Perf improvements to collections::BitSet.
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ray glover
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551a74dddd
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3a62f87b78
1 changed files with 76 additions and 74 deletions
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@ -1451,8 +1451,8 @@ impl BitSet {
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/// ```
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#[inline]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn iter(&self) -> bit_set::Iter {
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SetIter {set: self, next_idx: 0}
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pub fn iter<'a>(&'a self) -> bit_set::Iter<'a> {
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SetIter(BlockIter::from_blocks(self.bit_vec.blocks()))
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}
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/// Iterator over each u32 stored in `self` union `other`.
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@ -1477,13 +1477,11 @@ impl BitSet {
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pub fn union<'a>(&'a self, other: &'a BitSet) -> Union<'a> {
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fn or(w1: u32, w2: u32) -> u32 { w1 | w2 }
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Union(TwoBitPositions {
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set: self,
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other: other,
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Union(BlockIter::from_blocks(TwoBitPositions {
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set: self.bit_vec.blocks(),
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other: other.bit_vec.blocks(),
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merge: or,
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current_word: 0,
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next_idx: 0
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})
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}))
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}
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/// Iterator over each usize stored in `self` intersect `other`.
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@ -1508,13 +1506,12 @@ impl BitSet {
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pub fn intersection<'a>(&'a self, other: &'a BitSet) -> Intersection<'a> {
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fn bitand(w1: u32, w2: u32) -> u32 { w1 & w2 }
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let min = cmp::min(self.bit_vec.len(), other.bit_vec.len());
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Intersection(TwoBitPositions {
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set: self,
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other: other,
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Intersection(BlockIter::from_blocks(TwoBitPositions {
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set: self.bit_vec.blocks(),
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other: other.bit_vec.blocks(),
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merge: bitand,
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current_word: 0,
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next_idx: 0
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}.take(min))
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}).take(min))
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}
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/// Iterator over each usize stored in the `self` setminus `other`.
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@ -1546,13 +1543,11 @@ impl BitSet {
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pub fn difference<'a>(&'a self, other: &'a BitSet) -> Difference<'a> {
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fn diff(w1: u32, w2: u32) -> u32 { w1 & !w2 }
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Difference(TwoBitPositions {
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set: self,
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other: other,
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Difference(BlockIter::from_blocks(TwoBitPositions {
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set: self.bit_vec.blocks(),
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other: other.bit_vec.blocks(),
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merge: diff,
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current_word: 0,
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next_idx: 0
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})
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}))
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}
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/// Iterator over each u32 stored in the symmetric difference of `self` and `other`.
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@ -1578,13 +1573,11 @@ impl BitSet {
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pub fn symmetric_difference<'a>(&'a self, other: &'a BitSet) -> SymmetricDifference<'a> {
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fn bitxor(w1: u32, w2: u32) -> u32 { w1 ^ w2 }
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SymmetricDifference(TwoBitPositions {
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set: self,
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other: other,
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SymmetricDifference(BlockIter::from_blocks(TwoBitPositions {
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set: self.bit_vec.blocks(),
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other: other.bit_vec.blocks(),
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merge: bitxor,
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current_word: 0,
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next_idx: 0
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})
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}))
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}
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/// Unions in-place with the specified other bit vector.
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@ -1808,98 +1801,107 @@ impl hash::Hash for BitSet {
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}
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}
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/// An iterator for `BitSet`.
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#[derive(Clone)]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct SetIter<'a> {
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set: &'a BitSet,
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next_idx: usize
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struct BlockIter<T> where
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T: Iterator<Item=u32> {
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head: u32,
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head_offset: usize,
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tail: T
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}
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impl<'a, T> BlockIter<T> where
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T: Iterator<Item=u32> {
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fn from_blocks(mut blocks: T) -> BlockIter<T> {
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let h = blocks.next().unwrap_or(0);
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BlockIter {tail: blocks, head: h, head_offset: 0}
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}
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}
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/// An iterator combining two `BitSet` iterators.
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#[derive(Clone)]
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struct TwoBitPositions<'a> {
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set: &'a BitSet,
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other: &'a BitSet,
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set: Blocks<'a>,
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other: Blocks<'a>,
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merge: fn(u32, u32) -> u32,
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current_word: u32,
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next_idx: usize
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}
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/// An iterator for `BitSet`.
