Adding upstream version 124.0.1.upstream/124.0.1

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

1 files changed, 1608 insertions, 0 deletions

diff --git a/third_party/rust/bit-set/src/lib.rs b/third_party/rust/bit-set/src/lib.rs
new file mode 100644
index 0000000000..80ee6245f8
--- /dev/null
+++ b/third_party/rust/bit-set/src/lib.rs
@@ -0,0 +1,1608 @@
+// Copyright 2012-2014 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.
+
+//! An implementation of a set using a bit vector as an underlying
+//! representation for holding unsigned numerical elements.
+//!
+//! It should also be noted that the amount of storage necessary for holding a
+//! set of objects is proportional to the maximum of the objects when viewed
+//! as a `usize`.
+//!
+//! # Examples
+//!
+//! ```
+//! use bit_set::BitSet;
+//!
+//! // It's a regular set
+//! let mut s = BitSet::new();
+//! s.insert(0);
+//! s.insert(3);
+//! s.insert(7);
+//!
+//! s.remove(7);
+//!
+//! if !s.contains(7) {
+//!     println!("There is no 7");
+//! }
+//!
+//! // Can initialize from a `BitVec`
+//! let other = BitSet::from_bytes(&[0b11010000]);
+//!
+//! s.union_with(&other);
+//!
+//! // Print 0, 1, 3 in some order
+//! for x in s.iter() {
+//!     println!("{}", x);
+//! }
+//!
+//! // Can convert back to a `BitVec`
+//! let bv = s.into_bit_vec();
+//! assert!(bv[3]);
+//! ```
+
+#![no_std]
+#![cfg_attr(all(test, feature = "nightly"), feature(test))]
+extern crate bit_vec;
+#[cfg(all(test, feature = "nightly"))]
+extern crate rand;
+#[cfg(all(test, feature = "nightly"))]
+extern crate test;
+
+#[cfg(test)]
+#[macro_use]
+extern crate std;
+
+use bit_vec::{BitBlock, BitVec, Blocks};
+use core::cmp;
+use core::cmp::Ordering;
+use core::fmt;
+use core::hash;
+use core::iter::{self, Chain, Enumerate, FromIterator, Repeat, Skip, Take};
+
+type MatchWords<'a, B> = Chain<Enumerate<Blocks<'a, B>>, Skip<Take<Enumerate<Repeat<B>>>>>;
+
+/// 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 + 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
+    }
+}
+
+// Take two BitVec's, and return iterators of their words, where the shorter one
+// has been padded with 0's
+fn match_words<'a, 'b, B: BitBlock>(
+    a: &'a BitVec<B>,
+    b: &'b BitVec<B>,
+) -> (MatchWords<'a, B>, MatchWords<'b, B>) {
+    let a_len = a.storage().len();
+    let b_len = b.storage().len();
+
+    // have to uselessly pretend to pad the longer one for type matching
+    if a_len < b_len {
+        (
+            a.blocks()
+                .enumerate()
+                .chain(iter::repeat(B::zero()).enumerate().take(b_len).skip(a_len)),
+            b.blocks()
+                .enumerate()
+                .chain(iter::repeat(B::zero()).enumerate().take(0).skip(0)),
+        )
+    } else {
+        (
+            a.blocks()
+                .enumerate()
+                .chain(iter::repeat(B::zero()).enumerate().take(0).skip(0)),
+            b.blocks()
+                .enumerate()
+                .chain(iter::repeat(B::zero()).enumerate().take(a_len).skip(b_len)),
+        )
+    }
+}
+
+pub struct BitSet<B = u32> {
+    bit_vec: BitVec<B>,
+}
+
+impl<B: BitBlock> Clone for BitSet<B> {
+    fn clone(&self) -> Self {
+        BitSet {
+            bit_vec: self.bit_vec.clone(),
+        }
+    }
+
+    fn clone_from(&mut self, other: &Self) {
+        self.bit_vec.clone_from(&other.bit_vec);
+    }
+}
+
+impl<B: BitBlock> Default for BitSet<B> {
+    #[inline]
+    fn default() -> Self {
+        BitSet {
+            bit_vec: Default::default(),
+        }
+    }
+}
+
+impl<B: BitBlock> FromIterator<usize> for BitSet<B> {
+    fn from_iter<I: IntoIterator<Item = usize>>(iter: I) -> Self {
+        let mut ret = Self::default();
+        ret.extend(iter);
+        ret
+    }
+}
+
+impl<B: BitBlock> Extend<usize> for BitSet<B> {
+    #[inline]
+    fn extend<I: IntoIterator<Item = usize>>(&mut self, iter: I) {
+        for i in iter {
+            self.insert(i);
+        }
+    }
+}
+
+impl<B: BitBlock> PartialOrd for BitSet<B> {
+    #[inline]
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.iter().partial_cmp(other)
+    }
+}
+
+impl<B: BitBlock> Ord for BitSet<B> {
+    #[inline]
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.iter().cmp(other)
+    }
+}
+
+impl<B: BitBlock> PartialEq for BitSet<B> {
+    #[inline]
+    fn eq(&self, other: &Self) -> bool {
+        self.iter().eq(other)
+    }
+}
+
+impl<B: BitBlock> Eq for BitSet<B> {}
+
+impl BitSet<u32> {
+    /// Creates a new empty `BitSet`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let mut s = BitSet::new();
+    /// ```
+    #[inline]
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Creates a new `BitSet` with initially no contents, able to
+    /// hold `nbits` elements without resizing.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let mut s = BitSet::with_capacity(100);
+    /// assert!(s.capacity() >= 100);
+    /// ```
+    #[inline]
+    pub fn with_capacity(nbits: usize) -> Self {
+        let bit_vec = BitVec::from_elem(nbits, false);
+        Self::from_bit_vec(bit_vec)
+    }
+
+    /// Creates a new `BitSet` from the given bit vector.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// extern crate bit_vec;
+    /// extern crate bit_set;
+    ///
+    /// fn main() {
+    ///     use bit_vec::BitVec;
+    ///     use bit_set::BitSet;
+    ///
+    ///     let bv = BitVec::from_bytes(&[0b01100000]);
+    ///     let s = BitSet::from_bit_vec(bv);
+    ///
+    ///     // Print 1, 2 in arbitrary order
+    ///     for x in s.iter() {
+    ///         println!("{}", x);
+    ///     }
+    /// }
+    /// ```
+    #[inline]
+    pub fn from_bit_vec(bit_vec: BitVec) -> Self {
+        BitSet { bit_vec }
+    }
+
+    pub fn from_bytes(bytes: &[u8]) -> Self {
+        BitSet {
+            bit_vec: BitVec::from_bytes(bytes),
+        }
+    }
+}
+
+impl<B: BitBlock> BitSet<B> {
+    /// Returns the capacity in bits for this bit vector. Inserting any
+    /// element less than this amount will not trigger a resizing.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let mut s = BitSet::with_capacity(100);
+    /// assert!(s.capacity() >= 100);
+    /// ```
+    #[inline]
+    pub fn capacity(&self) -> usize {
+        self.bit_vec.capacity()
+    }
+
+    /// Reserves capacity for the given `BitSet` to contain `len` distinct elements. In the case
+    /// of `BitSet` this means reallocations will not occur as long as all inserted elements
+    /// are less than `len`.
