Adding upstream version 115.8.0esr.upstream/115.8.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2535 insertions, 0 deletions

diff --git a/third_party/rust/bit-vec/src/lib.rs b/third_party/rust/bit-vec/src/lib.rs
new file mode 100644
index 0000000000..5e6dcbaa49
--- /dev/null
+++ b/third_party/rust/bit-vec/src/lib.rs
@@ -0,0 +1,2535 @@
+// Copyright 2012-2020 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// FIXME(Gankro): BitVec and BitSet are very tightly coupled. Ideally (for
+// maintenance), they should be in separate files/modules, with BitSet only
+// using BitVec's public API. This will be hard for performance though, because
+// `BitVec` will not want to leak its internal representation while its internal
+// representation as `u32`s must be assumed for best performance.
+
+// (1) Be careful, most things can overflow here because the amount of bits in
+//     memory can overflow `usize`.
+// (2) Make sure that the underlying vector has no excess length:
+//     E. g. `nbits == 16`, `storage.len() == 2` would be excess length,
+//     because the last word isn't used at all. This is important because some
+//     methods rely on it (for *CORRECTNESS*).
+// (3) Make sure that the unused bits in the last word are zeroed out, again
+//     other methods rely on it for *CORRECTNESS*.
+// (4) `BitSet` is tightly coupled with `BitVec`, so any changes you make in
+// `BitVec` will need to be reflected in `BitSet`.
+
+//! Collections implemented with bit vectors.
+//!
+//! # Examples
+//!
+//! This is a simple example of the [Sieve of Eratosthenes][sieve]
+//! which calculates prime numbers up to a given limit.
+//!
+//! [sieve]: http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes
+//!
+//! ```
+//! use bit_vec::BitVec;
+//!
+//! let max_prime = 10000;
+//!
+//! // Store the primes as a BitVec
+//! let primes = {
+//!     // Assume all numbers are prime to begin, and then we
+//!     // cross off non-primes progressively
+//!     let mut bv = BitVec::from_elem(max_prime, true);
+//!
+//!     // Neither 0 nor 1 are prime
+//!     bv.set(0, false);
+//!     bv.set(1, false);
+//!
+//!     for i in 2.. 1 + (max_prime as f64).sqrt() as usize {
+//!         // if i is a prime
+//!         if bv[i] {
+//!             // Mark all multiples of i as non-prime (any multiples below i * i
+//!             // will have been marked as non-prime previously)
+//!             for j in i.. {
+//!                 if i * j >= max_prime {
+//!                     break;
+//!                 }
+//!                 bv.set(i * j, false)
+//!             }
+//!         }
+//!     }
+//!     bv
+//! };
+//!
+//! // Simple primality tests below our max bound
+//! let print_primes = 20;
+//! print!("The primes below {} are: ", print_primes);
+//! for x in 0..print_primes {
+//!     if primes.get(x).unwrap_or(false) {
+//!         print!("{} ", x);
+//!     }
+//! }
+//! println!();
+//!
+//! let num_primes = primes.iter().filter(|x| *x).count();
+//! println!("There are {} primes below {}", num_primes, max_prime);
+//! assert_eq!(num_primes, 1_229);
+//! ```
+
+#![doc(html_root_url = "https://docs.rs/bit-vec/0.6.3")]
+
+#![no_std]
+
+#[cfg(any(test, feature = "std"))]
+#[macro_use]
+extern crate std;
+#[cfg(feature="std")]
+use std::vec::Vec;
+
+#[cfg(feature="serde")]
+extern crate serde;
+#[cfg(feature="serde")]
+use serde::{Serialize, Deserialize};
+
+#[cfg(not(feature="std"))]
+#[macro_use]
+extern crate alloc;
+#[cfg(not(feature="std"))]
+use alloc::vec::Vec;
+
+use core::cmp::Ordering;
+use core::cmp;
+use core::fmt;
+use core::hash;
+use core::mem;
+use core::iter::FromIterator;
+use core::slice;
+use core::{u8, usize};
+use core::iter::repeat;
+use core::ops::*;
+
+type MutBlocks<'a, B> = slice::IterMut<'a, B>;
+
+/// Abstracts over a pile of bits (basically unsigned primitives)
+pub trait BitBlock:
+	Copy +
+	Add<Self, Output=Self> +
+	Sub<Self, Output=Self> +
+	Shl<usize, Output=Self> +
+	Shr<usize, Output=Self> +
+	Not<Output=Self> +
+	BitAnd<Self, Output=Self> +
+	BitOr<Self, Output=Self> +
+	BitXor<Self, Output=Self> +
+	Rem<Self, Output=Self> +
+	Eq +
+	Ord +
+	hash::Hash
+{
+	/// How many bits it has
+    fn bits() -> usize;
+    /// How many bytes it has
+    #[inline]
+    fn bytes() -> usize { Self::bits() / 8 }
+    /// Convert a byte into this type (lowest-order bits set)
+    fn from_byte(byte: u8) -> Self;
+    /// Count the number of 1's in the bitwise repr
+    fn count_ones(self) -> usize;
+    /// Get `0`
+    fn zero() -> Self;
+    /// Get `1`
+    fn one() -> Self;
+}
+
+macro_rules! bit_block_impl {
+    ($(($t: ident, $size: expr)),*) => ($(
+        impl BitBlock for $t {
+            #[inline]
+            fn bits() -> usize { $size }
+            #[inline]
+            fn from_byte(byte: u8) -> Self { $t::from(byte) }
+            #[inline]
+            fn count_ones(self) -> usize { self.count_ones() as usize }
+            #[inline]
+            fn one() -> Self { 1 }
+            #[inline]
+            fn zero() -> Self { 0 }
+        }
+    )*)
+}
+
+bit_block_impl!{
+    (u8, 8),
+    (u16, 16),
+    (u32, 32),
+    (u64, 64),
+    (usize, core::mem::size_of::<usize>() * 8)
+}
+
+fn reverse_bits(byte: u8) -> u8 {
+    let mut result = 0;
+    for i in 0..u8::bits() {
+        result |= ((byte >> i) & 1) << (u8::bits() - 1 - i);
+    }
+    result
+}
+
+static TRUE: bool = true;
+static FALSE: bool = false;
+
+/// The bitvector type.
+///
+/// # Examples
+///
+/// ```
+/// use bit_vec::BitVec;
+///
+/// let mut bv = BitVec::from_elem(10, false);
+///
+/// // insert all primes less than 10
+/// bv.set(2, true);
+/// bv.set(3, true);
+/// bv.set(5, true);
+/// bv.set(7, true);
+/// println!("{:?}", bv);
+/// println!("total bits set to true: {}", bv.iter().filter(|x| *x).count());
+///
+/// // flip all values in bitvector, producing non-primes less than 10
+/// bv.negate();
+/// println!("{:?}", bv);
+/// println!("total bits set to true: {}", bv.iter().filter(|x| *x).count());
+///
+/// // reset bitvector to empty
+/// bv.clear();
+/// println!("{:?}", bv);
+/// println!("total bits set to true: {}", bv.iter().filter(|x| *x).count());
+/// ```
+#[cfg_attr(feature="serde", derive(Serialize, Deserialize))]
+pub struct BitVec<B=u32> {
+    /// Internal representation of the bit vector
+    storage: Vec<B>,
+    /// The number of valid bits in the internal representation
+    nbits: usize
+}
+
+// FIXME(Gankro): NopeNopeNopeNopeNope (wait for IndexGet to be a thing)
+impl<B: BitBlock> Index<usize> for BitVec<B> {
+    type Output = bool;
+
+    #[inline]
+    fn index(&self, i: usize) -> &bool {
+        if self.get(i).expect("index out of bounds") {
+            &TRUE
+        } else {
+            &FALSE
+        }
+    }
+}
+
+/// Computes how many blocks are needed to store that many bits
+fn blocks_for_bits<B: BitBlock>(bits: usize) -> usize {
+    // If we want 17 bits, dividing by 32 will produce 0. So we add 1 to make sure we
+    // reserve enough. But if we want exactly a multiple of 32, this will actually allocate
+    // one too many. So we need to check if that's the case. We can do that by computing if
+    // bitwise AND by `32 - 1` is 0. But LLVM should be able to optimize the semantically
+    // superior modulo operator on a power of two to this.
+    //
+    // Note that we can technically avoid this branch with the expression
+    // `(nbits + U32_BITS - 1) / 32::BITS`, but if nbits is almost usize::MAX this will overflow.
+    if bits % B::bits() == 0 {
+        bits / B::bits()
+    } else {
+        bits / B::bits() + 1
+    }
+}
+
+/// Computes the bitmask for the final word of the vector
+fn mask_for_bits<B: BitBlock>(bits: usize) -> B {
+    // Note especially that a perfect multiple of U32_BITS should mask all 1s.
+    (!B::zero()) >> ((B::bits() - bits % B::bits()) % B::bits())
+}
+
+type B = u32;
+
+impl BitVec<u32> {
+
+    /// Creates an empty `BitVec`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    /// let mut bv = BitVec::new();
+    /// ```
+    #[inline]
+    pub fn new() -> Self {
+        Default::default()
+    }
+
+    /// Creates a `BitVec` that holds `nbits` elements, setting each element
+    /// to `bit`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_elem(10, false);
+    /// assert_eq!(bv.len(), 10);
+    /// for x in bv.iter() {
+    ///     assert_eq!(x, false);
+    /// }
+    /// ```
+    #[inline]
+    pub fn from_elem(nbits: usize, bit: bool) -> Self {
+        let nblocks = blocks_for_bits::<B>(nbits);
+        let mut bit_vec = BitVec {
+            storage: vec![if bit { !B::zero() } else { B::zero() }; nblocks],
+            nbits,
+        };
+        bit_vec.fix_last_block();
+        bit_vec
+    }
+
+    /// Constructs a new, empty `BitVec` with the specified capacity.
