java.lang.Object
- it.unimi.di.big.mg4j.index.AbstractIndexIterator
- - it.unimi.di.big.mg4j.index.BitStreamIndexReader.BitStreamIndexReaderIndexIterator

All Implemented Interfaces:: IndexIterator, DocumentIterator

Enclosing class:: BitStreamIndexReader

protected static final class BitStreamIndexReader.BitStreamIndexReaderIndexIterator
extends AbstractIndexIterator
implements IndexIterator

Field Summary

Fields
Modifier and Type	Field	Description
`protected int`	`b`	The parameter `b` for Golomb coding of pointers.
`protected int`	`count`	The current count (if this index contains counts).
`protected CompressionFlags.Coding`	`countCoding`	The cached copy of `index.countCoding`.
`protected long`	`currentDocument`	The last document pointer we read from current list, -1 if we just read the frequency, `DocumentIterator.END_OF_LIST` if we are beyond the end of list.
`protected int`	`currentPosition`	The index of the next position to be returned by `nextPosition()`.
`protected long`	`currentTerm`	The current term.
`protected long`	`frequency`	The current frequency.
`protected boolean`	`hasCounts`	The cached copy of `index.hasCounts`.
`protected boolean`	`hasPayloads`	The cached copy of `index.hasPayloads`.
`protected boolean`	`hasPointers`	Whether the current terms has pointers at all (this happens when the `frequency` is smaller than the number of documents).
`protected boolean`	`hasPositions`	The cached copy of `index.hasPositions`.
`protected boolean`	`hasSkips`	Whether the underlying index has skips.
`int`	`height`	The parameter `h` (the maximum height of a skip tower).
`protected InputBitStream`	`ibs`	The underlying input bit stream.
`protected BitStreamIndex`	`index`	The reference index.
`protected int`	`log2b`	The parameter `log2b` for Golomb coding of pointers; it is the most significant bit of `b`.
`protected long`	`numberOfDocumentRecord`	The number of the document record we are going to read inside the current inverted list.
`protected Payload`	`payload`	The payload, in case the index of this reader has payloads, or `null`.
`protected CompressionFlags.Coding`	`pointerCoding`	The cached copy of `index.pointerCoding`.
`protected int[]`	`positionCache`	The cached position array.
`protected CompressionFlags.Coding`	`positionCoding`	The cached copy of `index.positionCoding`.
`long`	`quantum`	The quantum.
`int`	`quantumDivisionShift`	The shift giving result of the division by `quantum`.
`long`	`quantumModuloMask`	The bit mask giving the remainder of the division by `quantum`.
`protected int`	`state`	This variable tracks the current state of the reader.

Fields inherited from class it.unimi.di.big.mg4j.index.AbstractIndexIterator
id, term, weight

Fields inherited from interface it.unimi.di.big.mg4j.search.DocumentIterator
END_OF_LIST

Fields inherited from interface it.unimi.di.big.mg4j.index.IndexIterator
END_OF_POSITIONS

Constructor Summary

Constructors
Constructor Description

BitStreamIndexReaderIndexIterator(BitStreamIndexReader parent, InputBitStream ibs)

Method Summary

Modifier and Type	Method	Description
`protected IndexIterator`	`advance()`
`int`	`count()`	Returns the count, that is, the number of occurrences of the term in the current document.
`void`	`dispose()`	Disposes this document iterator, releasing all resources.
`long`	`document()`	Returns the last document returned by `DocumentIterator.nextDocument()`.
`long`	`frequency()`	Returns the frequency, that is, the number of documents that will be returned by this iterator.
`Index`	`index()`	Returns the index over which this iterator is built.
`ReferenceSet<Index>`	`indices()`	Returns the set of indices over which this iterator is built.
`IntervalIterator`	`intervalIterator()`	Returns the interval iterator of this document iterator for single-index queries.
`IntervalIterator`	`intervalIterator(Index index)`	Returns the interval iterator of this document iterator for the given index.
`Reference2ReferenceMap<Index,IntervalIterator>`	`intervalIterators()`	Returns an unmodifiable map from indices to interval iterators.
`boolean`	`mayHaveNext()`	Returns whether there may be a next document, possibly with false positives.
`long`	`nextDocument()`	Returns the next document provided by this document iterator, or `DocumentIterator.END_OF_LIST` if no more documents are available.
`int`	`nextPosition()`	Returns the next position at which the term appears in the current document.
`Payload`	`payload()`	Returns the payload, if any, associated with the current document.
`protected void`	`position(long term)`	Positions the index on the inverted list of a given term.
`long`	`skipTo(long p)`	Skips all documents smaller than `n`.
`long`	`termNumber()`	Returns the number of the term whose inverted list is returned by this index iterator.
`String`	`toString()`
`protected void`	`updatePositionCache()`	We read positions, assuming state <= BEFORE_POSITIONS