+    ///
+    /// The collection may reserve more space to avoid frequent reallocations.
+    ///
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let mut s = BitSet::new();
+    /// s.reserve_len(10);
+    /// assert!(s.capacity() >= 10);
+    /// ```
+    pub fn reserve_len(&mut self, len: usize) {
+        let cur_len = self.bit_vec.len();
+        if len >= cur_len {
+            self.bit_vec.reserve(len - cur_len);
+        }
+    }
+
+    /// Reserves the minimum capacity for the given `BitSet` to contain `len` distinct elements.
+    /// In the case of `BitSet` this means reallocations will not occur as long as all inserted
+    /// elements are less than `len`.
+    ///
+    /// 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_len` if future
+    /// insertions are expected.
+    ///
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let mut s = BitSet::new();
+    /// s.reserve_len_exact(10);
+    /// assert!(s.capacity() >= 10);
+    /// ```
+    pub fn reserve_len_exact(&mut self, len: usize) {
+        let cur_len = self.bit_vec.len();
+        if len >= cur_len {
+            self.bit_vec.reserve_exact(len - cur_len);
+        }
+    }
+
+    /// Consumes this set to return the underlying bit vector.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let mut s = BitSet::new();
+    /// s.insert(0);
+    /// s.insert(3);
+    ///
+    /// let bv = s.into_bit_vec();
+    /// assert!(bv[0]);
+    /// assert!(bv[3]);
+    /// ```
+    #[inline]
+    pub fn into_bit_vec(self) -> BitVec<B> {
+        self.bit_vec
+    }
+
+    /// Returns a reference to the underlying bit vector.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let mut s = BitSet::new();
+    /// s.insert(0);
+    ///
+    /// let bv = s.get_ref();
+    /// assert_eq!(bv[0], true);
+    /// ```
+    #[inline]
+    pub fn get_ref(&self) -> &BitVec<B> {
+        &self.bit_vec
+    }
+
+    #[inline]
+    fn other_op<F>(&mut self, other: &Self, mut f: F)
+    where
+        F: FnMut(B, B) -> B,
+    {
+        // Unwrap BitVecs
+        let self_bit_vec = &mut self.bit_vec;
+        let other_bit_vec = &other.bit_vec;
+
+        let self_len = self_bit_vec.len();
+        let other_len = other_bit_vec.len();
+
+        // Expand the vector if necessary
+        if self_len < other_len {
+            self_bit_vec.grow(other_len - self_len, false);
+        }
+
+        // virtually pad other with 0's for equal lengths
+        let other_words = {
+            let (_, result) = match_words(self_bit_vec, other_bit_vec);
+            result
+        };
+
+        // Apply values found in other
+        for (i, w) in other_words {
+            let old = self_bit_vec.storage()[i];
+            let new = f(old, w);
+            unsafe {
+                self_bit_vec.storage_mut()[i] = new;
+            }
+        }
+    }
+
+    /// Truncates the underlying vector to the least length required.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let mut s = BitSet::new();
+    /// s.insert(32183231);
+    /// s.remove(32183231);
+    ///
+    /// // Internal storage will probably be bigger than necessary
+    /// println!("old capacity: {}", s.capacity());
+    ///
+    /// // Now should be smaller
+    /// s.shrink_to_fit();
+    /// println!("new capacity: {}", s.capacity());
+    /// ```
+    #[inline]
+    pub fn shrink_to_fit(&mut self) {
+        let bit_vec = &mut self.bit_vec;
+        // Obtain original length
+        let old_len = bit_vec.storage().len();
+        // Obtain coarse trailing zero length
+        let n = bit_vec
+            .storage()
+            .iter()
+            .rev()
+            .take_while(|&&n| n == B::zero())
+            .count();
+        // Truncate away all empty trailing blocks, then shrink_to_fit
+        let trunc_len = old_len - n;
+        unsafe {
+            bit_vec.storage_mut().truncate(trunc_len);
+            bit_vec.set_len(trunc_len * B::bits());
+            bit_vec.shrink_to_fit();
+        }
+    }
+
+    /// Iterator over each usize stored in the `BitSet`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let s = BitSet::from_bytes(&[0b01001010]);
+    ///
+    /// // Print 1, 4, 6 in arbitrary order
+    /// for x in s.iter() {
+    ///     println!("{}", x);
+    /// }
+    /// ```
+    #[inline]
+    pub fn iter(&self) -> Iter<B> {
+        Iter(BlockIter::from_blocks(self.bit_vec.blocks()))
+    }
+
+    /// Iterator over each usize stored in `self` union `other`.
