Package org.apache.lucene.util

Class OpenBitSetIterator

java.lang.Object
org.apache.lucene.search.DocIdSetIterator
org.apache.lucene.util.OpenBitSetIterator
public class OpenBitSetIterator extends DocIdSetIterator
An iterator to iterate over set bits in an OpenBitSet. This is faster than nextSetBit() for iterating over the complete set of bits, especially when the density of the bits set is high.

  • Field Summary

    Fields inherited from class org.apache.lucene.search.DocIdSetIterator

    NO_MORE_DOCS

  • Constructor Summary

    Constructors
    Constructor
    Description
    OpenBitSetIterator(long[] bits, int numWords)
     
    OpenBitSetIterator(OpenBitSet obs)
     

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    advance(int target)
    Advances to the first beyond the current whose document number is greater than or equal to target, and returns the document number itself.
    long
    cost()
    Returns the estimated cost of this DocIdSetIterator.
    int
    docID()
    Returns the following: -1 or DocIdSetIterator.NO_MORE_DOCS if DocIdSetIterator.nextDoc() or DocIdSetIterator.advance(int) were not called yet.
    int
    nextDoc()
    alternate shift implementations // 32 bit shifts, but a long shift needed at the end private void shift2() { int y = (int)word; if (y==0) {wordShift +=32; y = (int)(word >>>32); } if ((y invalid input: '&' 0x0000FFFF) == 0) { wordShift +=16; y>>>=16; } if ((y invalid input: '&' 0x000000FF) == 0) { wordShift +=8; y>>>=8; } indexArray = bitlist[y invalid input: '&' 0xff]; word >>>= (wordShift +1); } private void shift3() { int lower = (int)word; int lowByte = lower invalid input: '&' 0xff; if (lowByte != 0) { indexArray=bitlist[lowByte]; return; } shift(); }

    Methods inherited from class org.apache.lucene.search.DocIdSetIterator

    empty

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • OpenBitSetIterator

      public OpenBitSetIterator(OpenBitSet obs)

    • OpenBitSetIterator

      public OpenBitSetIterator(long[] bits, int numWords)

  • Method Details

    • nextDoc

      public int nextDoc()
      alternate shift implementations // 32 bit shifts, but a long shift needed at the end private void shift2() { int y = (int)word; if (y==0) {wordShift +=32; y = (int)(word >>>32); } if ((y invalid input: '&' 0x0000FFFF) == 0) { wordShift +=16; y>>>=16; } if ((y invalid input: '&' 0x000000FF) == 0) { wordShift +=8; y>>>=8; } indexArray = bitlist[y invalid input: '&' 0xff]; word >>>= (wordShift +1); } private void shift3() { int lower = (int)word; int lowByte = lower invalid input: '&' 0xff; if (lowByte != 0) { indexArray=bitlist[lowByte]; return; } shift(); }
      Specified by:
      nextDoc in class DocIdSetIterator

    • advance

      public int advance(int target)
      Description copied from class: DocIdSetIterator
      Advances to the first beyond the current whose document number is greater than or equal to target, and returns the document number itself. Exhausts the iterator and returns DocIdSetIterator.NO_MORE_DOCS if target is greater than the highest document number in the set.

      The behavior of this method is undefined when called with target ≤ current, or after the iterator has exhausted. Both cases may result in unpredicted behavior.

      When target > current it behaves as if written: 

       int advance(int target) {
   int doc;
   while ((doc = nextDoc()) < target) {
   }
   return doc;
 }
      Some implementations are considerably more efficient than that.

      NOTE: this method may be called with DocIdSetIterator.NO_MORE_DOCS for efficiency by some Scorers. If your implementation cannot efficiently determine that it should exhaust, it is recommended that you check for that value in each call to this method.

      Specified by:
      advance in class DocIdSetIterator

    • docID

      public int docID()
      Description copied from class: DocIdSetIterator
      Returns the following:

      Specified by:
      docID in class DocIdSetIterator

    • cost

      public long cost()
      Description copied from class: DocIdSetIterator
      Returns the estimated cost of this DocIdSetIterator.

      This is generally an upper bound of the number of documents this iterator might match, but may be a rough heuristic, hardcoded value, or otherwise completely inaccurate.

      Specified by:
      cost in class DocIdSetIterator