org.apache.lucene.util

Class LongBitSet



  • public final class LongBitSet
    extends Object
    BitSet of fixed length (numBits), backed by accessible (getBits()) long[], accessed with a long index. Use it only if you intend to store more than 2.1B bits, otherwise you should use FixedBitSet.
    • Constructor Summary

      Constructors 
      Constructor and Description
      LongBitSet(long numBits)
      Creates a new LongBitSet.
      LongBitSet(long[] storedBits, long numBits)
      Creates a new LongBitSet using the provided long[] array as backing store.
    • Constructor Detail

      • LongBitSet

        public LongBitSet(long 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
      • LongBitSet

        public LongBitSet(long[] storedBits,
                          long 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 LongBitSet ensureCapacity(LongBitSet bits,
                                                long numBits)
        If the given LongBitSet is large enough to hold numBits+1, returns the given bits, otherwise returns a new LongBitSet 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(long numBits)
        returns the number of 64 bit words it would take to hold numBits
      • length

        public long length()
        Returns the number of bits stored in this bitset.
      • getBits

        public long[] getBits()
        Expert.
      • cardinality

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

        public boolean get(long index)
      • set

        public void set(long index)
      • getAndSet

        public boolean getAndSet(long index)
      • clear

        public void clear(long index)
      • getAndClear

        public boolean getAndClear(long index)
      • nextSetBit

        public long nextSetBit(long index)
        Returns the index of the first set bit starting at the index specified. -1 is returned if there are no more set bits.
      • prevSetBit

        public long prevSetBit(long index)
        Returns the index of the last set bit before or on the index specified. -1 is returned if there are no more set bits.
      • or

        public void or(LongBitSet other)
        this = this OR other
      • intersects

        public boolean intersects(LongBitSet other)
        returns true if the sets have any elements in common
      • 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(long startIndex,
                         long endIndex)
        Flips a range of bits
        Parameters:
        startIndex - lower index
        endIndex - one-past the last bit to flip
      • flip

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

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

        public void clear(long startIndex,
                          long endIndex)
        Clears a range of bits.
        Parameters:
        startIndex - lower index
        endIndex - one-past the last bit to clear
      • equals

        public boolean equals(Object o)
        returns true if both sets have the same bits set
        Overrides:
        equals in class Object