+    ///
+    /// The bitvector will be able to hold at least `capacity` bits without
+    /// reallocating. If `capacity` is 0, it will not allocate.
+    ///
+    /// It is important to note that this function does not specify the
+    /// *length* of the returned bitvector, but only the *capacity*.
+    #[inline]
+    pub fn with_capacity(nbits: usize) -> Self {
+        BitVec {
+            storage: Vec::with_capacity(blocks_for_bits::<B>(nbits)),
+            nbits: 0,
+        }
+    }
+
+    /// Transforms a byte-vector into a `BitVec`. Each byte becomes eight bits,
+    /// with the most significant bits of each byte coming first. Each
+    /// bit becomes `true` if equal to 1 or `false` if equal to 0.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let bv = BitVec::from_bytes(&[0b10100000, 0b00010010]);
+    /// assert!(bv.eq_vec(&[true, false, true, false,
+    ///                     false, false, false, false,
+    ///                     false, false, false, true,
+    ///                     false, false, true, false]));
+    /// ```
+    pub fn from_bytes(bytes: &[u8]) -> Self {
+        let len = bytes.len().checked_mul(u8::bits()).expect("capacity overflow");
+        let mut bit_vec = BitVec::with_capacity(len);
+        let complete_words = bytes.len() / B::bytes();
+        let extra_bytes = bytes.len() % B::bytes();
+
+        bit_vec.nbits = len;
+
+        for i in 0..complete_words {
+            let mut accumulator = B::zero();
+            for idx in 0..B::bytes() {
+                accumulator |=
+                    B::from_byte(reverse_bits(bytes[i * B::bytes() + idx])) << (idx * 8)
+            }
+            bit_vec.storage.push(accumulator);
+        }
+
+        if extra_bytes > 0 {
+            let mut last_word = B::zero();
+            for (i, &byte) in bytes[complete_words * B::bytes()..].iter().enumerate() {
+                last_word |=
+                    B::from_byte(reverse_bits(byte)) << (i * 8);
+            }
+            bit_vec.storage.push(last_word);
+        }
+
+        bit_vec
+    }
+
+    /// Creates a `BitVec` of the specified length where the value at each index
+    /// is `f(index)`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let bv = BitVec::from_fn(5, |i| { i % 2 == 0 });
+    /// assert!(bv.eq_vec(&[true, false, true, false, true]));
+    /// ```
+    #[inline]
+    pub fn from_fn<F>(len: usize, mut f: F) -> Self
+        where F: FnMut(usize) -> bool
+    {
+        let mut bit_vec = BitVec::from_elem(len, false);
+        for i in 0..len {
+            bit_vec.set(i, f(i));
+        }
+        bit_vec
+    }
+}
+
+impl<B: BitBlock> BitVec<B> {
+    /// Applies the given operation to the blocks of self and other, and sets
+    /// self to be the result. This relies on the caller not to corrupt the
+    /// last word.
+    #[inline]
+    fn process<F>(&mut self, other: &BitVec<B>, mut op: F) -> bool
+    		where F: FnMut(B, B) -> B {
+        assert_eq!(self.len(), other.len());
+        debug_assert_eq!(self.storage.len(), other.storage.len());
+        let mut changed_bits = B::zero();
+        for (a, b) in self.blocks_mut().zip(other.blocks()) {
+            let w = op(*a, b);
+            changed_bits = changed_bits | (*a ^ w);
+            *a = w;
+        }
+        changed_bits != B::zero()
+    }
+
+    /// Iterator over mutable refs to  the underlying blocks of data.
+    #[inline]
+    fn blocks_mut(&mut self) -> MutBlocks<B> {
+        // (2)
+        self.storage.iter_mut()
+    }
+
+    /// Iterator over the underlying blocks of data
+    #[inline]
+    pub fn blocks(&self) -> Blocks<B> {
+        // (2)
+        Blocks{iter: self.storage.iter()}
+    }
+
+    /// Exposes the raw block storage of this BitVec
+    ///
+    /// Only really intended for BitSet.
+    #[inline]
+    pub fn storage(&self) -> &[B] {
+    	&self.storage
+    }
+
+    /// Exposes the raw block storage of this BitVec
+    ///
+    /// Can probably cause unsafety. Only really intended for BitSet.
+    #[inline]
+    pub unsafe fn storage_mut(&mut self) -> &mut Vec<B> {
+    	&mut self.storage
+    }
+
+    /// Helper for procedures involving spare space in the last block.
+    #[inline]
+    fn last_block_with_mask(&self) -> Option<(B, B)> {
+        let extra_bits = self.len() % B::bits();
+        if extra_bits > 0 {
+            let mask = (B::one() << extra_bits) - B::one();
+            let storage_len = self.storage.len();
+            Some((self.storage[storage_len - 1], mask))
+        } else {
+            None
+        }
+    }
+
+    /// Helper for procedures involving spare space in the last block.
+    #[inline]
+    fn last_block_mut_with_mask(&mut self) -> Option<(&mut B, B)> {
+        let extra_bits = self.len() % B::bits();
+        if extra_bits > 0 {
+            let mask = (B::one() << extra_bits) - B::one();
+            let storage_len = self.storage.len();
+            Some((&mut self.storage[storage_len - 1], mask))
+        } else {
+            None
+        }
+    }
+
+    /// An operation might screw up the unused bits in the last block of the
+    /// `BitVec`. As per (3), it's assumed to be all 0s. This method fixes it up.
+    fn fix_last_block(&mut self) {
+        if let Some((last_block, used_bits)) = self.last_block_mut_with_mask() {
+            *last_block = *last_block & used_bits;
+        }
+    }
+
+    /// Operations such as change detection for xnor, nor and nand are easiest
+    /// to implement when unused bits are all set to 1s.
+    fn fix_last_block_with_ones(&mut self) {
+        if let Some((last_block, used_bits)) = self.last_block_mut_with_mask() {
+            *last_block = *last_block | !used_bits;
+        }
+    }
+
+    /// Check whether last block's invariant is fine.
+    fn is_last_block_fixed(&self) -> bool {
+        if let Some((last_block, used_bits)) = self.last_block_with_mask() {
+            last_block & !used_bits == B::zero()
+        } else {
+            true
+        }
+    }
+
+    /// Ensure the invariant for the last block.
+    ///
+    /// An operation might screw up the unused bits in the last block of the
+    /// `BitVec`.
+    ///
+    /// This method fails in case the last block is not fixed. The check
+    /// is skipped outside testing.
+    #[inline]
+    fn ensure_invariant(&self) {
+        if cfg!(test) {
+            debug_assert!(self.is_last_block_fixed());
+        }
+    }
+
+    /// Retrieves the value at index `i`, or `None` if the index is out of bounds.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let bv = BitVec::from_bytes(&[0b01100000]);
+    /// assert_eq!(bv.get(0), Some(false));
+    /// assert_eq!(bv.get(1), Some(true));
+    /// assert_eq!(bv.get(100), None);
+    ///
+    /// // Can also use array indexing
+    /// assert_eq!(bv[1], true);
+    /// ```
+    #[inline]
+    pub fn get(&self, i: usize) -> Option<bool> {
+        self.ensure_invariant();
+        if i >= self.nbits {
+            return None;
+        }
+        let w = i / B::bits();
+        let b = i % B::bits();
+        self.storage.get(w).map(|&block|
+            (block & (B::one() << b)) != B::zero()
+        )
+    }
+
+    /// Sets the value of a bit at an index `i`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `i` is out of bounds.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_elem(5, false);
+    /// bv.set(3, true);
+    /// assert_eq!(bv[3], true);
+    /// ```
+    #[inline]
+    pub fn set(&mut self, i: usize, x: bool) {
+        self.ensure_invariant();
+        assert!(i < self.nbits, "index out of bounds: {:?} >= {:?}", i, self.nbits);
+        let w = i / B::bits();
+        let b = i % B::bits();
+        let flag = B::one() << b;
+        let val = if x { self.storage[w] | flag }
+                  else { self.storage[w] & !flag };
+        self.storage[w] = val;
+    }
+
+    /// Sets all bits to 1.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let before = 0b01100000;
+    /// let after  = 0b11111111;
+    ///
+    /// let mut bv = BitVec::from_bytes(&[before]);
+    /// bv.set_all();
+    /// assert_eq!(bv, BitVec::from_bytes(&[after]));
+    /// ```
+    #[inline]
+    pub fn set_all(&mut self) {
+        self.ensure_invariant();
+        for w in &mut self.storage { *w = !B::zero(); }
+        self.fix_last_block();
+    }
+
+    /// Flips all bits.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let before = 0b01100000;
+    /// let after  = 0b10011111;
+    ///
+    /// let mut bv = BitVec::from_bytes(&[before]);
+    /// bv.negate();
+    /// assert_eq!(bv, BitVec::from_bytes(&[after]));
+    /// ```
+    #[inline]
+    pub fn negate(&mut self) {
+        self.ensure_invariant();
+        for w in &mut self.storage { *w = !*w; }
+        self.fix_last_block();
+    }
+
+    /// Calculates the union of two bitvectors. This acts like the bitwise `or`
+    /// function.
+    ///
+    /// Sets `self` to the union of `self` and `other`. Both bitvectors must be
+    /// the same length. Returns `true` if `self` changed.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the bitvectors are of different lengths.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let a   = 0b01100100;
+    /// let b   = 0b01011010;
+    /// let res = 0b01111110;
+    ///
+    /// let mut a = BitVec::from_bytes(&[a]);
+    /// let b = BitVec::from_bytes(&[b]);
+    ///
+    /// assert!(a.union(&b));
+    /// assert_eq!(a, BitVec::from_bytes(&[res]));
+    /// ```
+    #[deprecated(
+        since = "0.7.0",
+        note = "Please use the 'or' function instead"
+    )]
+    #[inline]
+    pub fn union(&mut self, other: &Self) -> bool {
+        self.or(other)
+    }
+
+    /// Calculates the intersection of two bitvectors. This acts like the
+    /// bitwise `and` function.