Methods inherited from class it.unimi.di.big.mg4j.index.AbstractIndexIterator
accept, acceptOnTruePaths, id, id, term, term, weight, weight

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface it.unimi.di.big.mg4j.search.DocumentIterator
accept, acceptOnTruePaths, weight

Methods inherited from interface it.unimi.di.big.mg4j.index.IndexIterator
id, id, term, term, weight

- Field Detail
  - index
```
protected final BitStreamIndex index
```
    The reference index.
  - ibs
```
protected final InputBitStream ibs
```
    The underlying input bit stream.
  - hasPositions
```
protected final boolean hasPositions
```
    The cached copy of index.hasPositions.
  - hasCounts
```
protected final boolean hasCounts
```
    The cached copy of index.hasCounts.
  - hasPayloads
```
protected final boolean hasPayloads
```
    The cached copy of index.hasPayloads.
  - hasSkips
```
protected final boolean hasSkips
```
    Whether the underlying index has skips.
  - pointerCoding
```
protected final CompressionFlags.Coding pointerCoding
```
    The cached copy of index.pointerCoding.
  - countCoding
```
protected final CompressionFlags.Coding countCoding
```
    The cached copy of index.countCoding.
  - positionCoding
```
protected final CompressionFlags.Coding positionCoding
```
    The cached copy of index.positionCoding.
  - payload
```
protected final Payload payload
```
    The payload, in case the index of this reader has payloads, or null.
  - b
```
protected int b
```
    The parameter b for Golomb coding of pointers.
  - log2b
```
protected int log2b
```
    The parameter log2b for Golomb coding of pointers; it is the most significant bit of b.
  - currentTerm
```
protected long currentTerm
```
    The current term.
  - frequency
```
protected long frequency
```
    The current frequency.
  - hasPointers
```
protected boolean hasPointers
```
    Whether the current terms has pointers at all (this happens when the frequency is smaller than the number of documents).
  - count
```
protected int count
```
    The current count (if this index contains counts).
  - currentDocument
```
protected long currentDocument
```
    The last document pointer we read from current list, -1 if we just read the frequency, DocumentIterator.END_OF_LIST if we are beyond the end of list.
  - numberOfDocumentRecord
```
protected long numberOfDocumentRecord
```
    The number of the document record we are going to read inside the current inverted list.
  - state
```
protected int state
```
    This variable tracks the current state of the reader.
  - height
```
public final int height
```
    The parameter h (the maximum height of a skip tower).
  - quantum
```
public long quantum
```
    The quantum.
  - quantumModuloMask
```
public long quantumModuloMask
```
    The bit mask giving the remainder of the division by quantum.
  - quantumDivisionShift
```
public int quantumDivisionShift
```
    The shift giving result of the division by quantum.
  - currentPosition
```
protected int currentPosition
```
    The index of the next position to be returned by nextPosition().
  - positionCache
```
protected int[] positionCache
```
    The cached position array.
- Constructor Detail
  - BitStreamIndexReaderIndexIterator
```
public BitStreamIndexReaderIndexIterator(BitStreamIndexReader parent,
                                         InputBitStream ibs)
```
- Method Detail
  - position
```
protected void position(long term)
                 throws IOException
```
    Positions the index on the inverted list of a given term.
    This method can be called at any time. Note that it is always possible to call this method with argument 0, even if offsets have not been loaded.
    
    Parameters:
    
    term - a term.
    
    Throws:
    
    IOException
  - termNumber
```
public long termNumber()
```
    Description copied from interface: IndexIterator
    
    Returns the number of the term whose inverted list is returned by this index iterator.
    Usually, the term number is automatically set by IndexReader.documents(CharSequence) or IndexReader.documents(long).
    
