Module com.carrotsearch.hppc
Package com.carrotsearch.hppc

Class BitSet

java.lang.Object
com.carrotsearch.hppc.BitSet
All Implemented Interfaces:
Cloneable
public class BitSet extends Object implements Cloneable
An "open" BitSet implementation that allows direct access to the array of words storing the bits.

Unlike BitSet, the fact that bits are packed into an array of longs is part of the interface. This allows efficient implementation of other algorithms by someone other than the author. It also allows one to efficiently implement alternate serialization or interchange formats.

The index range for a bitset can easily exceed positive int range in Java (0x7fffffff), so many methods in this class accept or return a long. There are adapter methods that return views compatible with LongLookupContainer and IntLookupContainer interfaces.

See Also:

  • Field Details

    • bits

      public long[] bits
      Internal representation of bits in this bit set.

    • wlen

      public int wlen
      The number of words (longs) used in the bits array.

  • Constructor Details

    • BitSet

      public BitSet()
      Constructs a bit set with the default capacity.

    • BitSet

      public BitSet(long numBits)
      Constructs an BitSet large enough to hold numBits.
      Parameters:
      numBits - Number of bits

    • BitSet

      public BitSet(long[] bits, int numWords)
      Constructs an BitSet from an existing long[].

      The first 64 bits are in long[0], with bit index 0 at the least significant bit, and bit index 63 at the most significant. Given a bit index, the word containing it is long[index/64], and it is at bit number index%64 within that word.

      numWords are the number of elements in the array that contain set bits (non-zero longs). numWords should be <= bits.length, and any existing words in the array at position >= numWords should be zero.

      Parameters:
      bits - underlying bits buffer
      numWords - the number of elements in the array that contain set bits

  • Method Details

    • newInstance

      public static BitSet newInstance()
      Static constructor-like method similar to other (generic) collections.
      Returns:
      New instance.

    • iterator

      public BitSetIterator iterator()
      Returns:
      Returns an iterator over all set bits of this bitset. The iterator should be faster than using a loop around nextSetBit(int).

    • capacity

      public long capacity()
      Returns:
      Returns the current capacity in bits (1 greater than the index of the last bit).

    • size

      public long size()
      Returns:
      Returns the current capacity of this set. Included for compatibility. This is not equal to cardinality().
      See Also:

    • length

      public long length()
      Returns:
      Returns the "logical size" of this BitSet: the index of the highest set bit in the BitSet plus one.
      See Also:

    • isEmpty

      public boolean isEmpty()
      Returns:
      Returns true if there are no set bits

    • get

      public boolean get(int index)
      Parameters:
      index - The index.
      Returns:
      Returns true or false for the specified bit index.

    • get

      public boolean get(long index)
      Parameters:
      index - The index.
      Returns:
      Returns true or false for the specified bit index.

    • set

      public void set(long index)
      Sets a bit, expanding the set size if necessary.
      Parameters:
      index - the index to set

    • set

      public void set(long startIndex, long endIndex)
      Sets a range of bits, expanding the set size if necessary
      Parameters:
      startIndex - lower index
      endIndex - one-past the last bit to set

    • expandingWordNum

      protected int expandingWordNum(long index)

    • clear

      public void clear()
      Clears all bits.

    • clear

      public void clear(long index)
      clears a bit, allowing access beyond the current set size without changing the size.
      Parameters:
      index - the index to clear

    • clear

      public void clear(int startIndex, int endIndex)
      Clears a range of bits. Clearing past the end does not change the size of the set.
      Parameters:
      startIndex - lower index
      endIndex - one-past the last bit to clear

    • clear

      public void clear(long startIndex, long endIndex)
      Clears a range of bits. Clearing past the end does not change the size of the set.
      Parameters:
      startIndex - lower index
      endIndex - one-past the last bit to clear

    • getAndSet

      public boolean getAndSet(int index)
      Sets a bit and returns the previous value. The index should be less than the BitSet size.
      Parameters:
      index - the index to set
      Returns:
      previous state of the index

    • getAndSet

      public boolean getAndSet(long index)
      Sets a bit and returns the previous value. The index should be less than the BitSet size.
      Parameters:
      index - the index to set
      Returns:
      previous state of the index

    • flip

      public void flip(long index)
      Flips a bit, expanding the set size if necessary.
      Parameters:
      index - the index to flip