+    ///
+    /// Sets `self` to the intersection of `self` and `other`. Both bitvectors
+    /// must be the same length. Returns `true` if `self` changed.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the bitvectors are of different lengths.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let a   = 0b01100100;
+    /// let b   = 0b01011010;
+    /// let res = 0b01000000;
+    ///
+    /// let mut a = BitVec::from_bytes(&[a]);
+    /// let b = BitVec::from_bytes(&[b]);
+    ///
+    /// assert!(a.intersect(&b));
+    /// assert_eq!(a, BitVec::from_bytes(&[res]));
+    /// ```
+    #[deprecated(
+        since = "0.7.0",
+        note = "Please use the 'and' function instead"
+    )]
+    #[inline]
+    pub fn intersect(&mut self, other: &Self) -> bool {
+        self.and(other)
+    }
+
+    /// Calculates the bitwise `or` of two bitvectors.
+    ///
+    /// Sets `self` to the union of `self` and `other`. Both bitvectors must be
+    /// the same length. Returns `true` if `self` changed.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the bitvectors are of different lengths.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let a   = 0b01100100;
+    /// let b   = 0b01011010;
+    /// let res = 0b01111110;
+    ///
+    /// let mut a = BitVec::from_bytes(&[a]);
+    /// let b = BitVec::from_bytes(&[b]);
+    ///
+    /// assert!(a.or(&b));
+    /// assert_eq!(a, BitVec::from_bytes(&[res]));
+    /// ```
+    #[inline]
+    pub fn or(&mut self, other: &Self) -> bool {
+        self.ensure_invariant();
+        debug_assert!(other.is_last_block_fixed());
+        self.process(other, |w1, w2| (w1 | w2))
+    }
+
+    /// Calculates the bitwise `and` of two bitvectors.
+    ///
+    /// Sets `self` to the intersection of `self` and `other`. Both bitvectors
+    /// must be the same length. Returns `true` if `self` changed.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the bitvectors are of different lengths.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let a   = 0b01100100;
+    /// let b   = 0b01011010;
+    /// let res = 0b01000000;
+    ///
+    /// let mut a = BitVec::from_bytes(&[a]);
+    /// let b = BitVec::from_bytes(&[b]);
+    ///
+    /// assert!(a.and(&b));
+    /// assert_eq!(a, BitVec::from_bytes(&[res]));
+    /// ```
+    #[inline]
+    pub fn and(&mut self, other: &Self) -> bool {
+        self.ensure_invariant();
+        debug_assert!(other.is_last_block_fixed());
+        self.process(other, |w1, w2| (w1 & w2))
+    }
+
+    /// Calculates the difference between two bitvectors.
+    ///
+    /// Sets each element of `self` to the value of that element minus the
+    /// element of `other` at the same index. Both bitvectors must be the same
+    /// length. Returns `true` if `self` changed.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the bitvectors are of different length.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let a   = 0b01100100;
+    /// let b   = 0b01011010;
+    /// let a_b = 0b00100100; // a - b
+    /// let b_a = 0b00011010; // b - a
+    ///
+    /// let mut bva = BitVec::from_bytes(&[a]);
+    /// let bvb = BitVec::from_bytes(&[b]);
+    ///
+    /// assert!(bva.difference(&bvb));
+    /// assert_eq!(bva, BitVec::from_bytes(&[a_b]));
+    ///
+    /// let bva = BitVec::from_bytes(&[a]);
+    /// let mut bvb = BitVec::from_bytes(&[b]);
+    ///
+    /// assert!(bvb.difference(&bva));
+    /// assert_eq!(bvb, BitVec::from_bytes(&[b_a]));
+    /// ```
+    #[inline]
+    pub fn difference(&mut self, other: &Self) -> bool {
+        self.ensure_invariant();
+        debug_assert!(other.is_last_block_fixed());
+        self.process(other, |w1, w2| (w1 & !w2))
+    }
+
+    /// Calculates the xor of two bitvectors.
+    ///
+    /// Sets `self` to the xor of `self` and `other`. Both bitvectors must be
+    /// the same length. Returns `true` if `self` changed.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the bitvectors are of different length.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let a   = 0b01100110;
+    /// let b   = 0b01010100;
+    /// let res = 0b00110010;
+    ///
+    /// let mut a = BitVec::from_bytes(&[a]);
+    /// let b = BitVec::from_bytes(&[b]);
+    ///
+    /// assert!(a.xor(&b));
+    /// assert_eq!(a, BitVec::from_bytes(&[res]));
+    /// ```
+    #[inline]
+    pub fn xor(&mut self, other: &Self) -> bool {
+        self.ensure_invariant();
+        debug_assert!(other.is_last_block_fixed());
+        self.process(other, |w1, w2| (w1 ^ w2))
+    }
+
+    /// Calculates the nand of two bitvectors.
+    ///
+    /// Sets `self` to the nand of `self` and `other`. Both bitvectors must be
+    /// the same length. Returns `true` if `self` changed.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the bitvectors are of different length.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let a   = 0b01100110;
+    /// let b   = 0b01010100;
+    /// let res = 0b10111011;
+    ///
+    /// let mut a = BitVec::from_bytes(&[a]);
+    /// let b = BitVec::from_bytes(&[b]);
+    ///
+    /// assert!(a.nand(&b));
+    /// assert_eq!(a, BitVec::from_bytes(&[res]));
+    /// ```
+    #[inline]
+    pub fn nand(&mut self, other: &Self) -> bool {
+        self.ensure_invariant();
+        debug_assert!(other.is_last_block_fixed());
+        self.fix_last_block_with_ones();
+        let result = self.process(other, |w1, w2| !(w1 & w2));
+        self.fix_last_block();
+        result
+    }
+
+    /// Calculates the nor of two bitvectors.
+    ///
+    /// Sets `self` to the nor of `self` and `other`. Both bitvectors must be
+    /// the same length. Returns `true` if `self` changed.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the bitvectors are of different length.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let a   = 0b01100110;
+    /// let b   = 0b01010100;
+    /// let res = 0b10001001;
+    ///
+    /// let mut a = BitVec::from_bytes(&[a]);
+    /// let b = BitVec::from_bytes(&[b]);
+    ///
+    /// assert!(a.nor(&b));
+    /// assert_eq!(a, BitVec::from_bytes(&[res]));
+    /// ```
+    #[inline]
+    pub fn nor(&mut self, other: &Self) -> bool {
+        self.ensure_invariant();
+        debug_assert!(other.is_last_block_fixed());
+        self.fix_last_block_with_ones();
+        let result = self.process(other, |w1, w2| !(w1 | w2));
+        self.fix_last_block();
+        result
+    }
+
+    /// Calculates the xnor of two bitvectors.
+    ///
+    /// Sets `self` to the xnor of `self` and `other`. Both bitvectors must be
+    /// the same length. Returns `true` if `self` changed.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the bitvectors are of different length.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let a   = 0b01100110;
+    /// let b   = 0b01010100;
+    /// let res = 0b11001101;
+    ///
+    /// let mut a = BitVec::from_bytes(&[a]);
+    /// let b = BitVec::from_bytes(&[b]);
+    ///
+    /// assert!(a.xnor(&b));
+    /// assert_eq!(a, BitVec::from_bytes(&[res]));
+    /// ```
+    #[inline]
+    pub fn xnor(&mut self, other: &Self) -> bool {
+        self.ensure_invariant();
+        debug_assert!(other.is_last_block_fixed());
+        self.fix_last_block_with_ones();
+        let result = self.process(other, |w1, w2| !(w1 ^ w2));
+        self.fix_last_block();
+        result
+    }
+
+    /// Returns `true` if all bits are 1.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_elem(5, true);
+    /// assert_eq!(bv.all(), true);
+    ///
+    /// bv.set(1, false);
+    /// assert_eq!(bv.all(), false);
+    /// ```
+    #[inline]
+    pub fn all(&self) -> bool {
+        self.ensure_invariant();
+        let mut last_word = !B::zero();
+        // Check that every block but the last is all-ones...
