Class FixedBitSet

  • All Implemented Interfaces:
    Accountable, Bits

    public final class FixedBitSet
    extends BitSet
    BitSet of fixed length (numBits), backed by accessible (getBits()) long[], accessed with an int index, implementing Bits and DocIdSet. If you need to manage more than 2.1B bits, use LongBitSet.
    NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.
    • Constructor Detail

      • FixedBitSet

        public FixedBitSet​(int numBits)
        Creates a new LongBitSet. The internally allocated long array will be exactly the size needed to accommodate the numBits specified.
        Parameters:
        numBits - the number of bits needed
      • FixedBitSet

        public FixedBitSet​(long[] storedBits,
                           int numBits)
        Creates a new LongBitSet using the provided long[] array as backing store. The storedBits array must be large enough to accommodate the numBits specified, but may be larger. In that case the 'extra' or 'ghost' bits must be clear (or they may provoke spurious side-effects)
        Parameters:
        storedBits - the array to use as backing store
        numBits - the number of bits actually needed
    • Method Detail

      • ensureCapacity

        public static FixedBitSet ensureCapacity​(FixedBitSet bits,
                                                 int numBits)
        If the given FixedBitSet is large enough to hold numBits+1, returns the given bits, otherwise returns a new FixedBitSet which can hold the requested number of bits.

        NOTE: the returned bitset reuses the underlying long[] of the given bits if possible. Also, calling length() on the returned bits may return a value greater than numBits.

      • bits2words

        public static int bits2words​(int numBits)
        returns the number of 64 bit words it would take to hold numBits
      • intersectionCount

        public static long intersectionCount​(FixedBitSet a,
                                             FixedBitSet b)
        Returns the popcount or cardinality of the intersection of the two sets. Neither set is modified.
      • unionCount

        public static long unionCount​(FixedBitSet a,
                                      FixedBitSet b)
        Returns the popcount or cardinality of the union of the two sets. Neither set is modified.
      • andNotCount

        public static long andNotCount​(FixedBitSet a,
                                       FixedBitSet b)
        Returns the popcount or cardinality of "a and not b" or "intersection(a, not(b))". Neither set is modified.
      • length

        public int length()
        Description copied from interface: Bits
        Returns the number of bits in this set
      • ramBytesUsed

        public long ramBytesUsed()
        Description copied from interface: Accountable
        Return the memory usage of this object in bytes. Negative values are illegal.
      • getBits

        public long[] getBits()
        Expert.
      • cardinality

        public int cardinality()
        Returns number of set bits. NOTE: this visits every long in the backing bits array, and the result is not internally cached!
        Specified by:
        cardinality in class BitSet
      • approximateCardinality

        public int approximateCardinality()
        Description copied from class: BitSet
        Return an approximation of the cardinality of this set. Some implementations may trade accuracy for speed if they have the ability to estimate the cardinality of the set without iterating over all the data. The default implementation returns BitSet.cardinality().
        Specified by:
        approximateCardinality in class BitSet
      • get

        public boolean get​(int index)
        Description copied from interface: Bits
        Returns the value of the bit with the specified index.
        Parameters:
        index - index, should be non-negative and < Bits.length(). The result of passing negative or out of bounds values is undefined by this interface, just don't do it!
        Returns:
        true if the bit is set, false otherwise.
      • set

        public void set​(int index)
        Description copied from class: BitSet
        Set the bit at i.
        Specified by:
        set in class BitSet
      • getAndSet

        public boolean getAndSet​(int index)
        Description copied from class: BitSet
        Set the bit at i, returning true if it was previously set.
        Specified by:
        getAndSet in class BitSet
      • clear

        public void clear​(int index)
        Description copied from class: BitSet
        Clear the bit at i.
        Specified by:
        clear in class BitSet
      • getAndClear

        public boolean getAndClear​(int index)
      • nextSetBit

        public int nextSetBit​(int index)
        Description copied from class: BitSet
        Returns the index of the first set bit starting at the index specified. DocIdSetIterator.NO_MORE_DOCS is returned if there are no more set bits.
        Specified by:
        nextSetBit in class BitSet
      • prevSetBit

        public int prevSetBit​(int index)
        Description copied from class: BitSet
        Returns the index of the last set bit before or on the index specified. -1 is returned if there are no more set bits.
        Specified by:
        prevSetBit in class BitSet
      • or

        public void or​(DocIdSetIterator iter)
                throws IOException
        Description copied from class: BitSet
        Does in-place OR of the bits provided by the iterator. The state of the iterator after this operation terminates is undefined.
        Overrides:
        or in class BitSet
        Throws:
        IOException
      • or

        public void or​(FixedBitSet other)
        this = this OR other
      • xor

        public void xor​(FixedBitSet other)
        this = this XOR other
      • intersects

        public boolean intersects​(FixedBitSet other)
        returns true if the sets have any elements in common
      • and

        public void and​(FixedBitSet other)
        this = this AND other
      • andNot

        public void andNot​(FixedBitSet other)
        this = this AND NOT other
      • scanIsEmpty

        public boolean scanIsEmpty()
        Scans the backing store to check if all bits are clear. The method is deliberately not called "isEmpty" to emphasize it is not low cost (as isEmpty usually is).
        Returns:
        true if all bits are clear.
      • flip

        public void flip​(int startIndex,
                         int endIndex)
        Flips a range of bits
        Parameters:
        startIndex - lower index
        endIndex - one-past the last bit to flip
      • flip

        public void flip​(int index)
        Flip the bit at the provided index.
      • set

        public void set​(int startIndex,
                        int endIndex)
        Sets a range of bits
        Parameters:
        startIndex - lower index
        endIndex - one-past the last bit to set
      • clear

        public void clear​(int startIndex,
                          int endIndex)
        Description copied from class: BitSet
        Clears a range of bits.
        Specified by:
        clear in class BitSet
        Parameters:
        startIndex - lower index
        endIndex - one-past the last bit to clear
      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class Object
      • copyOf

        public static FixedBitSet copyOf​(Bits bits)
        Make a copy of the given bits.
      • asReadOnlyBits

        public Bits asReadOnlyBits()
        Convert this instance to read-only Bits. This is useful in the case that this FixedBitSet is returned as a Bits instance, to make sure that consumers may not get write access back by casting to a FixedBitSet. NOTE: Changes to this FixedBitSet will be reflected on the returned Bits.