// only be used when adjusting the liveness of the tail.
unsafe fn set_bits(&mut self, count: u8) {
assert!(count <= T::MASK, "Index out of range");
let elt = self.len() & !(T::MASK as usize);
self.inner.set_len(elt | count as usize);
}
/// Sets the element count to a new value.
///
/// This utility function unconditionally sets the rest of the bits of
/// `inner.len` to reflect how many elements in the `Vec` are fully filled.
/// It will always be one fewer than the number of elements the `Vec` would
/// consider live, were it consulted. It should only be used when adjusting
/// the liveness of the underlying `Vec`.
unsafe fn set_elts(&mut self, count: usize) {
assert!(count <= T::MAX_ELT, "Length out of range");
let bit = self.len() & (T::MASK as usize);
self.inner.set_len(T::join(count, bit as u8));
}
/// Sets the length directly.
///
/// This is *wildly* unsafe! It directly sets the length of the vector to
/// whatever you provide. As a sanity check, this absolutely will panic if
/// the provided length would go past the vector's allocated capacity.
pub unsafe fn set_len(&mut self, len: usize) {
assert!(len <= self.capacity(), "Length cannot exceed capacity");
self.inner.set_len(len);
}
/// Executes some operation with the storage `Vec` in sane condition.
///
/// The given function receives a sane `Vec<T>`, with the `len` attribute
/// set to reflect the reality of elements in use. The storage `Vec` is then
/// set back to the correct state for `BitVec` use after the given function
/// ends.
///
/// The given function may not return a reference into the `Vec`. It must
/// return a standalone value, or nothing. If access into the buffer is
/// needed, use `AsRef` or `AsMut`.
///
/// NOTE: If the operation changes the length of the underlying `Vec`, this
/// will assume that all elements are full, and the `bits()` cursor will be
/// wiped.
fn do_with_vec<F: Fn(&mut Vec<T>) -> R, R>(&mut self, op: F) -> R {
// Keep the old length in order to (maybe) restore it.
let len = self.len();
// Get the number of storage elements the `Vec` considers live.
let old = self.raw_len();
// `BitVec.inner.len` is used to store both element count and bit count
// which is a state that *cannot* be passed to operations on the `Vec`
// itself. Set the `Vec.len` member to be the number of live elements.
unsafe { self.inner.set_len(old); }
// Do the operation.
let ret = op(&mut self.inner);
// The operation may have changed how many elements are considered live
// so we must get the new count, manipulate it, and use that. (If the
// operation clears the `Vec`, then zero is a perfectly valid `len`.)
// There is not enough information in this call to set `bits()`
// correctly after a `Vec`-mutating call, so it is up to the caller to
// ensure that the `bits()` segment is correct after this returns.
let new = self.inner.len();
assert!(new <= T::MAX_ELT, "Length out of range!");
// If the length is unchanged before and after the call, restore the
// original bit length.
if new == old {
unsafe {
self.inner.set_len(len);
}
}
// If the length is different, give up and assume all the elements are
// full. Use `push_elt()` to manipulate allocations.
else {
unsafe {
self.set_bits(0);
self.set_elts(new);
}
}
ret
}
/// Executes some operation with the tail storage element.
///
/// If the bit cursor is at zero when this is called, then the current tail
/// element is not live, and one will be pushed onto the underlying `Vec`,
/// and this fresh element will be provided to the operation.
fn do_with_tail<F: Fn(&mut T) -> R, R>(&mut self, op: F) -> R {
// If the cursor is at zero, there is not necessarily an element
// allocated underneath it. Have the `Vec` try to push an element,
// allocating if need be, for use.
if self.bits() == 0 {
self.push_elt();
}
let old_len = self.inner.len();
let elts = self.elts();
// elts() counts how many elements are full. There is always one more
// element allocated and live than are full, so inform the `Vec` that
// it has `elts() + 1` elements live, act on the last one, and then
// restore the length to the correct value for `BitVec`'s purposes.
unsafe {
self.inner.set_len(elts + 1);
let ret = op(&mut self.inner[elts]);
self.inner.set_len(old_len);
ret
}
}
/// Pushes an element onto the end of the underlying store. This may or may
/// not call the allocator. After the element ensured to be allocated, the
/// old length is restored.
fn push_elt(&mut self) {
let len = self.len();
self.do_with_vec(|v| v.push(unsafe { mem::zeroed() }));
unsafe {
self.inner.set_len(len);
}
}
/// Formats the debug header for the type.
///
/// The body format is provided by `BitSlice`.
fn fmt_header(&self, fmt: &mut Formatter) -> fmt::Result {
write!(fmt, "BitVec<{}, {}>", C::TY, T::TY)
}
}
/// Signifies that `BitSlice` is the borrowed form of `BitVec`.
impl<C, T> Borrow<crate::BitSlice<C, T>> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Borrows the `BitVec` as a `BitSlice`.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// use std::borrow::Borrow;
/// let bv = bitvec![0; 8];
/// let bref: &BitSlice = bv.borrow();
/// assert!(!bref.get(7));
/// ```
fn borrow(&self) -> &crate::BitSlice<C, T> {
&*self
}
}
/// Signifies that `BitSlice` is the borrowed form of `BitVec`.
impl<C, T> BorrowMut<crate::BitSlice<C, T>> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Mutably borrows the `BitVec` as a `BitSlice`.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// use std::borrow::BorrowMut;
/// let mut bv = bitvec![0; 8];
/// let bref: &mut BitSlice = bv.borrow_mut();
/// assert!(!bref.get(7));
/// bref.set(7, true);
/// assert!(bref.get(7));
/// ```
fn borrow_mut(&mut self) -> &mut crate::BitSlice<C, T> {
&mut *self
}
}
impl<C, T> Clone for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
fn clone(&self) -> Self {
let mut out = Self::from(self.as_ref());
unsafe {
out.inner.set_len(self.len());
}
out
}
fn clone_from(&mut self, other: &Self) {
self.clear();
self.reserve(other.len());
unsafe {
let src = other.as_ptr();
let dst = self.as_mut_ptr();
let len = other.raw_len();
ptr::copy_nonoverlapping(src, dst, len);
}
}
}
impl<C, T> Eq for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {}
impl<C, T> Ord for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
fn cmp(&self, rhs: &Self) -> Ordering {
crate::BitSlice::cmp(&self, &rhs)
}
}
/// Tests if two `BitVec`s are semantically — not bitwise — equal.
///
/// It is valid to compare two vectors of different endianness or element types.