+        self.blocks().all(|elem| {
+            let tmp = last_word;
+            last_word = elem;
+            tmp == !B::zero()
+        // and then check the last one has enough ones
+        }) && (last_word == mask_for_bits(self.nbits))
+    }
+
+    /// Returns an iterator over the elements of the vector in order.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let bv = BitVec::from_bytes(&[0b01110100, 0b10010010]);
+    /// assert_eq!(bv.iter().filter(|x| *x).count(), 7);
+    /// ```
+    #[inline]
+    pub fn iter(&self) -> Iter<B> {
+        self.ensure_invariant();
+        Iter { bit_vec: self, range: 0..self.nbits }
+    }
+
+    /// Moves all bits from `other` into `Self`, leaving `other` empty.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut a = BitVec::from_bytes(&[0b10000000]);
+    /// let mut b = BitVec::from_bytes(&[0b01100001]);
+    ///
+    /// a.append(&mut b);
+    ///
+    /// assert_eq!(a.len(), 16);
+    /// assert_eq!(b.len(), 0);
+    /// assert!(a.eq_vec(&[true, false, false, false, false, false, false, false,
+    ///                    false, true, true, false, false, false, false, true]));
+    /// ```
+    pub fn append(&mut self, other: &mut Self) {
+        self.ensure_invariant();
+        debug_assert!(other.is_last_block_fixed());
+
+        let b = self.len() % B::bits();
+        let o = other.len() % B::bits();
+        let will_overflow = (b + o > B::bits()) || (o == 0 && b != 0);
+
+        self.nbits += other.len();
+        other.nbits = 0;
+
+        if b == 0 {
+            self.storage.append(&mut other.storage);
+        } else {
+            self.storage.reserve(other.storage.len());
+
+            for block in other.storage.drain(..) {
+            	{
+            		let last = self.storage.last_mut().unwrap();
+                	*last = *last | (block << b);
+                }
+                self.storage.push(block >> (B::bits() - b));
+            }
+
+            // Remove additional block if the last shift did not overflow
+            if !will_overflow {
+                self.storage.pop();
+            }
+        }
+    }
+
+    /// Splits the `BitVec` into two at the given bit,
+    /// retaining the first half in-place and returning the second one.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `at` is out of bounds.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    /// let mut a = BitVec::new();
+    /// a.push(true);
+    /// a.push(false);
+    /// a.push(false);
+    /// a.push(true);
+    ///
+    /// let b = a.split_off(2);
+    ///
+    /// assert_eq!(a.len(), 2);
+    /// assert_eq!(b.len(), 2);
+    /// assert!(a.eq_vec(&[true, false]));
+    /// assert!(b.eq_vec(&[false, true]));
+    /// ```
+    pub fn split_off(&mut self, at: usize) -> Self {
+        self.ensure_invariant();
+        assert!(at <= self.len(), "`at` out of bounds");
+
+        let mut other = BitVec::<B>::default();
+
+        if at == 0 {
+            mem::swap(self, &mut other);
+            return other;
+        } else if at == self.len() {
+            return other;
+        }
+
+        let w = at / B::bits();
+        let b = at % B::bits();
+        other.nbits = self.nbits - at;
+        self.nbits = at;
+        if b == 0 {
+            // Split at block boundary
+            other.storage = self.storage.split_off(w);
+        } else {
+            other.storage.reserve(self.storage.len() - w);
+
+            {
+                let mut iter = self.storage[w..].iter();
+                let mut last = *iter.next().unwrap();
+                for &cur in iter {
+                    other.storage.push((last >> b) | (cur << (B::bits() - b)));
+                    last = cur;
+                }
+                other.storage.push(last >> b);
+            }
+
+            self.storage.truncate(w + 1);
+            self.fix_last_block();
+        }
+
+        other
+    }
+
+    /// Returns `true` if all bits are 0.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_elem(10, false);
+    /// assert_eq!(bv.none(), true);
+    ///
+    /// bv.set(3, true);
+    /// assert_eq!(bv.none(), false);
+    /// ```
+    #[inline]
+    pub fn none(&self) -> bool {
+        self.blocks().all(|w| w == B::zero())
+    }
+
+    /// Returns `true` if any bit is 1.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_elem(10, false);
+    /// assert_eq!(bv.any(), false);
+    ///
+    /// bv.set(3, true);
+    /// assert_eq!(bv.any(), true);
+    /// ```
+    #[inline]
+    pub fn any(&self) -> bool {
+        !self.none()
+    }
+
+    /// Organises the bits into bytes, such that the first bit in the
+    /// `BitVec` becomes the high-order bit of the first byte. If the
+    /// size of the `BitVec` is not a multiple of eight then trailing bits
+    /// will be filled-in with `false`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_elem(3, true);
+    /// bv.set(1, false);
+    ///
+    /// assert_eq!(bv.to_bytes(), [0b10100000]);
+    ///
+    /// let mut bv = BitVec::from_elem(9, false);
+    /// bv.set(2, true);
+    /// bv.set(8, true);
+    ///
+    /// assert_eq!(bv.to_bytes(), [0b00100000, 0b10000000]);
+    /// ```
+    pub fn to_bytes(&self) -> Vec<u8> {
+        self.ensure_invariant();
+    	// Oh lord, we're mapping this to bytes bit-by-bit!
+        fn bit<B: BitBlock>(bit_vec: &BitVec<B>, byte: usize, bit: usize) -> u8 {
+            let offset = byte * 8 + bit;
+            if offset >= bit_vec.nbits {
+                0
+            } else {
+                (bit_vec[offset] as u8) << (7 - bit)
+            }
+        }
+
+        let len = self.nbits / 8 +
+                  if self.nbits % 8 == 0 { 0 } else { 1 };
+        (0..len).map(|i|
+            bit(self, i, 0) |
+            bit(self, i, 1) |
+            bit(self, i, 2) |
+            bit(self, i, 3) |
+            bit(self, i, 4) |
+            bit(self, i, 5) |
+            bit(self, i, 6) |
+            bit(self, i, 7)
+        ).collect()
+    }
+
+    /// Compares a `BitVec` to a slice of `bool`s.
+    /// Both the `BitVec` and slice must have the same length.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the `BitVec` and slice are of different length.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let bv = BitVec::from_bytes(&[0b10100000]);
+    ///
+    /// assert!(bv.eq_vec(&[true, false, true, false,
+    ///                     false, false, false, false]));
+    /// ```
+    #[inline]
+    pub fn eq_vec(&self, v: &[bool]) -> bool {
+        assert_eq!(self.nbits, v.len());
+        self.iter().zip(v.iter().cloned()).all(|(b1, b2)| b1 == b2)
+    }
+
+    /// Shortens a `BitVec`, dropping excess elements.
+    ///
+    /// If `len` is greater than the vector's current length, this has no
+    /// effect.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_bytes(&[0b01001011]);
+    /// bv.truncate(2);
+    /// assert!(bv.eq_vec(&[false, true]));
+    /// ```
+    #[inline]
+    pub fn truncate(&mut self, len: usize) {
+        self.ensure_invariant();
+        if len < self.len() {
+            self.nbits = len;
+            // This fixes (2).
+            self.storage.truncate(blocks_for_bits::<B>(len));
+            self.fix_last_block();
+        }
+    }
+
+    /// Reserves capacity for at least `additional` more bits to be inserted in the given
+    /// `BitVec`. The collection may reserve more space to avoid frequent reallocations.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the new capacity overflows `usize`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_elem(3, false);
+    /// bv.reserve(10);
+    /// assert_eq!(bv.len(), 3);
+    /// assert!(bv.capacity() >= 13);
+    /// ```
+    #[inline]
+    pub fn reserve(&mut self, additional: usize) {
+        let desired_cap = self.len().checked_add(additional).expect("capacity overflow");
+        let storage_len = self.storage.len();
+        if desired_cap > self.capacity() {
+            self.storage.reserve(blocks_for_bits::<B>(desired_cap) - storage_len);
+        }
+    }
+
+    /// Reserves the minimum capacity for exactly `additional` more bits to be inserted in the
+    /// given `BitVec`. Does nothing if the capacity is already sufficient.
+    ///
+    /// Note that the allocator may give the collection more space than it requests. Therefore
+    /// capacity can not be relied upon to be precisely minimal. Prefer `reserve` if future
+    /// insertions are expected.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the new capacity overflows `usize`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_elem(3, false);
+    /// bv.reserve(10);
+    /// assert_eq!(bv.len(), 3);
+    /// assert!(bv.capacity() >= 13);
+    /// ```
+    #[inline]
+    pub fn reserve_exact(&mut self, additional: usize) {
+        let desired_cap = self.len().checked_add(additional).expect("capacity overflow");
+        let storage_len = self.storage.len();
+        if desired_cap > self.capacity() {
+            self.storage.reserve_exact(blocks_for_bits::<B>(desired_cap) - storage_len);
+        }
+    }
+
+    /// Returns the capacity in bits for this bit vector. Inserting any
+    /// element less than this amount will not trigger a resizing.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::new();
+    /// bv.reserve(10);
+    /// assert!(bv.capacity() >= 10);
+    /// ```
+    #[inline]
+    pub fn capacity(&self) -> usize {
+        self.storage.capacity().checked_mul(B::bits()).unwrap_or(usize::MAX)
+    }
+
+    /// Grows the `BitVec` in-place, adding `n` copies of `value` to the `BitVec`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the new len overflows a `usize`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_bytes(&[0b01001011]);
+    /// bv.grow(2, true);
+    /// assert_eq!(bv.len(), 10);
+    /// assert_eq!(bv.to_bytes(), [0b01001011, 0b11000000]);
+    /// ```
+    pub fn grow(&mut self, n: usize, value: bool) {
+        self.ensure_invariant();
+
+        // Note: we just bulk set all the bits in the last word in this fn in multiple places
+        // which is technically wrong if not all of these bits are to be used. However, at the end
+        // of this fn we call `fix_last_block` at the end of this fn, which should fix this.
+
+        let new_nbits = self.nbits.checked_add(n).expect("capacity overflow");
+        let new_nblocks = blocks_for_bits::<B>(new_nbits);
+        let full_value = if value { !B::zero() } else { B::zero() };
+
+        // Correct the old tail word, setting or clearing formerly unused bits
+        let num_cur_blocks = blocks_for_bits::<B>(self.nbits);
+        if self.nbits % B::bits() > 0 {
+            let mask = mask_for_bits::<B>(self.nbits);
+            if value {
+            	let block = &mut self.storage[num_cur_blocks - 1];
+                *block = *block | !mask;
+            } else {
+                // Extra bits are already zero by invariant.
+            }
+        }
+
+        // Fill in words after the old tail word
+        let stop_idx = cmp::min(self.storage.len(), new_nblocks);
+        for idx in num_cur_blocks..stop_idx {
+            self.storage[idx] = full_value;
+        }
+
+        // Allocate new words, if needed
+        if new_nblocks > self.storage.len() {
+            let to_add = new_nblocks - self.storage.len();
+            self.storage.extend(repeat(full_value).take(to_add));
+        }
+
+        // Adjust internal bit count
+        self.nbits = new_nbits;
+
+        self.fix_last_block();
+    }
+
+    /// Removes the last bit from the BitVec, and returns it. Returns None if the BitVec is empty.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::from_bytes(&[0b01001001]);
+    /// assert_eq!(bv.pop(), Some(true));
+    /// assert_eq!(bv.pop(), Some(false));
+    /// assert_eq!(bv.len(), 6);
+    /// ```
+    #[inline]
+    pub fn pop(&mut self) -> Option<bool> {
+        self.ensure_invariant();
+
+        if self.is_empty() {
+            None
+        } else {
+            let i = self.nbits - 1;
+            let ret = self[i];
+            // (3)
+            self.set(i, false);
+            self.nbits = i;
+            if self.nbits % B::bits() == 0 {
+                // (2)
+                self.storage.pop();
+            }
+            Some(ret)
+        }
+    }
+
+    /// Pushes a `bool` onto the end.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_vec::BitVec;
+    ///
+    /// let mut bv = BitVec::new();
+    /// bv.push(true);
+    /// bv.push(false);
+    /// assert!(bv.eq_vec(&[true, false]));
+    /// ```
+    #[inline]
+    pub fn push(&mut self, elem: bool) {
+        if self.nbits % B::bits() == 0 {
+            self.storage.push(B::zero());
+        }
+        let insert_pos = self.nbits;
+        self.nbits = self.nbits.checked_add(1).expect("Capacity overflow");
+        self.set(insert_pos, elem);
+    }
+
+    /// Returns the total number of bits in this vector
+    #[inline]
+    pub fn len(&self) -> usize { self.nbits }
+
+    /// Sets the number of bits that this BitVec considers initialized.
