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use super::{ BitSlice, Bits, Endian, BigEndian, LittleEndian, TRUE, FALSE, }; use std::borrow::{ Borrow, BorrowMut, }; use std::clone::Clone; use std::cmp::{ Eq, Ord, Ordering, PartialEq, PartialOrd, }; use std::convert::{ AsMut, AsRef, From, }; use std::fmt::{ self, Debug, Display, Formatter, }; use std::iter::{ DoubleEndedIterator, ExactSizeIterator, Extend, FromIterator, Iterator, IntoIterator, }; use std::marker::PhantomData; use std::mem; use std::ops::{ BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Deref, DerefMut, Index, Not, Shl, ShlAssign, Shr, ShrAssign, }; use std::ptr; /** 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 **wildly** 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. - `E: Endian` must be an implementor of the `Endian` 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. **/ pub struct BitVec<E = BigEndian, T = u8> where E: Endian, T: Bits { inner: Vec<T>, _endian: PhantomData<E>, } impl<E, T> BitVec<E, T> where E: Endian, T: Bits { /// Construct a new, empty, `BitVec<E, 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 { inner: Vec::new(), _endian: PhantomData, } } /// Construct 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), _endian: PhantomData, } } /// Return 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 } /// Append 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() < ::std::usize::MAX, "Vector will overflow!"); let bit = self.bits(); // Get a cursor to the bit that matches the semantic count. let cursor = E::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); } } /// Remove 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) } /// Empty 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(|v| v.clear()); } /// Reserve 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)); } /// Shrink 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(|v| v.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); } } /// Convert 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() } /// Set 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); } /// Set 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)); } /// Set the length directly. pub(crate) unsafe fn set_len(&mut self, len: usize) { self.inner.set_len(len); } /// Execute 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 } /// Execute 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 } } /// Push 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(Default::default())); unsafe { self.inner.set_len(len); } } /// Format 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<{}, {}>", E::TY, T::TY) } } /// Give write access to all live elements in the underlying storage, including /// the partially-filled tail. impl<E, T> AsMut<[T]> for BitVec<E, T> where E: Endian, T: Bits { /// Access 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] { BitSlice::as_mut(self) } } /// Give read access to all live elements in the underlying storage, including /// the partially-filled tail. impl<E, T> AsRef<[T]> for BitVec<E, T> where E: Endian, T: Bits { /// Access 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] { BitSlice::as_ref(self) } } /// Perform 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<E, T, I> BitAnd<I> for BitVec<E, T> where E: Endian, T: Bits, I: IntoIterator<Item=bool> { type Output = Self; /// AND 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 } } /// Perform 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<E, T, I> BitAndAssign<I> for BitVec<E, T> where E: Endian, T: Bits, I: IntoIterator<Item=bool> { /// AND 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); } } /// Perform 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<E, T, I> BitOr<I> for BitVec<E, T> where E: Endian, T: Bits, I: IntoIterator<Item=bool> { type Output = Self; /// OR 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 or = lhs | rhs; /// assert_eq!("0111", &format!("{}", or)); /// ``` fn bitor(mut self, rhs: I) -> Self::Output { self |= rhs; self } } /// Perform 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<E, T, I> BitOrAssign<I> for BitVec<E, T> where E: Endian, T: Bits, I: IntoIterator<Item=bool> { /// OR 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!("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); } } /// Perform 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<E, T, I> BitXor<I> for BitVec<E, T> where E: Endian, T: Bits, I: IntoIterator<Item=bool> { type Output = Self; /// XOR 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 xor = lhs ^ rhs; /// assert_eq!("0110", &format!("{}", xor)); /// ``` fn bitxor(mut self, rhs: I) -> Self::Output { self ^= rhs; self } } /// Perform 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<E, T, I> BitXorAssign<I> for BitVec<E, T> where E: Endian, T: Bits, I: IntoIterator<Item=bool> { /// XOR 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!("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); } } /// Signify that `BitSlice` is the borrowed form of `BitVec`. impl<E, T> Borrow<BitSlice<E, T>> for BitVec<E, T> where E: Endian, T: Bits { /// Borrow 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) -> &BitSlice<E, T> { &*self } } /// Signify that `BitSlice` is the borrowed form of `BitVec`. impl<E, T> BorrowMut<BitSlice<E, T>> for BitVec<E, T> where E: Endian, T: Bits { /// Mutably borow 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 BitSlice<E, T> { &mut *self } } impl<E, T> Clone for BitVec<E, T> where E: Endian, T: 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); } } } /// Print the `BitVec` for debugging. /// /// The output is of the form `BitVec<E, T> [ELT, *]`, where `<E, 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<E, T> Debug for BitVec<E, T> where E: Endian, T: Bits { /// Render 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)?; } self.fmt_body(fmt, true)?; if alt { writeln!