+    /// See [union_with](#method.union_with) for an efficient in-place version.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let a = BitSet::from_bytes(&[0b01101000]);
+    /// let b = BitSet::from_bytes(&[0b10100000]);
+    ///
+    /// // Print 0, 1, 2, 4 in arbitrary order
+    /// for x in a.union(&b) {
+    ///     println!("{}", x);
+    /// }
+    /// ```
+    #[inline]
+    pub fn union<'a>(&'a self, other: &'a Self) -> Union<'a, B> {
+        fn or<B: BitBlock>(w1: B, w2: B) -> B {
+            w1 | w2
+        }
+
+        Union(BlockIter::from_blocks(TwoBitPositions {
+            set: self.bit_vec.blocks(),
+            other: other.bit_vec.blocks(),
+            merge: or,
+        }))
+    }
+
+    /// Iterator over each usize stored in `self` intersect `other`.
+    /// See [intersect_with](#method.intersect_with) for an efficient in-place version.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let a = BitSet::from_bytes(&[0b01101000]);
+    /// let b = BitSet::from_bytes(&[0b10100000]);
+    ///
+    /// // Print 2
+    /// for x in a.intersection(&b) {
+    ///     println!("{}", x);
+    /// }
+    /// ```
+    #[inline]
+    pub fn intersection<'a>(&'a self, other: &'a Self) -> Intersection<'a, B> {
+        fn bitand<B: BitBlock>(w1: B, w2: B) -> B {
+            w1 & w2
+        }
+        let min = cmp::min(self.bit_vec.len(), other.bit_vec.len());
+
+        Intersection(
+            BlockIter::from_blocks(TwoBitPositions {
+                set: self.bit_vec.blocks(),
+                other: other.bit_vec.blocks(),
+                merge: bitand,
+            })
+            .take(min),
+        )
+    }
+
+    /// Iterator over each usize stored in the `self` setminus `other`.
+    /// See [difference_with](#method.difference_with) for an efficient in-place version.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let a = BitSet::from_bytes(&[0b01101000]);
+    /// let b = BitSet::from_bytes(&[0b10100000]);
+    ///
+    /// // Print 1, 4 in arbitrary order
+    /// for x in a.difference(&b) {
+    ///     println!("{}", x);
+    /// }
+    ///
+    /// // Note that difference is not symmetric,
+    /// // and `b - a` means something else.
+    /// // This prints 0
+    /// for x in b.difference(&a) {
+    ///     println!("{}", x);
+    /// }
+    /// ```
+    #[inline]
+    pub fn difference<'a>(&'a self, other: &'a Self) -> Difference<'a, B> {
+        fn diff<B: BitBlock>(w1: B, w2: B) -> B {
+            w1 & !w2
+        }
+
+        Difference(BlockIter::from_blocks(TwoBitPositions {
+            set: self.bit_vec.blocks(),
+            other: other.bit_vec.blocks(),
+            merge: diff,
+        }))
+    }
+
+    /// Iterator over each usize stored in the symmetric difference of `self` and `other`.
+    /// See [symmetric_difference_with](#method.symmetric_difference_with) for
+    /// an efficient in-place version.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let a = BitSet::from_bytes(&[0b01101000]);
+    /// let b = BitSet::from_bytes(&[0b10100000]);
+    ///
+    /// // Print 0, 1, 4 in arbitrary order
+    /// for x in a.symmetric_difference(&b) {
+    ///     println!("{}", x);
+    /// }
+    /// ```
+    #[inline]
+    pub fn symmetric_difference<'a>(&'a self, other: &'a Self) -> SymmetricDifference<'a, B> {
+        fn bitxor<B: BitBlock>(w1: B, w2: B) -> B {
+            w1 ^ w2
+        }
+
+        SymmetricDifference(BlockIter::from_blocks(TwoBitPositions {
+            set: self.bit_vec.blocks(),
+            other: other.bit_vec.blocks(),
+            merge: bitxor,
+        }))
+    }
+
+    /// Unions in-place with the specified other bit vector.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let a   = 0b01101000;
+    /// let b   = 0b10100000;
+    /// let res = 0b11101000;
+    ///
+    /// let mut a = BitSet::from_bytes(&[a]);
+    /// let b = BitSet::from_bytes(&[b]);
+    /// let res = BitSet::from_bytes(&[res]);
+    ///
+    /// a.union_with(&b);
+    /// assert_eq!(a, res);
+    /// ```
+    #[inline]
+    pub fn union_with(&mut self, other: &Self) {
+        self.other_op(other, |w1, w2| w1 | w2);
+    }
+
+    /// Intersects in-place with the specified other bit vector.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let a   = 0b01101000;
+    /// let b   = 0b10100000;
+    /// let res = 0b00100000;
+    ///
+    /// let mut a = BitSet::from_bytes(&[a]);
+    /// let b = BitSet::from_bytes(&[b]);
+    /// let res = BitSet::from_bytes(&[res]);
+    ///
+    /// a.intersect_with(&b);
+    /// assert_eq!(a, res);
+    /// ```
+    #[inline]
+    pub fn intersect_with(&mut self, other: &Self) {
+        self.other_op(other, |w1, w2| w1 & w2);
+    }
+
+    /// Makes this bit vector the difference with the specified other bit vector
+    /// in-place.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let a   = 0b01101000;
+    /// let b   = 0b10100000;
+    /// let a_b = 0b01001000; // a - b
+    /// let b_a = 0b10000000; // b - a
+    ///
+    /// let mut bva = BitSet::from_bytes(&[a]);
+    /// let bvb = BitSet::from_bytes(&[b]);
+    /// let bva_b = BitSet::from_bytes(&[a_b]);
+    /// let bvb_a = BitSet::from_bytes(&[b_a]);
+    ///
+    /// bva.difference_with(&bvb);
+    /// assert_eq!(bva, bva_b);
+    ///
+    /// let bva = BitSet::from_bytes(&[a]);
+    /// let mut bvb = BitSet::from_bytes(&[b]);
+    ///
+    /// bvb.difference_with(&bva);
+    /// assert_eq!(bvb, bvb_a);
+    /// ```
+    #[inline]
+    pub fn difference_with(&mut self, other: &Self) {
+        self.other_op(other, |w1, w2| w1 & !w2);
+    }
+
+    /// Makes this bit vector the symmetric difference with the specified other
+    /// bit vector in-place.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bit_set::BitSet;
+    ///
+    /// let a   = 0b01101000;
+    /// let b   = 0b10100000;
+    /// let res = 0b11001000;
+    ///
+    /// let mut a = BitSet::from_bytes(&[a]);
+    /// let b = BitSet::from_bytes(&[b]);
+    /// let res = BitSet::from_bytes(&[res]);
+    ///
+    /// a.symmetric_difference_with(&b);
+    /// assert_eq!(a, res);
+    /// ```
+    #[inline]
+    pub fn symmetric_difference_with(&mut self, other: &Self) {
+        self.other_op(other, |w1, w2| w1 ^ w2);
+    }
+
+    /*
+        /// Moves all elements from `other` into `Self`, leaving `other` empty.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use bit_set::BitSet;
+        ///
+        /// let mut a = BitSet::new();
+        /// a.insert(2);
+        /// a.insert(6);
+        ///
+        /// let mut b = BitSet::new();
+        /// b.insert(1);
+        /// b.insert(3);
+        /// b.insert(6);
+        ///
+        /// a.append(&mut b);
+        ///
+        /// assert_eq!(a.len(), 4);
+        /// assert_eq!(b.len(), 0);
+        /// assert_eq!(a, BitSet::from_bytes(&[0b01110010]));
+        /// ```
+        pub fn append(&mut self, other: &mut Self) {
+            self.union_with(other);
+            other.clear();
+        }
+
+        /// Splits the `BitSet` into two at the given key including the key.