+    ///
+    /// Almost certainly can cause bad stuff. Only really intended for BitSet.
+    #[inline]
+    pub unsafe fn set_len(&mut self, len: usize) {
+    	self.nbits = len;
+    }
+
+    /// Returns true if there are no bits in this vector
+    #[inline]
+    pub fn is_empty(&self) -> bool { self.len() == 0 }
+
+    /// Clears all bits in this vector.
+    #[inline]
+    pub fn clear(&mut self) {
+        self.ensure_invariant();
+        for w in &mut self.storage { *w = B::zero(); }
+    }
+
+    /// Shrinks the capacity of the underlying storage as much as
+    /// possible.
+    ///
+    /// It will drop down as close as possible to the length but the
+    /// allocator may still inform the underlying storage that there
+    /// is space for a few more elements/bits.
+    pub fn shrink_to_fit(&mut self) {
+        self.storage.shrink_to_fit();
+    }
+}
+
+impl<B: BitBlock> Default for BitVec<B> {
+    #[inline]
+    fn default() -> Self { BitVec { storage: Vec::new(), nbits: 0 } }
+}
+
+impl<B: BitBlock> FromIterator<bool> for BitVec<B> {
+    #[inline]
+    fn from_iter<I: IntoIterator<Item=bool>>(iter: I) -> Self {
+        let mut ret: Self = Default::default();
+        ret.extend(iter);
+        ret
+    }
+}
+
+impl<B: BitBlock> Extend<bool> for BitVec<B> {
+    #[inline]
+    fn extend<I: IntoIterator<Item=bool>>(&mut self, iterable: I) {
+        self.ensure_invariant();
+        let iterator = iterable.into_iter();
+        let (min, _) = iterator.size_hint();
+        self.reserve(min);
+        for element in iterator {
+            self.push(element)
+        }
+    }
+}
+
+impl<B: BitBlock> Clone for BitVec<B> {
+    #[inline]
+    fn clone(&self) -> Self {
+        self.ensure_invariant();
+        BitVec { storage: self.storage.clone(), nbits: self.nbits }
+    }
+
+    #[inline]
+    fn clone_from(&mut self, source: &Self) {
+        debug_assert!(source.is_last_block_fixed());
+        self.nbits = source.nbits;
+        self.storage.clone_from(&source.storage);
+    }
+}
+
+impl<B: BitBlock> PartialOrd for BitVec<B> {
+    #[inline]
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl<B: BitBlock> Ord for BitVec<B> {
+    #[inline]
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.ensure_invariant();
+        debug_assert!(other.is_last_block_fixed());
+        let mut a = self.iter();
+        let mut b = other.iter();
+        loop {
+            match (a.next(), b.next()) {
+                (Some(x), Some(y)) => match x.cmp(&y) {
+                    Ordering::Equal => {}
+                    otherwise => return otherwise,
+                },
+                (None, None) => return Ordering::Equal,
+                (None, _) => return Ordering::Less,
+                (_, None) => return Ordering::Greater,
+            }
+        }
+    }
+}
+
+impl<B: BitBlock> fmt::Debug for BitVec<B> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        self.ensure_invariant();
+        for bit in self {
+            write!(fmt, "{}", if bit { 1 } else { 0 })?;
+        }
+        Ok(())
+    }
+}
+
+impl<B: BitBlock> hash::Hash for BitVec<B> {
+    #[inline]
+    fn hash<H: hash::Hasher>(&self, state: &mut H) {
+        self.ensure_invariant();
+        self.nbits.hash(state);
+        for elem in self.blocks() {
+            elem.hash(state);
+        }
+    }
+}
+
+impl<B: BitBlock> cmp::PartialEq for BitVec<B> {
+    #[inline]
+    fn eq(&self, other: &Self) -> bool {
+        if self.nbits != other.nbits {
+            self.ensure_invariant();
+            other.ensure_invariant();
+            return false;
+        }
+        self.blocks().zip(other.blocks()).all(|(w1, w2)| w1 == w2)
+    }
+}
+
+impl<B: BitBlock> cmp::Eq for BitVec<B> {}
+
+/// An iterator for `BitVec`.
+#[derive(Clone)]
+pub struct Iter<'a, B: 'a = u32> {
+    bit_vec: &'a BitVec<B>,
+    range: Range<usize>,
+}
+
+impl<'a, B: BitBlock> Iterator for Iter<'a, B> {
+    type Item = bool;
+
+    #[inline]
+    fn next(&mut self) -> Option<bool> {
+        // NB: indexing is slow for extern crates when it has to go through &TRUE or &FALSE
+        // variables.  get is more direct, and unwrap is fine since we're sure of the range.
+        self.range.next().map(|i| self.bit_vec.get(i).unwrap())
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.range.size_hint()
+    }
+}
+
+impl<'a, B: BitBlock> DoubleEndedIterator for Iter<'a, B> {
+    #[inline]
+    fn next_back(&mut self) -> Option<bool> {
+        self.range.next_back().map(|i| self.bit_vec.get(i).unwrap())
+    }
+}
+
+impl<'a, B: BitBlock> ExactSizeIterator for Iter<'a, B> {}
+
+impl<'a, B: BitBlock> IntoIterator for &'a BitVec<B> {
+    type Item = bool;
+    type IntoIter = Iter<'a, B>;
+
+    #[inline]
+    fn into_iter(self) -> Iter<'a, B> {
+        self.iter()
+    }
+}
+
+pub struct IntoIter<B=u32> {
+    bit_vec: BitVec<B>,
+    range: Range<usize>,
+}
+
+impl<B: BitBlock> Iterator for IntoIter<B> {
+    type Item = bool;
+
+    #[inline]
+    fn next(&mut self) -> Option<bool> {
+        self.range.next().map(|i| self.bit_vec.get(i).unwrap())
+    }
+}
+
+impl<B: BitBlock> DoubleEndedIterator for IntoIter<B> {
+    #[inline]
+    fn next_back(&mut self) -> Option<bool> {
+        self.range.next_back().map(|i| self.bit_vec.get(i).unwrap())
+    }
+}
+
+impl<B: BitBlock> ExactSizeIterator for IntoIter<B> {}
+
+impl<B: BitBlock> IntoIterator for BitVec<B> {
+    type Item = bool;
+    type IntoIter = IntoIter<B>;
+
+    #[inline]
+    fn into_iter(self) -> IntoIter<B> {
+        let nbits = self.nbits;
+        IntoIter { bit_vec: self, range: 0..nbits }
+    }
+}
+
+/// An iterator over the blocks of a `BitVec`.