    • flipAndGet

      public boolean flipAndGet(int index)
      flips a bit and returns the resulting bit value. The index should be less than the BitSet size.
      Parameters:
      index - the index to flip
      Returns:
      previous state of the index

    • flipAndGet

      public boolean flipAndGet(long index)
      flips a bit and returns the resulting bit value. The index should be less than the BitSet size.
      Parameters:
      index - the index to flip
      Returns:
      previous state of the index

    • flip

      public void flip(long startIndex, long endIndex)
      Flips a range of bits, expanding the set size if necessary
      Parameters:
      startIndex - lower index
      endIndex - one-past the last bit to flip

    • cardinality

      public long cardinality()
      Returns:
      the number of set bits

    • intersectionCount

      public static long intersectionCount(BitSet a, BitSet b)
      Parameters:
      a - The first set
      b - The second set
      Returns:
      Returns the popcount or cardinality of the intersection of the two sets. Neither set is modified.

    • unionCount

      public static long unionCount(BitSet a, BitSet b)
      Parameters:
      a - The first set
      b - The second set
      Returns:
      Returns the popcount or cardinality of the union of the two sets. Neither set is modified.

    • andNotCount

      public static long andNotCount(BitSet a, BitSet b)
      Parameters:
      a - The first set
      b - The second set
      Returns:
      Returns the popcount or cardinality of "a and not b" or "intersection(a, not(b))". Neither set is modified.

    • xorCount

      public static long xorCount(BitSet a, BitSet b)
      Parameters:
      a - The first set
      b - The second set
      Returns:
      Returns the popcount or cardinality of the exclusive-or of the two sets. Neither set is modified.

    • nextSetBit

      public int nextSetBit(int index)
      Parameters:
      index - The index to start scanning from, inclusive.
      Returns:
      Returns the index of the first set bit starting at the index specified. -1 is returned if there are no more set bits.

    • nextSetBit

      public long nextSetBit(long index)
      Parameters:
      index - The index to start scanning from, inclusive.
      Returns:
      Returns the index of the first set bit starting at the index specified. -1 is returned if there are no more set bits.

    • clone

      public Object clone()
      Overrides:
      clone in class Object

    • intersect

      public void intersect(BitSet other)
      this = this AND other
      Parameters:
      other - The bitset to intersect with.

    • union

      public void union(BitSet other)
      this = this OR other
      Parameters:
      other - The bitset to union with.

    • remove

      public void remove(BitSet other)
      Remove all elements set in other: this = this AND_NOT other
      Parameters:
      other - The other bitset.

    • xor

      public void xor(BitSet other)
      this = this XOR other
      Parameters:
      other - The other bitset.

    • and

      public void and(BitSet other)

    • or

      public void or(BitSet other)

    • andNot

      public void andNot(BitSet other)

    • intersects

      public boolean intersects(BitSet other)
      Parameters:
      other - The other bitset.
      Returns:
      true if the sets have any elements in common

    • ensureCapacityWords

      public void ensureCapacityWords(int numWords)
      Expand the long[] with the size given as a number of words (64 bit longs). getNumWords() is unchanged by this call.
      Parameters:
      numWords - The size to expand to (64-bit long words)

    • grow

      public static long[] grow(long[] array, int minSize)

    • getNextSize

      public static int getNextSize(int targetSize)

    • ensureCapacity

      public void ensureCapacity(long numBits)
      Ensure that the long[] is big enough to hold numBits, expanding it if necessary. getNumWords() is unchanged by this call.
      Parameters:
      numBits - The number of bits to expand to

    • trimTrailingZeros

      public void trimTrailingZeros()
      Lowers wlen, the number of words in use, by checking for trailing zero words.

    • bits2words

      public static int bits2words(long numBits)

    • equals

      public boolean equals(Object o)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • asIntLookupContainer

      public IntLookupContainer asIntLookupContainer()
      Returns a view over this bitset data compatible with IntLookupContainer. A new object is always returned, but its methods reflect the current state of the bitset (the view is not a snapshot).

      Methods of the returned IntLookupContainer may throw a RuntimeException if the cardinality of this bitset exceeds the int range.

      Returns:
      The view of this bitset as IntLookupContainer.

    • asLongLookupContainer

      public LongLookupContainer asLongLookupContainer()
      Returns a view over this bitset data compatible with LongLookupContainer. A new object is always returned, but its methods reflect the current state of the bitset (the view is not a snapshot).
      Returns:
      The view of this bitset as LongLookupContainer.