    Specified by:
    
    termNumber in interface IndexIterator
    
    Returns:
    
    the number of the term over which this iterator is built.
    
    See Also:
    
    IndexIterator.term()
  - advance
```
protected IndexIterator advance()
                         throws IOException
```
    Throws:
    
    IOException
  - index
```
public Index index()
```
    Description copied from interface: IndexIterator
    
    Returns the index over which this iterator is built.
    
    Specified by:
    
    index in interface IndexIterator
    
    Returns:
    
    the index over which this iterator is built.
  - frequency
```
public long frequency()
```
    Description copied from interface: IndexIterator
    
    Returns the frequency, that is, the number of documents that will be returned by this iterator.
    
    Specified by:
    
    frequency in interface IndexIterator
    
    Returns:
    
    the number of documents that will be returned by this iterator.
  - document
```
public long document()
```
    Description copied from interface: DocumentIterator
    
    Returns the last document returned by DocumentIterator.nextDocument().
    
    Specified by:
    
    document in interface DocumentIterator
    
    Returns:
    
    the last document returned by DocumentIterator.nextDocument(), -1 if no document has been returned yet, and DocumentIterator.END_OF_LIST if the list of results has been exhausted.
  - payload
```
public Payload payload()
                throws IOException
```
    Description copied from interface: IndexIterator
    
    Returns the payload, if any, associated with the current document.
    
    Specified by:
    
    payload in interface IndexIterator
    
    Returns:
    
    the payload associated with the current document.
    
    Throws:
    
    IOException
  - count
```
public int count()
          throws IOException
```
    Description copied from interface: IndexIterator
    
    Returns the count, that is, the number of occurrences of the term in the current document.
    
    Specified by:
    
    count in interface IndexIterator
    
    Returns:
    
    the count (number of occurrences) of the term in the current document.
    
    Throws:
    
    IOException
  - updatePositionCache
```
protected void updatePositionCache()
                            throws IOException
```
    We read positions, assuming state <= BEFORE_POSITIONS
    
    Throws:
    
    IOException
  - nextPosition
```
public int nextPosition()
                 throws IOException
```
    Description copied from interface: IndexIterator
    
    Returns the next position at which the term appears in the current document.
    
    Specified by:
    
    nextPosition in interface IndexIterator
    
    Returns:
    
    the next position of the current document in which the current term appears, or IndexIterator.END_OF_POSITIONS if there are no more positions.
    
    Throws:
    
    IOException
  - nextDocument
```
public long nextDocument()
                  throws IOException
```
    Description copied from interface: DocumentIterator
    
    Returns the next document provided by this document iterator, or DocumentIterator.END_OF_LIST if no more documents are available.
    
    Specified by:
    
    nextDocument in interface DocumentIterator
    
    Returns:
    
    the next document, or DocumentIterator.END_OF_LIST if no more documents are available.
    
    Throws:
    
    IOException
  - skipTo
```
public long skipTo(long p)
            throws IOException
```
    Description copied from interface: DocumentIterator
    Skips all documents smaller than n.
    Define the current document k associated with this document iterator as follows:
    
    -1, if DocumentIterator.nextDocument() and this method have never been called;
    DocumentIterator.END_OF_LIST, if a call to this method or to DocumentIterator.nextDocument() returned DocumentIterator.END_OF_LIST;
    the last value returned by a call to DocumentIterator.nextDocument() or this method, otherwise.
    
    If k is larger than or equal to n, then this method does nothing and returns k. Otherwise, a call to this method is equivalent to
    while( ( k = nextDocument() ) < n ); return k;
    
    Thus, when a result k ≠ DocumentIterator.END_OF_LIST is returned, the state of this iterator will be exactly the same as after a call to DocumentIterator.nextDocument() that returned k. In particular, the first document larger than or equal to n (when returned by this method) will not be returned by the next call to DocumentIterator.nextDocument().
    Specified by:
    
    skipTo in interface DocumentIterator
    
    Parameters:
    
    p - a document pointer.
    
    Returns:
    
    a document pointer larger than or equal to n if available, DocumentIterator.END_OF_LIST otherwise.
    
    Throws:
    
    IOException
  - dispose
```
public void dispose()
             throws IOException
```
    Description copied from interface: DocumentIterator
    
    Disposes this document iterator, releasing all resources.
    This method should propagate down to the underlying index iterators, where it should release resources such as open files and network connections. If you're doing your own resource tracking and pooling, then you do not need to call this method.
    