+#[derive(Clone)]
+pub struct Blocks<'a, B: 'a> {
+    iter: slice::Iter<'a, B>,
+}
+
+impl<'a, B: BitBlock> Iterator for Blocks<'a, B> {
+    type Item = B;
+
+    #[inline]
+    fn next(&mut self) -> Option<B> {
+        self.iter.next().cloned()
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+impl<'a, B: BitBlock> DoubleEndedIterator for Blocks<'a, B> {
+    #[inline]
+    fn next_back(&mut self) -> Option<B> {
+        self.iter.next_back().cloned()
+    }
+}
+
+impl<'a, B: BitBlock> ExactSizeIterator for Blocks<'a, B> {}
+
+#[cfg(test)]
+mod tests {
+    use super::{BitVec, Iter, Vec};
+
+    // This is stupid, but I want to differentiate from a "random" 32
+    const U32_BITS: usize = 32;
+
+    #[test]
+    fn test_to_str() {
+        let zerolen = BitVec::new();
+        assert_eq!(format!("{:?}", zerolen), "");
+
+        let eightbits = BitVec::from_elem(8, false);
+        assert_eq!(format!("{:?}", eightbits), "00000000")
+    }
+
+    #[test]
+    fn test_0_elements() {
+        let act = BitVec::new();
+        let exp = Vec::new();
+        assert!(act.eq_vec(&exp));
+        assert!(act.none() && act.all());
+    }
+
+    #[test]
+    fn test_1_element() {
+        let mut act = BitVec::from_elem(1, false);
+        assert!(act.eq_vec(&[false]));
+        assert!(act.none() && !act.all());
+        act = BitVec::from_elem(1, true);
+        assert!(act.eq_vec(&[true]));
+        assert!(!act.none() && act.all());
+    }
+
+    #[test]
+    fn test_2_elements() {
+        let mut b = BitVec::from_elem(2, false);
+        b.set(0, true);
+        b.set(1, false);
+        assert_eq!(format!("{:?}", b), "10");
+        assert!(!b.none() && !b.all());
+    }
+
+    #[test]
+    fn test_10_elements() {
+        let mut act;
+        // all 0
+
+        act = BitVec::from_elem(10, false);
+        assert!((act.eq_vec(
+                    &[false, false, false, false, false, false, false, false, false, false])));
+        assert!(act.none() && !act.all());
+        // all 1
+
+        act = BitVec::from_elem(10, true);
+        assert!((act.eq_vec(&[true, true, true, true, true, true, true, true, true, true])));
+        assert!(!act.none() && act.all());
+        // mixed
+
+        act = BitVec::from_elem(10, false);
+        act.set(0, true);
+        act.set(1, true);
+        act.set(2, true);
+        act.set(3, true);
+        act.set(4, true);
+        assert!((act.eq_vec(&[true, true, true, true, true, false, false, false, false, false])));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(10, false);
+        act.set(5, true);
+        act.set(6, true);
+        act.set(7, true);
+        act.set(8, true);
+        act.set(9, true);
+        assert!((act.eq_vec(&[false, false, false, false, false, true, true, true, true, true])));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(10, false);
+        act.set(0, true);
+        act.set(3, true);
+        act.set(6, true);
+        act.set(9, true);
+        assert!((act.eq_vec(&[true, false, false, true, false, false, true, false, false, true])));
+        assert!(!act.none() && !act.all());
+    }
+
+    #[test]
+    fn test_31_elements() {
+        let mut act;
+        // all 0
+
+        act = BitVec::from_elem(31, false);
+        assert!(act.eq_vec(
+                &[false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false]));
+        assert!(act.none() && !act.all());
+        // all 1
+
+        act = BitVec::from_elem(31, true);
+        assert!(act.eq_vec(
+                &[true, true, true, true, true, true, true, true, true, true, true, true, true,
+                  true, true, true, true, true, true, true, true, true, true, true, true, true,
+                  true, true, true, true, true]));
+        assert!(!act.none() && act.all());
+        // mixed
+
+        act = BitVec::from_elem(31, false);
+        act.set(0, true);
+        act.set(1, true);
+        act.set(2, true);
+        act.set(3, true);
+        act.set(4, true);
+        act.set(5, true);
+        act.set(6, true);
+        act.set(7, true);
+        assert!(act.eq_vec(
+                &[true, true, true, true, true, true, true, true, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false]));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(31, false);
+        act.set(16, true);
+        act.set(17, true);
+        act.set(18, true);
+        act.set(19, true);
+        act.set(20, true);
+        act.set(21, true);
+        act.set(22, true);
+        act.set(23, true);
+        assert!(act.eq_vec(
+                &[false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, true, true, true, true, true, true, true, true,
+                  false, false, false, false, false, false, false]));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(31, false);
+        act.set(24, true);
+        act.set(25, true);
+        act.set(26, true);
+        act.set(27, true);
+        act.set(28, true);
+        act.set(29, true);
+        act.set(30, true);
+        assert!(act.eq_vec(
+                &[false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, true, true, true, true, true, true, true]));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(31, false);
+        act.set(3, true);
+        act.set(17, true);
+        act.set(30, true);
+        assert!(act.eq_vec(
+                &[false, false, false, true, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, true, false, false, false, false, false, false,
+                  false, false, false, false, false, false, true]));
+        assert!(!act.none() && !act.all());
+    }
+
+    #[test]
+    fn test_32_elements() {
+        let mut act;
+        // all 0
+
+        act = BitVec::from_elem(32, false);
+        assert!(act.eq_vec(
+                &[false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false]));
+        assert!(act.none() && !act.all());
+        // all 1
+
+        act = BitVec::from_elem(32, true);
+        assert!(act.eq_vec(
+                &[true, true, true, true, true, true, true, true, true, true, true, true, true,
+                  true, true, true, true, true, true, true, true, true, true, true, true, true,
+                  true, true, true, true, true, true]));
+        assert!(!act.none() && act.all());
+        // mixed
+
+        act = BitVec::from_elem(32, false);
+        act.set(0, true);
+        act.set(1, true);
+        act.set(2, true);
+        act.set(3, true);
+        act.set(4, true);
+        act.set(5, true);
+        act.set(6, true);
+        act.set(7, true);
+        assert!(act.eq_vec(
+                &[true, true, true, true, true, true, true, true, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false]));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(32, false);
+        act.set(16, true);
+        act.set(17, true);
+        act.set(18, true);
+        act.set(19, true);
+        act.set(20, true);
+        act.set(21, true);
+        act.set(22, true);
+        act.set(23, true);
+        assert!(act.eq_vec(
+                &[false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, true, true, true, true, true, true, true, true,
+                  false, false, false, false, false, false, false, false]));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(32, false);
+        act.set(24, true);
+        act.set(25, true);
+        act.set(26, true);
+        act.set(27, true);
+        act.set(28, true);
+        act.set(29, true);
+        act.set(30, true);
+        act.set(31, true);
+        assert!(act.eq_vec(
+                &[false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, true, true, true, true, true, true, true, true]));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(32, false);
+        act.set(3, true);
+        act.set(17, true);
+        act.set(30, true);
+        act.set(31, true);
+        assert!(act.eq_vec(
+                &[false, false, false, true, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, true, false, false, false, false, false, false,
+                  false, false, false, false, false, false, true, true]));
+        assert!(!act.none() && !act.all());
+    }
+
+    #[test]
+    fn test_33_elements() {
+        let mut act;
+        // all 0
+
+        act = BitVec::from_elem(33, false);
+        assert!(act.eq_vec(
+                &[false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false, false]));
+        assert!(act.none() && !act.all());
+        // all 1
+
+        act = BitVec::from_elem(33, true);
+        assert!(act.eq_vec(
+                &[true, true, true, true, true, true, true, true, true, true, true, true, true,
+                  true, true, true, true, true, true, true, true, true, true, true, true, true,
+                  true, true, true, true, true, true, true]));
+        assert!(!act.none() && act.all());
+        // mixed
+
+        act = BitVec::from_elem(33, false);
+        act.set(0, true);
+        act.set(1, true);
+        act.set(2, true);
+        act.set(3, true);
+        act.set(4, true);
+        act.set(5, true);
+        act.set(6, true);
+        act.set(7, true);
+        assert!(act.eq_vec(
+                &[true, true, true, true, true, true, true, true, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false]));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(33, false);
+        act.set(16, true);
+        act.set(17, true);
+        act.set(18, true);
+        act.set(19, true);
+        act.set(20, true);
+        act.set(21, true);
+        act.set(22, true);
+        act.set(23, true);
+        assert!(act.eq_vec(
+                &[false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, true, true, true, true, true, true, true, true,
+                  false, false, false, false, false, false, false, false, false]));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(33, false);
+        act.set(24, true);
+        act.set(25, true);
+        act.set(26, true);
+        act.set(27, true);
+        act.set(28, true);
+        act.set(29, true);
+        act.set(30, true);
+        act.set(31, true);
+        assert!(act.eq_vec(
+                &[false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, false, false, false, false, false, false,
+                  false, false, true, true, true, true, true, true, true, true, false]));