+        /// Retains the first part in-place while returning the second part.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use bit_set::BitSet;
+        ///
+        /// let mut a = BitSet::new();
+        /// a.insert(2);
+        /// a.insert(6);
+        /// a.insert(1);
+        /// a.insert(3);
+        ///
+        /// let b = a.split_off(3);
+        ///
+        /// assert_eq!(a.len(), 2);
+        /// assert_eq!(b.len(), 2);
+        /// assert_eq!(a, BitSet::from_bytes(&[0b01100000]));
+        /// assert_eq!(b, BitSet::from_bytes(&[0b00010010]));
+        /// ```
+        pub fn split_off(&mut self, at: usize) -> Self {
+            let mut other = BitSet::new();
+
+            if at == 0 {
+                swap(self, &mut other);
+                return other;
+            } else if at >= self.bit_vec.len() {
+                return other;
+            }
+
+            // Calculate block and bit at which to split
+            let w = at / BITS;
+            let b = at % BITS;
+
+            // Pad `other` with `w` zero blocks,
+            // append `self`'s blocks in the range from `w` to the end to `other`
+            other.bit_vec.storage_mut().extend(repeat(0u32).take(w)
+                                         .chain(self.bit_vec.storage()[w..].iter().cloned()));
+            other.bit_vec.nbits = self.bit_vec.nbits;
+
+            if b > 0 {
+                other.bit_vec.storage_mut()[w] &= !0 << b;
+            }
+
+            // Sets `bit_vec.len()` and fixes the last block as well
+            self.bit_vec.truncate(at);
+
+            other
+        }
+    */
+
+    /// Returns the number of set bits in this set.
+    #[inline]
+    pub fn len(&self) -> usize {
+        self.bit_vec
+            .blocks()
+            .fold(0, |acc, n| acc + n.count_ones() as usize)
+    }
+
+    /// Returns whether there are no bits set in this set
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.bit_vec.none()
+    }
+
+    /// Clears all bits in this set
+    #[inline]
+    pub fn clear(&mut self) {
+        self.bit_vec.clear();
+    }
+
+    /// Returns `true` if this set contains the specified integer.
+    #[inline]
+    pub fn contains(&self, value: usize) -> bool {
+        let bit_vec = &self.bit_vec;
+        value < bit_vec.len() && bit_vec[value]
+    }
+
+    /// Returns `true` if the set has no elements in common with `other`.
+    /// This is equivalent to checking for an empty intersection.
+    #[inline]
+    pub fn is_disjoint(&self, other: &Self) -> bool {
+        self.intersection(other).next().is_none()
+    }
+
+    /// Returns `true` if the set is a subset of another.
+    #[inline]
+    pub fn is_subset(&self, other: &Self) -> bool {
+        let self_bit_vec = &self.bit_vec;
+        let other_bit_vec = &other.bit_vec;
+        let other_blocks = blocks_for_bits::<B>(other_bit_vec.len());
+
+        // Check that `self` intersect `other` is self
+        self_bit_vec.blocks().zip(other_bit_vec.blocks()).all(|(w1, w2)| w1 & w2 == w1) &&
+        // Make sure if `self` has any more blocks than `other`, they're all 0
+        self_bit_vec.blocks().skip(other_blocks).all(|w| w == B::zero())
+    }
+
+    /// Returns `true` if the set is a superset of another.
+    #[inline]
+    pub fn is_superset(&self, other: &Self) -> bool {
+        other.is_subset(self)
+    }
+
+    /// Adds a value to the set. Returns `true` if the value was not already
+    /// present in the set.
+    pub fn insert(&mut self, value: usize) -> bool {
+        if self.contains(value) {
+            return false;
+        }
+
+        // Ensure we have enough space to hold the new element
+        let len = self.bit_vec.len();
+        if value >= len {
+            self.bit_vec.grow(value - len + 1, false)
+        }
+
+        self.bit_vec.set(value, true);
+        true
+    }
+
+    /// Removes a value from the set. Returns `true` if the value was
+    /// present in the set.