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#[derive(Clone)]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct Union<'a>(TwoBitPositions<'a>);
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pub struct SetIter<'a>(BlockIter<Blocks<'a>>);
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#[derive(Clone)]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct Intersection<'a>(Take<TwoBitPositions<'a>>);
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pub struct Union<'a>(BlockIter<TwoBitPositions<'a>>);
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#[derive(Clone)]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct Difference<'a>(TwoBitPositions<'a>);
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pub struct Intersection<'a>(Take<BlockIter<TwoBitPositions<'a>>>);
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#[derive(Clone)]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct SymmetricDifference<'a>(TwoBitPositions<'a>);
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pub struct Difference<'a>(BlockIter<TwoBitPositions<'a>>);
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#[derive(Clone)]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct SymmetricDifference<'a>(BlockIter<TwoBitPositions<'a>>);
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a> Iterator for SetIter<'a> {
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impl<'a, T> Iterator for BlockIter<T> where T: Iterator<Item=u32> {
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type Item = usize;
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fn next(&mut self) -> Option<usize> {
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while self.next_idx < self.set.bit_vec.len() {
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let idx = self.next_idx;
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self.next_idx += 1;
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if self.set.contains(&idx) {
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return Some(idx);
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while self.head == 0 {
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match self.tail.next() {
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Some(w) => self.head = w,
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_ => return None
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}
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self.head_offset += u32::BITS;
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}
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return None;
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let t = self.head & !self.head + 1;
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// remove the least significant bit
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self.head &= self.head - 1;
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// return index of lsb
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Some(self.head_offset + (u32::count_ones(t-1) as usize))
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}
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#[inline]
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fn size_hint(&self) -> (usize, Option<usize>) {
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(0, Some(self.set.bit_vec.len() - self.next_idx))
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match self.tail.size_hint() {
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(_, Some(h)) => (0, Some(1 + h * (u32::BITS as usize))),
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_ => (0, None)
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}
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a> Iterator for TwoBitPositions<'a> {
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type Item = usize;
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type Item = u32;
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fn next(&mut self) -> Option<usize> {
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while self.next_idx < self.set.bit_vec.len() ||
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self.next_idx < self.other.bit_vec.len() {
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let bit_idx = self.next_idx % u32::BITS;
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if bit_idx == 0 {
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let s_bit_vec = &self.set.bit_vec;
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let o_bit_vec = &self.other.bit_vec;
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// Merging the two words is a bit of an awkward dance since
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// one BitVec might be longer than the other
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let word_idx = self.next_idx / u32::BITS;
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let w1 = if word_idx < s_bit_vec.storage.len() {
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s_bit_vec.storage[word_idx]
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} else { 0 };
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let w2 = if word_idx < o_bit_vec.storage.len() {
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o_bit_vec.storage[word_idx]
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} else { 0 };
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self.current_word = (self.merge)(w1, w2);
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}
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self.next_idx += 1;
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if self.current_word & (1 << bit_idx) != 0 {
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return Some(self.next_idx - 1);
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}
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fn next(&mut self) -> Option<u32> {
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match (self.set.next(), self.other.next()) {
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(Some(a), Some(b)) => Some((self.merge)(a, b)),
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(Some(a), None) => Some((self.merge)(a, 0)),
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(None, Some(b)) => Some((self.merge)(0, b)),
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_ => return None
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}
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return None;
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}
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#[inline]
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fn size_hint(&self) -> (usize, Option<usize>) {
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let cap = cmp::max(self.set.bit_vec.len(), self.other.bit_vec.len());
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(0, Some(cap - self.next_idx))
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let (a, al) = self.set.size_hint();
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let (b, bl) = self.set.size_hint();
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assert_eq!(a, b);
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(a, cmp::max(al, bl))
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a> Iterator for SetIter<'a> {
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type Item = usize;
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#[inline] fn next(&mut self) -> Option<usize> { self.0.next() }
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#[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.0.size_hint() }
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a> Iterator for Union<'a> {
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type Item = usize;
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