///
/// The equality condition requires that they have the same number of stored
/// bits and that each pair of bits in semantic order are identical.
impl<A, B, C, D> PartialEq<BitVec<C, D>> for BitVec<A, B>
where A: crate::Cursor, B: crate::Bits, C: crate::Cursor, D: crate::Bits {
/// Performs a comparison by `==`.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let l: BitVec<LittleEndian, u16> = bitvec![LittleEndian, u16; 0, 1, 0, 1];
/// let r: BitVec<BigEndian, u32> = bitvec![BigEndian, u32; 0, 1, 0, 1];
/// assert!(l == r);
/// ```
///
/// This example uses the same types to prove that raw, bitwise, values are
/// not used for equality comparison.
///
/// ```rust
/// use bitvec::*;
/// let l: BitVec<BigEndian, u8> = bitvec![BigEndian, u8; 0, 1, 0, 1];
/// let r: BitVec<LittleEndian, u8> = bitvec![LittleEndian, u8; 0, 1, 0, 1];
///
/// assert_eq!(l, r);
/// assert_ne!(l.as_ref(), r.as_ref());
/// ```
fn eq(&self, rhs: &BitVec<C, D>) -> bool {
crate::BitSlice::eq(&self, &rhs)
}
}
/// Compares two `BitVec`s by semantic — not bitwise — ordering.
///
/// The comparison sorts by testing each index for one vector to have a set bit
/// where the other vector has an unset bit. If the vectors are different, the
/// vector with the set bit sorts greater than the vector with the unset bit.
///
/// If one of the vectors is exhausted before they differ, the longer vector is
/// greater.
impl<A, B, C, D> PartialOrd<BitVec<C, D>> for BitVec<A, B>
where A: crate::Cursor, B: crate::Bits, C: crate::Cursor, D: crate::Bits {
/// Performs a comparison by `<` or `>`.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// use bitvec::*;
/// let a = bitvec![0, 1, 0, 0];
/// let b = bitvec![0, 1, 0, 1];
/// let c = bitvec![0, 1, 0, 1, 1];
/// assert!(a < b);
/// assert!(b < c);
/// ```
fn partial_cmp(&self, rhs: &BitVec<C, D>) -> Option<Ordering> {
crate::BitSlice::partial_cmp(&self, &rhs)
}
}
/// Gives write access to all live elements in the underlying storage, including
/// the partially-filled tail.
impl<C, T> AsMut<[T]> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Accesses the underlying store.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv: BitVec = bitvec![0, 0, 0, 0, 0, 0, 0, 0, 1];
/// for elt in bv.as_mut() {
/// *elt += 2;
/// }
/// assert_eq!(&[2, 0b1000_0010], bv.as_ref());
/// ```
fn as_mut(&mut self) -> &mut [T] {
crate::BitSlice::as_mut(self)
}
}
/// Gives read access to all live elements in the underlying storage, including
/// the partially-filled tail.
impl<C, T> AsRef<[T]> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Accesses the underlying store.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![0, 0, 0, 0, 0, 0, 0, 0, 1];
/// assert_eq!(&[0, 0b1000_0000], bv.as_ref());
/// ```
fn as_ref(&self) -> &[T] {
crate::BitSlice::as_ref(self)
}
}
/// Copies a `BitSlice` into an owned `BitVec`.
///
/// The idiomatic `BitSlice` to `BitVec` conversion is `BitSlice::to_owned`, but
/// just as `&[T].into()` yields a `Vec`, `&BitSlice.into()` yields a `BitVec`.
impl<'a, C, T> From<&'a crate::BitSlice<C, T>> for BitVec<C, T>
where C: crate::Cursor, T: 'a + crate::Bits {
fn from(src: &'a crate::BitSlice<C, T>) -> Self {
src.to_owned()
}
}
/// Builds a `BitVec` out of a slice of `bool`.
///
/// This is primarily for the `bitvec!` macro; it is not recommended for general
/// use.
impl<'a, C, T> From<&'a [bool]> for BitVec<C, T>
where C: crate::Cursor, T: 'a + crate::Bits {
fn from(src: &'a [bool]) -> Self {
let mut out = Self::with_capacity(src.len());
for bit in src {
out.push(*bit);
}
out
}
}
/// Builds a `BitVec` out of a borrowed slice of elements.
///
/// This copies the memory as-is from the source buffer into the new `BitVec`.
/// The source buffer will be unchanged by this operation, so you don't need to
/// worry about using the correct cursor type for the read.
///
/// This operation does a copy from the source buffer into a new allocation, as
/// it can only borrow the source and not take ownership.
impl<'a, C, T> From<&'a [T]> for BitVec<C, T>
where C: crate::Cursor, T: 'a + crate::Bits {
/// Builds a `BitVec<C: Cursor, T: Bits>` from a borrowed `&[T]`.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let src: &[u8] = &[5, 10];
/// let bv: BitVec = src.into();
/// assert_eq!("00000101 00001010", &format!("{}", bv));
/// ```
fn from(src: &'a [T]) -> Self {
<&crate::BitSlice<C, T>>::from(src).to_owned()
}
}
/// Builds a `BitVec` out of an owned slice of elements.
///
/// This moves the memory as-is from the source buffer into the new `BitVec`.
/// The source buffer will be unchanged by this operation, so you don't need to
/// worry about using the correct cursor type.
impl<C, T> From<Box<[T]>> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Consumes a `Box<[T: Bits]>` and creates a `BitVec<C: Cursor, T>` from
/// it.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let src: Box<[u8]> = Box::new([3, 6, 9, 12, 15]);
/// let bv: BitVec = src.into();
/// assert_eq!("00000011 00000110 00001001 00001100 00001111", &format!("{}", bv));
/// ```
fn from(src: Box<[T]>) -> Self {
assert!(src.len() <= T::MAX_ELT, "Source slice too long!");
Self::from(Vec::from(src))
}
}
/// Builds a `BitVec` out of a `Vec` of elements.
///
/// This moves the memory as-is from the source buffer into the new `BitVec`.
/// The source buffer will be unchanged by this operation, so you don't need to
/// worry about using the correct cursor type.
impl<C, T> From<Vec<T>> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Consumes a `Vec<T: Bits>` and creates a `BitVec<C: Cursor, T>` from it.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let src: Vec<u8> = vec![1, 2, 4, 8];
/// let bv: BitVec = src.into();
/// assert_eq!("00000001 00000010 00000100 00001000", &format!("{}", bv));
/// ```
fn from(src: Vec<T>) -> Self {
let elts = src.len();
assert!(elts <= T::MAX_ELT, "Source vector too long!");
let mut out = Self {
inner: src,
_cursor: PhantomData::<C>,
};
unsafe {
out.set_bits(0);
out.set_elts(elts);
}
out
}
}
/// Changes cursors on a `BitVec` without mutating the underlying data.