+    pub fn remove(&mut self, value: usize) -> bool {
+        if !self.contains(value) {
+            return false;
+        }
+
+        self.bit_vec.set(value, false);
+
+        true
+    }
+}
+
+impl<B: BitBlock> fmt::Debug for BitSet<B> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        fmt.debug_set().entries(self).finish()
+    }
+}
+
+impl<B: BitBlock> hash::Hash for BitSet<B> {
+    fn hash<H: hash::Hasher>(&self, state: &mut H) {
+        for pos in self {
+            pos.hash(state);
+        }
+    }
+}
+
+#[derive(Clone)]
+struct BlockIter<T, B> {
+    head: B,
+    head_offset: usize,
+    tail: T,
+}
+
+impl<T, B: BitBlock> BlockIter<T, B>
+where
+    T: Iterator<Item = B>,
+{
+    fn from_blocks(mut blocks: T) -> BlockIter<T, B> {
+        let h = blocks.next().unwrap_or_else(B::zero);
+        BlockIter {
+            tail: blocks,
+            head: h,
+            head_offset: 0,
+        }
+    }
+}
+
+/// An iterator combining two `BitSet` iterators.
+#[derive(Clone)]
+struct TwoBitPositions<'a, B: 'a> {
+    set: Blocks<'a, B>,
+    other: Blocks<'a, B>,
+    merge: fn(B, B) -> B,
+}
+
+/// An iterator for `BitSet`.
+#[derive(Clone)]
+pub struct Iter<'a, B: 'a>(BlockIter<Blocks<'a, B>, B>);
+#[derive(Clone)]
+pub struct Union<'a, B: 'a>(BlockIter<TwoBitPositions<'a, B>, B>);
+#[derive(Clone)]
+pub struct Intersection<'a, B: 'a>(Take<BlockIter<TwoBitPositions<'a, B>, B>>);
+#[derive(Clone)]
+pub struct Difference<'a, B: 'a>(BlockIter<TwoBitPositions<'a, B>, B>);
+#[derive(Clone)]
+pub struct SymmetricDifference<'a, B: 'a>(BlockIter<TwoBitPositions<'a, B>, B>);
+
+impl<'a, T, B: BitBlock> Iterator for BlockIter<T, B>
+where
+    T: Iterator<Item = B>,
+{
+    type Item = usize;
+
+    fn next(&mut self) -> Option<usize> {
+        while self.head == B::zero() {
+            match self.tail.next() {
+                Some(w) => self.head = w,
+                None => return None,
+            }
+            self.head_offset += B::bits();
+        }
+
+        // from the current block, isolate the
+        // LSB and subtract 1, producing k:
+        // a block with a number of set bits
+        // equal to the index of the LSB
+        let k = (self.head & (!self.head + B::one())) - B::one();
+        // update block, removing the LSB
+        self.head = self.head & (self.head - B::one());
+        // return offset + (index of LSB)
+        Some(self.head_offset + (B::count_ones(k) as usize))
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        match self.tail.size_hint() {
+            (_, Some(h)) => (0, Some(1 + h * B::bits())),
+            _ => (0, None),
+        }
+    }
+}
+
+impl<'a, B: BitBlock> Iterator for TwoBitPositions<'a, B> {
+    type Item = B;
+
+    fn next(&mut self) -> Option<B> {
+        match (self.set.next(), self.other.next()) {
+            (Some(a), Some(b)) => Some((self.merge)(a, b)),
+            (Some(a), None) => Some((self.merge)(a, B::zero())),
+            (None, Some(b)) => Some((self.merge)(B::zero(), b)),
+            _ => None,
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let (a, au) = self.set.size_hint();
+        let (b, bu) = self.other.size_hint();
+
+        let upper = match (au, bu) {
+            (Some(au), Some(bu)) => Some(cmp::max(au, bu)),
+            _ => None,
+        };
+
+        (cmp::max(a, b), upper)
+    }
+}
+
+impl<'a, B: BitBlock> Iterator for Iter<'a, B> {
+    type Item = usize;
+
+    #[inline]
+    fn next(&mut self) -> Option<usize> {
+        self.0.next()
+    }
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.0.size_hint()
+    }
+}
+
+impl<'a, B: BitBlock> Iterator for Union<'a, B> {
+    type Item = usize;
+
+    #[inline]
+    fn next(&mut self) -> Option<usize> {
+        self.0.next()
+    }
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.0.size_hint()
+    }
+}
+
+impl<'a, B: BitBlock> Iterator for Intersection<'a, B> {
+    type Item = usize;
+
+    #[inline]
+    fn next(&mut self) -> Option<usize> {
+        self.0.next()
+    }
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.0.size_hint()
+    }
+}
+
+impl<'a, B: BitBlock> Iterator for Difference<'a, B> {
+    type Item = usize;
+
+    #[inline]
+    fn next(&mut self) -> Option<usize> {
+        self.0.next()
+    }
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.0.size_hint()
+    }
+}
+
+impl<'a, B: BitBlock> Iterator for SymmetricDifference<'a, B> {
+    type Item = usize;
+
+    #[inline]
+    fn next(&mut self) -> Option<usize> {
+        self.0.next()
+    }
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.0.size_hint()
+    }
+}
+
+impl<'a, B: BitBlock> IntoIterator for &'a BitSet<B> {
+    type Item = usize;
+    type IntoIter = Iter<'a, B>;
+
+    fn into_iter(self) -> Iter<'a, B> {
+        self.iter()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::BitSet;
+    use bit_vec::BitVec;
+    use std::cmp::Ordering::{Equal, Greater, Less};
+    use std::vec::Vec;
+
+    #[test]
+    fn test_bit_set_show() {
