public class RemappingDocumentIterator extends Object implements DocumentIterator
Sometimes it is necessary to combine with positional operators
ConsecutiveDocumentIterator) intervals from different indices.
By wrapping with an instance of this class a
DocumentIterator, the requests
for intervals will be remapped following a map given at construction time.
This class distinguishes between internal indices, which are those actually
provided by the underlying
DocumentIterator, and external indices, which
are those exposed by
indices(), and with which
should be called.
The map provided at construction time should remap external indices to internal
indices (note the inversion w.r.t.
In many cases, a singleton map
will be appropriate.
|Constructor and Description|
Creates a new remapping document iterator wrapping a given document iterator and remapping interval-iterator requests through a given mapping from external to internal indices.
|Modifier and Type||Method and Description|
Accepts a visitor.
Accepts a visitor after a call to
Disposes this document iterator, releasing all resources.
Returns the last document returned by
Returns the set of indices over which this iterator is built.
Returns the interval iterator of this document iterator for single-index queries.
Returns the interval iterator of this document iterator for the given index.
Returns an unmodifiable map from indices to interval iterators.
Returns whether there may be a next document, possibly with false positives.
Returns the next document provided by this document iterator, or
Skips all documents smaller than
Returns the weight associated with this iterator.
Sets the weight of this index iterator.
public RemappingDocumentIterator(DocumentIterator documentIterator, Reference2ReferenceMap<? extends Index,? extends Index> indexInverseRemapping)
documentIterator- the underlying document iterator.
indexInverseRemapping- the mapping from external to internal indices.
public long document()
public ReferenceSet<Index> indices()
public IntervalIterator intervalIterator(Index index) throws IOException
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
Thus, in presence of indices without positions it is possible that no
intervals at all are available.
public IntervalIterator intervalIterator() throws IOException
This is a commodity method that can be used only for queries built over a single index.
public Reference2ReferenceMap<Index,IntervalIterator> intervalIterators() throws IOException
After a call to
DocumentIterator.nextDocument(), this map
can be used to retrieve the intervals in the current document. An invocation of
on this map with argument
index yields the same result as
public long nextDocument() throws IOException
DocumentIterator.END_OF_LISTif no more documents are available.
public boolean mayHaveNext()
public long skipTo(long n) throws IOException
Define the current document
k associated with this document iterator
DocumentIterator.nextDocument()and this method have never been called;
DocumentIterator.END_OF_LIST, if a call to this method or to
DocumentIterator.nextDocument()or this method, otherwise.
k is larger than or equal to
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
is returned, the state of this iterator
will be exactly the same as after a call to
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
public void dispose() throws IOException
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.
public <T> T accept(DocumentIteratorVisitor<T> visitor) throws IOException
A document iterator is usually structured as composite,
with operators as internal nodes and
as leaves. This method implements the visitor pattern.
public <T> T acceptOnTruePaths(DocumentIteratorVisitor<T> visitor) throws IOException
DocumentIterator.nextDocument(), limiting recursion to true paths.
After a call to
DocumentIterator.nextDocument(), a document iterator
is positioned over a document. This call is equivalent to
but visits only along true paths.
We define a true path as a path from the root of the composite that passes only through
nodes whose associated subtree is positioned on the same document of the root. Note that
detach exhausted iterators from the composite tree, so true paths define the subtree that is causing
the current document to satisfy the query represented by this document iterator.
For more elaboration, and the main application of this method, see
public IntervalIterator iterator()
public double weight()
The number returned by this method has no fixed semantics: different scorers might choose different interpretations, or even ignore it.
public DocumentIterator weight(double weight)