///
/// I don't know why this would be useful at the time of writing, as the `From`
/// implementations on collections crawl the collection elements in the order
/// requested and so the source and destination storage collections will be
/// bitwise identical, but here's the option anyway.
///
/// If the tail element is partially filled, then this operation will shift the
/// tail element so that the edge of the filled section is on the correct edge
/// of the tail element.
impl<T: crate::Bits> From<BitVec<crate::LittleEndian, T>>
for BitVec<crate::BigEndian, T> {
fn from(mut src: BitVec<crate::LittleEndian, T>) -> Self {
let bits = src.bits();
// If bits() is zero, then the tail is full and cannot shift.
// If bits() is nonzero, then the shamt is WIDTH - bits().
// E.g. a WIDTH of 32 and a bits() of 31 means bit 30 is the highest
// bit set, and the element should shl by 1 so that bit 31 is the
// highest bit set, and bit 0 will be empty.
if bits > 0 {
let shamt = T::WIDTH - bits;
src.do_with_tail(|elt| *elt <<= shamt);
}
// The cursor is stored in PhantomData, and known only to the complier.
// Transmutation is perfectly safe, since the only concrete item is the
// storage, which this explicitly does not alter.
unsafe { mem::transmute(src) }
}
}
/// Changes cursors on a `BitVec` without mutating the underlying data.
///
/// I don't know why this would be useful at the time of writing, as the `From`
/// implementations on collections crawl the collection elements in the order
/// requested and so the source and destination storage collections will be
/// bitwise identical, but here's the option anyway.
///
/// If the tail element is partially filled, then this operation will shift the
/// tail element so that the edge of the filled section is on the correct edge
/// of the tail element.
impl<T: crate::Bits> From<BitVec<crate::BigEndian, T>>
for BitVec<crate::LittleEndian, T> {
fn from(mut src: BitVec<crate::BigEndian, T>) -> Self {
let bits = src.bits();
if bits > 0 {
let shamt = T::WIDTH - bits;
src.do_with_tail(|elt| *elt >>= shamt);
}
unsafe { mem::transmute(src) }
}
}
impl<C, T> Default for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
fn default() -> Self {
Self {
inner: Default::default(),
_cursor: Default::default(),
}
}
}
/// Prints the `BitVec` for debugging.
///
/// The output is of the form `BitVec<C, T> [ELT, *]`, where `<C, T>` is the
/// endianness and element type, with square brackets on each end of the bits
/// and all the live elements in the vector printed in binary. The printout is
/// always in semantic order, and may not reflect the underlying store. To see
/// the underlying store, use `format!("{:?}", self.as_ref());` instead.
///
/// The alternate character `{:#?}` prints each element on its own line, rather
/// than separated by a space.
impl<C, T> Debug for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Renders the `BitVec` type header and contents for debug.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![LittleEndian, u16;
/// 0, 1, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 1
/// ];
/// assert_eq!(
/// "BitVec<LittleEndian, u16> [0101000011110101]",
/// &format!("{:?}", bv)
/// );
/// ```
fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
let alt = fmt.alternate();
self.fmt_header(fmt)?;
fmt.write_str(" [")?;
if alt { writeln!(fmt)?; fmt.write_str(" ")?; }
self.fmt_body(fmt, true)?;
if alt { writeln!(fmt)?; }
fmt.write_str("]")
}
}
/// Prints the `BitVec` for displaying.
///
/// This prints each element in turn, formatted in binary in semantic order (so
/// the first bit seen is printed first and the last bit seen printed last).
/// Each element of storage is separated by a space for ease of reading.
///
/// The alternate character `{:#}` prints each element on its own line.
///
/// To see the in-memory representation, use `AsRef` to get access to the raw
/// elements and print that slice instead.
impl<C, T> Display for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Renders the `BitVec` contents for display.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![BigEndian, u8; 0, 1, 0, 0, 1, 0, 1, 1, 0, 1];
/// assert_eq!("01001011 01", &format!("{}", bv));
/// ```
fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
self.fmt_body(fmt, false)
}
}
/// Writes the contents of the `BitVec`, in semantic bit order, into a hasher.
impl<C, T> Hash for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Writes each bit of the `BitVec`, as a full `bool`, into the hasher.
fn hash<H>(&self, hasher: &mut H)
where H: Hasher {
<crate::BitSlice<C, T> as Hash>::hash(&self, hasher)
}
}
/// Extends a `BitVec` with the contents of another bitstream.
///
/// At present, this just calls `.push()` in a loop. When specialization becomes
/// available, it will be able to more intelligently perform bulk moves from the
/// source into `self` when the source is `BitSlice`-compatible.
impl<C, T> Extend<bool> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Extends a `BitVec` from another bitstream.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv = bitvec![0; 4];
/// bv.extend(bitvec![1; 4]);
/// assert_eq!("00001111", &format!("{}", bv));
/// ```
fn extend<I>(&mut self, src: I)
where I: IntoIterator<Item=bool> {
let iter = src.into_iter();
match iter.size_hint() {
(_, Some(hi)) => self.reserve(hi),
(lo, None) => self.reserve(lo),
}
for bit in iter {
self.push(bit);
}
self.shrink_to_fit();
}
}
/// Permits the construction of a `BitVec` by using `.collect()` on an iterator
/// of `bool`.
impl<C, T> FromIterator<bool> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Collects an iterator of `bool` into a vector.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// use std::iter::repeat;
/// let bv: BitVec = repeat(true).take(4).chain(repeat(false).take(4)).collect();
/// assert_eq!("11110000", &format!("{}", bv));
/// ```
fn from_iter<I: IntoIterator<Item=bool>>(src: I) -> Self {
let iter = src.into_iter();
let mut out = match iter.size_hint() {
(_, Some(len)) |
(len, _) if len > 0 => Self::with_capacity(len),
_ => Self::new(),
};
for bit in iter {
out.push(bit);
}
out
}
}
/// Produces an iterator over all the bits in the vector.
///
/// This iterator follows the ordering in the vector type, and implements
/// `ExactSizeIterator`, since `BitVec`s always know exactly how large they are,
/// and `DoubleEndedIterator`, since they have known ends.
impl<C, T> IntoIterator for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
type Item = bool;
#[doc(hidden)]
type IntoIter = IntoIter<C, T>;
/// Iterates over the vector.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![BigEndian, u8; 1, 1, 1, 1, 0, 0, 0, 0];
/// let mut count = 0;
/// for bit in bv {
/// if bit { count += 1; }
/// }
/// assert_eq!(count, 4);
/// ```
fn into_iter(self) -> Self::IntoIter {
Self::IntoIter::from(self)
}
}
/// Adds two `BitVec`s together, zero-extending the shorter.