+        let mut s = BitSet::new();
+        s.insert(1);
+        s.insert(10);
+        s.insert(50);
+        s.insert(2);
+        assert_eq!("{1, 2, 10, 50}", format!("{:?}", s));
+    }
+
+    #[test]
+    fn test_bit_set_from_usizes() {
+        let usizes = vec![0, 2, 2, 3];
+        let a: BitSet = usizes.into_iter().collect();
+        let mut b = BitSet::new();
+        b.insert(0);
+        b.insert(2);
+        b.insert(3);
+        assert_eq!(a, b);
+    }
+
+    #[test]
+    fn test_bit_set_iterator() {
+        let usizes = vec![0, 2, 2, 3];
+        let bit_vec: BitSet = usizes.into_iter().collect();
+
+        let idxs: Vec<_> = bit_vec.iter().collect();
+        assert_eq!(idxs, [0, 2, 3]);
+
+        let long: BitSet = (0..10000).filter(|&n| n % 2 == 0).collect();
+        let real: Vec<_> = (0..10000 / 2).map(|x| x * 2).collect();
+
+        let idxs: Vec<_> = long.iter().collect();
+        assert_eq!(idxs, real);
+    }
+
+    #[test]
+    fn test_bit_set_frombit_vec_init() {
+        let bools = [true, false];
+        let lengths = [10, 64, 100];
+        for &b in &bools {
+            for &l in &lengths {
+                let bitset = BitSet::from_bit_vec(BitVec::from_elem(l, b));
+                assert_eq!(bitset.contains(1), b);
+                assert_eq!(bitset.contains(l - 1), b);
+                assert!(!bitset.contains(l));
+            }
+        }
+    }
+
+    #[test]
+    fn test_bit_vec_masking() {
+        let b = BitVec::from_elem(140, true);
+        let mut bs = BitSet::from_bit_vec(b);
+        assert!(bs.contains(139));
+        assert!(!bs.contains(140));
+        assert!(bs.insert(150));
+        assert!(!bs.contains(140));
+        assert!(!bs.contains(149));
+        assert!(bs.contains(150));
+        assert!(!bs.contains(151));
+    }
+
+    #[test]
+    fn test_bit_set_basic() {
+        let mut b = BitSet::new();
+        assert!(b.insert(3));
+        assert!(!b.insert(3));
+        assert!(b.contains(3));
+        assert!(b.insert(4));
+        assert!(!b.insert(4));
+        assert!(b.contains(3));
+        assert!(b.insert(400));
+        assert!(!b.insert(400));
+        assert!(b.contains(400));
+        assert_eq!(b.len(), 3);
+    }
+
+    #[test]
+    fn test_bit_set_intersection() {
+        let mut a = BitSet::new();
+        let mut b = BitSet::new();
+
+        assert!(a.insert(11));
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(77));
+        assert!(a.insert(103));
+        assert!(a.insert(5));
+
+        assert!(b.insert(2));
+        assert!(b.insert(11));
+        assert!(b.insert(77));
+        assert!(b.insert(5));
+        assert!(b.insert(3));
+
+        let expected = [3, 5, 11, 77];
+        let actual: Vec<_> = a.intersection(&b).collect();
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_bit_set_difference() {
+        let mut a = BitSet::new();
+        let mut b = BitSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(200));
+        assert!(a.insert(500));
+
+        assert!(b.insert(3));
+        assert!(b.insert(200));
+
+        let expected = [1, 5, 500];
+        let actual: Vec<_> = a.difference(&b).collect();
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_bit_set_symmetric_difference() {
+        let mut a = BitSet::new();
+        let mut b = BitSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+
+        assert!(b.insert(3));
+        assert!(b.insert(9));
+        assert!(b.insert(14));
+        assert!(b.insert(220));
+
+        let expected = [1, 5, 11, 14, 220];
+        let actual: Vec<_> = a.symmetric_difference(&b).collect();
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_bit_set_union() {
+        let mut a = BitSet::new();
+        let mut b = BitSet::new();
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+        assert!(a.insert(160));
+        assert!(a.insert(19));
+        assert!(a.insert(24));
+        assert!(a.insert(200));
+
+        assert!(b.insert(1));
+        assert!(b.insert(5));
+        assert!(b.insert(9));
+        assert!(b.insert(13));
+        assert!(b.insert(19));
+
+        let expected = [1, 3, 5, 9, 11, 13, 19, 24, 160, 200];
+        let actual: Vec<_> = a.union(&b).collect();
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_bit_set_subset() {
+        let mut set1 = BitSet::new();
+        let mut set2 = BitSet::new();
+
+        assert!(set1.is_subset(&set2)); //  {}  {}
+        set2.insert(100);
+        assert!(set1.is_subset(&set2)); //  {}  { 1 }
+        set2.insert(200);
+        assert!(set1.is_subset(&set2)); //  {}  { 1, 2 }
+        set1.insert(200);
+        assert!(set1.is_subset(&set2)); //  { 2 }  { 1, 2 }
+        set1.insert(300);
+        assert!(!set1.is_subset(&set2)); // { 2, 3 }  { 1, 2 }
+        set2.insert(300);
+        assert!(set1.is_subset(&set2)); // { 2, 3 }  { 1, 2, 3 }
+        set2.insert(400);
+        assert!(set1.is_subset(&set2)); // { 2, 3 }  { 1, 2, 3, 4 }
+        set2.remove(100);
+        assert!(set1.is_subset(&set2)); // { 2, 3 }  { 2, 3, 4 }