+        assert!(!act.none() && !act.all());
+        // mixed
+
+        act = BitVec::from_elem(33, false);
+        act.set(3, true);
+        act.set(17, true);
+        act.set(30, true);
+        act.set(31, true);
+        act.set(32, true);
+        assert!(act.eq_vec(
+                &[false, false, false, true, false, false, false, false, false, false, false, false,
+                  false, false, false, false, false, true, false, false, false, false, false, false,
+                  false, false, false, false, false, false, true, true, true]));
+        assert!(!act.none() && !act.all());
+    }
+
+    #[test]
+    fn test_equal_differing_sizes() {
+        let v0 = BitVec::from_elem(10, false);
+        let v1 = BitVec::from_elem(11, false);
+        assert_ne!(v0, v1);
+    }
+
+    #[test]
+    fn test_equal_greatly_differing_sizes() {
+        let v0 = BitVec::from_elem(10, false);
+        let v1 = BitVec::from_elem(110, false);
+        assert_ne!(v0, v1);
+    }
+
+    #[test]
+    fn test_equal_sneaky_small() {
+        let mut a = BitVec::from_elem(1, false);
+        a.set(0, true);
+
+        let mut b = BitVec::from_elem(1, true);
+        b.set(0, true);
+
+        assert_eq!(a, b);
+    }
+
+    #[test]
+    fn test_equal_sneaky_big() {
+        let mut a = BitVec::from_elem(100, false);
+        for i in 0..100 {
+            a.set(i, true);
+        }
+
+        let mut b = BitVec::from_elem(100, true);
+        for i in 0..100 {
+            b.set(i, true);
+        }
+
+        assert_eq!(a, b);
+    }
+
+    #[test]
+    fn test_from_bytes() {
+        let bit_vec = BitVec::from_bytes(&[0b10110110, 0b00000000, 0b11111111]);
+        let str = concat!("10110110", "00000000", "11111111");
+        assert_eq!(format!("{:?}", bit_vec), str);
+    }
+
+    #[test]
+    fn test_to_bytes() {
+        let mut bv = BitVec::from_elem(3, true);
+        bv.set(1, false);
+        assert_eq!(bv.to_bytes(), [0b10100000]);
+
+        let mut bv = BitVec::from_elem(9, false);
+        bv.set(2, true);
+        bv.set(8, true);
+        assert_eq!(bv.to_bytes(), [0b00100000, 0b10000000]);
+    }
+
+    #[test]
+    fn test_from_bools() {
+        let bools = vec![true, false, true, true];
+        let bit_vec: BitVec = bools.iter().map(|n| *n).collect();
+        assert_eq!(format!("{:?}", bit_vec), "1011");
+    }
+
+    #[test]
+    fn test_to_bools() {
+        let bools = vec![false, false, true, false, false, true, true, false];
+        assert_eq!(BitVec::from_bytes(&[0b00100110]).iter().collect::<Vec<bool>>(), bools);
+    }
+
+    #[test]
+    fn test_bit_vec_iterator() {
+        let bools = vec![true, false, true, true];
+        let bit_vec: BitVec = bools.iter().map(|n| *n).collect();
+
+        assert_eq!(bit_vec.iter().collect::<Vec<bool>>(), bools);
+
+        let long: Vec<_> = (0..10000).map(|i| i % 2 == 0).collect();
+        let bit_vec: BitVec = long.iter().map(|n| *n).collect();
+        assert_eq!(bit_vec.iter().collect::<Vec<bool>>(), long)
+    }
+
+    #[test]
+    fn test_small_difference() {
+        let mut b1 = BitVec::from_elem(3, false);
+        let mut b2 = BitVec::from_elem(3, false);
+        b1.set(0, true);
+        b1.set(1, true);
+        b2.set(1, true);
+        b2.set(2, true);
+        assert!(b1.difference(&b2));
+        assert!(b1[0]);
+        assert!(!b1[1]);
+        assert!(!b1[2]);
+    }
+
+    #[test]
+    fn test_big_difference() {
+        let mut b1 = BitVec::from_elem(100, false);
+        let mut b2 = BitVec::from_elem(100, false);
+        b1.set(0, true);
+        b1.set(40, true);
+        b2.set(40, true);
+        b2.set(80, true);
+        assert!(b1.difference(&b2));
+        assert!(b1[0]);
+        assert!(!b1[40]);
+        assert!(!b1[80]);
+    }
+
+    #[test]
+    fn test_small_xor() {
+        let mut a = BitVec::from_bytes(&[0b0011]);
+        let b = BitVec::from_bytes(&[0b0101]);
+        let c = BitVec::from_bytes(&[0b0110]);
+        assert!(a.xor(&b));
+        assert_eq!(a,c);
+    }
+
+    #[test]
+    fn test_small_xnor() {
+        let mut a = BitVec::from_bytes(&[0b0011]);
+        let b = BitVec::from_bytes(&[0b1111_0101]);
+        let c = BitVec::from_bytes(&[0b1001]);
+        assert!(a.xnor(&b));
+        assert_eq!(a,c);
+    }
+
+    #[test]
+    fn test_small_nand() {
+        let mut a = BitVec::from_bytes(&[0b1111_0011]);
+        let b = BitVec::from_bytes(&[0b1111_0101]);
+        let c = BitVec::from_bytes(&[0b1110]);
+        assert!(a.nand(&b));
+        assert_eq!(a,c);
+    }
+
+    #[test]
+    fn test_small_nor() {
+        let mut a = BitVec::from_bytes(&[0b0011]);
+        let b = BitVec::from_bytes(&[0b1111_0101]);
+        let c = BitVec::from_bytes(&[0b1000]);
+        assert!(a.nor(&b));
+        assert_eq!(a,c);
+    }
+
+    #[test]
+    fn test_big_xor() {
+        let mut a = BitVec::from_bytes(&[ // 88 bits
+            0, 0, 0b00010100, 0,
+            0, 0, 0, 0b00110100,
+            0, 0, 0]);
+        let b = BitVec::from_bytes(&[ // 88 bits
+            0, 0, 0b00010100, 0,
+            0, 0, 0, 0,
+            0, 0, 0b00110100]);
+        let c = BitVec::from_bytes(&[ // 88 bits
+            0, 0, 0, 0,
+            0, 0, 0, 0b00110100,
+            0, 0, 0b00110100]);
+        assert!(a.xor(&b));
+        assert_eq!(a,c);
+    }
+
+    #[test]
+    fn test_big_xnor() {
+        let mut a = BitVec::from_bytes(&[ // 88 bits
+            0, 0, 0b00010100, 0,
+            0, 0, 0, 0b00110100,
+            0, 0, 0]);
+        let b = BitVec::from_bytes(&[ // 88 bits
+            0, 0, 0b00010100, 0,
+            0, 0, 0, 0,
+            0, 0, 0b00110100]);
+        let c = BitVec::from_bytes(&[ // 88 bits
+            !0, !0, !0, !0,
+            !0, !0, !0, !0b00110100,
+            !0, !0, !0b00110100]);
+        assert!(a.xnor(&b));
+        assert_eq!(a,c);
+    }
+
+    #[test]
+    fn test_small_clear() {
+        let mut b = BitVec::from_elem(14, true);
+        assert!(!b.none() && b.all());
+        b.clear();
+        assert!(b.none() && !b.all());
+    }
+
+    #[test]
+    fn test_big_clear() {
+        let mut b = BitVec::from_elem(140, true);
+        assert!(!b.none() && b.all());
+        b.clear();
+        assert!(b.none() && !b.all());
+    }
+
+    #[test]
+    fn test_bit_vec_lt() {
+        let mut a = BitVec::from_elem(5, false);
+        let mut b = BitVec::from_elem(5, false);
+
+        assert!(!(a < b) && !(b < a));
+        b.set(2, true);
+        assert!(a < b);
+        a.set(3, true);
+        assert!(a < b);
+        a.set(2, true);
+        assert!(!(a < b) && b < a);
+        b.set(0, true);
+        assert!(a < b);
+    }
+
+    #[test]
+    fn test_ord() {
+        let mut a = BitVec::from_elem(5, false);
+        let mut b = BitVec::from_elem(5, false);
+
+        assert!(a <= b && a >= b);
+        a.set(1, true);
+        assert!(a > b && a >= b);
+        assert!(b < a && b <= a);
+        b.set(1, true);
+        b.set(2, true);
+        assert!(b > a && b >= a);
+        assert!(a < b && a <= b);
+    }
+
+    #[test]
+    fn test_small_bit_vec_tests() {
+        let v = BitVec::from_bytes(&[0]);
+        assert!(!v.all());
+        assert!(!v.any());
+        assert!(v.none());
+
+        let v = BitVec::from_bytes(&[0b00010100]);
+        assert!(!v.all());
+        assert!(v.any());
+        assert!(!v.none());
+
+        let v = BitVec::from_bytes(&[0xFF]);
+        assert!(v.all());
+        assert!(v.any());
+        assert!(!v.none());
+    }
+
+    #[test]
+    fn test_big_bit_vec_tests() {
+        let v = BitVec::from_bytes(&[ // 88 bits
+            0, 0, 0, 0,
+            0, 0, 0, 0,
+            0, 0, 0]);
+        assert!(!v.all());
+        assert!(!v.any());
+        assert!(v.none());
+
+        let v = BitVec::from_bytes(&[ // 88 bits
+            0, 0, 0b00010100, 0,
+            0, 0, 0, 0b00110100,
+            0, 0, 0]);
+        assert!(!v.all());
+        assert!(v.any());
+        assert!(!v.none());
+
+        let v = BitVec::from_bytes(&[ // 88 bits
+            0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF]);
+        assert!(v.all());
+        assert!(v.any());
+        assert!(!v.none());
+    }
+
+    #[test]
+    fn test_bit_vec_push_pop() {
+        let mut s = BitVec::from_elem(5 * U32_BITS - 2, false);
+        assert_eq!(s.len(), 5 * U32_BITS - 2);
+        assert_eq!(s[5 * U32_BITS - 3], false);
+        s.push(true);
+        s.push(true);
+        assert_eq!(s[5 * U32_BITS - 2], true);
+        assert_eq!(s[5 * U32_BITS - 1], true);
+        // Here the internal vector will need to be extended
+        s.push(false);
+        assert_eq!(s[5 * U32_BITS], false);
+        s.push(false);
+        assert_eq!(s[5 * U32_BITS + 1], false);
+        assert_eq!(s.len(), 5 * U32_BITS + 2);
+        // Pop it all off
+        assert_eq!(s.pop(), Some(false));
+        assert_eq!(s.pop(), Some(false));
+        assert_eq!(s.pop(), Some(true));
+        assert_eq!(s.pop(), Some(true));
+        assert_eq!(s.len(), 5 * U32_BITS - 2);
+    }
+
+    #[test]
+    fn test_bit_vec_truncate() {
+        let mut s = BitVec::from_elem(5 * U32_BITS, true);
+
+        assert_eq!(s, BitVec::from_elem(5 * U32_BITS, true));
+        assert_eq!(s.len(), 5 * U32_BITS);
+        s.truncate(4 * U32_BITS);
+        assert_eq!(s, BitVec::from_elem(4 * U32_BITS, true));
+        assert_eq!(s.len(), 4 * U32_BITS);
+        // Truncating to a size > s.len() should be a noop
+        s.truncate(5 * U32_BITS);
+        assert_eq!(s, BitVec::from_elem(4 * U32_BITS, true));
+        assert_eq!(s.len(), 4 * U32_BITS);
+        s.truncate(3 * U32_BITS - 10);
+        assert_eq!(s, BitVec::from_elem(3 * U32_BITS - 10, true));
+        assert_eq!(s.len(), 3 * U32_BITS - 10);
+        s.truncate(0);
+        assert_eq!(s, BitVec::from_elem(0, true));
+        assert_eq!(s.len(), 0);
+    }
+
+    #[test]
+    fn test_bit_vec_reserve() {
+        let mut s = BitVec::from_elem(5 * U32_BITS, true);
+        // Check capacity
+        assert!(s.capacity() >= 5 * U32_BITS);
+        s.reserve(2 * U32_BITS);
+        assert!(s.capacity() >= 7 * U32_BITS);
+        s.reserve(7 * U32_BITS);
+        assert!(s.capacity() >= 12 * U32_BITS);
+        s.reserve_exact(7 * U32_BITS);