(fmt)?; } fmt.write_str("]") } } /// Reborrow the `BitVec` as a `BitSlice`. /// /// This mimics the separation between `Vec<T>` and `[T]`. impl<E, T> Deref for BitVec<E, T> where E: Endian, T: Bits { type Target = BitSlice<E, T>; /// Dereference `&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]) } } } /// Reborrow the `BitVec` as a `BitSlice`. /// /// This mimics the separation between `Vec<T>` and `[T]`. impl<E, T> DerefMut for BitVec<E, T> where E: Endian, T: Bits { /// Dereference `&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]) } } } /// Print 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<E, T> Display for BitVec<E, T> where E: Endian, T: Bits { /// Render 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) } } /// Ready the underlying storage for Drop. impl<E, T> Drop for BitVec<E, T> where E: Endian, T: Bits { fn drop(&mut self) { // If the `Vec` is non-empty, set the length to the number of used // elements as preparation for drop. The bits do not need to be wiped. // // If we don't do this, the `Vec` drop will treat the bit total as the // number of elements and try to loop through all of them, which will // not take 2 ** T::BITS times as long to run as expected, because // it'll segfault. let raw = self.raw_len(); unsafe { self.inner.set_len(raw); } } } /// Extend 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<E, T> Extend<bool> for BitVec<E, T> where E: Endian, T: Bits { /// Extend 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(); } } /// Clone 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, E, T> From<&'a BitSlice<E, T>> for BitVec<E, T> where E: Endian, T: 'a + Bits { fn from(src: &'a BitSlice<E, T>) -> Self { src.to_owned() } } /// Build a `BitVec` out of a slice of `bool`. /// /// This is primarily for the `bitvec!` macro; it is not recommended for general /// use. impl<'a, E, T> From<&'a [bool]> for BitVec<E, T> where E: Endian, T: 'a + Bits { fn from(src: &'a [bool]) -> Self { let mut out = Self::with_capacity(src.len()); for bit in src { out.push(*bit); } out } } /// Build 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, E, T> From<&'a [T]> for BitVec<E, T> where E: Endian, T: 'a + Bits { /// Build a `BitVec<E: Endian, 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 { <&BitSlice<E, T>>::from(src).to_owned() } } /// Build 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<E, T> From<Box<[T]>> for BitVec<E, T> where E: Endian, T: Bits { /// Consume a `Box<[T: Bits]>` and creates a `BitVec<E: Endian, 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)) } } /// Build 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<E, T> From<Vec<T>> for BitVec<E, T> where E: Endian, T: Bits { /// Consume a `Vec<T: Bits>` and creates a `BitVec<E: Endian, 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, _endian: PhantomData::<E>, }; unsafe { out.set_bits(0); out.set_elts(elts); } out } } /// Change 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: Bits> From<BitVec<LittleEndian, T>> for BitVec<BigEndian, T> { fn from(mut src: BitVec<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) } } } /// Change 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: Bits> From<BitVec<BigEndian, T>> for BitVec<LittleEndian, T> { fn from(mut src: BitVec<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) } } } /// Permit the construction of a `BitVec` by using `.collect()` on an iterator /// of `bool`. impl<E, T> FromIterator<bool> for BitVec<E, T> where E: Endian, T: Bits { /// Collect 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 } } /// Get the bit at a specific index. The index must be less than the length of /// the `BitVec`. impl<E, T> Index<usize> for BitVec<E, T> where E: Endian, T: Bits { type Output = bool; /// Look 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.inner.len(), "Index out of range!"); self.index(T::split(cursor)) } } /// Get 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<E, T> Index<(usize, u8)> for BitVec<E, T> where E: Endian, T: Bits { type Output = bool; /// Index 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!"); match (self.inner[elt]).get(E::curr::<T>(bit)) { true => &TRUE, false => &FALSE, } } } /// Produce 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<E, T> IntoIterator for BitVec<E, T> where E: Endian, T: Bits { type Item = bool; #[doc(hidden)] type IntoIter = IntoIter<E, T>; /// Iterate 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) } } /// Flip 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<E, T> Not for BitVec<E, T> where E: Endian, T: Bits { type Output = Self; /// Invert 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 { !&mut *self; self } } /// Test 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: Endian, B: Bits, C: Endian, D: Bits { /// Perform 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); /// ``` fn eq(&self, rhs: &BitVec<C, D>) -> bool { BitSlice::eq(&self, &rhs) } } impl<E, T> Eq for BitVec<E, T> where E: Endian, T: Bits {} /// Compare 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: Endian, B: Bits, C: Endian, D: Bits { /// Perform 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> { BitSlice::partial_cmp(&self, &rhs) } } impl<E, T> Ord for BitVec<E, T> where E: Endian, T: Bits { fn cmp(&self, rhs: &Self) -> Ordering { BitSlice::cmp(&self, &rhs) } } __bitvec_shift!(u8, u16, u32, u64, i8, i16, i32, i64); /// Shift 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<E, T> Shl<usize> for BitVec<E, T> where E: Endian, T: Bits { type Output = Self; /// Shift 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 } } /// Shift 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<E, T> ShlAssign<usize> for BitVec<E, T> where E: Endian, T: Bits { /// Shift 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 { ::std::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); } } /// Shift 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<E, T> Shr<usize> for BitVec<E, T> where E: Endian, T: Bits { type Output = Self; /// Shift 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 } } /// Shift 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<E, T> ShrAssign<usize> for BitVec<E, T> where E: Endian, T: Bits { /// Shift 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(); // Implement `Extend` to make this more efficient 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); } } } /// Iterate over an owned `BitVec`. #[doc(hidden)] pub struct IntoIter<E, T> where E: Endian, T: Bits { bv: BitVec<E, T>, head: usize, tail: usize, } impl<E, T> IntoIter<E, T> where E: Endian, T: Bits { fn new(bv: BitVec<E, T>) -> Self { let tail = bv.len(); Self { bv, head: 0, tail, } } fn reset(&mut self) { self.head = 0; self.tail = self.bv.len(); } } impl<E, T> DoubleEndedIterator for IntoIter<E, T> where E: Endian, T: Bits { /// Yield 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<E, T> ExactSizeIterator for IntoIter<E, T> where E: Endian, T: 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<E, T> From<BitVec<E, T>> for IntoIter<E, T> where E: Endian, T: Bits { fn from(bv: BitVec<E, T>) -> Self { Self::new(bv) } } impl<E, T> Iterator for IntoIter<E, T> where E: Endian, T: Bits { type Item = bool; /// Advance 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)) } /// Count 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) } /// Advance 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 initiol 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 += n; self.next() } /// Consume 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() } }