+        set2.remove(300);
+        assert!(!set1.is_subset(&set2)); // { 2, 3 }  { 2, 4 }
+        set1.remove(300);
+        assert!(set1.is_subset(&set2)); // { 2 }  { 2, 4 }
+    }
+
+    #[test]
+    fn test_bit_set_is_disjoint() {
+        let a = BitSet::from_bytes(&[0b10100010]);
+        let b = BitSet::from_bytes(&[0b01000000]);
+        let c = BitSet::new();
+        let d = BitSet::from_bytes(&[0b00110000]);
+
+        assert!(!a.is_disjoint(&d));
+        assert!(!d.is_disjoint(&a));
+
+        assert!(a.is_disjoint(&b));
+        assert!(a.is_disjoint(&c));
+        assert!(b.is_disjoint(&a));
+        assert!(b.is_disjoint(&c));
+        assert!(c.is_disjoint(&a));
+        assert!(c.is_disjoint(&b));
+    }
+
+    #[test]
+    fn test_bit_set_union_with() {
+        //a should grow to include larger elements
+        let mut a = BitSet::new();
+        a.insert(0);
+        let mut b = BitSet::new();
+        b.insert(5);
+        let expected = BitSet::from_bytes(&[0b10000100]);
+        a.union_with(&b);
+        assert_eq!(a, expected);
+
+        // Standard
+        let mut a = BitSet::from_bytes(&[0b10100010]);
+        let mut b = BitSet::from_bytes(&[0b01100010]);
+        let c = a.clone();
+        a.union_with(&b);
+        b.union_with(&c);
+        assert_eq!(a.len(), 4);
+        assert_eq!(b.len(), 4);
+    }
+
+    #[test]
+    fn test_bit_set_intersect_with() {
+        // Explicitly 0'ed bits
+        let mut a = BitSet::from_bytes(&[0b10100010]);
+        let mut b = BitSet::from_bytes(&[0b00000000]);
+        let c = a.clone();
+        a.intersect_with(&b);
+        b.intersect_with(&c);
+        assert!(a.is_empty());
+        assert!(b.is_empty());
+
+        // Uninitialized bits should behave like 0's
+        let mut a = BitSet::from_bytes(&[0b10100010]);
+        let mut b = BitSet::new();
+        let c = a.clone();
+        a.intersect_with(&b);
+        b.intersect_with(&c);
+        assert!(a.is_empty());
+        assert!(b.is_empty());
+
+        // Standard
+        let mut a = BitSet::from_bytes(&[0b10100010]);
+        let mut b = BitSet::from_bytes(&[0b01100010]);
+        let c = a.clone();
+        a.intersect_with(&b);
+        b.intersect_with(&c);
+        assert_eq!(a.len(), 2);
+        assert_eq!(b.len(), 2);
+    }
+
+    #[test]
+    fn test_bit_set_difference_with() {
+        // Explicitly 0'ed bits
+        let mut a = BitSet::from_bytes(&[0b00000000]);
+        let b = BitSet::from_bytes(&[0b10100010]);
+        a.difference_with(&b);
+        assert!(a.is_empty());
+
+        // Uninitialized bits should behave like 0's
+        let mut a = BitSet::new();
+        let b = BitSet::from_bytes(&[0b11111111]);
+        a.difference_with(&b);
+        assert!(a.is_empty());
+
+        // Standard
+        let mut a = BitSet::from_bytes(&[0b10100010]);
+        let mut b = BitSet::from_bytes(&[0b01100010]);
+        let c = a.clone();
+        a.difference_with(&b);
+        b.difference_with(&c);
+        assert_eq!(a.len(), 1);
+        assert_eq!(b.len(), 1);
+    }
+
+    #[test]
+    fn test_bit_set_symmetric_difference_with() {
+        //a should grow to include larger elements
+        let mut a = BitSet::new();
+        a.insert(0);
+        a.insert(1);
+        let mut b = BitSet::new();
+        b.insert(1);
+        b.insert(5);
+        let expected = BitSet::from_bytes(&[0b10000100]);
+        a.symmetric_difference_with(&b);
+        assert_eq!(a, expected);
+
+        let mut a = BitSet::from_bytes(&[0b10100010]);
+        let b = BitSet::new();
+        let c = a.clone();
+        a.symmetric_difference_with(&b);
+        assert_eq!(a, c);
+
+        // Standard
+        let mut a = BitSet::from_bytes(&[0b11100010]);
+        let mut b = BitSet::from_bytes(&[0b01101010]);
+        let c = a.clone();
+        a.symmetric_difference_with(&b);
+        b.symmetric_difference_with(&c);
+        assert_eq!(a.len(), 2);
+        assert_eq!(b.len(), 2);
+    }
+
+    #[test]
+    fn test_bit_set_eq() {
+        let a = BitSet::from_bytes(&[0b10100010]);
+        let b = BitSet::from_bytes(&[0b00000000]);
+        let c = BitSet::new();
+
+        assert!(a == a);
+        assert!(a != b);
+        assert!(a != c);
+        assert!(b == b);
+        assert!(b == c);
+        assert!(c == c);
+    }
+
+    #[test]
+    fn test_bit_set_cmp() {
+        let a = BitSet::from_bytes(&[0b10100010]);
+        let b = BitSet::from_bytes(&[0b00000000]);
+        let c = BitSet::new();
+
+        assert_eq!(a.cmp(&b), Greater);
+        assert_eq!(a.cmp(&c), Greater);
+        assert_eq!(b.cmp(&a), Less);
+        assert_eq!(b.cmp(&c), Equal);
+        assert_eq!(c.cmp(&a), Less);
+        assert_eq!(c.cmp(&b), Equal);
+    }
+
+    #[test]
+    fn test_bit_set_shrink_to_fit_new() {
+        // There was a strange bug where we refused to truncate to 0
+        // and this would end up actually growing the array in a way
+        // that (safely corrupted the state).