+        assert!(s.capacity() >= 12 * U32_BITS);
+        s.reserve(7 * U32_BITS + 1);
+        assert!(s.capacity() >= 12 * U32_BITS + 1);
+        // Check that length hasn't changed
+        assert_eq!(s.len(), 5 * U32_BITS);
+        s.push(true);
+        s.push(false);
+        s.push(true);
+        assert_eq!(s[5 * U32_BITS - 1], true);
+        assert_eq!(s[5 * U32_BITS - 0], true);
+        assert_eq!(s[5 * U32_BITS + 1], false);
+        assert_eq!(s[5 * U32_BITS + 2], true);
+    }
+
+    #[test]
+    fn test_bit_vec_grow() {
+        let mut bit_vec = BitVec::from_bytes(&[0b10110110, 0b00000000, 0b10101010]);
+        bit_vec.grow(32, true);
+        assert_eq!(bit_vec, BitVec::from_bytes(&[0b10110110, 0b00000000, 0b10101010,
+                                     0xFF, 0xFF, 0xFF, 0xFF]));
+        bit_vec.grow(64, false);
+        assert_eq!(bit_vec, BitVec::from_bytes(&[0b10110110, 0b00000000, 0b10101010,
+                                     0xFF, 0xFF, 0xFF, 0xFF, 0, 0, 0, 0, 0, 0, 0, 0]));
+        bit_vec.grow(16, true);
+        assert_eq!(bit_vec, BitVec::from_bytes(&[0b10110110, 0b00000000, 0b10101010,
+                                     0xFF, 0xFF, 0xFF, 0xFF, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF]));
+    }
+
+    #[test]
+    fn test_bit_vec_extend() {
+        let mut bit_vec = BitVec::from_bytes(&[0b10110110, 0b00000000, 0b11111111]);
+        let ext = BitVec::from_bytes(&[0b01001001, 0b10010010, 0b10111101]);
+        bit_vec.extend(ext.iter());
+        assert_eq!(bit_vec, BitVec::from_bytes(&[0b10110110, 0b00000000, 0b11111111,
+                                     0b01001001, 0b10010010, 0b10111101]));
+    }
+
+    #[test]
+    fn test_bit_vec_append() {
+        // Append to BitVec that holds a multiple of U32_BITS bits
+        let mut a = BitVec::from_bytes(&[0b10100000, 0b00010010, 0b10010010, 0b00110011]);
+        let mut b = BitVec::new();
+        b.push(false);
+        b.push(true);
+        b.push(true);
+
+        a.append(&mut b);
+
+        assert_eq!(a.len(), 35);
+        assert_eq!(b.len(), 0);
+        assert!(b.capacity() >= 3);
+
+        assert!(a.eq_vec(&[true, false, true, false, false, false, false, false,
+                           false, false, false, true, false, false, true, false,
+                           true, false, false, true, false, false, true, false,
+                           false, false, true, true, false, false, true, true,
+                           false, true, true]));
+
+        // Append to arbitrary BitVec
+        let mut a = BitVec::new();
+        a.push(true);
+        a.push(false);
+
+        let mut b = BitVec::from_bytes(&[0b10100000, 0b00010010, 0b10010010, 0b00110011, 0b10010101]);
+
+        a.append(&mut b);
+
+        assert_eq!(a.len(), 42);
+        assert_eq!(b.len(), 0);
+        assert!(b.capacity() >= 40);
+
+        assert!(a.eq_vec(&[true, false, true, false, true, false, false, false,
+                           false, false, false, false, false, true, false, false,
+                           true, false, true, false, false, true, false, false,
+                           true, false, false, false, true, true, false, false,
+                           true, true, true, false, false, true, false, true,
+                           false, true]));
+
+        // Append to empty BitVec
+        let mut a = BitVec::new();
+        let mut b = BitVec::from_bytes(&[0b10100000, 0b00010010, 0b10010010, 0b00110011, 0b10010101]);
+
+        a.append(&mut b);
+
+        assert_eq!(a.len(), 40);
+        assert_eq!(b.len(), 0);
+        assert!(b.capacity() >= 40);
+
+        assert!(a.eq_vec(&[true, false, true, false, false, false, false, false,
+                           false, false, false, true, false, false, true, false,
+                           true, false, false, true, false, false, true, false,
+                           false, false, true, true, false, false, true, true,
+                           true, false, false, true, false, true, false, true]));
+
+        // Append empty BitVec
+        let mut a = BitVec::from_bytes(&[0b10100000, 0b00010010, 0b10010010, 0b00110011, 0b10010101]);
+        let mut b = BitVec::new();
+
+        a.append(&mut b);
+
+        assert_eq!(a.len(), 40);
+        assert_eq!(b.len(), 0);
+
+        assert!(a.eq_vec(&[true, false, true, false, false, false, false, false,
+                           false, false, false, true, false, false, true, false,
+                           true, false, false, true, false, false, true, false,
+                           false, false, true, true, false, false, true, true,
+                           true, false, false, true, false, true, false, true]));
+    }
+
+    #[test]
+    fn test_bit_vec_split_off() {
+        // Split at 0
+        let mut a = BitVec::new();
+        a.push(true);
+        a.push(false);
+        a.push(false);
+        a.push(true);
+
+        let b = a.split_off(0);
+
+        assert_eq!(a.len(), 0);
+        assert_eq!(b.len(), 4);
+
+        assert!(b.eq_vec(&[true, false, false, true]));
+
+        // Split at last bit
+        a.truncate(0);
+        a.push(true);
+        a.push(false);
+        a.push(false);
+        a.push(true);
+
+        let b = a.split_off(4);
+
+        assert_eq!(a.len(), 4);
+        assert_eq!(b.len(), 0);
+
+        assert!(a.eq_vec(&[true, false, false, true]));
+
+        // Split at block boundary
+        let mut a = BitVec::from_bytes(&[0b10100000, 0b00010010, 0b10010010, 0b00110011, 0b11110011]);
+
+        let b = a.split_off(32);
+
+        assert_eq!(a.len(), 32);
+        assert_eq!(b.len(), 8);
+
+        assert!(a.eq_vec(&[true, false, true, false, false, false, false, false,
+                           false, false, false, true, false, false, true, false,
+                           true, false, false, true, false, false, true, false,
+                           false, false, true, true, false, false, true, true]));
+        assert!(b.eq_vec(&[true, true, true, true, false, false, true, true]));
+
+        // Don't split at block boundary
+        let mut a = BitVec::from_bytes(&[0b10100000, 0b00010010, 0b10010010, 0b00110011,
+                                         0b01101011, 0b10101101]);
+
+        let b = a.split_off(13);
+
+        assert_eq!(a.len(), 13);
+        assert_eq!(b.len(), 35);
+
+        assert!(a.eq_vec(&[true, false, true, false, false, false, false, false,
+                           false, false, false, true, false]));
+        assert!(b.eq_vec(&[false, true, false, true, false, false, true, false,
+                           false, true, false, false, false, true, true, false,
+                           false, true, true, false, true, true, false, true,
+                           false, true, true,  true, false, true, false, true,
+                           true, false, true]));
+    }
+
+    #[test]
+    fn test_into_iter() {
+        let bools = vec![true, false, true, true];
+        let bit_vec: BitVec = bools.iter().map(|n| *n).collect();
+        let mut iter = bit_vec.into_iter();
+        assert_eq!(Some(true), iter.next());
+        assert_eq!(Some(false), iter.next());
+        assert_eq!(Some(true), iter.next());
+        assert_eq!(Some(true), iter.next());
+        assert_eq!(None, iter.next());
+        assert_eq!(None, iter.next());
+
+        let bit_vec: BitVec = bools.iter().map(|n| *n).collect();
+        let mut iter = bit_vec.into_iter();
+        assert_eq!(Some(true), iter.next_back());
+        assert_eq!(Some(true), iter.next_back());
+        assert_eq!(Some(false), iter.next_back());
+        assert_eq!(Some(true), iter.next_back());
+        assert_eq!(None, iter.next_back());
+        assert_eq!(None, iter.next_back());
+
+        let bit_vec: BitVec = bools.iter().map(|n| *n).collect();
+        let mut iter = bit_vec.into_iter();
+        assert_eq!(Some(true), iter.next_back());
+        assert_eq!(Some(true), iter.next());
+        assert_eq!(Some(false), iter.next());
+        assert_eq!(Some(true), iter.next_back());
+        assert_eq!(None, iter.next());
+        assert_eq!(None, iter.next_back());
+    }
+
+    #[test]
+    fn iter() {
+        let b = BitVec::with_capacity(10);
+        let _a: Iter = b.iter();
+    }
+
+    #[cfg(feature="serde")]
+    #[test]
+    fn test_serialization() {
+        let bit_vec: BitVec = BitVec::new();
+        let serialized = serde_json::to_string(&bit_vec).unwrap();
+        let unserialized: BitVec = serde_json::from_str(&serialized).unwrap();
+        assert_eq!(bit_vec, unserialized);
+
+        let bools = vec![true, false, true, true];
+        let bit_vec: BitVec = bools.iter().map(|n| *n).collect();
+        let serialized = serde_json::to_string(&bit_vec).unwrap();
+        let unserialized = serde_json::from_str(&serialized).unwrap();
+        assert_eq!(bit_vec, unserialized);
+    }
+
+    #[test]
+    fn test_bit_vec_unaligned_small_append() {
+        let mut a = BitVec::from_elem(8, false);
+        a.set(7, true);
+
+        let mut b = BitVec::from_elem(16, false);
+        b.set(14, true);
+
+        let mut c = BitVec::from_elem(8, false);
+        c.set(6, true);
+        c.set(7, true);
+
+        a.append(&mut b);
+        a.append(&mut c);
+
+        assert_eq!(&[01, 00, 02, 03][..], &*a.to_bytes());
+    }
+
+    #[test]
+    fn test_bit_vec_unaligned_large_append() {
+        let mut a = BitVec::from_elem(48, false);
+        a.set(47, true);
+
+        let mut b = BitVec::from_elem(48, false);
+        b.set(46, true);
+
+        let mut c = BitVec::from_elem(48, false);
+        c.set(46, true);
+        c.set(47, true);
+
+        a.append(&mut b);
+        a.append(&mut c);
+
+        assert_eq!(&[0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+                     0x00, 0x00, 0x00, 0x00, 0x00, 0x02,
+                     0x00, 0x00, 0x00, 0x00, 0x00, 0x03][..], &*a.to_bytes());
+    }
+
+    #[test]
+    fn test_bit_vec_append_aligned_to_unaligned() {
+        let mut a = BitVec::from_elem(2, true);
+        let mut b = BitVec::from_elem(32, false);
+        let mut c = BitVec::from_elem(8, true);
+        a.append(&mut b);
+        a.append(&mut c);
+        assert_eq!(&[0xc0, 0x00, 0x00, 0x00, 0x3f, 0xc0][..], &*a.to_bytes());
+    }
+}