///
/// `BitVec` addition works just like adding numbers longhand on paper. The
/// first bits in the `BitVec` are the highest, so addition works from right to
/// left, and the shorter `BitVec` is assumed to be extended to the left with
/// zero.
///
/// The output `BitVec` may be one bit longer than the longer input, if addition
/// overflowed.
///
/// Numeric arithmetic is provided on `BitVec` as a convenience. Serious numeric
/// computation on variable-length integers should use the `num_bigint` crate
/// instead, which is written specifically for that use case. `BitVec`s are not
/// intended for arithmetic, and `bitvec` makes no guarantees about sustained
/// correctness in arithmetic at this time.
impl<C, T> Add for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
type Output = Self;
/// Adds two `BitVec`s.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let a = bitvec![0, 1, 0, 1];
/// let b = bitvec![0, 0, 1, 1];
/// let s = a + b;
/// assert_eq!(bitvec![1, 0, 0, 0], s);
/// ```
///
/// This example demonstrates the addition of differently-sized `BitVec`s,
/// and will overflow.
///
/// ```rust
/// use bitvec::*;
/// let a = bitvec![1; 4];
/// let b = bitvec![1; 1];
/// let s = b + a;
/// assert_eq!(bitvec![1, 0, 0, 0, 0], s);
/// ```
fn add(mut self, addend: Self) -> Self::Output {
self += addend;
self
}
}
/// Adds another `BitVec` into `self`, zero-extending the shorter.
///
/// `BitVec` addition works just like adding numbers longhand on paper. The
/// first bits in the `BitVec` are the highest, so addition works from right to
/// left, and the shorter `BitVec` is assumed to be extended to the left with
/// zero.
///
/// The output `BitVec` may be one bit longer than the longer input, if addition
/// overflowed.
///
/// Numeric arithmetic is provided on `BitVec` as a convenience. Serious numeric
/// computation on variable-length integers should use the `num_bigint` crate
/// instead, which is written specifically for that use case. `BitVec`s are not
/// intended for arithmetic, and `bitvec` makes no guarantees about sustained
/// correctness in arithmetic at this time.
impl<C, T> AddAssign for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Adds another `BitVec` into `self`.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut a = bitvec![1, 0, 0, 1];
/// let b = bitvec![0, 1, 1, 1];
/// a += b;
/// assert_eq!(a, bitvec![1, 0, 0, 0, 0]);
/// ```
fn add_assign(&mut self, mut addend: Self) {
use core::iter::repeat;
// If the other vec is longer, swap them and try again.
if addend.len() > self.len() {
mem::swap(self, &mut addend);
return *self += addend;
}
// Now that self.len() >= addend.len(), proceed with addition.
//
// I don't, at this time, want to implement a carry-lookahead adder in
// software, so this is going to be a plain ripple-carry adder with
// O(n) runtime. Furthermore, until I think of an optimization
// strategy, it is going to build up another bitvec to use as a stack.
//
// Computers are fast. Whatever.
let mut c = false;
let mut stack = BitVec::<C, T>::with_capacity(self.len());
// Reverse self, reverse addend and zero-extend, and zip both together.
// This walks both vecs from rightmost to leftmost, and considers an
// early expiration of addend to continue with 0 bits.
//
// 100111
// + 0010
// ^^---- semantically zero
for (a, b) in self.iter().rev().zip(addend.into_iter().rev().chain(repeat(false))) {
// Addition is a finite state machine that can be precomputed into
// a single jump table rather than requiring more complex
// branching. The table is indexed as (carry, a, b) and returns
// (bit, carry).
static JUMP: [u8; 8] = [
0, // 0 + 0 + 0 => (0, 0)
2, // 0 + 1 + 0 => (1, 0)
2, // 1 + 0 + 0 => (1, 0)
1, // 1 + 1 + 1 => (0, 1)
2, // 0 + 0 + 1 => (1, 0)
1, // 0 + 1 + 0 => (0, 1)
1, // 1 + 0 + 0 => (0, 1)
3, // 1 + 1 + 1 => (1, 1)
];
let idx = ((c as u8) << 2) | ((a as u8) << 1) | (b as u8);
let yz = JUMP[idx as usize];
let (y, z) = (yz & 2 != 0, yz & 1 != 0);
// Note: I checked in Godbolt, and the above comes out to ten
// simple instructions with the JUMP baked in as immediate values.
// The more semantically clear match statement does not optimize
// nearly as well.
stack.push(y);
c = z;
}
// If the carry made it to the end, push it.
if c {
stack.push(true);
}
// Unwind the stack into `self`.
self.clear();
while let Some(bit) = stack.pop() {
self.push(bit);
}
}
}
/// Performs the Boolean `AND` operation between each element of a `BitVec` and
/// anything that can provide a stream of `bool` values (such as another
/// `BitVec`, or any `bool` generator of your choice). The `BitVec` emitted will
/// have the length of the shorter sequence of bits -- if one is longer than the
/// other, the extra bits will be ignored.
impl<C, T, I> BitAnd<I> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits, I: IntoIterator<Item=bool> {
type Output = Self;
/// `AND`s a vector and a bitstream, producing a new vector.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let lhs = bitvec![BigEndian, u8; 0, 1, 0, 1];
/// let rhs = bitvec![BigEndian, u8; 0, 0, 1, 1];
/// let and = lhs & rhs;
/// assert_eq!("0001", &format!("{}", and));
/// ```
fn bitand(mut self, rhs: I) -> Self::Output {
self &= rhs;
self
}
}
/// Performs the Boolean `AND` operation in place on a `BitVec`, using a stream
/// of `bool` values as the other bit for each operation. If the other stream is
/// shorter than `self`, `self` will be truncated when the other stream expires.
impl<C, T, I> BitAndAssign<I> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits, I: IntoIterator<Item=bool> {
/// `AND`s another bitstream into a vector.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut src = bitvec![BigEndian, u8; 0, 1, 0, 1];
/// src &= bitvec![BigEndian, u8; 0, 0, 1, 1];
/// assert_eq!("0001", &format!("{}", src));
/// ```
fn bitand_assign(&mut self, rhs: I) {
let mut len = 0;
for (idx, other) in (0 .. self.len()).zip(rhs.into_iter()) {
let val = self.get(idx) & other;
self.set(idx, val);
len += 1;
}
self.truncate(len);
}
}
/// Performs the Boolean `OR` operation between each element of a `BitVec` and
/// anything that can provide a stream of `bool` values (such as another
/// `BitVec`, or any `bool` generator of your choice). The `BitVec` emitted will
/// have the length of the shorter sequence of bits -- if one is longer than the
/// other, the extra bits will be ignored.
