Package org.apache.lucene.util
Class OpenBitSetIterator
- java.lang.Object
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- org.apache.lucene.search.DocIdSetIterator
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- org.apache.lucene.util.OpenBitSetIterator
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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.
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Field Summary
Fields Modifier and Type Field Description protected static int[]
bitlist
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Fields inherited from class org.apache.lucene.search.DocIdSetIterator
NO_MORE_DOCS
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Constructor Summary
Constructors Constructor Description OpenBitSetIterator(long[] bits, int numWords)
OpenBitSetIterator(OpenBitSet obs)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
advance(int target)
Advances to the first beyond (see NOTE below) the current whose document number is greater than or equal to target.int
docID()
Returns the following: -1 orDocIdSetIterator.NO_MORE_DOCS
ifDocIdSetIterator.nextDoc()
orDocIdSetIterator.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 & 0x0000FFFF) == 0) { wordShift +=16; y>>>=16; } if ((y & 0x000000FF) == 0) { wordShift +=8; y>>>=8; } indexArray = bitlist[y & 0xff]; word >>>= (wordShift +1); } private void shift3() { int lower = (int)word; int lowByte = lower & 0xff; if (lowByte != 0) { indexArray=bitlist[lowByte]; return; } shift(); }
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Constructor Detail
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OpenBitSetIterator
public OpenBitSetIterator(OpenBitSet obs)
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OpenBitSetIterator
public OpenBitSetIterator(long[] bits, int numWords)
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Method Detail
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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 & 0x0000FFFF) == 0) { wordShift +=16; y>>>=16; } if ((y & 0x000000FF) == 0) { wordShift +=8; y>>>=8; } indexArray = bitlist[y & 0xff]; word >>>= (wordShift +1); } private void shift3() { int lower = (int)word; int lowByte = lower & 0xff; if (lowByte != 0) { indexArray=bitlist[lowByte]; return; } shift(); }- Specified by:
nextDoc
in classDocIdSetIterator
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advance
public int advance(int target)
Description copied from class:DocIdSetIterator
Advances to the first beyond (see NOTE below) the current whose document number is greater than or equal to target. Returns the current document number orDocIdSetIterator.NO_MORE_DOCS
if there are no more docs in the set.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: when
target ≤ current
implementations may opt not to advance beyond their currentDocIdSetIterator.docID()
.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.NOTE: after the iterator has exhausted you should not call this method, as it may result in unpredicted behavior.
- Specified by:
advance
in classDocIdSetIterator
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docID
public int docID()
Description copied from class:DocIdSetIterator
Returns the following:- -1 or
DocIdSetIterator.NO_MORE_DOCS
ifDocIdSetIterator.nextDoc()
orDocIdSetIterator.advance(int)
were not called yet. DocIdSetIterator.NO_MORE_DOCS
if the iterator has exhausted.- Otherwise it should return the doc ID it is currently on.
- Specified by:
docID
in classDocIdSetIterator
- -1 or
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