    Specified by:
    
    dispose in interface DocumentIterator
    
    Throws:
    
    IOException
  - mayHaveNext
```
public boolean mayHaveNext()
```
    Description copied from interface: DocumentIterator
    
    Returns whether there may be a next document, possibly with false positives.
    
    Specified by:
    
    mayHaveNext in interface DocumentIterator
    
    Returns:
    
    true there may be a next document; false if certainly there is no next document.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - intervalIterators
```
public Reference2ReferenceMap<Index,IntervalIterator> intervalIterators()
                                                                       throws IOException
```
    Description copied from interface: DocumentIterator
    
    Returns an unmodifiable map from indices to interval iterators.
    After a call to DocumentIterator.nextDocument(), this map can be used to retrieve the intervals in the current document. An invocation of Map.get(java.lang.Object) on this map with argument index yields the same result as intervalIterator(index).
    
    Specified by:
    
    intervalIterators in interface DocumentIterator
    
    Returns:
    
    a map from indices to interval iterators over the current document.
    
    Throws:
    
    IOException
    
    See Also:
    
    DocumentIterator.intervalIterator(Index)
  - intervalIterator
```
public IntervalIterator intervalIterator()
                                  throws IOException
```
    Description copied from interface: DocumentIterator
    
    Returns the interval iterator of this document iterator for single-index queries.
    This is a commodity method that can be used only for queries built over a single index.
    
    Specified by:
    
    intervalIterator in interface DocumentIterator
    
    Returns:
    
    an interval iterator.
    
    Throws:
    
    IOException
    
    See Also:
    
    DocumentIterator.intervalIterator(Index)
  - intervalIterator
```
public IntervalIterator intervalIterator(Index index)
                                  throws IOException
```
    Description copied from interface: DocumentIterator
    
    Returns the interval iterator of this document iterator for the given index.
    After a call to DocumentIterator.nextDocument(), this iterator can be used to retrieve the intervals in the current document (the one returned by DocumentIterator.nextDocument()) for the index index.
    Note that if all indices have positions, it is guaranteed that at least one index will return an interval. However, for disjunctive queries it cannot be guaranteed that all indices will return an interval.
    Indices without positions always return IntervalIterators.TRUE. Thus, in presence of indices without positions it is possible that no intervals at all are available.
    
    Specified by:
    
    intervalIterator in interface DocumentIterator
    
    Parameters:
    
    index - an index (must be one over which the query was built).
    
    Returns:
    
    an interval iterator over the current document in index.
    
    Throws:
    
    IOException
  - indices
```
public ReferenceSet<Index> indices()
```
    Description copied from interface: DocumentIterator
    
    Returns the set of indices over which this iterator is built.
    
    Specified by:
    
    indices in interface DocumentIterator
    
    Returns:
    
    the set of indices over which this iterator is built.

Class BitStreamIndexReader.BitStreamIndexReaderIndexIterator

Field Summary

Fields inherited from class it.unimi.di.big.mg4j.index.AbstractIndexIterator

Fields inherited from interface it.unimi.di.big.mg4j.search.DocumentIterator

Fields inherited from interface it.unimi.di.big.mg4j.index.IndexIterator

Constructor Summary

Method Summary

Methods inherited from class it.unimi.di.big.mg4j.index.AbstractIndexIterator

Methods inherited from class java.lang.Object

Methods inherited from interface it.unimi.di.big.mg4j.search.DocumentIterator

Methods inherited from interface it.unimi.di.big.mg4j.index.IndexIterator

Field Detail

index

ibs

hasPositions

hasCounts

hasPayloads

hasSkips

pointerCoding

countCoding

positionCoding

payload

b

log2b

currentTerm

frequency

hasPointers

count

currentDocument

numberOfDocumentRecord

state

height

quantum

quantumModuloMask

quantumDivisionShift

currentPosition

positionCache

Constructor Detail

BitStreamIndexReaderIndexIterator

Method Detail

position

termNumber

advance

index

frequency

document

payload

count

updatePositionCache

nextPosition

nextDocument

skipTo

dispose

mayHaveNext

toString

intervalIterators

intervalIterator

intervalIterator

indices