impl<C, T, I> BitOr<I> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits, I: IntoIterator<Item=bool> {
type Output = Self;
/// `OR`s a vector and a bitstream, producing a new vector.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let lhs = bitvec![0, 1, 0, 1];
/// let rhs = bitvec![0, 0, 1, 1];
/// let or = lhs | rhs;
/// assert_eq!("0111", &format!("{}", or));
/// ```
fn bitor(mut self, rhs: I) -> Self::Output {
self |= rhs;
self
}
}
/// Performs the Boolean `OR` operation in place on a `BitVec`, using a stream
/// of `bool` values as the other bit for each operation. If the other stream is
/// shorter than `self`, `self` will be truncated when the other stream expires.
impl<C, T, I> BitOrAssign<I> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits, I: IntoIterator<Item=bool> {
/// `OR`s another bitstream into a vector.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut src = bitvec![0, 1, 0, 1];
/// src |= bitvec![0, 0, 1, 1];
/// assert_eq!("0111", &format!("{}", src));
/// ```
fn bitor_assign(&mut self, rhs: I) {
let mut len = 0;
for (idx, other) in (0 .. self.len()).zip(rhs.into_iter()) {
let val = self.get(idx) | other;
self.set(idx, val);
len += 1;
}
self.truncate(len);
}
}
/// Performs the Boolean `XOR` operation between each element of a `BitVec` and
/// anything that can provide a stream of `bool` values (such as another
/// `BitVec`, or any `bool` generator of your choice). The `BitVec` emitted will
/// have the length of the shorter sequence of bits -- if one is longer than the
/// other, the extra bits will be ignored.
impl<C, T, I> BitXor<I> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits, I: IntoIterator<Item=bool> {
type Output = Self;
/// `XOR`s a vector and a bitstream, producing a new vector.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let lhs = bitvec![0, 1, 0, 1];
/// let rhs = bitvec![0, 0, 1, 1];
/// let xor = lhs ^ rhs;
/// assert_eq!("0110", &format!("{}", xor));
/// ```
fn bitxor(mut self, rhs: I) -> Self::Output {
self ^= rhs;
self
}
}
/// Performs the Boolean `XOR` operation in place on a `BitVec`, using a stream
/// of `bool` values as the other bit for each operation. If the other stream is
/// shorter than `self`, `self` will be truncated when the other stream expires.
impl<C, T, I> BitXorAssign<I> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits, I: IntoIterator<Item=bool> {
/// `XOR`s another bitstream into a vector.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut src = bitvec![0, 1, 0, 1];
/// src ^= bitvec![0, 0, 1, 1];
/// assert_eq!("0110", &format!("{}", src));
/// ```
fn bitxor_assign(&mut self, rhs: I) {
let mut len = 0;
for (idx, other) in (0 .. self.len()).zip(rhs.into_iter()) {
let val = self.get(idx) ^ other;
self.set(idx, val);
len += 1;
}
self.truncate(len);
}
}
/// Reborrows the `BitVec` as a `BitSlice`.
///
/// This mimics the separation between `Vec<T>` and `[T]`.
impl<C, T> Deref for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
type Target = crate::BitSlice<C, T>;
/// Dereferences `&BitVec` down to `&BitSlice`.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv: BitVec = bitvec![1; 4];
/// let bref: &BitSlice = &bv;
/// assert!(bref.get(2));
/// ```
fn deref(&self) -> &Self::Target {
// `BitVec`'s representation of its inner `Vec` matches exactly the
// invariants of how `BitSlice` references must look. This is fine.
unsafe { mem::transmute(&self.inner as &[T]) }
}
}
/// Mutably reborrows the `BitVec` as a `BitSlice`.
///
/// This mimics the separation between `Vec<T>` and `[T]`.
impl<C, T> DerefMut for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Dereferences `&mut BitVec` down to `&mut BitSlice`.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv: BitVec = bitvec![0; 6];
/// let bref: &mut BitSlice = &mut bv;
/// assert!(!bref.get(5));
/// bref.set(5, true);
/// assert!(bref.get(5));
/// ```
fn deref_mut(&mut self) -> &mut Self::Target {
unsafe { mem::transmute(&mut self.inner as &mut [T]) }
}
}
/// Readies the underlying storage for Drop.
impl<C, T> Drop for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Restore the interior `Vec` to sane condition before it drops.
fn drop(&mut self) {
// The only modification `BitVec` makes to the inner `Vec` is the
// length. Strictly speaking, this does not need to be restored before
// drop, but it’s good to be proactive.
let raw = self.raw_len();
unsafe { self.inner.set_len(raw); }
}
}
/// Gets the bit at a specific index. The index must be less than the length of
/// the `BitVec`.
impl<C, T> Index<usize> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
type Output = bool;
/// Looks up a single bit by semantic count.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![BigEndian, u8; 0, 0, 0, 0, 0, 0, 0, 0, 1, 0];
/// assert!(!bv[7]); // ---------------------------------^ | |
/// assert!( bv[8]); // ------------------------------------^ |
/// assert!(!bv[9]); // ---------------------------------------^
/// ```
///
/// If the index is greater than or equal to the length, indexing will
/// panic.
///
/// The below test will panic when accessing index 1, as only index 0 is
/// valid.
///
/// ```rust,should_panic
/// use bitvec::*;
/// let mut bv: BitVec = BitVec::new();
/// bv.push(true);
/// bv[1];
/// ```
fn index(&self, cursor: usize) -> &Self::Output {
assert!(cursor < self.len(), "Index out of range!");
let (elt, bit) = T::split(cursor);
if (self.inner[elt]).get(C::curr::<T>(bit)) { &true } else { &false }
}
}
/// Gets the bit in a specific element. The element index must be less than or
/// equal to the value returned by `elts()`, and the bit index must be less
/// than the width of the storage type.
///
/// If the `BitVec` has a partially-filled tail, then the value returned by
/// `elts()` is a valid index.
///
/// The element and bit indices are combined using `Bits::join` for the storage
/// type.
///
/// This index is not recommended for public use.
impl<C, T> Index<(usize, u8)> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
type Output = bool;
/// Indexes into a `BitVec` using a known element index and a count into
/// that element. The count must not be converted for endianness outside the
/// call.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![BigEndian, u8; 1, 1, 1, 1, 0, 0, 0, 0, 0, 1];
/// assert!(bv[(1, 1)]); // -----------------------------------^
/// ```
fn index(&self, (elt, bit): (usize, u8)) -> &Self::Output {
assert!(T::join(elt, bit) < self.len(), "Index out of range!");
if (self.inner[elt]).get(C::curr::<T>(bit)) { &true } else { &false }
}
}
/// 2’s-complement negation of a `BitVec`.