+        let mut a = BitSet::new();
+        assert_eq!(a.len(), 0);
+        assert_eq!(a.capacity(), 0);
+        a.shrink_to_fit();
+        assert_eq!(a.len(), 0);
+        assert_eq!(a.capacity(), 0);
+        assert!(!a.contains(1));
+        a.insert(3);
+        assert!(a.contains(3));
+        assert_eq!(a.len(), 1);
+        assert!(a.capacity() > 0);
+        a.shrink_to_fit();
+        assert!(a.contains(3));
+        assert_eq!(a.len(), 1);
+        assert!(a.capacity() > 0);
+    }
+
+    #[test]
+    fn test_bit_set_shrink_to_fit() {
+        let mut a = BitSet::new();
+        assert_eq!(a.len(), 0);
+        assert_eq!(a.capacity(), 0);
+        a.insert(259);
+        a.insert(98);
+        a.insert(3);
+        assert_eq!(a.len(), 3);
+        assert!(a.capacity() > 0);
+        assert!(!a.contains(1));
+        assert!(a.contains(259));
+        assert!(a.contains(98));
+        assert!(a.contains(3));
+
+        a.shrink_to_fit();
+        assert!(!a.contains(1));
+        assert!(a.contains(259));
+        assert!(a.contains(98));
+        assert!(a.contains(3));
+        assert_eq!(a.len(), 3);
+        assert!(a.capacity() > 0);
+
+        let old_cap = a.capacity();
+        assert!(a.remove(259));
+        a.shrink_to_fit();
+        assert!(a.capacity() < old_cap, "{} {}", a.capacity(), old_cap);
+        assert!(!a.contains(1));
+        assert!(!a.contains(259));
+        assert!(a.contains(98));
+        assert!(a.contains(3));
+        assert_eq!(a.len(), 2);
+
+        let old_cap2 = a.capacity();
+        a.clear();
+        assert_eq!(a.capacity(), old_cap2);
+        assert_eq!(a.len(), 0);
+        assert!(!a.contains(1));
+        assert!(!a.contains(259));
+        assert!(!a.contains(98));
+        assert!(!a.contains(3));
+
+        a.insert(512);
+        assert!(a.capacity() > 0);
+        assert_eq!(a.len(), 1);
+        assert!(a.contains(512));
+        assert!(!a.contains(1));
+        assert!(!a.contains(259));
+        assert!(!a.contains(98));
+        assert!(!a.contains(3));
+
+        a.remove(512);
+        a.shrink_to_fit();
+        assert_eq!(a.capacity(), 0);
+        assert_eq!(a.len(), 0);
+        assert!(!a.contains(512));
+        assert!(!a.contains(1));
+        assert!(!a.contains(259));
+        assert!(!a.contains(98));
+        assert!(!a.contains(3));
+        assert!(!a.contains(0));
+    }
+
+    #[test]
+    fn test_bit_vec_remove() {
+        let mut a = BitSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.remove(1));
+
+        assert!(a.insert(100));
+        assert!(a.remove(100));
+
+        assert!(a.insert(1000));
+        assert!(a.remove(1000));
+        a.shrink_to_fit();
+    }
+
+    #[test]
+    fn test_bit_vec_clone() {
+        let mut a = BitSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(100));
+        assert!(a.insert(1000));
+
+        let mut b = a.clone();
+
+        assert!(a == b);
+
+        assert!(b.remove(1));
+        assert!(a.contains(1));
+
+        assert!(a.remove(1000));
+        assert!(b.contains(1000));
+    }
+
+    /*
+        #[test]
+        fn test_bit_set_append() {
+            let mut a = BitSet::new();
+            a.insert(2);
+            a.insert(6);
+
+            let mut b = BitSet::new();
+            b.insert(1);
+            b.insert(3);
+            b.insert(6);
+
+            a.append(&mut b);
+
+            assert_eq!(a.len(), 4);
+            assert_eq!(b.len(), 0);
+            assert!(b.capacity() >= 6);
+
+            assert_eq!(a, BitSet::from_bytes(&[0b01110010]));
+        }
+
+        #[test]
+        fn test_bit_set_split_off() {
+            // Split at 0
+            let mut a = BitSet::from_bytes(&[0b10100000, 0b00010010, 0b10010010,
+                                             0b00110011, 0b01101011, 0b10101101]);
+
+            let b = a.split_off(0);
+
+            assert_eq!(a.len(), 0);
+            assert_eq!(b.len(), 21);
+
+            assert_eq!(b, BitSet::from_bytes(&[0b10100000, 0b00010010, 0b10010010,
+                                               0b00110011, 0b01101011, 0b10101101]);
+
+            // Split behind last element
+            let mut a = BitSet::from_bytes(&[0b10100000, 0b00010010, 0b10010010,
+                                             0b00110011, 0b01101011, 0b10101101]);
+
+            let b = a.split_off(50);
+
+            assert_eq!(a.len(), 21);
+            assert_eq!(b.len(), 0);
+
+            assert_eq!(a, BitSet::from_bytes(&[0b10100000, 0b00010010, 0b10010010,
+                                               0b00110011, 0b01101011, 0b10101101]));
+
+            // Split at arbitrary element
+            let mut a = BitSet::from_bytes(&[0b10100000, 0b00010010, 0b10010010,
+                                             0b00110011, 0b01101011, 0b10101101]);
+
+            let b = a.split_off(34);
+
+            assert_eq!(a.len(), 12);
+            assert_eq!(b.len(), 9);
+
+            assert_eq!(a, BitSet::from_bytes(&[0b10100000, 0b00010010, 0b10010010,
+                                               0b00110011, 0b01000000]));
+            assert_eq!(b, BitSet::from_bytes(&[0, 0, 0, 0,
+                                               0b00101011, 0b10101101]));
+        }
+    */
+}
+
+#[cfg(all(test, feature = "nightly"))]
+mod bench {
+    use super::BitSet;
+    use bit_vec::BitVec;
+    use rand::{thread_rng, Rng, ThreadRng};
+
+    use test::{black_box, Bencher};
+
+    const BENCH_BITS: usize = 1 << 14;
+    const BITS: usize = 32;
+
+    fn rng() -> ThreadRng {
+        thread_rng()
+    }
+
+    #[bench]
+    fn bench_bit_vecset_small(b: &mut Bencher) {
+        let mut r = rng();
+        let mut bit_vec = BitSet::new();
+        b.iter(|| {
+            for _ in 0..100 {
+                bit_vec.insert((r.next_u32() as usize) % BITS);
+            }
+            black_box(&bit_vec);
+        });
+    }
+
+    #[bench]
+    fn bench_bit_vecset_big(b: &mut Bencher) {
+        let mut r = rng();
+        let mut bit_vec = BitSet::new();
+        b.iter(|| {
+            for _ in 0..100 {
+                bit_vec.insert((r.next_u32() as usize) % BENCH_BITS);
+            }
+            black_box(&bit_vec);
+        });
+    }
+
+    #[bench]
+    fn bench_bit_vecset_iter(b: &mut Bencher) {
+        let bit_vec = BitSet::from_bit_vec(BitVec::from_fn(BENCH_BITS, |idx| idx % 3 == 0));
+        b.iter(|| {
+            let mut sum = 0;
+            for idx in &bit_vec {
+                sum += idx as usize;
+            }
+            sum
+        })
+    }
+}