///
/// In 2’s-complement, negation is defined as bit-inversion followed by adding
/// one.
///
/// Numeric arithmetic is provided on `BitVec` as a convenience. Serious numeric
/// computation on variable-length integers should use the `num_bigint` crate
/// instead, which is written specifically for that use case. `BitVec`s are not
/// intended for arithmetic, and `bitvec` makes no guarantees about sustained
/// correctness in arithmetic at this time.
impl<C, T> Neg for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
type Output = Self;
/// Numerically negates a `BitVec` using 2’s-complement arithmetic.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![0, 1, 1];
/// let ne = -bv;
/// assert_eq!("101", &format!("{}", ne));
/// ```
fn neg(mut self) -> Self::Output {
// An empty vector does nothing.
// Negative zero is zero. Without this check, -[0+] becomes[10+1].
if self.is_empty() || self.not_any() {
return self;
}
self = !self;
self += BitVec::<C, T>::from(&[true] as &[bool]);
self
}
}
/// Flips all bits in the vector.
///
/// This invokes the `!` operator on each element of the borrowed storage, and
/// so it will also flip bits in the tail that are outside the `BitVec` length
/// if any. Use `^= repeat(true)` to flip only the bits actually inside the
/// `BitVec` purview. `^=` also has the advantage of being a borrowing operator
/// rather than a consuming/returning operator.
impl<C, T> Not for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
type Output = Self;
/// Inverts all bits in the vector.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv: BitVec<BigEndian, u32> = BitVec::from(&[0u32] as &[u32]);
/// let flip = !bv;
/// assert_eq!(!0u32, flip.as_ref()[0]);
/// ```
// Because self does not have to interact with any other `BitVec`, and bits
// beyond `BitVec.len()` are uninitialized and don't matter, this is free
// to simply negate the elements in place and then return self.
fn not(mut self) -> Self::Output {
// ignore the returned reference
let _ = !(&mut *self);
self
}
}
__bitvec_shift!(u8, u16, u32, u64, i8, i16, i32, i64);
/// Shifts all bits in the vector to the left – **DOWN AND TOWARDS THE FRONT**.
///
/// On primitives, the left-shift operator `<<` moves bits away from origin and
/// towards the ceiling. This is because we label the bits in a primitive with
/// the minimum on the right and the maximum on the left, which is big-endian
/// bit order. This increases the value of the primitive being shifted.
///
/// **THAT IS NOT HOW `BITVEC` WORKS!**
///
/// `BitVec` defines its layout with the minimum on the left and the maximum on
/// the right! Thus, left-shifting moves bits towards the **minimum**.
///
/// In BigEndian order, the effect in memory will be what you expect the `<<`
/// operator to do.
///
/// **In LittleEndian order, the effect will be equivalent to using `>>` on**
/// **the primitives in memory!**
///
/// # Notes
///
/// In order to preserve the effects in memory that this operator traditionally
/// expects, the bits that are emptied by this operation are zeroed rather than
/// left to their old value.
///
/// The length of the vector is decreased by the shift amount.
///
/// If the shift amount is greater than the length, the vector calls `clear()`
/// and zeroes its memory. This is *not* an error.
impl<C, T> Shl<usize> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
type Output = Self;
/// Shifts a `BitVec` to the left, shortening it.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![BigEndian, u8; 0, 0, 0, 1, 1, 1];
/// assert_eq!("000111", &format!("{}", bv));
/// assert_eq!(0b0001_1100, bv.as_ref()[0]);
/// assert_eq!(bv.len(), 6);
/// let ls = bv << 2usize;
/// assert_eq!("0111", &format!("{}", ls));
/// assert_eq!(0b0111_0000, ls.as_ref()[0]);
/// assert_eq!(ls.len(), 4);
/// ```
fn shl(mut self, shamt: usize) -> Self::Output {
self <<= shamt;
self
}
}
/// Shifts all bits in the vector to the left – **DOWN AND TOWARDS THE FRONT**.
///
/// On primitives, the left-shift operator `<<` moves bits away from origin and
/// towards the ceiling. This is because we label the bits in a primitive with
/// the minimum on the right and the maximum on the left, which is big-endian
/// bit order. This increases the value of the primitive being shifted.
///
/// **THAT IS NOT HOW `BITVEC` WORKS!**
///
/// `BitVec` defines its layout with the minimum on the left and the maximum on
/// the right! Thus, left-shifting moves bits towards the **minimum**.
///
/// In BigEndian order, the effect in memory will be what you expect the `<<`
/// operator to do.
///
/// **In LittleEndian order, the effect will be equivalent to using `>>` on**
/// **the primitives in memory!**
///
/// # Notes
///
/// In order to preserve the effects in memory that this operator traditionally
/// expects, the bits that are emptied by this operation are zeroed rather than
/// left to their old value.
///
/// The length of the vector is decreased by the shift amount.
///
/// If the shift amount is greater than the length, the vector calls `clear()`
/// and zeroes its memory. This is *not* an error.
impl<C, T> ShlAssign<usize> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Shifts a `BitVec` to the left in place, shortening it.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv = bitvec![LittleEndian, u8; 0, 0, 0, 1, 1, 1];
/// assert_eq!("000111", &format!("{}", bv));
/// assert_eq!(0b0011_1000, bv.as_ref()[0]);
/// assert_eq!(bv.len(), 6);
/// bv <<= 2;
/// assert_eq!("0111", &format!("{}", bv));
/// assert_eq!(0b0000_1110, bv.as_ref()[0]);
/// assert_eq!(bv.len(), 4);
/// ```
fn shl_assign(&mut self, shamt: usize) {
let len = self.len();
if shamt >= len {
self.clear();
let buf = self.as_mut();
let ptr = buf.as_mut_ptr();
let len = buf.len();
unsafe { core::ptr::write_bytes(ptr, 0, len); }
return;
}
for idx in shamt .. len {
let val = self.get(idx);
self.set(idx - shamt, val);
}
let trunc = len - shamt;
for idx in trunc .. len {
self.set(idx, false);
}
self.truncate(trunc);
}
}
/// Shifts all bits in the vector to the right – **UP AND TOWARDS THE BACK**.
///
/// On primitives, the right-shift operator `>>` moves bits towards the origin
/// and away from the ceiling. This is because we label the bits in a primitive
/// with the minimum on the right and the maximum on the left, which is
/// big-endian bit order. This decreases the value of the primitive being
/// shifted.
///
/// **THAT IS NOT HOW `BITVEC` WORKS!**
///
/// `BitVec` defines its layout with the minimum on the left and the maximum on
/// the right! Thus, right-shifting moves bits towards the **maximum**.
///
/// In BigEndian order, the effect in memory will be what you expect the `>>`
/// operator to do.
///
/// **In LittleEndian order, the effect will be equivalent to using `<<` on**
/// **the primitives in memory!**
///
/// # Notes
///
/// In order to preserve the effects in memory that this operator traditionally
/// expects, the bits that are emptied by this operation are zeroed rather than
/// left to their old value.
///
/// The length of the vector is increased by the shift amount.
///
/// If the new length of the vector would overflow, a panic occurs. This *is* an
/// error.
impl<C, T> Shr<usize> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
type Output = Self;
/// Shifts a `BitVec` to the right, lengthening it and filling the front
/// with 0.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![BigEndian, u8; 0, 0, 0, 1, 1, 1];
/// assert_eq!("000111", &format!("{}", bv));
/// assert_eq!(0b0001_1100, bv.as_ref()[0]);
/// assert_eq!(bv.len(), 6);
/// let rs = bv >> 2usize;
/// assert_eq!("00000111", &format!("{}", rs));
/// assert_eq!(0b0000_0111, rs.as_ref()[0]);
/// assert_eq!(rs.len(), 8);
/// ```
fn shr(mut self, shamt: usize) -> Self::Output {
self >>= shamt;
self
}
}
/// Shifts all bits in the vector to the right – **UP AND TOWARDS THE BACK**.
///
/// On primitives, the right-shift operator `>>` moves bits towards the origin
/// and away from the ceiling. This is because we label the bits in a primitive
/// with the minimum on the right and the maximum on the left, which is
/// big-endian bit order. This decreases the value of the primitive being
/// shifted.
///
/// **THAT IS NOT HOW `BITVEC` WORKS!**
///
/// `BitVec` defines its layout with the minimum on the left and the maximum on
/// the right! Thus, right-shifting moves bits towards the **maximum**.
///
/// In BigEndian order, the effect in memory will be what you expect the `>>`
/// operator to do.
///
/// **In LittleEndian order, the effect will be equivalent to using `<<` on**
/// **the primitives in memory!**
///
/// # Notes
///
/// In order to preserve the effects in memory that this operator traditionally
/// expects, the bits that are emptied by this operation are zeroed rather than
/// left to their old value.
///
/// The length of the vector is increased by the shift amount.
///
/// If the new length of the vector would overflow, a panic occurs. This *is* an
/// error.
impl<C, T> ShrAssign<usize> for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Shifts a `BitVec` to the right in place, lengthening it and filling the
/// front with 0.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let mut bv = bitvec![LittleEndian, u8; 0, 0, 0, 1, 1, 1];
/// assert_eq!("000111", &format!("{}", bv));
/// assert_eq!(0b0011_1000, bv.as_ref()[0]);
/// assert_eq!(bv.len(), 6);
/// bv >>= 2;
/// assert_eq!("00000111", &format!("{}", bv));
/// assert_eq!(0b1110_0000, bv.as_ref()[0]);
/// assert_eq!(bv.len(), 8);
/// ```
fn shr_assign(&mut self, shamt: usize) {
let old_len = self.len();
for _ in 0 .. shamt {
self.push(false);
}
for idx in (0 .. old_len).rev() {
let val = self.get(idx);
self.set(idx + shamt, val);
}
for idx in 0 .. shamt {
self.set(idx, false);
}
}
}
/// Subtracts one `BitVec` from another assuming 2’s-complement encoding.
///
/// Subtraction is a more complex operation than addition. The bit-level work is
/// largely the same, but semantic distinctions must be made. Unlike addition,
/// which is commutative and tolerant of switching the order of the addends,
/// subtraction cannot swap the minuend (LHS) and subtrahend (RHS).
///
/// Because of the properties of 2’s-complement arithmetic, M - S is equivalent
/// to M + (!S + 1). Subtraction therefore bitflips the subtrahend and adds one.
/// This may, in a degenerate case, cause the subtrahend to increase in length.
///
/// Once the subtrahend is stable, the minuend zero-extends its left side in
/// order to match the length of the subtrahend if needed (this is provided by
/// the `>>` operator).
///
/// When the minuend is stable, the minuend and subtrahend are added together
/// by the `<BitVec as Add>` implementation. The output will be encoded in
/// 2’s-complement, so a leading one means that the output is considered
/// negative.
///
/// Interpreting the contents of a `BitVec` as an integer is beyond the scope of
/// this crate.
///
/// Numeric arithmetic is provided on `BitVec` as a convenience. Serious numeric
/// computation on variable-length integers should use the `num_bigint` crate
/// instead, which is written specifically for that use case. `BitVec`s are not
/// intended for arithmetic, and `bitvec` makes no guarantees about sustained
/// correctness in arithmetic at this time.
impl<C, T> Sub for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
type Output = Self;
/// Subtracts one `BitVec` from another.
///
/// # Examples
///
/// Minuend larger than subtrahend, positive difference.
///
/// ```rust
/// use bitvec::*;
/// let a = bitvec![1, 0];
/// let b = bitvec![ 1];
/// let c = a - b;
/// assert_eq!(bitvec![0, 1], c);
/// ```
///
/// Minuend smaller than subtrahend, negative difference.
///
/// ```rust
/// use bitvec::*;
/// let a = bitvec![ 1];
/// let b = bitvec![1, 0];
/// let c = a - b;
/// assert_eq!(bitvec![1, 1], c);
/// ```
///
/// Subtraction from self is correctly handled.
///
/// ```rust
/// use bitvec::*;
/// let a = bitvec![1; 4];
/// let b = a.clone();
/// let c = a - b;
/// assert!(c.not_any(), "{:?}", c);
/// ```
fn sub(mut self, subtrahend: Self) -> Self::Output {
self -= subtrahend;
self
}
}
/// Subtracts another `BitVec` from `self`, assuming 2’s-complement encoding.
///
/// The minuend is zero-extended, or the subtrahend sign-extended, as needed to
/// ensure that the vectors are the same width before subtraction occurs.
///
/// The `Sub` trait has more documentation on the subtraction process.
///
/// Numeric arithmetic is provided on `BitVec` as a convenience. Serious numeric
/// computation on variable-length integers should use the `num_bigint` crate
/// instead, which is written specifically for that use case. `BitVec`s are not
/// intended for arithmetic, and `bitvec` makes no guarantees about sustained
/// correctness in arithmetic at this time.
impl<C, T> SubAssign for BitVec<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Subtracts another `BitVec` from `self`.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let a = bitvec![0, 0, 0, 1];
/// let b = bitvec![0, 0, 0, 0];
/// let c = a - b;
/// assert_eq!(c, bitvec![0, 0, 0, 1]);
/// ```
fn sub_assign(&mut self, mut subtrahend: Self) {
// Test for a zero subtrahend. Subtraction of zero is the identity
// function, and can exit immediately.
if subtrahend.not_any() {
return;
}
// Invert the subtrahend in preparation for addition
subtrahend = -subtrahend;
let (llen, rlen) = (self.len(), subtrahend.len());
// If the subtrahend is longer than the minuend, 0-extend the minuend.
if rlen > llen {
let diff = rlen - llen;
*self >>= diff;
*self += subtrahend;
}
else {
// If the minuend is longer than the subtrahend, 1-extend the
// subtrahend.
if llen > rlen {
let diff = llen - rlen;
let sign = subtrahend.get(0);
subtrahend >>= diff;
// Implementing BitVec >> (usize, bool) would permit sign
// extension in fewer steps.
for idx in 0 .. diff {
subtrahend.set(idx, sign);
}
}
let old = self.len();
*self += subtrahend;
// If the subtraction emitted a carry, remove it.
if self.len() > old {
*self <<= 1;
}
}
}
}
/// Iterates over an owned `BitVec`.
#[doc(hidden)]
pub struct IntoIter<C, T>
where C: crate::Cursor, T: crate::Bits {
bv: BitVec<C, T>,
head: usize,
tail: usize,
}
impl<C, T> IntoIter<C, T>
where C: crate::Cursor, T: crate::Bits {
fn new(bv: BitVec<C, T>) -> Self {
let tail = bv.len();
Self {
bv,
head: 0,
tail,
}
}
fn reset(&mut self) {
self.head = 0;
self.tail = self.bv.len();
}
}
impl<C, T> DoubleEndedIterator for IntoIter<C, T>
where C: crate::Cursor, T: crate::Bits {
/// Yields the back-most bit of the collection.
///
/// This iterator is self-resetting; when the cursor reaches the front of
/// the collection, it returns None after setting the cursor to the length
/// of the underlying collection. If the collection is not empty when this
/// occurs, then the iterator will resume at the back if called again.
fn next_back(&mut self) -> Option<Self::Item> {
if self.tail > self.head && self.tail <= self.bv.len() {
self.tail -= 1;
Some(self.bv[self.tail])
}
else {
self.reset();
None
}
}
}
impl<C, T> ExactSizeIterator for IntoIter<C, T>
where C: crate::Cursor, T: crate::Bits {
// Override the default implementation with a fixed calculation. The type
// is guaranteed to be well-behaved, so there is no point in building two
// copies of the remnant, checking an always-safe condition, and dropping
// one.
//
// THIS IS A LOAD BEARING OVERRIDE! IF IT IS REMOVED, THEN
// Iterator::size_hint MUST BE CHANGED TO NOT CALL THIS FUNCTION, BECAUSE
// THE DEFAULT IMPLEMENTATION CALLS Iterator::size_hint! FAILURE TO DO SO
// WILL RESULT IN A VALID COMPILE AND A BLOWN STACK AT RUNTIME DUE TO
// INFINITE MUTUAL RECURSION!
fn len(&self) -> usize {
self.tail - self.head
}
}
impl<C, T> From<BitVec<C, T>> for IntoIter<C, T>
where C: crate::Cursor, T: crate::Bits {
fn from(bv: BitVec<C, T>) -> Self {
Self::new(bv)
}
}
impl<C, T> Iterator for IntoIter<C, T>
where C: crate::Cursor, T: crate::Bits {
type Item = bool;
/// Advances the iterator forward, yielding the front-most bit.
///
/// This iterator is self-resetting: when the cursor reaches the back of the
/// collection, it returns None after setting the cursor to zero. If the
/// collection is not empty when this occurs, then the iterator will resume
/// at the front if called again.
fn next(&mut self) -> Option<Self::Item> {
if self.head < self.tail {
let ret = self.bv[self.head];
self.head += 1;
Some(ret)
}
else {
self.reset();
None
}
}
// Note that the default `ExactSizeIterator::len` calls this method, so
// removing that implementation will cause an infinite mutual recursion,
// only detectable *at runtime* when the stack blows.
//
// THIS METHOD MUST BE CHANGED TO NOT CALL `ExactSizeIterator::len` BEFORE
// REMOVING THE SPECIALIZATION FOR ESI! THE DEFAULT IMPLEMENTATION OF ESI
// CALLS THIS FUNCTION, WHICH WILL COMPILE CLEANLY AND THEN BLOW THE STACK
// AT RUNTIME DUE TO INFINITE MUTUAL RECURSION!
fn size_hint(&self) -> (usize, Option<usize>) {
let rem = ExactSizeIterator::len(self);
(rem, Some(rem))
}
/// Counts how many bits are live in the iterator, consuming it.
///
/// You are probably looking to use this on a borrowed iterator rather than
/// an owning iterator. See `BitSlice`.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![BigEndian, u8; 0, 1, 0, 1, 0];
/// assert_eq!(bv.into_iter().count(), 5);
/// ```
fn count(self) -> usize {
ExactSizeIterator::len(&self)
}
/// Advances the iterator by `n` bits, starting from zero.
///
/// It is not an error to advance past the end of the iterator! Doing so
/// returns `None`, and resets the iterator to its beginning.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![BigEndian, u8; 0, 0, 0, 1];
/// let mut bv_iter = bv.into_iter();
/// assert_eq!(bv_iter.len(), 4);
/// assert!(bv_iter.nth(3).unwrap());
/// ```
///
/// This example intentionally overshoots the iterator bounds, which causes
/// a reset to the initial state. It then demonstrates that `nth` is
/// stateful, and is not an absolute index, by seeking ahead by two (to the
/// third zero bit) and then taking the bit immediately after it, which is
/// set. This shows that the argument to `nth` is how many bits to discard
/// before yielding the next.
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![BigEndian, u8; 0, 0, 0, 1];
/// let mut bv_iter = bv.into_iter();
/// assert!(bv_iter.nth(4).is_none());
/// assert!(!bv_iter.nth(2).unwrap());
/// assert!(bv_iter.nth(0).unwrap());
/// ```
fn nth(&mut self, n: usize) -> Option<bool> {
self.head = self.head.saturating_add(n);
self.next()
}
/// Consumes the iterator, returning only the last bit.
///
/// # Examples
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![BigEndian, u8; 0, 0, 0, 1];
/// assert!(bv.into_iter().last().unwrap());
/// ```
///
/// Empty iterators return `None`
///
/// ```rust
/// use bitvec::*;
/// let bv = bitvec![];
/// assert!(bv.into_iter().last().is_none());
/// ```
fn last(mut self) -> Option<bool> {
self.next_back()
}
}